Article

Peak power output predicts maximal oxygen uptake and performance time

January 1992
European Journal of Applied Physiology and Occupational Physiology 65(1):79-83

Authors:

Australian Catholic University

The purposes of this study were firstly to determine the relationship between the peak power output (W peak) and maximal oxygen uptake (VO2max) attained during a laboratory cycling test to exhaustion, and secondly to assess the relationship betweenW peak and times in a 20-km cycling trial. One hundred trained cyclists (54 men, 46 women) participated in the first part of this investigation. Each cyclist performed a minimum of one maximal test during whichW max andVO2max were determined. For the second part of the study 19 cyclists completed a maximal test for the determination ofW peak, and also a 20-km cycling time trial. Highly significant relationships were obtained betweenW peak andVO2max (r=0.97,P<0.0001) and betweenW peak and 20-km cycle time (r= –0.91,P<0.001). Thus,W peak explained 94% of the variance in measuredVO2max and 82% of the variability in cycle time over 20 km. We concluded that for trained cyclists, theVO2max can be accurately predicted fromW peak, and thatW peak is a valid predictor of 20-km cycle time.

Development of Cycling Performance-Variables and Durability in Female and Male National Team Cyclists: From Junior to Senior

Article

Full-text available

Jun 2023
MED SCI SPORT EXER

Aim: This study investigated the development of power profiles and performance-related measures from the junior level (<19 years) via U23 (19-23 years) to senior level (>23 years) in 19 female and 100 male Norwegian national team cyclists. Methods: A total of 285 tests were performed in a 3-day laboratory-standardized testing regime. The tests included power profiles with shorter duration (6-60 s) and longer durations (12-30 min) together with performance-related measures: Critical power (CP), work capacity above CP (W'), power output at 4 and 2 mmol·L-1 [BLa-] (L4 and L2), maximal aerobic power (Wmax), and maximal oxygen uptake (VO2max), gross efficiency (GE), and pedalling efficiency. Results: Females and males evolve similarly when maturing from junior via U23 to senior categories (all p > 0.07), except for VO2max which increased in females (but not males) from junior to senior level (534 ± 436 ml·min-1, p = 0.013). In general, only performances of longer durations improved with age (12-min and 30-min, p = 0.028, and p = 0.042, respectively). Performance-related measures like Wmax, VO2max, CP, L4, L2, and pedalling efficiency in the fresh state improved with age (all p ≤ 0.025). Importantly, performance in the semi-fatigued state during a 5-min maximal test, was also improved with age (p = 0.045) despite a higher external energy expenditure prior to the test (p = 0.026). Conclusions: Junior cyclists show highly developed sprint-abilities, and the primary improvements of absolute power outputs and performance-related measures are seen for durations >60 s when maturing to U23 and senior categories. However, the durability, i.e., the capacity to maintain performance in a semi-fatigued state is improved with age.

Carbohydrate periodisation via a “sleep low – train low” model and the impact of environmental heat stress: a practical and metabolomic exploration

Thesis

Jun 2022

Samuel Bennett

Endurance athletes have traditionally been advised to consume high carbohydrate intake before, during and after exercise to support high training loads and facilitate recovery. Accumulating evidence suggests periodically training with low carbohydrate availability, termed “train-low”, augments skeletal oxidative adaptations. Comparably, to account for increased carbohydrate utilisation during exercise in hot environmental conditions, nutritional guidelines advocate high carbohydrate intake. Recent evidence suggests heat stress induces oxidative adaptation in skeletal muscle, augmenting mitochondrial adaptation during endurance training. This thesis aimed to assess the efficacy of training with reduced carbohydrate and the impact of elevated ambient temperatures on performance and metabolism. Chapter 4 demonstrated 3 weeks of Sleep Low-Train Low (SL-TL) improves performance when prescribed and completed remotely. Chapter 5 implemented SL-TL in hot and temperate conditions, confirming SL-TL improves performance and substrate metabolism, whilst additional heat stress failed to enhance performance in hot and temperate conditions following the intervention. Chapters 6 and 7 optimised and implemented a novel in vitro skeletal muscle exercise model combining electrical pulse stimulation and heat stress. Metabolomics analysis revealed an ‘exercise-induced metabolic response, with no direct metabolomic impact of heat stress. Chapter 8 characterised the systemic metabolomic response to acute exercise in the heat following SL-TL and heat stress intervention revealing distinct metabolic signatures associated with exercise under heat stress. In summary, this thesis provides data supporting the application of the SL-TL strategy during endurance training to augment adaptation. Data also highlights the impact of exercise, environmental temperature and substrate availability on skeletal muscle metabolism and the systemic metabolome. Together, these data provide practical support for the efficacy of the SL-TL strategy to improve performance and adaptation whilst casting doubt on the utility of this approach in hot environments in endurance-trained athletes.

Laboratory-based determinants of simulated time trial performance in cyclists

Article

Full-text available

Apr 2023

Different laboratory-based variables are individually associated with cycling performance, but scarce evidence exists on which of them, when all assessed in combination, could best explain cycling performance. The present study aimed to examine the combined association between laboratory-based endurance, strength/ power and body composition indicators with time trial performance iṅhigh-level cyclists. Ninety-four male cyclists were recruited (age: 20 ± 3.5 years, maximum oxygen uptake [VO2max]: 77.7 ± 5.4 ml · kg−1 · min−1). Participants performed a maximal incremental cycling test for the assessment of endurance indicators (peak power output [PPO], V̇ O2max, ventilatory threshold [VT] and respiratory compensation point [RCP]), and an incremental loading test to assess muscle strength and power-related outcomes (1-repetition maximum, mean maximal power) in the squat, lunge and hip-thrust exercises. Body composition was assessed by dual energy X-ray absorptiometry. On a separate visit, participants performed a simulated 8-minute time trial to assess cycling performance (determined as the mean power output attained). Strong-to-very-strong correlations were found between all endurance indicators and time trial performance (most r-values ranging between 0.68–0.92), whereas weaker correlations were found for strength/power (r-values < 0.5) or body composition (r-values < 0.7) indicators. Multivariate regression analyses revealed that VT, RCP and PPO explained together 92% of the variance in time trial performance (p < 0.001), with no significant contribution of the remaining variables. Although different endurance, strength/power and body composition individually correlate with simulated time trial performance in high-level cyclists, the former (and particularly VT, RCP and PPO) show the strongest association when all studied in combination. These findings underscore the importance of endurance capabilities (above strength/power or body composition) for maximizing time trial performance.

Estimated power output for a distance run and maximal oxygen uptake in young adults

Article

Full-text available

Feb 2023

Background: Both cardiopulmonary exercise testing (CPET) and run field tests are recommended by the American Heart Association for assessing the maximal oxygen uptake (VO2 max) of youth. Power output was highly correlated with VO2 max in CPET. However, it is unclear regarding the correlations of time and estimated power output (EPO) for a run field test with VO2 max obtained from CPET in young adults. Methods: This study included 45 participants, aged 20–40 years, from a sample of 1,120 military personnel who completed a 3,000-m run field test in Taiwan in 2020. The participants subsequently received CPET using the Bruce protocol to assess VO2 max in the same year. According to the physics rule, EPO (watts) for the run field test was defined as the product of half body mass (kg) and [distance (3000-m)/time (s) for a run field test]. Pearson product–moment correlation analyses were performed. Results: The Pearson correlation coefficient (r) of time against EPO for the run field test was estimated to be 0.708 (p <0.001). The correlation coefficient between the time for the run field test and VO2 max (L/min) in CPET was estimated to be 0.462 (p = 0.001). In contrast, the correlation coefficient between time for the run field test and VO2 max scaled to body mass in CPET was estimated to be 0.729 (p <0.001). The correlation coefficient of EPO for the run field test against VO2 max in CPET was estimated to be 0.813 (p <0.001). Conclusion: In young adults, although the time for a run field test was a reliable estimate of VO2 max scaled to body mass, EPO proportional to the mean square velocity was found as a superior estimate of VO2 max.

Effects of Quercetin and Citrulline on Nitric Oxide Metabolites and Antioxidant Biomarkers in Trained Cyclists

Article

Full-text available

Jan 2025

Background: Quercetin (QCT) and citrulline (CIT) have been independently associated with improved antioxidant capacity and nitric oxide (NO) production, potentially enhancing cardiovascular function and exercise performance. This study aimed to evaluate the combined and independent effects of QCT and CIT supplementation on NO metabolites and antioxidant biomarkers in 50 trained cyclists undergoing a 20 km cycling time trial (TT). Methods: In a randomized, double-blind, placebo-controlled design, forty-two male and eight female trained cyclists were assigned to QCT + CIT, QCT, CIT, or placebo (PL) groups. Supplements were consumed twice daily for 28 days. Biochemical assessments included NO metabolites (nitrate/nitrite), ferric reducing antioxidant power (FRAP), superoxide dismutase (SOD) activity, and antioxidant capacity, measured pre- and post-TT. Results: NO metabolites were significantly elevated post-supplementation (p = 0.03); however, no significant interaction effects were observed for NO metabolites, FRAP, SOD, or antioxidant capacity across the groups (p > 0.05). Post-hoc analyses revealed that QCT significantly reduced FRAP concentrations compared to PL (p = 0.01), while no significant changes in SOD or antioxidant capacity were found across any groups. Conclusions: These findings suggest that combined and independent QCT and CIT supplementation did not significantly improve these biomarkers, suggesting that baseline training adaptations, supplementation timing, and individual variability may influence the efficacy of these compounds in enhancing exercise performance and oxidative stress markers. The ergogenic efficacy of QCT + CIT on antioxidant-related markers remains inconclusive.

Modelo preditivo do desempenho de ciclistas durante competição de rua simulada

Article

Full-text available

Dec 2024

Variáveis fisiológicas obtidas em testes do tipo abertos ou fechados são sugeridas para predizer o desempenho atlético em ciclistas. Contudo, não se sabe quais destas variáveis conseguiriam explicar melhor o desempenho no ciclismo. Este estudo analisou quais variáveis poderiam predizer o desempenho em um simulado de ciclismo (63,5km). Ciclistas (n=15) foram submetidos a diferentes testes para a obtenção das seguintes variáveis: VO2MAX, WPICO, LAn e o TLIM. Em adição, testes fechados de 20 km (TT20km) e 5 km (TT5km), foram realizados. Significantes correlações foram observadas entre o desempenho no simulado de ciclismo e a WPICO (r= -0,83; p= 0,00), o TT20km (r= 0,71; p= 0,00), e a WLAn (r= -0,63; p= 0,01). Modelos regressivos simples e múltiplos Stepwise apresentaram a WPICO e o TT20km como as variáveis a prover as melhores estimativas, com menor erro padrão de estimativa (< 3 minutos). Contudo, a WPICO foi a única variável a entrar no modelo regressivo múltiplo, explicando 68% da variância do tempo. Apesar do apelo teórico apontando maior validade ecológica nos testes fechados, foi uma variável derivada do teste aberto, a WPICO, a melhor explicar o rendimento na competição simulada.

The effect of quercetin and citrulline on cycling time trial performance

Article

Oct 2024
Sports Nutr Rev J

Background: There is growing interest in the use of nutrition and dietary supplements to optimize training and time-trial (TT) performance in cyclists. Separately, quercetin (QCT) and citrulline (CIT) have been used as ergogenic aids to improve oxygen (VO2) kinetics, perceived effort, and cycling TT performance. However, whether the combination of QCT and CIT can provide additive benefits and further enhance cycling performance production is currently unknown. Methods: We examined 28-days of QCT + CIT supplementation on TT performance and several performance measures (i.e. mean power, VO2, respiratory exchange ratio (RER), and rate of perceived exertion (RPE)). Forty-eight highly trained cyclists were assigned to one of four supplementation groups: (1) QCT + CIT (QCT: 500 mg, CIT: 3000 g), (2) QCT (500 mg), (3) CIT (3000 mg), or (4) placebo (3500 mg of a zero-calorie flavored crystal light package). Supplements were consumed two times per day for 28 consecutive days. Participants performed a 20-km cycling time-trial race, pre- and post-supplementation to determine the impact of the combined effects of QCT + CIT. Results: There were no potential benefits of QCT +CIT supplementation on TT performance and several performance measures. However, there was an improvement in VO2 from pre-to-post-supplementation in QCT (p = 0.05) and CIT (p = 0.04) groups, but not in the QCT+CIT and PL groups. Conclusions: QCT + CIT does not seem beneficial for 20-km TT performance; further exploration with a focus on an increase in cycling duration or QCT+CIT combined with additional polyphenols may amplify any perceived bioactive or metabolic effects on cycling performance. The efficacy of QCT + CIT supplementation to improve cycling performance remains ambiguous.

A computational predictor of the anaerobic mechanical power outputs from a clinical exercise stress test

Article

Full-text available

May 2023
PLOS ONE

We previously were able to predict the anaerobic mechanical power outputs using features taken from a maximal incremental cardiopulmonary exercise stress test (CPET). Since a standard aerobic exercise stress test (with electrocardiogram and blood pressure measurements) has no gas exchange measurement and is more popular than CPET, our goal, in the current paper, was to investigate whether features taken from a clinical exercise stress test (GXT), either submaximal or maximal, can predict the anaerobic mechanical power outputs to the same level as we found with CPET variables. We have used data taken from young healthy subjects undergoing CPET aerobic test and the Wingate anaerobic test, and developed a computational predictive algorithm, based on greedy heuristic multiple linear regression, which enabled the prediction of the anaerobic mechanical power outputs from a corresponding GXT measures (exercise test time, treadmill speed and slope). We found that for submaximal GXT of 85% age predicted HRmax, a combination of 3 and 4 variables produced a correlation of r = 0.93 and r = 0.92 with % error equal to 15 ± 3 and 16 ± 3 on the validation set between real and predicted values of the peak and mean anaerobic mechanical power outputs (p < 0.001), respectively. For maximal GXT (100% of age predicted HRmax), a combination of 4 and 2 variables produced a correlation of r = 0.92 and r = 0.94 with % error equal to 12 ± 2 and 14 ± 3 on the validation set between real and predicted values of the peak and mean anaerobic mechanical power outputs (p < 0.001), respectively. The newly developed model allows to accurately predict the anaerobic mechanical power outputs from a standard, submaximal and maximal GXT. Nevertheless, in the current study the subjects were healthy, normal individuals and therefore the assessment of additional subjects is desirable for the development of a test applicable to other populations.

The muscle proteome reflects changes in mitochondrial function, cellular stress and proteolysis after 14 days of unilateral lower limb immobilization in active young men

Article

Full-text available

Sep 2022
PLOS ONE

Skeletal muscle unloading due to joint immobilization induces muscle atrophy, which has primarily been attributed to reductions in protein synthesis in humans. However, no study has evaluated the skeletal muscle proteome response to limb immobilization using SWATH proteomic methods. This study characterized the shifts in individual muscle protein abundance and corresponding gene sets after 3 and 14 d of unilateral lower limb immobilization in otherwise healthy young men. Eighteen male participants (25.4 ±5.5 y, 81.2 ±11.6 kg) underwent 14 d of unilateral knee-brace immobilization with dietary provision and following four-weeks of training to standardise acute training history. Participant phenotype was characterized before and after 14 days of immobilization, and muscle biopsies were obtained from the vastus lateralis at baseline (pre-immobilization) and at 3 and 14 d of immobilization for analysis by SWATH-MS and subsequent gene-set enrichment analysis (GSEA). Immobilization reduced vastus group cross sectional area (-9.6 ±4.6%, P <0.0001), immobilized leg lean mass (-3.3 ±3.9%, P = 0.002), unilateral 3-repetition maximum leg press (-15.6 ±9.2%, P <0.0001), and maximal oxygen uptake (-2.9 ±5.2%, P = 0.044). SWATH analyses consistently identified 2281 proteins. Compared to baseline, two and 99 proteins were differentially expressed (FDR <0.05) after 3 and 14 d of immobilization, respectively. After 14 d of immobilization, 322 biological processes were different to baseline (FDR <0.05, P <0.001). Most (77%) biological processes were positively enriched and characterized by cellular stress, targeted proteolysis, and protein-DNA complex modifications. In contrast, mitochondrial organization and energy metabolism were negatively enriched processes. This study is the first to use data independent proteomics and GSEA to show that unilateral lower limb immobilization evokes mitochondrial dysfunction, cellular stress, and proteolysis. Through GSEA and network mapping, we identify 27 hub proteins as potential protein/gene candidates for further exploration.

Heat Acclimation with or without Normobaric Hypoxia Exposure Leads to Similar Improvements in Endurance Performance in the Heat

Article

Full-text available

Apr 2022

Background: Combining the key adaptation of plasma volume (PV) expansion with synergistic physiological effects of other acclimation interventions to maximise endurance performance in the heat has potential. The current study investigated the effects of heat acclimation alone (H), combined with normobaric hypoxia exposure (H+NH), on endurance athletic performance. Methods: Well-trained participants completed a heat-stress trial (30 °C, 80% relative humidity (RH), 20.8% fraction of inspired oxygen (FiO2)) of a 75 min steady-state cycling (fixed workload) and a subsequent 15 min cycling time trial for distance before and after intervention. Participants completed 12 consecutive indoor training days with either heat acclimation (H; 60 min·day⁻¹, 30 °C, 80% RH; 20.8% FiO2) or heat acclimation and overnight hypoxic environment (H+NH; ~12 h, 60% RH; 16% FiO2 simulating altitude of ~2500 m). Control (CON) group trained outdoors with average maximum daily temperature of 16.5 °C and 60% RH. Results: Both H and H+NH significantly improved time trial cycling distance by ~5.5% compared to CON, with no difference between environmental exposures. PV increased (+3.8%) and decreased (−4.1%) following H and H+NH, respectively, whereas haemoglobin concentration decreased (−2%) and increased (+3%) in H and H+NH, respectively. Conclusion: Our results show that despite contrasting physiological adaptations to different environmental acclimation protocols, heat acclimation with or without hypoxic exposure demonstrated similar improvements in short-duration exercise performance in a hot environment.

Cardiovascular and cerebral hemodynamics during static and dynamic breath-holding

Article

Full-text available

Mar 2025
EUR J APPL PHYSIOL

Purpose The study investigated the changes in cardiovascular and cerebral hemodynamics elicited by the diving response during static (SBH) and dynamic (DYNBH) breath-holding (BH) in moderately trained recreational breath-hold divers (BHDs). Methods Nineteen BHDs (42.9 ± 7.8 years, 5.7 ± 2.5 years of breath-hold practice) participated in the study. Cardiovascular and cerebral hemodynamics, along with muscle and pre-frontal cortex oxygenation, were continuously tracked throughout a single SBH and DYNBH by means of arterial volume clamp, transcranial Doppler ultrasound, and near-infrared spectroscopy. In addition, neuron-specific enolase (NSE) was measured pre- and post-BH to evaluate potential neuronal stress. Results At the end of BH, the manifestations of the diving response were similar in both conditions, characterized by a bradycardic response (SBH: − 14 ± 6%, p < 0.05; DYNBH: − 13 ± 18%, p < 0.05) and an increase in total peripheral resistance (SBH: + 127 ± 46%, p < 0.05; DYNBH: + 116 ± 110%, p < 0.05). Mean middle cerebral artery blood velocity increased significantly more during SBH (+ 139 ± 17%, p < 0.05) than DYNBH (+ 109 ± 23%, p < 0.05). Relative changes in pre-frontal cortex deoxygenated hemoglobin were higher during DYNBH compared to SBH (+ 350 ± 106% vs. + 128 ± 27%, p < 0.05). NSE levels did not change pre- and post- SBH and DYNBH. Conclusion Due to relatively attenuated increase in cerebral blood velocity, DYNBH resulted in a greater imbalance between oxygen supply and pre-frontal oxygen consumption than SBH. However, NSE levels remained unchanged from baseline values, suggesting that no acute neuronal damage occurred in either condition.

Do Power Meter Data Depend on the Device on Which They Are Collected? Comparison of Eleven Different Recordings

Article

Full-text available

Jan 2025
SENSORS-BASEL

This study evaluated the influence of cycle computers on the accuracy of power and cadence data. The research was divided into three phases: (1) a graded exercise test (GXT) at different constant loads to record power and cadence data; (2) a self-paced effort lasting 1 min to measure mean maximal power output (MMP); and (3) a short all-out effort. Eight cyclists completed the GXT, ten participated in the 1-min test, and thirty participated in the sprint effort. All participants pedaled on a controlled-resistance cycle ergometer, and the data were recorded using the ergometer itself and ten synchronized cycle computers of the same brand, configured to record at 1 Hz. The results showed minimal variations in power and cadence between devices during the GXT, suggesting adequate accuracy for constant efforts lasting a certain duration. However, in self-paced and high-intensity efforts (1-min and short all-out efforts), significant differences were observed between several devices, particularly in cadence and mean power, highlighting the relevance of device selection in these contexts. These findings suggest that, while variations in constant efforts may be negligible, in short-duration, high-intensity activities, the choice of device may be crucial for the accuracy and reliability of the data.

Greater Relative First and Second Lactate Thresholds in Females Compared With Males: Consideration for Exercise Prescription

Article

Oct 2024

Purpose : To investigate differences between females and males at lactate thresholds 1 (LT1) and 2 (LT2). Methods : Twenty-four female and twenty male participants performed an incremental cycle-ergometer test until exhaustion, where LT1 and LT2 were determined in each volunteer. Results : Power output at LT1 and LT2 was lower in females than in males ( P < .001). In addition, power output relative to peak power was higher in females at LT1 and LT2 ( P < .001). However, heart rate was higher in females than males at LT1 and LT2 ( P = .008). Furthermore, the heart rate relative to maximal heart rate was higher in females compared with males at LT1 and LT2 ( P = .002). Conclusion : Females and males may be in a different metabolic situation at the same percentage of maximum. This study helps to reduce sex bias in science, and future guidelines should consider establishing exercise prescription recommendations according to sex. Clinical Trial: NCT06104150.

A Bayesian Inference Comparing Collegiate Female Cyclists to Elite Female Cyclists from a Meta-Analysis

Article

Jan 2016

The effect of age on heart rate variability indices during and following high-intensity continuous exercise in masters and young cyclists

Article

Full-text available

Aug 2024
EUR J APPL PHYSIOL

This study compared heart rate variability (HRV) parameters of cardiovascular autonomic regulation between well-trained masters and young cyclists at rest, during and following a continuous cycle (CTS) protocol. Ten masters (age = 56 ± 5 years) and eight young (age = 26 ± 3 years) cyclists completed a 100 min experimental protocol consisting of a 60 min CTS cycling bout at 95% of Ventilatory Threshold 2 followed by 40 min of supine recovery. Beat-to-beat heart rate was measured continuously, and HRV parameters analysed at standardised 5 min intervals during rest, exercise and recovery. The root mean square of the successive differences (RMSSD), low-frequency power and high-frequency power parameters were corrected by division of the R-R interval (time domain), or R-R interval squared (frequency domain). Further, the RMSSD and RMSSD:RR for successive 60-s R-R intervals at the onset (0–10 min) and offset (60–70 min) of CTS exercise were analysed over 10-min periods. The natural logarithm (Ln) of skewed parameters was taken for analysis. Significant interaction effects (P < 0.05) for 5 min segments were found for (LnRMSSD, LnRMSSD:RR, LnHF and LnHF:RR². Masters cyclists demonstrated lower values of parasympathetic activity at rest and during recovery (15–20 min and 35–40 min) compared to younger cyclists. However, similar HRV responses were observed during exercise, including throughout the acute onset and offset periods (P > 0.05). This data shows that cardiac autonomic regulation during, or immediately following CTS exercise may not be influenced by age, but masters athletes may exhibit a lower baseline for parasympathetic activity.

HUBUNGAN DAYA LEDAK OTOT TUNGKAI DENGAN HASIL SMASH OPEN SPIKE PESERTA EKSTRAKURIKULER BOLA VOLI PUTRI DI SMAN 1 TANJUNGSARI TAHUN 2023/2024

Thesis

Full-text available

Jun 2024

Dodot Limar Ketangi

Penelitian ini bertujuan untuk mengetahui ada tidaknya hubungan daya ledak otot tungkai dengan hasil smash open spike pada peserta ekstrakurikuler bola voli putri di SMAN 1 Tanjungsari Tahun 2023/2024. Penelitian ini menggunakan desain penelitian kuantitatif dengan metode korelasional. Populasi dan sampel penelitian terdiri dari 15 siswi yang aktif mengikuti ekstrakurikuler bola voli putri. Daya ledak otot tungkai diukur menggunakan tes vertical jump, sedangkan hasil smash open spike diukur menggunakan battery test smash bola voli. Data yang terkumpul dianalisis menggunakan uji korelasi Pearson. Hasil penelitian ini menunjukkan bahwa terdapat hubungan yang signifikan daya ledak otot tungkai dengan hasil smash open spike bola voli, dapat diketahui bahwa nilai pearson correlation daya ledak otot tungkai dan hasil smash open spike adalah 0,809 maka keeratan hubungan antar variabel memiliki tingkat hubungan yang sangat kuat. Nilai signifikansi yang dihasilkan <0,01 atau lebih kecil dari 0,05. Hal ini menunjukkan bahwa daya ledak otot tungkai memiliki kontribusi yang positif dengan hasil smash open spike peserta ekstrakurikuler bola voli putri di SMAN 1 Tanjungsari. Keadaan ini menunjukkan bahwa semakin baik daya ledak otot tungkai maka semakin baik pula hasil smash open spike bola voli. Kata Kunci : Daya Ledak Otot Tungkai, Smash Open Spike, Permainan Bola Voli

Blood flow restriction Exercise in the perioperative setting to Prevent loss of muscle mass in patients with pancreatic, biliary tract, and liver cancer: study protocol for the PREV-Ex randomized controlled trial

Article

Full-text available

Jun 2024
TRIALS

Background Patients diagnosed with pancreatic, biliary tract, and liver cancer often suffer from a progressive loss of muscle mass. Given the considerable functional impairments in these patients, high musculoskeletal weight loads may not be well tolerated by all individuals. The use of blood-flow restricted resistance training (BFR-T) which only requires low training loads may allow for a faster recovery of muscle due to avoidance of high levels of mechanical muscle stress associated with high-load resistance exercise. This study aims to investigate whether BFR-T can prevent or slow down the loss of skeletal muscle mass and enhance the functional capacity and mental health of patients with pancreatic, biliary tract, and liver cancer. Methods The PREV-Ex exercise trial is a multicenter two-armed randomized controlled trial. Patients will be randomized to an exercise program consisting of home-based low-load BFR-T during a combined pre- and postoperative period for a total of 6–10 weeks (prehabilitation and rehabilitation), or to a control group. Protein supplementation will be given to both groups to ensure adequate protein intake. The primary outcomes, skeletal muscle thickness and muscle cross-sectional area, will be assessed by ultrasound. Secondary outcomes include the following: (i) muscle catabolism-related and inflammatory bio-markers (molecular characteristics will be assessed from a vastus lateralis biopsy and blood samples will be obtained from a sub-sample of patients); (ii) patient-reported outcome measures (self-reported fatigue, health-related quality of life, and nutritional status will be assessed through validated questionnaires); (iii) physical fitness/performance/activity (validated tests will be used to evaluate physical function, cardiorespiratory fitness and maximal isometric muscle strength. Physical activity and sedentary behavior (assessed using an activity monitor); (iv) clinical outcomes: hospitalization rates and blood status will be recorded from the patients’ medical records; (v) explorative outcomes of patients’ experience of the exercise program which will be evaluated using focus group/individual interviews. Discussion It is worthwhile to investigate new strategies that have the potential to counteract the deterioration of skeletal muscle mass, muscle function, strength, and physical function, all of which have debilitating consequences for patients with pancreatic, biliary tract, and liver cancer. The expected findings could improve prognosis, help patients stay independent for longer, and possibly reduce treatment-related costs. Trial registration ClinicalTrials.gov NCT05044065. Registered on September 14, 2021.

Adding LIT to HIIT - Is Low-Intensity Training Vital for Endurance-Trained Athletes during a 7-day HIIT Shock Microcycle?

Preprint

Apr 2024
MED SCI SPORT EXER

Purpose To investigate the effects of a 7-day high-intensity interval training shock microcycle (HIIT-SM) with or without additional low-intensity training (LIT) on aerobic fitness and endurance performance compared to a control group. Methods Thirty-three endurance-trained athletes (7 women, 26 men, mean ± SD: age, 30.2 ± 6.9 yr; maximal oxygen uptake (V̇O 2max ), 59.8 ± 4.9 mL·min ⁻¹ ·kg ⁻¹ ) performed exercise testing at T1 and were randomly assigned to one of three groups: i) HSM: 10 running-based HIIT sessions (5 x 4 min at 90-95% maximal heart rate) over 7 days ii) HSM + LIT: equal to HSM with additional 30-min of LIT after each HIIT iii) CG: regular training. Exercise testing was repeated 3 days (T2), 7 days (T3), and 14 days (T4) after the intervention. A 5-km time trial (TT 5km ) was performed 3-4 days before T1 and 10-11 days after the intervention. Data was analyzed by two-way repeated-measures ANOVA. Results No interaction effect was found for V̇O 2max (P = 0.170, p η ² = 0.09), peak power output (P = 0.734, p η ² = 0.04), and work economy (P = 0.804, p η ² = 0.03). There was an interaction for velocity at lactate threshold (P = 0.006, p η ² = 0.18) with increased velocity in HSM at T2 (3.2%, P = 0.030), T3 (4%, P = 0.006), T4 (4%, P = 0.003), as well as in HSM + LIT for T2 (3.2%, P = 0.011), while CG showed no change. There was an interaction for TT 5km (P = 0.044, p η ² = 0.19) with HSM improving 2.7% (P = 0.003), HSM + LIT 2.3% (P = 0.010), while CG was on average – 0.3% (P = 0.821) slower. Conclusions HIIT-SM with or without additional LIT has negligible effects on V̇O 2max but improves other key endurance variables in endurance-trained athletes. No superiority of either intervention group was demonstrated. Therefore, additional LIT during HIIT-SM is not beneficial.

A Five-Week Periodized Carbohydrate Diet Does Not Improve Maximal Lactate Steady-State Exercise Capacity and Substrate Oxidation in Well-Trained Cyclists compared to a High-Carbohydrate Diet

Article

Full-text available

Jan 2024

There is a growing interest in studies involving carbohydrate (CHO) manipulation and subsequent adaptations to endurance training. This study aimed to analyze whether a periodized carbohydrate feeding strategy based on a daily training session has any advantages compared to a high-carbohydrate diet in well-trained cyclists. Seventeen trained cyclists (VO2peak = 70.8 ± 6.5 mL·kg−1·min−1) were divided into two groups, a periodized (PCHO) group and a high-carbohydrate (HCHO) group. Both groups performed the same training sessions for five weeks. In the PCHO group, 13 training sessions were performed with low carbohydrate availability. In the HCHO group, all sessions were completed following previous carbohydrate intake to ensure high pre-exercise glycogen levels. In both groups, there was an increase in the maximal lactate steady state (MLSS) (PCHO: 244.1 ± 29.9 W to 253.2 ± 28.4 W; p = 0.008; HCHO: 235.8 ± 21.4 W to 246.9 ± 16.7 W; p = 0.012) but not in the time to exhaustion at MLSS intensity. Both groups increased the percentage of muscle mass (PCHO: p = 0.021; HCHO: p = 0.042) and decreased the percent body fat (PCHO: p = 0.021; HCHO: p = 0.012). We found no differences in carbohydrate or lipid oxidation, heart rate, and post-exercise lactate concentration. Periodizing the CHO intake in well-trained cyclists during a 5-week intervention did not elicit superior results to an energy intake-matched high-carbohydrate diet in any of the measured outcomes.

Seasonal changes of field and laboratory-based performance indicators in Junior cyclists

Article

Dec 2023

This study aimed to assess the seasonal evolution of field-based and laboratory-based performance indicators in cyclists. Thirteen Junior male road cyclists (age 17.4±0.5 years) were followed-up during a season, which was divided in three phases: early-season (involving mainly training sessions), mid-season (including the first competitions), and late-season (including the major competitions of the season). During each phase, field-based power output data were registered for the assessment of maximum mean power values, and laboratory-based endurance (ramp test and simulated 8-minute time trial), muscle strength/power (squat, lunge, hip thrust) and body composition indicators (dual energy X-ray absorptiometry) were also assessed. A progressive (p<0.01) increase in maximum mean power values (e.g., 3.8±0.3 and 4.5±0.4 watts/kg in early and late-season, respectively, for 60-minute efforts) and on 8-minute time trial performance (i.e., 5.3±0.3 and 5.6±0.4 watts/kg, respectively) was observed through the season. Yet, more ‘traditional’ endurance indicators (i.e., ventilatory threshold, respiratory compensation point, or maximum oxygen uptake) seemed to show a ceiling effect beyond the mid-season. In addition, neither peak power output, body composition, nor muscle strength indicators, followed a similar pattern to the aforementioned field-based indicators. In summary, in Junior cyclists field-based indicators seem more sensitive to monitor changes in performance capacity than more ‘traditional’ laboratory-based markers.

Is Running Power a Useful Metric? Quantifying Training Intensity and Aerobic Fitness Using Stryd Running Power Near the Maximal Lactate Steady State

Article

Full-text available

Oct 2023
SENSORS-BASEL

We sought to determine the utility of Stryd, a commercially available inertial measurement unit, to quantify running intensity and aerobic fitness. Fifteen (eight male, seven female) runners (age = 30.2 [4.3] years; V·O2max = 54.5 [6.5] ml·kg⁻¹·min⁻¹) performed moderate- and heavy-intensity step transitions, an incremental exercise test, and constant-speed running trials to establish the maximal lactate steady state (MLSS). Stryd running power stability, sensitivity, and reliability were evaluated near the MLSS. Stryd running power was also compared to running speed, V·O2, and metabolic power measures to estimate running mechanical efficiency (EFF) and to determine the efficacy of using Stryd to delineate exercise intensities, quantify aerobic fitness, and estimate running economy (RE). Stryd running power was strongly associated with V·O2 (R² = 0.84; p < 0.001) and running speed at the MLSS (R² = 0.91; p < 0.001). Stryd running power measures were strongly correlated with RE at the MLSS when combined with metabolic data (R² = 0.79; p < 0.001) but not in isolation from the metabolic data (R² = 0.08; p = 0.313). Measures of running EFF near the MLSS were not different across intensities (~21%; p > 0.05). In conclusion, although Stryd could not quantify RE in isolation, it provided a stable, sensitive, and reliable metric that can estimate aerobic fitness, delineate exercise intensities, and approximate the metabolic requirements of running near the MLSS.

Medicine ® Mean power output for muscular endurance exercises and maximal oxygen uptake in military young adults

Article

Full-text available

Oct 2023
MEDICINE

The American Heart Association recommends a cardiopulmonary exercise test (CPET) and some alternative exercise tests to evaluate maximal oxygen uptake (VO 2 max) of youth. Power output has shown a high correlation with VO 2 max on a CPET. However, the correlations between mean power output (MPO) for muscular endurance exercises and VO 2 max measured from a CPET are not established in young adults. Forty-five volunteers, with an average age of 29.93 ± 7.05 years, from a sample of 1120 military personnel in Taiwan who attended a 2-minute pushup test and a 2-minute sit-up test were included in the current study. These volunteers subsequently underwent a CPET using the Bruce protocol to assess VO 2 max. According to the physics rule, MPO (watts) for the muscular endurance test was defined as a product of moving distance and force: [1/5 × body height (m) × numbers performed × body mass (kg) × gravity (9.8 m/s 2)]. Pearson correlation analyses were performed. For the 2-min pushups, the correlations (r) between pushup numbers and VO 2 max with and without body mass adjustment were 0.541 (P < .01) and 0.188 (P = .21), respectively, while the correlation (r) between MPO and VO 2 max with and without body mass adjustment were 0.410 and 0.557 (both P < .01), respectively. For the 2-minute sit-ups, the correlations (r) between sit-up numbers and VO 2 max with and without body mass adjustment were 0.529 (P < .01) and 0.291 (P = .052), respectively, while the correlations (r) between MPO and VO 2 max with and without body mass adjustment were 0.318 (P = .03) and 0.705 (P < .01), respectively. In military young adults, MPO for both the 2-minute sit-up and the 2-minute pushup tests could be used as alternative field-based methods to estimate VO 2 max. Abbreviations: CHIEF = cardiorespiratory fitness and health in eastern armed forces study, CPET = cardiopulmonary exercise testing, CRF = cardiorespiratory fitness, MPO = mean power output, VO 2 max = maximal oxygen uptake.

Environmental heat stress offsets adaptation associated with carbohydrate periodization in trained male triathletes

Article

Full-text available

Jun 2023
SCAND J MED SCI SPOR

Purpose Carbohydrate (CHO) intake periodization via the sleep low train low (SL‐TL) diet–exercise model increases fat oxidation during exercise and may enhance endurance‐training adaptation and performance. Conversely, training under environmental heat stress increases CHO oxidation, but the potential of combined SL‐TL and heat stress to enhance metabolic and performance outcomes is unknown. Methods Twenty‐three endurance‐trained males were randomly assigned to either control (n = 7, CON), SL‐TL (n = 8, SLTemp) or SL‐TL + heat stress (n = 8, SLHeat) groups and prescribed identical 2‐week cycling training interventions. CON and SLTemp completed all sessions at 20°C, but SLHeat at 35°C. All groups consumed matched CHO intake (6 g·kg⁻¹·day⁻¹) but timed differently to promote low CHO availability overnight and during morning exercise in both SL groups. Submaximal substrate utilization was assessed (at 20°C), and 30‐min performance tests (at 20 and 35°C) were performed Pre‐, Post‐, and 1‐week post‐intervention (Post+1). Results SLTemp improved fat oxidation rates at 60% MAP (~66% VO2peak) at Post+1 compared with CON (p < 0.01). Compared with SLTemp, fat oxidation rates were significantly lower in SLHeat at Post (p = 0.02) and Post+1 (p < 0.05). Compared with CON, performance was improved at Post in SLTemp in temperate conditions. Performance was not different between any groups or time points in hot conditions. Conclusion SL‐TL enhanced metabolic adaptation and performance compared with CON and combined SL‐TL and heat stress. Additional environmental heat stress may impair positive adaptations associated with SL‐TL.

Richtlijn voedingsadvisering en dieetbehandeling bij sport en zware fysieke activiteit

Research

Jul 2022

Physiological and Mechanical Responses to a Graded Exercise Test in Traditional Rowing

Article

Full-text available

Feb 2023
Int J Environ Res Publ Health

Maximum oxygen consumption and maximum power output are critical measures for training prescription in endurance sports such as rowing. The objective of this investigation was twofold: to compare the physiological and mechanical responses of female and male traditional rowers during a graded exercise test and to establish reference values in this specific rowing modality that have not yet been documented, unlike in Olympic rowing. Twenty-one highly trained/national level rowers participated in the study: 11 female (age: 30.1 ± 10.6 years, height: 167.3 ± 5.0 cm, body mass: 61.9 ± 4.9 kg) and 10 males (age: 33.5 ± 6.6 years, height: 180.8 ± 6.9 cm, body mass: 74.4 ± 6.9 kg). Significant differences (p < 0.05) were found in rowing performance between sexes, with a very large effect size (d = 7.2). The peak power output for the female rowers was 180.9 ± 11.4 W and 287.0 ± 17.7 W for the male rowers. The female rowers reached a VO2max of 51.2 ± 6.6 mL/kg/min at a mean of 174.5 ± 12.9 W, while the males' VO2max was 62.1 ± 4.7 mL/kg/min at a mean of 280.0 ± 20.5 W. These differences in VO2max and maximal aerobic capacity were significant (p < 0.05), with a large (d = 1.9) and very large (d = 6.2) effect size, respectively. A moderate association between VO2max, and rowing performance expressed in watts per kilogram of muscle mass was observed in the female rowers (r = 0.40, p = 0.228). For the male rowers, the correlation between VO2max and relative peak power output in watts per kilogram of body mass was strong (r = 0.68; p = 0.031). This study highlights the differences in the kinetics of ventilatory and mechanical parameters between female and male rowers and the importance of these differences for specific physical preparation in traditional rowing.

VO 2max prediction based on submaximal cardiorespiratory relationships and body composition in male runners and cyclists: a population study

Preprint

Full-text available

Feb 2023

Background: Oxygen uptake (VO2) is one of the most important measures of fitness and critical vital sign. CPET is a valuable method of assessing fitness in sport and clinical settings. This study aimed to: (1) derive prediction models for maximal VO2 (VO2max) based on exercise variables at anaerobic threshold (AT) or respiratory compensation point (RCP) or only somatic and (2) internally validate provided equations. Methods: 4424 male endurance athletes (EA) underwent maximal symptom-limited CPET on a treadmill (n=3330) or cycle ergometer (n=1094). The cohort was randomly divided between: variables selection (nrunners=1998; ncyclist=656), model building (nrunners=666; ncyclist=219) and validation (nrunners=666; ncyclist=219). Random Forest was used to select the most significant variables. Models were derived and internally validated with Multiple Linear Regression. Results: Runners were 36.24±8.45 yrs.; BMI=23.94±2.43 kg·m−2; VO2max=53.81±6.67 mL·min−1·kg−1. Cyclists were 37.33±9.13 yr.; BMI=24.34±2.63 kg·m−2; VO2max=51.74±7.99 mL·min−1·kg−1. VO2 at AT and RCP were the most contributing variables to exercise equations. Body mass and body fat had the highest impact on the somatic equation. Model performance for VO2max based on variables at AT was R2=0.81, at RCP was R2=0.91, at AT&RCP was R2=0.91 and for somatic-only was R2=0.43. Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO2max based on submaximal exercise performance or somatic variables. Presented models are applicable for sport and clinical settling. They are a valuable supplementary method for fitness practitioners to adjust individualised training recommendations. Funding: The author(s) received no specific funding for this work.

External validation of VO2max prediction models based on recreational and elite endurance athletes

Article

Full-text available

Jan 2023
PLOS ONE

In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max by assessing the transferability of the currently available prediction models based on their R², calibration-in-the-large, and calibration slope. 5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min⁻¹·kg⁻¹, BMI 23.59±2.73 kg·m⁻²). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and “transition”) and four age subgroups (18–30, 31–45, 46–60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R² = 0.64), females on CE (Kokkinos R² = 0.65), males on a treadmill (TE) (Wasserman R² = 0.26), females on TE (Wasserman R² = 0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA. All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.

Acute heat stress amplifies exercise‐induced metabolomic perturbations and reveals variation in circulating amino acids in endurance‐trained males

Article

Full-text available

Jan 2023
EXP PHYSIOL

Using untargeted metabolomics, we aimed to characterise the systemic impact of environmental heat stress during exercise. Twenty‐three trained male triathletes (V̇O2peak

{\dot V_{{{\rm{O}}_2}{\rm{peak}}}}

= 64.8 ± 9.2 ml kg min⁻¹) completed a 30‐min exercise test in hot (35°C) and temperate (21°C) conditions. Venous blood samples were collected immediately pre‐ and post‐exercise, and the serum fraction was assessed via untargeted ¹H‐NMR metabolomics. Data were analysed via uni‐ and multivariate analyses to identify differences between conditions. Mean power output was higher in temperate (231 ± 36 W) versus hot (223 ± 31 W) conditions (P < 0.001). Mean heart rate (temperate, 162 ± 10 beats min⁻¹, hot, 167 ± 9 beats min⁻¹, P < 0.001), peak core temperature (Trec), core temperature change (ΔTrec) (P < 0.001) and peak rating of perceived exertion (P = 0.005) were higher in hot versus temperate conditions. Change in metabolite abundance following exercise revealed distinct clustering following multivariate analysis. Six metabolites increased (2‐hydroxyvaleric acid, acetate, alanine, glucarate, glucose, lactate) in hot relative to temperate (P < 0.05) conditions. Leucine and lysine decreased in both conditions but to a greater extent in temperate conditions (P < 0.05). Citrate (P = 0.04) was greater in temperate conditions whilst creatinine decreased in hot conditions only (P > 0.05). Environmental heat stress increased glycolytic metabolite abundance and led to distinct alterations in the circulating amino acid availability, including increased alanine, glutamine, leucine and isoleucine. The data highlight the need for additional exercise nutrition and metabolism research, specifically focusing on protein requirements for exercise under heat stress.

Impact of an Acute Bout of Submaximal Aerobic Exercise on Circulating Leukocytes in Individuals with Spinal Cord Injury

Article

Full-text available

Jul 2022

Individuals with spinal cord injury (SCI) may experience cardiovascular, musculoskeletal and organ function dysregulation. Sequelae include reduced catecholamine secretion and attenuated immune responses which may impact exercise-induced leukocytosis. The purpose of this study was to characterize major leukocyte subtypes following 30 minutes of acute, submaximal aerobic exercise, in line with updated international SCI exercise guidelines for adults. It was hypothesized that exercise would increase major leukocyte subtypes when compared to fasted baseline. Eight participants with SCI (incomplete n = 6; complete n = 2) completed a 30-minute bout of aerobic exercise on an arm cycle ergometer at 60% of their peak power output followed by 90 minutes of recovery, or a 2-hour seated control condition, in a randomized crossover design, separated by 7-14 days. Blood samples were taken at baseline, post exercise, and 90 minutes after exercise (with time matched control). Leukocyte subtypes were analyzed via flow cytometry and plasma catecholamines by ELISA. Several leukocytes increased from pre- to post-exercise (time X condition interaction; all P < 0.05; mean ± SD), including CD3+ Lymphocytes (19 ± 16%), CD4+ T helper (16 ± 13%), CD8+ T cytotoxic (24 ± 23%), CD3+/CD56+ natural killer T (31 ± 34%), and CD3-/CD56+ natural killer (63 ± 82%). CD16+/CD14dim monocytes decreased by 27 ± 38% following exercise to 90 minutes post-exercise. No changes were observed for catecholamines for either condition. Thirty minutes of acute submaximal aerobic exercise sufficiently increased most lymphocyte subsets with effector functions, while leading to decreased proinflammatory monocytes during the recovery phase. This exercise duration and intensity appear to be an appropriate option for modulating circulating immune cells in individuals with SCI.

Acute effects of two different work-to-rest ratio of high-intensity interval training on brain-derived neurotrophic factor in untrained young men

Article

Full-text available

Sep 2022

Background: Aerobic exercise could produce a positive effect on the brain by releasing brain-derived neurotrophic factor (BDNF). In untrained healthy humans there seems to be a linear correlation between exercise duration and the positive effect of acute aerobic exercise on brain-derived neurotrophic factor levels. Therefore, we performed two different duration of high-intensity interval training protocols (HIIT), both known to improve cardiovascular fitness, to determine whether then have a similar efficacy in affecting brain-derived neurotrophic factor levels. Methods: 12 untrained young males (aged 23.7 ± 1.8 years), participated in a randomized controlled cross-over trial. They underwent two different work-to-rest ratio high-intensity interval training protocols: high-intensity interval training 1 (30 min, 15 intervals of 1 min efforts at 85%–90% VO2max with 1 min of active recovery at 50%–60% VO2max) and HIIT2 (30 min, 10 intervals of 2 min efforts at 85%–90% VO2max with 1 min of active recovery at 50%–60% VO2max). Serum cortisol, brain-derived neurotrophic factor were collected at baseline, immediately following intervention, and 30 min into recovery for measurements using a Sandwich ELISA method, blood lactate was measured by using a portable lactate analyzer. Results: Our results showed that the similar serum brain-derived neurotrophic factor change in both high-intensity interval training protocols, with maximal serum brain-derived neurotrophic factor levels being reached toward the end of intervention. There was no significant change in serum brain-derived neurotrophic factor from baseline after 30 min recovery. We then showed that both high-intensity interval training protocols significantly increase blood lactate and serum cortisol compared with baseline value (high-intensity interval training p < 0.01; high-intensity interval training 2 p < 0.01), with high-intensity interval training 2 reaching higher blood lactate levels than high-intensity interval training 1 (p = 0.027), but no difference was observed in serum cortisol between both protocols. Moreover, changes in serum brain-derived neurotrophic factor did corelate with change in blood lactate (high-intensity interval training 1 r = 0.577, p < 0.05; high-intensity interval training 2 r = 0.635, p < 0.05), but did not correlate with the change in serum cortisol. Conclusions: brain-derived neurotrophic factor levels in untrained young men are significantly increased in response to different work-to-rest ratio of high-intensity interval training protocols, and the magnitude of increase is exercise duration independent. Moreover, the higher blood lactate did not raise circulating brain-derived neurotrophic factor. Therefore, given that prolonged exercise causes higher levels of cortisol. We suggest that the 1:1work-to-rest ratio of high-intensity interval training protocol might represent a preferred intervention for promoting brain health.

Elite versus non-elite cyclist – Stepping up to the international/elite ranks from U23 cycling

Article

Aug 2022

This study investigated the physiological, performance and training characteristics of U23 cyclists and assessed the requirements of stepping up to the elite/international ranks. Twenty highly trained U23 cyclists (age, 22.1 ± 0.8 years; body mass, 69.1 ± 6.8 kg; VO2max, 76.1 ± 3.9 ml·kg⁻¹·min⁻¹) participated in this study. The cyclists were a posteriori divided into two groups based on whether or not they stepped up to elite/international level cycling (U23ELITE vs. U23NON-ELITE). Physiological, performance and training and racing characteristics were determined and compared between groups. U23ELITE demonstrated higher absolute peak power output (p = .016), 2 min (p = .026) 5 min (p = .042) and 12 min (p ≤ .001) power output as well as higher absolute critical power (p = .002). Further, U23ELITE recorded more accumulated hours (p ≤ .001), covered distance (p ≤ .001), climbing metres (p ≤ .001), total sessions (p ≤ .001), total work (p ≤ .001) and scored more UCI points (p ≤ .001). These findings indicate that U23ELITE substantially differed from U23NON-ELITE regarding physiological, performance and training and racing characteristics derived from laboratory and field. These variables should be considered by practitioners supporting young cyclists throughout their development towards the elite/international ranks.

Temporal Skin Temperature as an Indicator of Cardiorespiratory Fitness Assessed with Selected Methods

Article

Full-text available

Jun 2022

Simple Summary The aim of this study was to investigate whether it is possible to use infrared thermography to assess cardiovascular fitness and aerobic capacity. Changes in temporal temperature during and after a single bout of high-intensity exercise were measured from subjects with varying levels of physical activity. Significant correlation between the temporal temperature measured during recovery time with cardiovascular fitness parameters (HRR and HRV) and maximum oxygen consumption confirm the usefulness of thermal imagining in aerobic capacity evaluation. These results could foster the employment of infrared thermography to monitor athletic/athletes’ performance. Abstract The aim of this study was to determine whether there are associations between cardiovascular fitness (and aerobic capacity) and changes in temporal skin temperature during and after a single bout of high-intensity exercise. Twenty-three men with varying levels of physical activity (VO2max: 59.03 ± 11.19 (mL/kg/min), body mass 71.5 ± 10.4 (kg), body height 179 ± 8 (cm)) participated in the study. Each subject performed an incremental test and, after a 48-h interval, a 110%Pmax power test combined with an analysis of the thermal parameters, heart rate recovery and heart rate variability. Thermal radiation density from the body surface (temple) was measured using a Sonel KT384 thermal imaging camera immediately after warm-up (Tb), immediately after exercise (Te) and 120 sec after the end of exercise (Tr). The differences between measurements were then calculated. The correlation analysis between the thermal and cardiovascular function parameters during the recovery period showed strong positive associations between the Tr-Te difference and measures of cardiovascular fitness (50 < r < 69, p < 0.05). For example, the correlation coefficient between Tr-Te and VO2max reached 0.55 and between Tr-Te and Pmax reached 0.68. The results obtained indicate that the measurement of temporal temperature during and after an intense 3-min bout of exercise can be used to assess aerobic physical capacity and cardiovascular fitness.

Ketogenic and High-Carbohydrate Diets in Cyclists and Triathletes: Performance Indicators and Methodological Considerations From a Pilot Study

Article

Full-text available

Aug 2022

Endurance athletes frequently employ nutritional strategies to enhance performance. While professional organizations recommend high carbohydrate (HC) diets to maximize performance, many athletes, and researchers have recently shown renewed interest in the ketogenic diet (KD) in hopes to promote “fat adaptation”, which would allow athletes to make use of the essentially unlimited energy resources from stored body fat. This would circumvent one fatigue mechanism, the depletion of muscle glycogen stores, that has been considered central to performance outcomes in endurance events. The present study investigated the effects of participants’ habitual diet (HD), HC, and KD on endurance performance in a 30-km simulated cycling time trial (TT), physiological responses during the TT, and muscle session fuel percentile (SFP) before and after the TT using ultrasonic imaging. Due to the COVID-19 pandemic, data collection ceased after only six recreational cyclists and triathletes (f = 4, m = 6; age: 37.2 ± 12.2; VO2max: 46.8 ± 6.8 ml/kg/min; weekly cycling distance: 225.3 ± 64.2 km). Due to the small sample size, we do not report inferential statistics for our primary outcome measure, cycling performance. Participants completed the KD at the lowest power output. Oxygen consumption (V̇O2), heart rate (HR), and perceived exertion (RPE) during the TT were similar in all conditions. FATox rates were highest in the KD condition and lowest in the HC condition. SFP was lower during KD compared with HD and lower following the TT compared with fasted resting values across all conditions. We discuss methodological considerations into the use of exercise equipment, nutritional interventions, and statistical analysis strategies for study designs like the present. Further research is needed to assess the impact of HC and KD on TT performance in this population. ClinicalTrials.gov Identifier: NCT04097171; OSF preregistration: https://osf.io/ujx6e/

Comparative analysis of endurance, strength and body composition indicators in professional, under-23 and junior cyclists

Article

Full-text available

Aug 2022

Purpose: To compare endurance, strength and body composition indicators between cyclists of three different competition age categories. Methods: Fifty-one male road cyclists classified as either junior (n = 13, age 16.4 ± 0.5 years), under-23 [(U23), n = 24, 19.2 ± 1.3 years] or professional (n = 14, 26.1 ± 4.8 years) were studied. Endurance (assessed through a maximal incremental test and an 8-minute time-trial), strength/power (assessed through incremental loading tests for the squat, lunge and hip thrust exercises) and body composition (assessed through dual energy X-ray absorptiometry) were determined on three different testing sessions. Results: U23 and, particularly professional, cyclists attained significantly (p < 0.05) higher values than juniors for most of the analyzed endurance indicators [time-trial performance, maximum oxygen uptake (VO2max), peak power output (PPO), respiratory compensation point (RCP), and ventilatory threshold (VT)]. Significant differences (p < 0.05) between U23 and professionals were also found for time-trial performance, PPO and VT, but not for other markers such as VO2max or RCP. Professional cyclists also showed significantly (p < 0.05) lower relative fat mass and higher muscle mass levels than U23 and, particularly, juniors. No consistent differences between age categories were found for muscle strength/power indicators. Conclusion: Endurance (particularly time-trial performance, PPO and VT) and body composition (fat and muscle mass) appear as factors that best differentiate between cyclists of different age categories, whereas no consistent differences are found for muscle strength/power. These findings might help in performance prediction and/or talent identification and may aid in guiding coaches in the design of training programs focused on improving those variables that appear more determinant.

External validation of VO2max prediction models based on recreational and elite endurance athletes

Preprint

Full-text available

Mar 2022

In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max. 5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min⁻¹·kg⁻¹, BMI 23.59±2.73 kg·m⁻²). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and “transition”) and four age subgroups (18-30, 31-45, 46-60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R²=0.64), females on CE (Kokkinos R²=0.65), males on a treadmill (TE) (Wasserman R2 =0.26), females on TE (Wasserman R²=0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA. All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.

Reducing fatigue following acquired brain injury: A feasibility study of high intensity interval training for young adults

Article

Full-text available

Mar 2022

The aim was to evaluate feasibility of high-intensity interval training (HIIT) in fatigued adults (20-40 years old) with acquired brain injury (ABI). A prospective pre-post single-arm intervention trial was conducted, including 6-8 months follow-up assessment and interview. Intervention was 18 sessions of intermittent exercise on a cycle ergometer over six weeks. Six out of ten participants without motor impairments completed the intervention (all females, mean age = 30.2 years, months post-injury = 22). On average, participants attended 88% of sessions and achieved high intensity (93% of max heart rate). VO2max improved by 0.53 l/min (SD = 0.29), and participants continued exercising post-intervention. All participants were satisfied with HIIT, were more inclined to exercise, and reported positive effects of exercising for self-management of fatigue. Three sessions a week were demanding to some participants. Findings support feasibility of HIIT as a promising intervention for young adults with post-ABI fatigue.

Athletic identity and autonomous motivation as predictors of endurance performance during high intensity exercise

Article

May 2025
PSYCHOL SPORT EXERC

The effect of saddle height on pedalling mechanical efficiency during cycling

Article

Apr 2025

Dynamic validation method of a wireless three-dimensional force sensor integrated into a cycling pedal

Preprint

Full-text available

Mar 2025

This study aimed to propose and to apply a validation method for a novel three-axis force sensor integrated into a cycling pedal. Innovative features of this sensor include being wireless and pliancy to any bike or ergocycle. A measurement rig was designed to compare the outputs of this sensor with those of a reference sensor. A dynamic protocol, during which the sensor was tested in five different orientations, was performed to assess the validity of the new pedal sensor in both directions of each sensor axis. Data from the two sensors were compared using Bland-Altman analysis, intra-class correlation, and root mean squared error. The intra-class correlation coefficient for peak force was superior to 0.99 under all conditions. The maximum root mean squared error for the normal axis was 14N. The validation method indicates that the novel force sensor accurately measures foot pedal reaction forces.

Effects of individual characteristics and local body functions on sweating response: A review

Article

Full-text available

Aug 2024
INT J BIOMETEOROL

In this study, we conducted a literature review to deepen our understanding of the sweating response of the thermoregulatory system, focusing on the influence of individual characteristics and local body functions. Among the factors related to individual characteristics, improvement in aerobic fitness had a positive effect on the sweating response, whereas aging exerted an inhibitory effect. Short-term artificial acclimation and seasonal heat acclimatization promoted sweating, whereas long-term geographical acclimatization suppressed sweating. Male exhibited higher sweat rates than female when the metabolic heat production was high. Individuals with smaller surface area-to-mass ratios tended to have higher sweat rates than those with larger ratios. Regarding local body functions, sweat distribution in the resting state showed high regional sweat rates in the lower limbs and torso, with higher values in the lower limbs when in the supine position and higher values in the torso when in the seated position. During exercise, the regional sweat rates was high in the torso, whereas the limbs exhibited relatively low sweat rates. These differences in sweat distribution stem from the thermoregulatory potential of each body region, which aims to efficiently regulate body temperature. Local effects have only been examined in the thigh and forearm, with temperature coefficient Q 10 ranging from 2 to 5. Only the forehead showed significantly high thermosensitivity among all body regions.

Executive functions in male and female older adults with aligned levels of VO2max

Article

Jul 2024
J SPORT MED PHYS FIT

Background: Studies have shown a positive relationship between cardiorespiratory fitness (CRF) and executive functioning in older adults. Although this relationship has been well established, there seems to be a gap in the literature on the role of sex differences concerning CRF and executive functions. The current study aimed to assess the effect of sex in the relationship between CRF and cognition in older adults by stratifying the results to examine effects in males and females. Methods: Ninety-six older adults (61 females) gave their written, informed consent to participate in this cross-sectional study. All participants underwent a maximal continuous graded exercise test on a cycle ergometer to assess their maximal oxygen uptake (VO 2max ) and a computerized Stroop task (naming, inhibition, and switching) to assess their executive functions. According to VO 2max test results and the American College of Sports Medicine's guidelines, females and males were classified into higher-fit and lower-fit groups. A general linear model and estimated marginal means analyses were applied. Results: Results showed no significant differences in the naming, inhibition and switching performance tests between male and female older adults (P>0.05). Conclusions: Based on the observed positive relationship between CRF and executive functioning, the data of the current study supports the idea that aerobic exercise, which typically increases CRF, is well-situated to improve executive functioning in older adults, irrespective of sex.

Blood Flow Restriction Exercise in the Perioperative Setting to Prevent Loss of Muscle Mass in Patients with Pancreatic, Biliary Tract, and Liver Cancer: Study protocol for the PREV-Ex Randomized Controlled Trial

Preprint

Full-text available

May 2024

Background: Patients diagnosed with pancreatic, biliary tract, and liver cancer often suffer from a progressive loss of muscle mass. Given the considerable functional impairments in these patients, high musculoskeletal weight loads may not be well tolerated by all individuals. The use of blood-flow restricted resistance training (BFR-T) which only requires low training loads may allow for a faster recovery of muscle due to avoidance of high levels of mechanical muscle stress associated with high-load resistance exercise. This study aims to investigate whether BFR-T can prevent or slow down the loss of skeletal muscle mass and enhance functional capacity and mental health of patients with pancreatic, biliary tract, and liver cancer. Methods: The PREV-Ex exercise trial is a multicentre two-armed randomized-controlled trial. Patients will be randomized to an exercise program consisting of home-based low-load BFR-T during a pre- and postoperative period for a total of 6-10 weeks, or to a control group. Protein supplementation will be given to both groups to ensure adequate protein intake. The primary outcome, skeletal muscle thickness and muscle cross-sectional area will be assessed by ultrasound. Secondary outcomes include: i) muscle catabolism related and inflammatory bio-markers (molecular characteristics will be assessed from a vastus lateralis biopsy and blood samples will be obtained from a sub-sample of patients); ii) Patient-reported outcome measures (self-reported fatigue, health-related quality of life, and nutritional status will be assessed through validated questionnaires); iii) Physical fitness/performance/activity (validated tests will be used to evaluate physical function, cardiorespiratory fitness and maximal isometric muscle strength. Physical activity and sedentary behaviour (assessed using an activity monitor); iv) Clinical outcomes: hospitalization rates and blood status will be recorded from the patients’ medical records; v) Explorative outcomes of patients’ experience of the exercise program will be evaluated using focus group/individual interviews. Discussion: It is worthwhile to investigate new strategies that have potential to counteract the deterioration of skeletal muscle mass, muscle function, strength, and physical function, all of which have debilitating consequences for patients with pancreatic, biliary tract, and liver cancer. The expected findings could improve prognosis, help patients stay independent for longer, and possibly reduce treatment related costs. Trial registration: Clinicaltrials.gov, NCT05044065, date of registration: September 14th 2021, https://clinicaltrials.gov/study/NCT05044065

Krafttraining für Radsportler

Chapter

Dec 2023

Bent R Rønnestad

The impact of natural menstrual cycle and oral contraceptive pill phase on substrate oxidation during rest and acute submaximal aerobic exercise

Article

Jul 2023
J APPL PHYSIOL

Background: Previous research has identified sex differences in substrate oxidation during submaximal aerobic exercise including a lower respiratory exchange ratio (RER) in females compared to males. These differences may be related to differences in sex hormones. Our purpose was to examine the impact of the natural menstrual cycle (NAT) and 2nd and 3rd generation oral contraceptive pill (OCP2, OCP3) cycle phases on substrate oxidation during rest and submaximal aerobic exercise. Methods: Fifty female participants (18 NAT, 17 OCP2, 15 OCP3) performed two experimental trials that coincided with the low (i.e., non-active pill/early follicular) and the high hormone (i.e., active pill/mid-luteal) phase of their cycle. RER and carbohydrate and lipid oxidation rates were determined from gas exchange measurements performed during 10min of supine rest, 5min of seated rest, and two 8min bouts of submaximal cycling exercise at ~40% and ~65% of peak oxygen uptake (V̇O2peak). Results: For all groups, there were no differences in RER between the low and high hormone phases during supine rest (0.73±0.05 vs 0.74±0.05), seated rest (0.72±0.04 vs 0.72±0.04), exercise at 40% (0.77±0.04 vs 0.78±0.04) and 65% V̇O2peak (0.85±0.04 vs 0.86±0.03; p>0.19 for all). Similarly, carbohydrate and lipid oxidation rates remained largely unchanged across phases during both rest and exercise, apart from higher carbohydrate oxidation in NAT versus OCP2 at 40% V̇O2peak (p=0.019) and 65% V̇O2peak (p=0.001). Conclusion: NAT and OCPs do not appear to largely influence substrate oxidation at rest and during acute submaximal aerobic exercise.

Comparação e Concordância dos Métodos de Determinação de Índices Aeróbios no Remo

Thesis

Full-text available

Feb 2020

Leonardo Trevisol Possamai

The maximal lactate steady state (MLSS) and critical power (CP) represent the transition from heavy to severe domain and present important relationship with aerobic performance. Due the difficults on determination of these intensities, physiological index derived from incremental tests has been used in estimation. The muscle deoxihemoglobin ([HHb]BP) derivated of near infrared spectroscopy (NIRs) report the muscle oxygen extraction, which present a plateau in response during incremental test, identifying a break point ([HHb]BP), that has been associated with some index of second physiological transition and MLSS. This association, however, has not yet been determined in rowing, sport in which index of second physiological transition overestimated the MLSS. The aim of the present study was to compare the MLSS and CP intensities with the [HHb]BP in vastus lateralis muscle in incremental test with (INC3min) and without (INC1min) recovery in rowing ergometer. In addition, to verify their correlation with performance. Fourteen rowers (age: 26 ± 13 years; body mass: 81.0 ± 7.6 kg; height: 1.82 ± 0.05 m; 2000m time: 415 ± 18 s) performed: I) anthropometric assessment; II) INC3min, with initial load of 130 W and 30 W exercise steps of 3-min and 30 s of passive recovery; III) MLSS determination, through 30-min constant load tests; IV) INC1min, with initial load of 130 W and 30 W exercise steps of 1-min without recovery and V) CP determination through 500, 1000, 2000 and 6000m tests. The vastus lateralis muscle oxygenation was measured by NIRs for determination of [HHb]BP in INC3min ([HHb]BP3min) and INC1min ([HHb]BP1min), that was compared with power of MLSS, CP and first and second physiological transition indexes derivate of blood lactate, heart rate, ventilation and performance tests. The data were expressed as mean and ± SD. The comparison were performed using ANOVA one-way. Pearson correlation with confidence intervals of 95%, mean difference (Δ) and typical error of estimate (TEE) for such indexes with significance level of p < 0.05. The [HHb]BP1min (204 ± 29W) and [HHb]BP3min (207 ± 29W) showed low correspondence from each other (Δ: -3.4%; TEE: 13.2%; r = 0.51), overestimated the MLSS (Δ: 8.4 and 13.1%; TEE: 15.3 and 15.6%) and underestimated the CP (Δ: -20.4% and -17.4%; TEE: 12.3% and 10.5%). The CP was higher than MLSS (Δ: 37.6%; TEE: 10.8%; p < 0.01). The 18 second transition indexes overestimated MLSS (Δ: 12.5 to 44.9%; TEE: 5.6 to 14.3%), while LL2,0 (186 ± 27 W) and VT1 (193 ± 18 W) presented the smallest TEE (11.0 and 9.5%) and Δ (-2.3 and 4.0%), respectively, with magnitudes from trivial to medium. The time (r = -0.87) and mean power (r = 0.86) of 1000m test showed a very large correlation with MLSS. The [HHb]3min and [HHb]1min presented low correlations with performance tests. In conclusion, despite the [HHb]3min and [HHb]1min did not show significant diferences from MLSS, it was observed high variability with high TEE and mean difference that suggest a small correspondence between these indexes. In addition, the CP was higher than [HHb]BP and MLSS. Taking into account the better association of first physiological transition index with the MLSS, which clearly underestimated CP, it is possible that these markers correspond to the lower and the upper boundaries of the heavy domain on rowing exercise.

Effects of branched chain amino acids, l-citrulline, and alpha-glycerylphosphorylcholine supplementation on exercise performance in trained cyclists: a randomized crossover trial

Article

May 2023
Sports Nutr Rev J

Renee Harrington

Background: Nutrition plays a key role in training and athletic performance and dietary supplements can make a small, but potentially valuable, contribution to achieving peak athletic performance. This study is the first to investigate the effects of supplementation from the combination of BCAAs, L-citrulline, and A-GPC on exercise performance. Methods: In this randomized, double-blind, crossover study 30 male trained cyclists (age: 43.7 ± 8.5 years) completed a 20 km cycling time trial (TT) test and a high intensity endurance cycling (HIEC) test following a 7-day supplementation period with either a supplement containing 8 g BCAAs, 6 g L-citrulline, and 300 mg A-GPC or a placebo (15 g maltodextrin). For each trial, mean values for time to completion, peak and average power output, OMNI rating of perceived exertion, and visual analogue scale (VAS) responses on perceived exertion were computed for the 20 km TT test. Mean values for time to fatigue and VAS responses on perceived exertion were computed for the HIEC test. Procedures for dietary intake and exercise patterns were implemented to achieve consistency throughout the study period. Results: There was a significant increase (p = .003) in peak power in the 20 km TT (354.27 ± 87.88 and 321.67 ± 63.65, for supplement and placebo trials, respectively) and a significant increase (p = .001) in time to fatigue in the HIEC test (0:19:49 ± 0:11:13 min and 0:14:33 ± 0:09:59 min, for supplement and placebo trials, respectively) with the test supplement compared to the placebo. With the test supplement, there was an average increase in TT peak power of 11% and an average increase in time to fatigue of 36.2% in the HIEC test compared to the placebo. There was no significant improvement in time to completion, average power, OMNI rating of perceived exertion, or VAS responses on perceived exertion in the TT test and no significant improvement in VAS measures of perceived exertion in the HIEC test. Conclusions: The combination of BCAAs, L-citrulline, and A-GPC used in this study improves cycling performance and may be useful for individuals seeking to improve athletic performance, particularly in disciplines requiring lower body muscular strength and endurance.

VO2max prediction based on submaximal cardiorespiratory relationships and body composition in male runners and cyclists: a population study

Article

Full-text available

May 2023
eLife

Backround: Oxygen uptake (VO 2 ) is one of the most important measures of fitness and critical vital sign. Cardiopulmonary exercise testing (CPET) is a valuable method of assessing fitness in sport and clinical settings. There is a lack of large studies on athletic populations to predict VO 2max using somatic or submaximal CPET variables. Thus, this study aimed to: (1) derive prediction models for maximal VO 2 (VO 2max ) based on submaximal exercise variables at anaerobic threshold (AT) or respiratory compensation point (RCP) or only somatic and (2) internally validate provided equations. Methods: 4424 male endurance athletes (EA) underwent maximal symptom-limited CPET on a treadmill (n=3330) or cycle ergometer (n=1094). The cohort was randomly divided between: variables selection (n runners =1998; n cyclist =656), model building (n runners =666; n cyclist =219) and validation (n runners =666; n cyclist =219). Random Forest was used to select the most significant variables. Models were derived and internally validated with Multiple Linear Regression. Results: Runners were 36.24±8.45 yrs.; BMI=23.94±2.43 kg·m ⁻² ; VO 2max =53.81±6.67 mL·min ⁻¹ ·kg ⁻¹ . Cyclists were 37.33±9.13 yr.; BMI=24.34±2.63 kg·m ⁻² ; VO 2max =51.74±7.99 mL·min ⁻¹ ·kg ⁻¹ . VO 2 at AT and RCP were the most contributing variables to exercise equations. Body mass and body fat had the highest impact on the somatic equation. Model performance for VO 2max based on variables at AT was R ² =0.81, at RCP was R ² =0.91, at AT&RCP was R ² =0.91 and for somatic-only was R ² =0.43. Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO 2max based on submaximal exercise performance or somatic variables. Presented models are applicable for sport and clinical settling. They are a valuable supplementary method for fitness practitioners to adjust individualised training recommendations. Funding: No external funding was received for this work.

Ausdauer und Ausdauertraining im Sport: Anwendungsbereiche, Diagnostik, Trainingsformen, Organisation, Methoden, Anpassungen

Chapter

Mar 2023

Die Ausdauerleistungsfähigkeit bezeichnet die Fähigkeit, körperliche Belastungen über einen längeren Zeitraum aufrechtzuerhalten bzw. die Ermüdung hinauszuzögern. Sie ist im Wesentlichen durch die Kapazität des Herz-Kreislauf-Systems und Stoffwechsels determiniert. Eine Ausdauerleistungsdiagnostik ist indiziert, wenn eine generelle Bestimmung des aktuellen Leistungsniveaus erforderlich ist, mit dem Ziel die maximale Kapazität von Herz-Kreislauf-System und/oder Stoffwechsel zu beurteilen. Bei der Auswahl geeigneter Testverfahren sollten Sicherheitsüberlegungen, mögliche Kontraindikationen, eine für den gegebenen Zweck ausreichende Standardisierung und die Einhaltung wissenschaftlicher Testgütekriterien berücksichtigt werden. Zur Verbesserung der Ausdauerleistungsfähigkeit existiert eine Reihe von Trainingsmethoden. Die Auswahl der geeigneten Trainingsmethode hängt vom Leistungsniveau, vom Trainingshintergrund sowie – zumindest teilweise – von individuellen Präferenzen der einzelnen Person ab. Dieser Beitrag ist Teil der Sektion Sportmotorische Fähigkeiten und sportliches Training, herausgegeben vom Teilherausgeber Michael Fröhlich, innerhalb des Handbuchs Sport und Sportwissenschaft, herausgegeben von Arne Güllich und Michael Krüger.

Monitoring the Effects of Brain and Physical Endurance Training on Overreaching Indices in Active Individuals

Article

Full-text available

Nov 2020

Abstract Background and Purpose: The increasing process of overreaching in the development or decline of the athlete's performance acts as a moving that stops in the axis timely will improve the athlete's performance and achieve the goal. Therefore, the aim of the present study was investigated the effects of concurrent exercise physical and brain endurance on overreaching factors in active people. Methodology: Subjects included 20 active male and female physical education students (Mean ±SD; age: 22.3 ± 4.4 years, height: 177.56 ± 6.12 cm, BMI: 22± 4.5 kg/m2). Participants were divided into two groups of concurrent endurance and brain training (BET) and endurance training (ET), according to the results of the maximum oxygen consumption test. Physical exercise training was performed on cycle ergometer and brain training using computer with monitor on front of subjects during cycling. To analyze the results of the tests, Mix ANOVA. Significance level (P≤0.05) was considered. Results: The results showed that the maximum oxygen consumption after the training period, regardless of the type of activity, increased significantly (P = 0.00). Monitoring resting heart rate. POMS questionnaire indicators and resting cortisol levels did not show a significant increase indicating non-functional overreaching, respectively (P≤0/51). The rating of perceived exertion index was higher in the group that did physical endurance activity along with brain endurance training (P= 0/5). Conclusion: These findings showed despite the increase stimulant to concurrent physical and brain endurance training did not cause non-functional overreaching and overtraining, but also based on the results of performance improvement, it can be said that the subject achieved functional overreaching and super compensation during the training period, which was able to experience progress. Key words: Overreaching, Mental Fatigue, Training Monitoring, Improve Performance, Amount of Effort Perceived

Hepcidin and Erythroferrone Complement the Athlete Biological Passport in the Detection of Autologous Blood Transfusion

Article

Apr 2022
MED SCI SPORT EXER

Purpose: We investigated whether hepcidin and erythroferrone (ERFE) could complement the Athlete Biological Passport (ABP) in indirectly detecting a 130 mL packed red blood cells (RBCs) autologous blood transfusion. Endurance performance was evaluated. Methods: Forty-eight healthy men (n = 24) and women (n = 24) participated. Baseline samples were collected weekly followed by randomization to a blood transfusion (BT, n = 24) or control group (CON, n = 24). Only the BT group donated 450 mL whole blood from which 130 mL RBCs was reinfused four weeks later. Blood samples were collected 3, 7, 14, 21 and 28 days after donation, and 3, 6, and 24 hours and 2, 3, and 6 days following reinfusion. In the CON group samples were collected with the same frequency. Endurance performance was evaluated by a 650-kCal time trial (n = 13) before and one and six days after reinfusion. Results: A time×treatment effect existed (P < 0.05) for hepcidin and ERFE. Hepcidin was increased (P < 0.01) ~110 and 89% six and 24 hours after reinfusion. Using an individual approach (99% specificity, e.g. allowing 1:100 false-positive), sensitivities, i.e. true positives, of 30% and 61% was found for hepcidin and ERFE, respectively. For the ABP, the most sensitive marker was Off-hr score ([Hb] (g/L) - 60 × √RET%) (P < 0.05) with a maximal sensitivity of ~58% and ~ 9% following donation and reinfusion, respectively. Combining the findings for hepcidin, ERFE and the ABP yielded a sensitivity across all time-points of 83% following reinfusion in BT. Endurance performance increased 24 hours (+6.4%, P < 0.01) and six days following reinfusion (+5.8%, P < 0.01). Conclusions: Hepcidin and ERFE may serve as biomarkers in an anti-doping context following an ergogenic, small-volume blood transfusion.

VO2 max and training indices as determinants of competitive running performance

Article

Full-text available

Mar 1983

Carl Foster

The importance of the maximal oxygen uptake (VO2 max) for competitive running performance is established. Although of clear importance, the quantitative association between the volume and intensity of training, and running performance has not been established. The purpose of this investigation was to quantify the relative importance of VO2 max, training volume (miles/week) and intensity for running performance at distances ranging from 1.0 to 26.2 miles. Seventy‐eight well‐trained runners of widely varying ability were studied during uphill treadmill running to determine VO2 max. They provided training records to determine training volume and intensity, and participated in races of 1.0 (n = 31), 2.0 (n = 55), 3.0 (n = 28), 6.0 (n= 17), 10.0 (n = 20) and 26.2 (n = 25) miles. The relationship of VO2 max and training volume and intensity to performance was determined using multiple regression. Performance (running time) was highly correlated with VO2 max (r= ‐0.91, ‐0.92, ‐0.94, ‐0.96, ‐0.95 and ‐0.96 for 1.0, 2.0, 3.0, 6.0, 10.0 and 26.2 miles, respectively). The addition of training measures improved the multiple correlations in some (1.0, 2.0, 3.0 and 6.0 miles) but not all (10.0 and 26.2 miles) events. However, even when addition of one or both training indices improved the multiple correlation, the net reduction in the standard error of estimate was small. The results imply that the volume and intensity of training, per se, are relatively minor determinants of cross‐sectional differences in competitive running performance.

Organization and function of the sympathetic innervation of human liver

Article

Full-text available

Feb 1977
Acta Physiol Scand Suppl

This study presents the finding of a sympathetic innervation of liver parenchymal cells in man. Aspects on the functional role of this innervation in glucose regulation is also given.

Effects of elevated plasma FFA and insulin on muscle glycogen usage during exercise

Article

Full-text available

Nov 1977

Seven men were studied during 30 min of treadmill exercise (approximately 70% VO2 max) to determine the effects of increased availability of plasma free fatty acids (FFA) and elevated plasma insulin on the utilization of muscle glycogen. This elevation of plasma FFA (1.01 mmol/1) with heparin (2,000 units) decreased the rate of muscle glycogen depletion by 40% as compared to the control experiment (FFA = 0.21 mmol/1). The ingestion of 75 g of glucose 45 min before exercise produced a 3.3-fold increase in plasma insulin and a 38% rise in plasma glucose at 0 min of exercise. Subsequent exercise increased muscle glycogen utilization and total carbohydrate (CHO) oxidation 17 and 13%, respectively, when compared to the control trial. This elevation of plasma insulin produced hypoglycemia (less than 3.5 mmol/1) in most subjects throughout the exercise. These data illustrate the regulatory influence of both plasma insulin and FFA on the rate of CHO usage during prolonged severe muscular activity.

Muscle power predicts freestyle swimming performance

Article

Full-text available

Oct 1992

The purpose of this study was to determine the relationship between non-invasive laboratory measures of 'muscle power' and swim performance over sprint (50 m) and middle-distance (400 m) events. Twenty-two swimmers performed an upper and lower body Wingate Anaerobic Test (WAT) and a maximal sustained power output test (MPO) for the upper body. Peak power (PP) and mean power (MP) were determined for the WAT, while peak sustained workload (WLpeak) was determined for the MPO. Timed swims over 50 m and 400 m were undertaken by all swimmers during which the number of arm strokes per length was recorded. Highly significant relationships were found between sprint-swim speed (S50) and mean power of the arms (MP(arms)) (r = 0.63, P less than 0.01), between S50 and mean power of the legs (MP(legs)) (r = 0.76, P less than 0.001) and between S50 and the distance covered with each arm stroke (DS) (r = 0.91, P less than 0.001). Multiple regression analyses revealed that WAT power indices for the legs did not significantly increase explained variance in S50 above that of the arms. The relationship between WL(peak) and S400 was highly significant (r = 0.70, P less than 0.001) and indicates the importance of arm power in the longer distance swim events.

Accurate prediction of VO2max in cycle ergometry

Article

Full-text available

Nov 1990

Numerous equations exist for predicting VO2max from the duration (an analog of maximal work rate, Wmax) of a treadmill graded exercise test (GXT). Since a similar equation for cycle ergometry (CE) was not available, we saw the need to develop such an equation, hypothesizing that CE VO2max could be accurately predicted due to its more direct relationship with W. Thus, healthy, sedentary males (N = 115) and females (N = 116), aged 20-70 yr, were given a 15 W.min-1 CE GXT. The following multiple linear regression equations which predict VO2max (ml.min-1) from the independent variables of Wmax (W), body weight (kg), and age (yr) were derived from our subjects: Males: Y = 10.51 (W) + 6.35 (kg) - 10.49 (yr) + 519.3 ml.min-1; R = 0.939, SEE = 212 ml.min-1. Females: Y = 9.39 (W) + 7.7 (kg) - 5.88 (yr) + 136.7 ml.min-1; R = 0.932, SEE = 147 ml.min-1 Using the 95% confidence limits as examples of worst case errors, our equations predict VO2max to within 10% of its true value. Internal (double cross-validation) and external cross-validation analyses yielded r values ranging between 0.920 and 0.950 for the male and female regression equations. These results indicate that use of the equations generated in this study for a 15 W.min-1 CE GXT provides accurate estimates of VO2max.

Can Maximal Cardiopulmonary Capacity be Recognized by a Plateau in Oxygen Uptake?

Article

Full-text available

Jan 1990

The failure of oxygen uptake to increase with increasing work has been considered a marker of the limits of the cardiopulmonary system for many years. However, the concept has suffered from inconsistencies in definition, criteria, and data sampling, all of which affect the interpretation of the relation between changes in work and oxygen uptake. To evaluate the response and reproducibility of the slope in oxygen uptake at peak exercise, six subjects (mean age, 33 +/- 6 years) performed two individualized ramp treadmill tests on separate days. During exercise, oxygen uptake (for a given sample of 30 eight-breath running averages) was regressed with time and the slope was calculated. Maximal oxygen uptake, maximal heart rate and maximal perceived exertion were reproducible from day 1 to day 2 (mean difference, 0.4 ml/kg/min, 1.0 beats per minute, and 0.2 for maximal oxygen uptake, heart rate, and maximal perceived exertion, respectively [not significant]). Considerable variability in the slopes was observed during each test and from day to day. This occurred despite the use of large gas exchange samples, averaging techniques, and constant, consistent changes in external work. A plateau, defined as the slope of an oxygen uptake sample at peak exercise that did not differ significantly from a slope of zero, was not a consistent finding within subjects between days. We conclude that marked variability in the slope of the change in oxygen uptake occurs throughout progressive exercise, despite the use of large samples and a linear change in external work. These findings appear to preclude the determination of a plateau by common definitions.

Gaesser G A, Brooks G AMetabolic bases of excessive post-exercise oxygen consumption: a review. Med Sci Sports Exerc 1984; 16: 29-43

Article

Full-text available

Feb 1984

The classical "oxygen debt" hypothesis formulated by Hill and associates in the 1920s was an attempt to link the metabolism of lactic acid with the O2 consumption in excess of resting that occurs after exercise. The O2 debt was hypothesized to represent the oxidation of a minor fraction (1/5) of the lactate formed during exercise, to provide the energy to reconvert the remainder (4/5) of the lactate to glycogen during recovery. In 1933 Margaria et al. modified this hypothesis by distinguishing between initial, fast ("alactacid"), and second, slow ("lactacid"), O2-debt curve components. They hypothesized that the fast phase of the post-exercise O2 consumption curve was due to the restoration of phosphagen (ATP + CP). It is now probable that the original lactic acid explanation of the O2 debt was too simplistic. Numerous studies on several species have provided evidence demonstrating a dissociation between the kinetics of lactate removal and the slow component of the post-exercise VO2. The metabolism of lactate, a readily oxidizable substrate, following exercise appears to be directed primarily toward energy production in mitochondria. The elevated concentration of lactate present at the end of exercise may be viewed as a "reservoir of carbon," which may serve as a source of oxidative ATP production or as a source of carbon skeletons for the synthesis of glucose, glycogen, amino acids, and TCA cycle intermediates. The metabolic basis of the elevated post-exercise VO2 may be understood in terms of those factors which directly or indirectly influence mitochondrial O2 consumption. Included among these factors are catecholamines, thyroxine, glucocorticoids, fatty acids, calcium ions, and temperature. Of these, elevated temperature is perhaps the most important. As no complete explanation of the post-exercise metabolism exists, it is recommended that the term "O2 debt" be used to describe a set of phenomena during recovery from exercise. The terms "alactacid debt" and "lactacid debt," which suggest a mechanism, are inappropriate. Use of alternative terms, e.g., "excess post-exercise oxygen consumption" (EPOC) and "recovery O2," will avoid implication of causality in describing the elevation in metabolic rate above resting levels after exercise.

Textbook of work physiology. Physiological basis of exercise

Article

Jan 1977

CRITERIA FOR DEFINING VO2 MAX

Article

Apr 1986

Über das Minutenvolum des Herzens bei Ruhe und bei Muskelarbeit

Article

Jan 1915

J. Lindhard

Accurate prediction of &OV0312;O2max in cycle ergometry

Article

Oct 1990

New Records in Human Power

Article

Oct 1955

P.-O. Åstrand

UNDER this heading Robinson, Edwards and Dill1 published in 1937 results of investigations of five young men of international renown in distance running. Lash, who held the world's record for the 2-mile race, running on a treadmill at 21.6 km./hr. with no gradient, attained an oxygen intake of 5.35 l./min. or 81.5 ml. per kgm. of body-weight per min.2.

Criteria for Defining Vo2 Max: A New Approach to An Old Problem

Article

Apr 1986

Maximal Oxygen Intake as an Objective Measure of Cardio-Respiratory Performance

Article

Jul 1955
J Appl Physiol

Muscle Metabolism and Enzyme Activities after Training in Boys 11–13 Years Old

Article

Dec 2008
Acta Physiol Scand

The effect of training on the skeletal muscle metabolism of 11-to 13-year-old boys was examined. In one experiment changes in blood lactate, and muscle lactate, CP, ATP, and glycogen were determined at rest and following exercise before and after 4 months of training. The concentrations of glycogen, CP and ATP at rest were higher (P<0.01) following training. Blood and muscle lactate were 23 and 56 % higher after maximal work following training. A greater reduction in muscle glycogen occurred during maximal work after training but the pattern for ATP and CP depletion was unchanged. In a second experiment boys trained by pedalling a bicycle ergometer an average of 30 min 3 times a week for 6 weeks. Biopsy samples of the vastus lateralis were examined for oxidative (succinate dehydrogenase) and anaerobic (phosphofructokinase) capacity before and after training. The fiber composition and relative oxidative capacity in the fibers was determined histochemically. Succinate dehydrogenase and phosphofructokinase activities increased 30 and 83 %, respectively, following training. Fiber distribution was unchanged by training but the oxidative capacity of both fiber types appeared to increase.

R�ponse adr�nergique � l'exercice musculaire intense chez le sujet s�dentaire en fonction de l'emotivit� et de l'entrainement

Article

Jun 1979
Eur J Appl Physiol Occup Physiol

Seven male sedentary human subjects were studied during intense muscular work (80% of maximal oxygen uptake) performed either for 15 min or until exhaustion (mean duration: 47±2 min). Plasma catecholamines were estimated before and after the experiment by means of an original fluorimetric assay. Epinephrine and norepinephrine were individually isolated from plasma and assayed in single extracts by a highly sensitive fluorimetric method. Epinephrine or norepinephrine levels as low as 15 ng per liter were detectable by this procedure in human plasma. The adrenergic pattern was found to be greatly different from one subject to another and related to emotivity: the effect of this factor was revealed by the predominance of epinephrine in plasma at rest or under exercise (ratio NA/A <1). In nonemotive subjects (ratio NA/A>1 at rest) plasma epinephrine and norepinephrine increased progressively during exercise. Increments after exercise were higher for norepinephrine changes; however, the fact that epinephrine concentrations correlated significantly with norepinephrine suggests a simultaneous and coordinated stimulation of adrenal glands and orthosympathetic nervous system. In emotive subjects (ratio NA/A<1 at rest) the apprehension of muscular work promoted a difference in catecholamine responses: norepinephrine release was not affected by subject's anxiety, while epinephrine secretion, already elevated before the test, reached a high degree of magnitude in the first minutes of muscular work, remaining nearly constant until exhaustion. Physical training of nonemotive subjects, during 2 months with two intense exercises by a week, reduced strongly norepinephrine release after exhaustive muscular work. In the same conditions, the adrenal-medullary response was not significantly modified when compared with untrained subjects. Our results suggest that the adrenergic behaviour during exercise is a function of effort intensity to be supplied; catecholamines seem to be important factors in regulating body homeostasy during muscular work in man. In addition, emotive subjects exhibit amplified adrenal-medullary response, which may be related to psychological stimuli.

Einflu\ einer stufenweisen Laufbandergometrie bei Kindern und Erwachsenen auf die Plasmacatecholamine, die aerobe und anaerobe KapazitÄt

Article

Nov 1981
Eur J Appl Physiol Occup Physiol

Adrenaline, noradrenaline, lactate and glucose levels in the blood, together with the heart rate and oxygen intake were examined in eight boys (12.8±0.8 years) and seven adults (27.8±2.9 years) during a graduated treadmill exercise. At rest, noradrenaline is higher in the adults, while adrenaline, lactate, glucose, heart rate and relative oxygen intake show no differences between the groups. At the same exercise levels, adrenaline (+90–180%), noradrenaline (+28–77%) and the heart rate are higher in boys, corresponding to a higher relative exercise load, and glucose, lactate and the relative oxygen intake show no differences. During maximum treadmill exercise adrenaline, glucose and the relative oxygen intake show no differences between the groups, whereas the noradrenaline (−30%) and lactate levels (−25%) are lower and the heart rate is 4% higher in the boys. There is an identical increase in lactate and catecholamine levels (r=0.92 and 0.87) with a lower correlation with high intensity “anaerobic” physical exercise, which shows no age dependent difference until about the age of 40. The maximum catecholamine (adrenaline and noradrenaline) and lactate concentration is 25% lower in the boys; an indication of reduced maximum sympathetic activity and reduced maximum anaerobic capacity is seen. The constant relationship between adrenaline and noradrenaline during physical work (r=0.90 and 0.85), also with a lower correlation at high intensiv physical exercise, changes from 1∶3.5 (boys) to 1∶5.5 (adults) (p<0.001), based on higher noradrenaline levels in the adults at rest, at submaximum exercise levels and during maximum ergometric work; these changes are seen to be the cause of an age dependent negative chronotropic effect.

Zur aeroben und anaeroben KapazitÄt sowie Catecholaminexkretion von Kindern und Jugendlichen wÄhrend langdauernder submaximaler Körperarbeit

Article

Feb 1982
Eur J Appl Physiol Occup Physiol

Elf ausdauertrainierte Knaben (12,81,2 Jahre) und 12 Jugendliche (17,70,5 Jahre) wurden einer stufenweisen Laufbandergometrie und einem 10 000-m-Lauf unterzogen. Im Laborversuch wurde das Sauerstoffaufnahmevermgen, die maximale Lactatazidose sowie die anaerobe Schwelle, die Herzfrequenz und der Glucosespiegel im Blut, whrend des Feldversuches die Catecholaminausscheidung, das Verhalten des Glucose-, Lactat-, Glycerinspiegels und der freien Fettsuren untersucht.Das Sauerstoffaufnahmevermgen der Jugendlichen und das absolute Herzvolumen ist gr\er, unterscheidet sich aber gewichtsbezogen nicht von den Knaben. Die maximale Lactatezidose der Knaben ist niedriger, unterscheidet sich aber auf submaximalen Stufen, bezogen auf die relative Sauerstoffaufnahme nicht von den Jugendlichen. Die Sauerstoffaufnahme im Bereich der anaeroben Schwelle als Ausdruck der Gte der Ausdauertrainiertheit betrgt bei beiden Gruppen bereinstimmend ca. 55 ml/kgmin und entspricht ca. 80–90% des Sauerstoffaufnahmevermgens. Die Herzfrequenz der Knaben liegt auf gleichen submaximalen Stufen und bei maximaler Ergometerarbeit hher und bleibt auch in bezug auf die relative Sauerstoffaufnahme und im Bereich der anaeroben Schwelle 5–10 Schlge/min hher. Der Glucosespiegel nimmt bei Knaben und Jugendlichen gleicherma\en whrend der Ergometerarbeit 20–25% zu. Die Basisexkretion freier Catecholamine zeigt keinen Unterschied zwischen beiden Gruppen; sie steigt whrend des 10 000-m-Laufes vier- bis fnffach an und zeigt gewichtsbezogen keinen Unterschied zwischen beiden Gruppen; der Lactatspiegel nimmt 217% (Knaben) und 338% (Jugendliche), der Glucosespiegel 36 und 61%, die freien Fettsuren 131 und 69% und Glycerin ca. 300% zu. Die Differenzen zwischen beiden Gruppen sind nicht signifikant. Hinsichtlich der Trainierbarkeit und der Ausdauerleistungsfhigkeit, kenntlich an der relativen Herzgr\e, dem gewichtsbezogenen Sauerstoffaufnahmevermgen, der relativen Catecholaminexkretion (ng/minkg) sowie der relativen Sauerstoffaufnahme im Bereich der anaeroben Schwelle und der Vernderung energiereicher Substrate ist keine Unterlegenheit der Knaben gegenber Jugendlichen anzunehmen. Aus Grnden der Vergleichbarkeit wird vorgeschlagen, die Catecholaminausscheidung auf das Krpergewicht zu beziehen.Eleven endurance trained young boys and 12 adolescents were examined during a graduated treadmill ergometric test and one week later during a 10,000m race. Aerobic capacity (oxygen intake), anaerobic capacity (lactate), anaerobic threshold, heart rate, and blood glucose levels were determined during laboratory testing. The sympathoadrenergic activity (excretion of free adrenaline and noradrenaline in urine), and the influence of prolonged submaximum exercise on carbohydrate- (glucose, lactate) and lipid metabolism (glycerine, free fatty acids) were determined during the field experiment. Aerobic capacity in adolescents, like the absolute heart volume, is larger than in young boys but shows no weight related differences. Anaerobic capacity of young boys is shown to be lower, but shows no difference to the adolescents at the same submaximum levels related to the relative oxygen intake. Oxygen intake at the anaerobic threshold is a sign of the endurance condition and reaches approx 55 ml/kgmin in both groups, and corresponds to about 80–90% of aerobic capacity. Heart rate in the young boys is higher at the same submaximum levels and during maximum ergometric exercise; also in relation to the relative oxygen intake and at the anaerobic threshold the heart rate remains 5–10 beats/min higher. The glucose level increases 20–25% in both the young boys and the adolescents during ergometric exercise. The excretion at rest of free catecholamine shows no difference between the groups. The average excretion during the 10,000 m race increases four to five times and shows no weight related differences between the groups. The lactate level increases 217% (young boys) and 338% (adolescents), the glucose level 36 and 61%, the free fatty acids 131 and 69%, and glycerine about 300%. The differences between both groups are not significant. In regard to trainability and endurance capacity, recognizable by the rleative heart volume, the relative aerobic capacity and the relative catecholamine excretion as well as the relative oxygen intake at the anaerobic threshold and changes of the energy rich substrates, the young boys show no disadvantage to the adolescents. For reasons of comparison it is suggested that catecholamine excretion be refered to body weight.

Submaximal and maximal working capacity of elite distance runners. Part I: Cardiorespiratory aspects

Article

Feb 1977

M L Pollock

Maximal oxygen uptake (V̇O2 max) has been described as an important characteristic of endurance athletes. Early investigations by Robinson, Edwards, and Dill, and Saltin and Astrand reported V̇O2 max values above 80 ml/kg.min for distance runners and cross-country skiers. Saltin and Astrand further documented a differentiation in V̇O2 max in a variety of athletic types. A more recent study showed that although V̇O2 max differentiated well in endurance athletes of diverse abilities, there was a limitation of using V̇O2 max to predict distance running performance of good runners. Costill et al. and Costill, Thomason, and Roberts found that the fractional utilization of VO2 at a standard running speed to be an important measure in predicting V̇O2 capacity in good distance runners. Running efficiency from the standpoint of energy expenditure may also be an important factor in differentiating distance runners. It has been suggested that differences may exist in some metabolic variables between elite marathon runners (26.2 miles or 42 km) and other elite types of middle-long distance runners (1-6 miles or 1,500-10,000 m). As metabolic and efficiency differences may prove more predictive in differentiating among elite runners, it was the purpose of this investigation to study the submaximal and maximal metabolic characteristics of a large sample of elite runners to observe if specific differentiation into the types of runner could be made.

Dynamic peak torque related to age, sex, and performance

Article

Jun 1979

The present study was designed to investigate the isokinetic peak torque at the highest speed of muscle shortening (210 degrees/second) related to age, sex, and physical performance. The subjects were 569 normal boys and girls, 13 to 17 years of age, and 35 swimmers, 11 to 21 years of age. Peak torque of knee extensor muscles increased linearly with age for boys from 13 to 17 years, while it remained relatively constant for girls 14 to 17 years of age. The relationship (boys r = .688, p < .001; girls r = .373, p < .01) between peak torque of knee extensors and mean speed in meters per second of 50 meters maximal run was significant. Significant correlations (boys r = .728, p < .001; girls r = .515, p < .05) were also obtained between peak torque of arm pull muscles and the best record in time of 100 meters free style swimming.

Lipid metabolism in skeletal muscle of endurance-trained males and females

Article

Nov 1979

Bipsies were obtained from the gastrocnemius muscle of 13 male and 12 female distance runners and analyzed for [14C]palmitoyl-CoA oxidation, fiber composition, and the activities of selected enzymes. The male and female runners were similar in terms of maximal oxygen uptake (VO2max), training mileage, fiber compositions, and data collected during a 60-min treadmill run at 70% VO2max. Muscle succinate dehydrogenase and carnitine palmitoyl transferase activities were, however, significantly greater (P less than 0.05) in the male than in female runners. In addition, the male runners' muscle also showed a greater capacity to oxidize palmitoyl CoA. Little relationship, however, was found between muscle lipid metabolism, enzyme activities, and the calculated (respiratory exchange) fraction of energy derived from fat during 60 min of running at 70% VO2max. Although these data support the concept that endurance training (80-115 km/wk) markedly enhances the capacity of muscles to metabolize fats, the factors that regulate the usage of lipids during prolonged exercise do not appear to be limited by the capacity of the fibers to oxidize fatty acids, as determined by in vitro measurements.

The effect of pedalling speed on the validity of the Astrand-Rhyming aerobic work capacity test

Article

Jan 1978

A major problem in administering the Astrand-Ryhming Test to low-fit individuals is their inability to maintain a workload sufficient to produce exercise heart rates. Since differences in perceived exertion have been observed at different pedalling speeds, the use of a higher pedalling speed might be preferred. The purpose of this study was to determine the validity of the Astrand-Ryhming Test administered at 50 and 80 rpm. Thirty male volunteer subjects were randomly assigned to test order groups. The tests consisted of: Astrand-Ryhming Test administered at 50 rpm; Astrand-Ryhming test administered at 80 rpm; and maximum oxygen intake determined at the end of a graded exercise test. The results revealed relatively low validity coefficients of r(xy) = 0.64 and r(xy) equals 0.63 for Astrand-Ryhming Tests administered at 50 and 80 rpm, respectively. The correlation between the 50 and 80 rpm tests was r=0.85. One-way analysis of variance for repeated measures, and subsequent Duncan's New Multiple Range Test, revealed that the criterion maximal oxygen intake values were significantly higher than those predicted by the Astrand-Ryhming Test. No differences were observed between the 50 and 80 rpm Astrand-Ryhming protocols. It was concluded that the administration of Astrand-Ryhming Tests at 80 rpm is acceptable, and the resultant predictions of maximal oxygen intake are clinically accurate. It was suggested that use of the Astrand-Ryhming Tests be limited to general fitness screening situations where more sophisticated techniques are unavailable.

Cardiopulmonary adjustment and metabolic response to maximal and submaximal physical exercise of boys and girls at different stages of maturity

Article

Nov 1978
Eur J Appl Physiol Occup Physiol

Cardiopulmonary and metabolic variables were investigated at maximal and submaximal bicycle ergometer exercises in 41 swimmers of both sexes, 8–18 years old.

\dot V

O2 max and

\dot V

O2 max·HR−1 were higher in boys than in girls and increased with maturity, while

\dot V

O2 max·kg−1 and HVE were not influenced by this. The HV increased clearly during this growth period, the pubertal and postpubertal subjects showing 16 and 17% higher values for HV and HV·kg−1 than those reported in normal schoolchildren populations. During the submaximal exercise at 70%

\dot V

O2 max the highest HR values were found in the prepubertal group, whilst the lowest were observed in the postpubertal subjects. These findings suggest that a given percentage of

\dot V

O2 max as a reference unit, is more reliable than a certain HR to obtain comparable results in subjects with different ages. Blood samples were collected before, during, and after the submaximal exercise. Blood glucose and FFA did not differ in relation to the stages of maturity. During exercise, insulin decreased in prepubertal children, did not alter in pubertal adolescents, and increased in postpubertal subjects. The lactate concentration, during exercise, increased in relation to maturity. The same results were found for HGH, but no differences were found with regard to sex. Since the pattern of HGH secretion during exercise is similar to that found after arginine and insulin administration it is assumed that the same mechanism (i.e., sex hormones) triggers the HGH release.

Reliability and reproducibility of maximal oxygen uptake measurement in children

Article

Feb 1977
Med Sci Sports

Maximal aerobic capacity of 66 ten year old ice hockey players was measured on a treadmill twice over a 4 to 5 month period. This time approximated mid (T1) to post (T2) competitive season. The results of these VO2 max tests were grouped according to the presence or absence of a plateau in the oxygen uptake (less than 2.1 ml/kg-min) during the last work loads before fatigue. The mean values for T1 and T2 were not significantly different for any of the measurements made; the reproducibility was considered to be high. The reliability of the measures varied with the presence or absence of a plateau at maximum, for example; VO2 max, plateau r = 0.74, no plateau r = 0.27; heart rate, plateau r = 0.92, no plateau r = 0.40. The differences between the mean values for the "double plateau" group when compared to the "no plateau" group were not significant for VO2 max, HR or VE. The differences were significant for the post-exercise blood lactate and respiratory exchange values at T2 only; the "double plateau" group reached higher values in each case (R = 1.00 vs 0.92; blood lactate 6.5 vs 5.4 mM/1).

Prolonged exercise in prepubertal boys. II. Changes in plasma volume and in some blood constituents

Article

Oct 1976
Eur J Appl Physiol Occup Physiol

A group of 10 prepubertal boys was studied during prolonged exercise (60 min) on bicycle ergometer and on treadmill at two levels of work load (appr. 40% and 60% VO2 max). The hematocrit, serum proteins, Cl- and K+ were followed, and from the blood hematocrit changes the plasma volume changes were calculated. At the exercises of lower intensity of both types a slight hemodilution was found (appr. +5% increase in plasma volume), at higher intensity practically no changes could be demonstrated. These findings are supported by the values of serum protein concentration, where no increase was found, and by the fact that at the lower work loads a rather decreasing trend was found for this blood constituent. These findings are at variance with those in adults under similar conditions. The authors suggest that different changes of plasma volume during exercise in boys than in adults could be related to the disparate lactate production and fate in these age groups.

Prolonged exercise in prepubertal boys - I. Cardiovascular and metabolic adjustment

Article

Oct 1976
Eur J Appl Physiol Occup Physiol

The circulatory and metabolic changes during prolonged exercise (60 min) were studied in a group of 10 healthy prepubertal boys. The boys worked on the treadmill and on the bicycle ergometer at two levels of load, namely at oxygen uptakes of 36--39%, and 60% of the respective VO2 max for both types of exercise. The identical relative work loads represent higher metabolic rate at the treadmill exercise. The rectal temperature was higher after exercises on treadmill than on bicycle. The heart rate increase during prolonged exercise was lower in boys than in adults in both types of exercise. Better cardiovascular adjustment is suggested. The blood lactate increase was negligible in the initial phase of exercise with subsequent removal from the blood during extended exercise, which was more pronounced at the treadmill exercises. The increasing blood free glycerol concentration indicates similar fat share on energy release in children as in adults. No biological handicap could be found for prolonged exercise in children. The preference of short-time exercises in children lies probably in the psychological sphere.

Relationship Between Upper Body Anaerobic Power and Freestyle Swimming Performance

Article

Mar 1991

The purpose of this study was to examine the role of upper body anaerobic power, as measured by the Wingate Anaerobic Arm Test (WAAT), in 50-m sprint swim performance. Thirty competitive age-group swimmers (14 males and 16 females) participated in this investigation. Subjects had been training daily for 5 months prior to the study, swimming an average of 6,000 m.d-1, 6 d.wk-1. Swimmers performed a WAAT and a 50-m time-trial. Peak power (PP), mean power (MP) and fatigue index (FI) were determined for the WAAT. Subjects also reported their current competition performances for all distances up to 400 m. Significant relationships were obtained between swim speed over 50 m (S50) and PP (r = 0.82, p less than 0.001), S50 and MP (r = 0.83, p less than 0.001), and S50 and FI (r = 0.41, p less than 0.05). PP and MP showed significant but generally decreasing correlations with swim speed as distance increased. Substantial relationships (r = 0.74-0.96, p less than 0.001) were found between S50 and swim speeds over distances up to and including 400 m. This study shows a strong relationship exists between upper body anaerobic power, as measured by the WAAT, and performance in both sprint and longer distance (400 m) swim events. The WAAT may serve as a useful tool for coaches to objectively evaluate and monitor the upper body anaerobic power of competitive swimmers.

Exercise endurance and fuel utilization: A reevaluation of the effects of fasting

Article

Apr 1991

The effect of fasting on energy utilization during running or swimming was studied in adult male Wistar rats. Compared with fed rats, fasted animals displayed a decreased contribution of carbohydrates in energy supply, with decreased liver and muscle glycogen contents and decreased rate of glycogen breakdown. This was compensated by an enhanced rate of beta-oxidation. In addition, fasting induced an exaggerated sympathoadrenal response during exercise, reflected by a greater epinephrine plasma level and a higher norepinephrine turnover rate in both liver and soleus. Nevertheless, endurance capacity was similar in fasted and fed animals. These results contrast with the impairment of endurance observed in fasting humans but also with the improvement of endurance in rats previously reported by Dohm et al. (J. Appl. Physiol. 55: 830-833, 1983). These data suggest that the metabolic responses to exercise subsequent to food deprivation depend not only on the considered species but also, in the same species (rat), on the age of the animals and the duration of the fast. These factors probably determine the hormonal secretion and substrate utilization during prolonged exercise in fasting conditions.

Effect of sampling variability and plateau on oxygen uptake

Article

Feb 1990

To evaluate the effect of the gas exchange sampling interval on variability and plateau in O2 uptake (VO2), 10 subjects underwent steady-state treadmill exercise at 50% maximal VO2 and 6 subjects underwent maximal testing using a ramp protocol. During steady-state exercise, gas exchange data were acquired by using 10 different sampling intervals. The variability in VO2 was greater as the sampling interval shortened (SD = 4.5 ml.kg-1.min-1 for breath-by-breath vs. 0.8 ml.kg-1.min-1 for 60-s samples). The breath-by-breath data suggested a Gaussian distribution, and most of the variability was attributable to tidal volume (51%). During ramp testing, the slope of the change in VO2 (for each sample) was regressed with time. Considerable variability in the slopes was observed throughout exercise, and in each subject the slopes varied about zero, demonstrating both positive and negative values throughout submaximal effort. These observations were made despite the use of large sampling intervals. Shortening the sample resulted in even greater variability. We conclude that 1) the sampling interval can have a major impact on gas exchange data during exercise and 2) considerable variability exists in the slope of the change in VO2 with a consistent change in external work regardless of the sample used, suggesting that a plateau (defined as the slope of a VO2 sample at peak exercise that does not differ significantly from a slope of zero) in VO2 is not a reliable physiological marker for maximal effort.

Peak treadmill running velocity during the VO2 max test predicts running performance

Article

Feb 1990

Twenty specialist marathon runners and 23 specialist ultra-marathon runners underwent maximal exercise testing to determine the relative value of maximum oxygen consumption (VO2max), peak treadmill running velocity, running velocity at the lactate turnpoint, VO2 at 16 km h-1, % VO2max at 16 km h-1, and running time in other races, for predicting performance in races of 10-90 km. Race time at 10 or 21.1 km was the best predictor of performance at 42.2 km in specialist marathon runners and at 42.2 and 90 km in specialist ultra-marathon runners (r = 0.91-0.97). Peak treadmill running velocity was the best laboratory-measured predictor of performance (r = -0.88(-)-0.94) at all distances in ultra-marathon specialists and at all distances except 42.2 km in marathon specialists. Other predictive variables were running velocity at the lactate turnpoint (r = -0.80(-)-0.92); % VO2max at 16 km h-1 (r = 0.76-0.90) and VO2max (r = 0.55(-)-0.86). Peak blood lactate concentrations (r = 0.68-0.71) and VO2 at 16 km h-1 (r = 0.10-0.61) were less good predictors. These data indicate: (i) that in groups of trained long distance runners, the physiological factors that determine success in races of 10-90 km are the same; thus there may not be variables that predict success uniquely in either 10 km, marathon or ultra-marathon runners, and (ii) that peak treadmill running velocity is at least as good a predictor of running performance as is the lactate turnpoint. Factors that determine the peak treadmill running velocity are not known but are not likely to be related to maximum rates of muscle oxygen utilization.

Thermoregulation at rest and during exercise in prepubertal boys

Article

Feb 1990
Eur J Appl Physiol Occup Physiol

Thermal balance was studied in 11 boys, aged 10–12 years, with various values for maximal oxygen uptake (

\dot V_{O_{2 max} }

), during two standardized sweating tests performed in a climatic chamber in randomized order. One of the tests consisted in a 90-min passive heat exposure [dry bulb temperature (T db) 45° C] at rest. The second test was represented by a 60-min ergocycle exercise at 60% of individual

\dot V_{O_{2 max} }

(T db 20° C). At rest, rectal temperature increased during heat exposure similar to observations made in adults, but the combined heat transfer coefficient reached higher values, reflecting greater radiative and convective heat gains in the children. Children also exhibited a greater increase in mean skin temperature, and a greater heat dissipation through sweating. Conversely, during the exercise sweating-test, although the increase in rectal temperature did not differ from that of adults for similar levels of exercise, evaporative heat loss was much lower in children, suggesting a greater radiative and convective heat loss due to the relatively greater body surface area. Thermophysiological reactions were not related to

\dot V_{O_{2 max} }

in children, in contrast to adults.

Ten kilometer performance and predicted velocity at V̇O2 among well-trained male runners

Article

Mar 1989

Previous research (study 1) has shown that a significant relationship exists between 10 km run time (RT) and predicted running velocity at VO2max (vVO2max) among well-trained males heterogeneous in VO2max. Since competitive runners often display a homogeneous fitness profile, the purpose of this study was to determine the association between 10 km RT and vVO2max among a group of trained runners exhibiting nearly identical VO2max values (study 2). Running economy (RE), vVO2max, and velocity at a 4 mM blood lactate concentration (v at 4 mM BL) were calculated in both studies. Correlations were obtained as shown in Table 2. The relationship between VO2max and 10 km RT achieved statistical significance only in study 1, while RE explained a greater amount of performance variation in study 2. In both studies, variation in 10 km RT attributable to vVO2max was similar and exceeded that due to either VO2max or RE. vVO2max also accounted for essentially the same amount of variation in 10 km RT as did v at 4 mM BL. It was concluded that, among well-trained subjects homogeneous in VO2max, a strong relationship exists between 10 km RT and vVO2max that appears to be mediated to a large extent by RE.

Implications of exercise testing for prediction of athletic performance: A contemporary perspective

Article

Sep 1988

Timothy D Noakes

One of the most fundamental beliefs in exercise physiology is that performance during maximum exercise of short duration is limited by the inability of the heart and lungs to provide oxygen at a rate sufficiently fast to fuel energy production by the active muscle mass. This belief originates from work undertaken in the 1920's by Hill and Lupton. A result is that most, if not all, of the studies explaining the effects of exercise training or detraining or other interventions on human physiology explain these changes in terms either of central adaptations increasing oxygen delivery to muscle or of peripheral adaptations that modify the rates of oxygen or fuel utilization by the active muscles. Yet a critical review of Hill and Lupton's results shows that they inferred but certainly did not prove that oxygen limitation develops during maximal exercise. Furthermore, more modern studies suggest that, if such an oxygen limitation does indeed occur during maximal exercise, it develops in about 50% of test subjects. Thus, an alternative mechanism may need to be evoked to explain exhaustion during maximal exercise in a rather large group of subjects. This review proposes that the factors limiting maximal exercise performance might be better explained in terms of a failure of muscle contractility ("muscle power"), which may be independent of tissue oxygen deficiency. The implications for exercise testing and the prediction of athletic performance are discussed.

Normal Values of Catecholamines in Blood Plasma Determined by High-Performance Liquid Chromatography with Amperometric Detection*

Article

Sep 1988

Norepinephrine (NE), epinephrine (EPI), and dopamine (DA) were determined in the blood plasma of 122 subjects by high-performance liquid chromatography with amperometric detection (HPLCA). The range of normal values in the supine position was 0.15-3.50 nmol/1 for NE, 0.01-0.80 nmol/1 for EPI, and 0.04-4.50 nmol/1 for DA. The effect induced by inserting intravenous catheters, food intake, cigarette smoking, varying body positions, and sex differences are also presented in this paper. As a modified HPLCA method was used, we were able to examine a large collective group. Thus, it was possible to compare the results of other authors which have been found in smaller collective groups.

Glucoregulation during exercise: Hypoglycemia is prevented by redundant glucoregulatory systems, sympathochromaffin activation, and changes in islet hormone secretion

Article

Feb 1986

During mild or moderate nonexhausting exercise, glucose utilization increases sharply but is normally matched by increased glucose production such that hypoglycemia does not occur. To test the hypothesis that redundant glucoregulatory systems including sympathochromaffin activation and changes in pancreatic islet hormone secretion underlie this precise matching, eight young adults exercised at 55-60% of maximal oxygen consumption for 60 min on separate occasions under four conditions: (a) control study (saline infusion); (b) islet clamp study (insulin and glucagon held constant by somatostatin infusion with glucagon and insulin replacement at fixed rates before, during and after exercise with insulin doses determined individually and shown to produce normal and stable plasma glucose concentrations prior to each study); (c) adrenergic blockage study (infusions of the alpha- and beta-adrenergic antagonists phentolamine and propranolol); (d) adrenergic blockade plus islet clamp study. Glucose production matched increased glucose utilization during exercise in the control study and plasma glucose did not fall (92 +/- 1 mg/dl at base line, 90 +/- 2 mg/dl at the end of exercise). Plasma glucose also did not fall during exercise when changes in insulin and glucagon were prevented in the islet clamp study. In the adrenergic blockade study, plasma glucose declined initially during exercise because of a greater initial increase in glucose utilization, then plateaued with an end-exercise value of 74 +/- 3 mg/dl (P less than 0.01 vs. control). In contrast, in the adrenergic blockade plus islet clamp study, exercise was associated with glucose production substantially lower than control and plasma glucose fell progressively to 58 +/- 7 mg/dl (P less than 0.001); end-exercise plasma glucose concentrations ranged from 34 to 72 mg/dl. Thus, we conclude that: (a) redundant glucoregulatory systems are involved in the precise matching of increased glucose utilization and glucose production that normally prevents hypoglycemia during moderate exercise in humans. (b) Sympathochromaffin activation, perhaps sympathetic neural norepinephrine release, plays a primary glucoregulatory role by limiting glucose utilization as well as stimulating glucose production. (c) Changes in pancreatic islet hormone secretion (decrements in insulin, increments in glucagon, or both) are not normally critical but become critical when catecholamine action is deficient. (d) Glucoregulation fails, and hypoglycemia can develop, both when catecholamine action is deficient and when changes in islet hormones do not occur during exercise in humans.

Influence of body size on oxygen consumption during bicycling

Article

Mar 1987

Energy in bicycling is primarily expended to overcome air resistance, which is proportional to a cyclist's surface area (SA). Thus we hypothesized that large cyclists should have a lower O2 consumption normalized to body weight (VO2/BW) than small cyclists because of the former's lower SA/BW. We measured the VO2/BW of small (BW = 59.4 +/- 4.1 kg) and large (BW = 84.4 +/- 3.2 kg) cyclists while they bicycled on a flat road at 10, 15, and 20 mph. The large cyclists had a 22% lower VO2/BW than the small cyclists at all speeds. However, the SA/BW ratio of the large cyclists was only 11% lower than that of the small cyclists. We then photographically determined the frontal area (FA) of the cyclists in a racing posture, and found that the large cyclists had a 16% lower FA/BW ratio than the small cyclists. We conclude that large cyclists are at a distinct advantage, in terms of VO2/BW, while bicycling on level roads, and this advantage is principally due to their lower FA/BW ratio.

Fluence of weekly training distance on fractional utilization of maximum aerobic capacity in marathon and ultramarathon runners

Article

Feb 1986
Eur J Appl Physiol Occup Physiol

This study was designed to examine the interrelationships between performance in endurance running events from 10 to 90 km, training volume 3-5 weeks prior to competition, and the fractional utilization of maximal aerobic capacity (%VO2max) during each of the events. Thirty male subjects underwent horizontal treadmill testing to determine their VO2max, and steady-state VO2 at specific speeds to allow for calculation of %VO2max sustained during competition. Runners were divided into groups of ten according to their weekly training distance (group A trained less than 60 km X week-1, group B 60 to 100 km X week-1, and group C more than 100 km X week-1). Runners training more than 100 km X week-1 had significantly faster running times (average 19.2%) in all events than did those training less than 100 km X week-1. VO2max or %VO2max sustained during competition was not different between groups. The faster running speed of the more trained runners, running at the same %VO2max during competition, was due to their superior running economy (19.9%). Thus all of the group differences in running performance could be explained on the basis of their differences in running economy. These findings suggest either that the main effect of training more than 100 km X week-1 may be to increase running economy, or that runners who train more than 100 km X week-1 may have inherited superior running economy.(ABSTRACT TRUNCATED AT 250 WORDS)

A physiologist's view of running economy

Article

Jul 1985

J T Daniels

The relationship between VO2 and velocity of running (running economy) has been rather casually dealt with until very recently, and there still remains considerable disagreement as to the importance of this variable. Various factors which have been shown, or appear, to affect running economy include environment (temperature, altitude, running surface), fatigue, age, weight, state of fitness, and inherent differences. That differences between individuals and within individuals can and do exist seems clear; the questions which need to be addressed in future research are: (1) What type of training is most effective in bringing about changes in running economy? and (2) How much change in economy can be expected with optimum training? Furthermore, it is suggested that running economy be investigated as an entity, so that changes that may take place with time or training can be more accurately related to their cause.

Variability of Aerobic Performance in the Laboratory and Its Physiologic Correlates

Article

Sep 1985

To study the physiologic basis of variability of physical performance in the laboratory, ten male subjects were studied once a week, during a 9-12 month period. Previously, the reference maximal work load attained (Wref) was determined in each subject. The test protocol of the actual study was based on the individual Wref and started at 70% Wref for 5 min whereupon the work load was increased by 5% Wref every 2.5 min to exhaustion. The maximal work load attained (Wmax) was considered as the test performance. Heart rate, respiratory variables, oxygen uptake (VO2), and blood lactate concentration were determined at each work load. The rate of perceived exertion during submaximal and maximal work was also scored. In all subjects, Wmax and VO2max varied randomly, while the coefficient of variation in VO2max (4.20% - 11.35%) exceeded that in Wmax (2.95%-6.83%). No seasonal influences on VO2 max and Wmax were observed. In all subjects the physiologic variables, when plotted as a function of external work load, were shifted to the right with higher Wmax values and to the left with lower Wmax values. With lower Wmax values, the rate of perceived exertion during submaximal work tended to increase. The results suggest that the magnitude of physiologic responses to exercise is related to relative work load and that variability of physical performance is related to changes in gross mechanical efficiency.

Regulation of glucose uptake by muscle. 8. Effects of fatty acids, ketone bodies and pyruvate, and of alloxan-diabetes and starvation, on the uptake and metabolic fate of glucose in rat heart and diaphragm muscles

Article

Jan 1965

Physical training, oxygen supply and muscle metabolism in 11-13-year old boys

Article

Feb 1972
Acta Physiol Scand Suppl

B O Eriksson

Criteria for maximum oxygen uptake in men over 40 in a population survey

Article

Feb 1972
Med Sci Sports

There was no correlation between four criteria for maximal Yo2 in sixty-five men, aged 40-65 years. 78% of subjects had lactic acid values above 8 mMol/l, 74% had heart rates within 5 beats of average maximal for age, 54% had respiratory quotient values over 1.12 and 43% of subjects had Vo2 valves below 90% of the expected Vo2 for the work load used. There was no difficulty in having these unfit subjects cycle for fifteen minutes. The average maxYo2 was about 30 ml/kg-min-1;and as there was no attempt to show a plateau for Vo2 it is preferable to use the term “near maximal” rather than maximal.

Hormonal and metabolic changes during and after prolonged muscular work in pre-pubertal boys

Article

Feb 1971
Acta Paediatr Scand Suppl

The effects of repeated prolonged exercise on plasma growth hormone, insulin, glucose, free fatty acids, glycerol, lactate and -hydroxybutyric acid in 13-year old boys and in adults

Article

Feb 1971
Acta Paediatr Scand Suppl

Maximal oxygen intake among marathon runners

Article

Jul 1970
ARCH PHYS MED REHAB

Muscle Glycogen during Prolonged Severe Exercise

Article

Oct 1967

10 well trained and 10 untrained subjects worked to complete exhaustion on a bicycle ergometer with work loads averaging 77 (76–87) per cent of their individual maximal aerobic power. Determinations of glycogen used by working muscles (biopsy of lateral portion of the quadriceps femoris muscles) and of combusted carbohydrate (Vo2 and RQ) were performed at certain intervals from the start of work to exhaustion. At a combustion rate of about 3 g carbohydrate per minute (RQ around 0.9 or higher) and at average values for glycogen in resting muscle of 1.6 (1.1–2.5)g/100 wet muscle, the effective work time was around 85 min for the untrained and 90 min for the trained subjects. At the end of the exhaustive exercise the glycogen content averaged 0.06 g in the untrained and 0.12 g/100 g wet muscle in the trained subjects. A close relationship between utilized glycogen and combusted carbohydrate was found, and it seems highly probable that at high relative workloads primarily the glycogen stores in the exercising muscles will limit the capacity for prolonged strenuous work.

The relationship between selected physiological variables and distance running performance

Article

Jul 1967

David L Costill

The effect of a 20-week endurance training program on adipose-tissue morphology and lipolysis in men and women

Article

Apr 1984
METABOLISM

In order to assess the effect of endurance training on adipose-tissue morphology and lipolysis, 22 adult subjects (11 men and 11 women) took part in a 20-week ergocycle training program, four to five days a week, 40 minutes a day, at 80% of their maximal heart rate. Before and after training, they were submitted to an adipose-tissue biopsy in the suprailiac region. Fat cell weight (FCW), and lipolytic activity were determined on isolated fat cells. For the whole sample, training significantly reduced FCW (pre: 0.40 +/- 0.13 (mean +/- SD) versus post: 0.36 +/- 0.13 micrograms; P less than 0.05), percentage of fat (pre: 22.0 +/- 8.3 versus post: 19.7 +/- 8.1%; P less than 0.05), and increased adipocyte epinephrine maximal stimulated lipolysis (ESL) (pre: 1.08 +/- 0.49 versus post: 1.69 +/- 0.67 mumol glycerol/30 min/10(6) cells; P less than 0.001). No changes were observed in fat cell number. In women, however, training induced no changes in the fatness indicators (% fat, sum of skinfolds, FCW). The exercise program significantly lowered the adiposity of men (% fat: P less than 0.001; sum of skinfolds: P less than 0.01; FCW: P less than 0.05). In both sexes, a significant increase in ESL was observed after training. ESL of men, however, responded better than that of women to training (ESL of women: 1.36 +/- 0.67 versus ESL of men: 2.02 +/- 0.50 mumol glycerol/30 min/10(6) cells; P less than 0.05), with increases over pre-training values of 46% and 66% in women and men, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men

Article

Feb 1980
Eur J Appl Physiol Occup Physiol

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p<0.01), aldosterone 13 times (p<0.05), Np 2.6 times (p<0.05), and AVP 4.8 times (p<0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.

Enzyme activities in skeletal muscle of 13-15 years old adolescents

Article

Jan 1982

G Haralambie

The activity of 22 enzymes of energy metabolism was determined in m. vastus lateralis quadricipitis of 14 adolescents aged 13-15 years (7 girls) and 14 adults aged 22 to 42 years (7 female subjects). The measurements were performed kinetically, at 37 degrees C, using optimal or near-to-optimal procedures. With the exception of one enzyme, enolase, no differences between sexes were observed in the two age groups. Glycolytic enzymes, including fructose-6-phosphate kinase, showed no significant differences in their activity in adults as compared to adolescents. The activity of enolase was lower in females of both age groups, but no difference due to age was found in this respect. Of the oxidative enzymes studied, only citrate synthase showed no significant difference in adults vs adolescents, whereas the activities of lipoamide dehydrogenase (+ 40%), NADP-isocitrate dehydrogenase (+ 44%), fumarase (+ 24.5%), total malate dehydrogenase (+ 42.2%) and NADH-dehydrogenase (+ 39%) were all significantly higher in the latter group. Aspartate aminotransferase was also 44% higher in adolescents. The possible physiological importance of these observations is discussed with regard to the functional capacity of the skeletal muscle. The hypothesis was considered that adolescents of this age may have a glycolytic capacity comparable to adults, but that they may oxidize pyruvate at a rate higher than adults.

Peak power output predicts maximal oxygen uptake and performance time

Abstract

No full-text available

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