Article

Determinants of endurance in well-trained cyclists

July 1988
Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology 64(6):2622-30

DOI:10.1152/jappl.1988.64.6.2622

Source
PubMed

Authors:

United States Army Institute of Surgical Research

Fourteen competitive cyclists who possessed a similar maximum O2 consumption (VO2 max; range, 4.6-5.0 l/min) were compared regarding blood lactate responses, glycogen usage, and endurance during submaximal exercise. Seven subjects reached their blood lactate threshold (LT) during exercise of a relatively low intensity (group L) (i.e., 65.8 +/- 1.7% VO2 max), whereas exercise of a relatively high intensity was required to elicit LT in the other seven men (group H) (i.e., 81.5 +/- 1.8% VO2 max; P less than 0.001). Time to fatigue during exercise at 88% of VO2 max was more than twofold longer in group H compared with group L (60.8 +/- 3.1 vs. 29.1 +/- 5.0 min; P less than 0.001). Over 92% of the variance in performance was related to the % VO2 max at LT and muscle capillary density. The vastus lateralis muscle of group L was stressed more than that of group H during submaximal cycling (i.e., 79% VO2 max), as reflected by more than a twofold greater (P less than 0.001) rate of glycogen utilization and blood lactate concentration. The quality of the vastus lateralis in groups H and L was similar regarding mitochondrial enzyme activity, whereas group H possessed a greater percentage of type I muscle fibers (66.7 +/- 5.2 vs. 46.9 +/- 3.8; P less than 0.01). The differing metabolic responses to submaximal exercise observed between the two groups appeared to be specific to the leg extension phase of cycling, since the blood lactate responses of the two groups were comparable during uphill running. These data indicate that endurance can vary greatly among individuals with an equal VO2 max.(ABSTRACT TRUNCATED AT 250 WORDS)

Conventional methods to prescribe exercise intensity are ineffective for exhaustive interval training

Article

Full-text available

Mar 2023
EUR J APPL PHYSIOL

Purpose: To compare methods of relative intensity prescription for their ability to normalise performance (i.e., time to exhaustion), physiological, and perceptual responses to high-intensity interval training (HIIT) between individuals. Methods: Sixteen male and two female cyclists (age: 38 ± 11 years, height: 177 ± 7 cm, body mass: 71.6 ± 7.9 kg, maximal oxygen uptake ([Formula: see text]O2max): 54.3 ± 8.9 ml·kg-1 min-1) initially undertook an incremental test to exhaustion, a 3 min all-out test, and a 20 min time-trial to determine prescription benchmarks. Then, four HIIT sessions (4 min on, 2 min off) were each performed to exhaustion at: the work rate associated with the gas exchange threshold ([Formula: see text]GET) plus 70% of the difference between [Formula: see text]GET and the work rate associated with [Formula: see text]O2max; 85% of the maximal work rate of the incremental test (85%[Formula: see text]max); 120% of the mean work rate of the 20 min time-trial (120%TT); and the work rate predicted to expend, in 4 min, 80% of the work capacity above critical power. Acute HIIT responses were modelled with participant as a random effect to provide estimates of inter-individual variability. Results: For all dependent variables, the magnitude of inter-individual variability was high, and confidence intervals overlapped substantially, indicating that the relative intensity normalisation methods were similarly poor. Inter-individual coefficients of variation for time to exhaustion varied from 44.2% (85%[Formula: see text]max) to 59.1% (120%TT), making it difficult to predict acute HIIT responses for an individual. Conclusion: The present study suggests that the methods of intensity prescription investigated do not normalise acute responses to HIIT between individuals.

Enhancing Team Pursuit Performance using Blood Flow Restriction.

Thesis

Full-text available

Mar 2024

Charles Pugh

The studies in this thesis investigated the physiological determinants of 4-km team-pursuit (TP) track cycling performance and critically evaluated the use of modelling finite work capacity (W′) and its dynamic balance (W′BAL) during the TP. This thesis also examined the integration of blood flow restriction (BFR) into high-intensity interval training (HIIT) as an intervention to improve factors related to TP performance. A series of related investigations were conducted with trained cyclists up to the Olympic level. Study One recruited male TP squads from International, National, and Regional performance levels. The TP squads were assessed for their critical power (CP) and W′. Maximal 4-km TP efforts confirmed different performance times of 3:49.9, 3:56.7, and 4:05.4 (minutes:s) for International, National, and Regional, respectively. Four TP simulation trials quantified W′ reconstitution from 0 to 100 W below CP. Results showed that the International squad were differentiated from National and Regional performance levels with greater CP (p < 0.05), likely preserving W′ for leading efforts. Furthermore, the International team possessed the fastest rates of W′ reconstitution at recovery intensities within 50 W of CP (p < 0.05), demonstrating the importance of W′ reconstitution at intensities near CP for recovery in the TP. The International team also expended a greater total quantity of W′ than its initial size (104 ± 5%), further demonstrating the capacity to utilise the reconstituted W′. In conclusion, we found that the TP relies on high aerobic capacity and rapid metabolic recovery abilities. An intervention was conceived based on the demands of the TP and the existing training sessions of elite TP cyclists. The training intervention included principles of TP training philosophy where cyclists repeatedly practice competition demands, at their TP lead intensity. As elite TP cyclists engage in substantial training volumes, it was important not to substantially exceed current training workloads. Based on previous BFR research with trained cyclists, an intervention integrating BFR into the recovery between TP efforts was devised. The intervention was performed on an ergometer to enable greater control over conditions and intensity. To evaluate the metabolic demands of the BFR intervention, the Study Two assessed the acute physiological responses in 11 male and female highly-trained cyclists (V̇O2PEAK 65 ± 9 mL·kg-1·minute-1). Using a within-subject design, participants performed two work- and duration-matched HIIT sessions. The HIIT consisted of six high-intensity repetitions with BFR occlusion between work bouts at 200 mmHg for 2-minutes applied proximally on the thighs (BFR) or HIIT alone without BFR (CON). Work intensity was set as 85% of the mean power output of a maximal 30-s test to simulate TP lead intensity. Cardiopulmonary variables (O2 uptake, V̇O2; carbon dioxide production V̇CO2; and ventilation, V̇E) and muscle oxygenation responses were measured during the HIIT, and vascular endothelial growth factor (VEGF) was measured pre- and 3-hours post-HIIT. Results demonstrated that BFR increased V̇CO2 and V̇E (both p < 0.05) during work bouts but did not affect V̇O2 and TSI (both p>0.05). Compared to CON, the BFR intervention significantly decreased V̇O2, V̇CO2, V̇E, and TSI during BFR occlusion (all p<0.05). Following cuff release, there were significantly higher values of V̇O2, V̇CO2, and V̇E, whereas TSI was suppressed (all p < 0.05). There were significant enhancements of serum VEGF concentration at 3-hours post-HIIT after BFR when compared to CON. As BFR appeared to delay recovery, it was hypothesised that BFR may increase metabolic and oxidative stress by delaying recovery processes. The delay in recovery may enhance the adaptations to HIIT without increasing training workload. After demonstrating that applying BFR during recovery in high-intensity work bouts increased markers of physiological stress, Study Three assessed the performance and physiological effects of the training as a chronic intervention. Using a between-subject design, ten performance-matched male trained cyclists (weekly volume >6-hours·week-1) were assigned to BFR or CON conditions. Participants performed pre- and post-intervention tests to determine lactate thresholds, 30-s maximal sprint cycling performance, and an intermittent test designed with high-intensity bouts comparable to the TP. Work bouts were performed at 85% of the mean power output of the maximal 30-s test. Muscle oxygenation and cardiopulmonary measures were continually assessed throughout the intermittent test. Participants performed four-weeks of work- and duration-matched HIIT either with 2-minutes of 200 mmHg thigh BFR between work bouts or HIIT alone (CON). Following BFR intervention, there were significant improvements in intermittent test time to exhaustion, 30-s mean power output, and submaximal lactate thresholds compared to CON (all p < 0.05). Furthermore, BFR led to significant intermittent test improvements for V̇O2PEAK and the rate of muscle tissue reoxygenation (all p < 0.05). There were no significant changes over the intervention period for CON, indicating that HIIT was ineffective in this cohort when BFR was not incorporated. Therefore, it was demonstrated that the integration of BFR between HIIT work bouts improves intermittent performance and a range of physiological factors associated with performance in trained cyclists. Finally, the BFR intervention was integrated into two HIIT sessions within a training camp of an elite TP squad preparing for the Olympic Games to test its potential efficacy and feasibility. As in the previous BFR studies, this case-study (Study Four) applied 2-minutes of 200 mmHg thigh BFR between high-intensity bouts. Work intensities were set at the individual cyclists’ TP lead intensity. A questionnaire was developed to assess the pain, tolerance, enjoyment, and compare the intervention to other training modalities. Questionnaire responses indicated that the elite cyclists enjoyed and positively perceived the intervention, appreciating the variety and efficiency of the training stimulus. All but one elite cyclist tolerated that intervention. Further investigation in conjunction with medical staff indicated that the intolerant cyclist had a pre-existing undiagnosed cardiovascular condition and presented with femoral artery claudication (discussed in the addendum). Thus, integrating BFR into HIIT for elite track cyclists was feasible and tolerable when no contraindications existed. In summary, elite TP performance relies on high sustained aerobic power output and rapid W′ recovery between efforts. This thesis showed integrating BFR between HIIT work bouts provides an additional training stimulus and can improve factors related to aerobic capacity and high-intensity intermittent performance in trained cyclists. The BFR intervention is tolerable within an elite cohort and may improve TP performance without increasing training workload.

Peripheral limitations for performance: Muscle capillarization

Article

Full-text available

Sep 2023
SCAND J MED SCI SPOR

Sufficient delivery of oxygen and metabolic substrates, together with removal of waste products, are key elements of muscle performance. Capillaries are the primary site for this exchange in skeletal muscle and the degree of muscle capillarization affects diffusion conditions by influencing mean transit time, capillary surface area and diffusion distance. Muscle capillarization may thus represent a limiting factor for performance. Exercise training increases the number of capillaries per muscle fiber by about 10%–20% within a few weeks in untrained subjects, whereas capillary growth progresses more slowly in well‐trained endurance athletes. Studies show that capillaries are tortuous, situated along and across the length of the fibers with an arrangement related to muscle fascicles. Although direct data is lacking, it is possible that years of training not only enhances capillary density but also optimizes the positioning of capillaries, to further improve the diffusion conditions. Muscle capillarization has been shown to increase oxygen extraction during exercise in humans, but direct evidence for a causal link between increased muscle capillarization and performance is scarce. This review covers current knowledge on the implications of muscle capillarization for oxygen and glucose uptake as well as performance. A brief overview of the process of capillary growth and of physical factors, inherent to exercise, which promote angiogenesis, provides the foundation for a discussion on how different training modalities may influence muscle capillary growth. Finally, we identify three areas for future research on the role of capillarization for exercise performance.

Molecular Responses to Acute Exercise and Their Relevance for Adaptations in Skeletal Muscle to Exercise Training

Article

Jul 2023
PHYSIOL REV

Repeated, episodic bouts of skeletal muscle contraction undertaken frequently as structured exercise training is a potent stimulus for physiological adaptation in many organs. Specifically in skeletal muscle, remarkable plasticity is demonstrated by the remodeling of muscle structure and function in terms of muscular size, force, endurance, and contractile velocity as a result of the functional demands induced by various types of exercise training. This plasticity, and the mechanistic basis for adaptations to skeletal muscle in response to exercise training, is underpinned by activation and/or repression of molecular pathways and processes induced in response to each individual acute exercise session. These pathways include the transduction of signals arising from neuronal, mechanical, metabolic, and hormonal stimuli through complex signal transduction networks, which are linked to a myriad of effector proteins involved in the regulation of pre- and post-transcriptional processes, and protein translation and degradation processes. This review therefore describes acute exercise-induced signal transduction and the molecular responses to acute exercise in skeletal muscle including emerging concepts such as epigenetic pre- and post-transcriptional regulation, and the regulation of protein translation and degradation. A critical appraisal of methodological approaches and the current state of knowledge informs a series of recommendations offered as future directions in the field.

Exercise and Muscle Glycogen Metabolism

Chapter

Jan 2022

Muscle glycogen is an important fuel source for contracting skeletal muscle, and it is well documented that exercise performance is impaired when the muscle’s stores of glycogen are exhausted. The role of carbohydrate (CHO) availability on exercise performance has been known for more than a century, while the specific role of muscle glycogen for muscle function has been known for half a century. Nonetheless, the precise cellular and molecular mechanisms by which glycogen availability regulates cell function and contractile-induced fatigue are unresolved. Alterations of pre-exercise muscle glycogen reserves by dietary and exercise manipulations or modifying the degree of dependency on endogenous glycogen during exercise have collectively established a close relationship between muscle glycogen and the resistance to fatigue. It is also apparent that glycogen availability regulates rates of muscle glycogenolysis and resynthesis, muscle glucose uptake, key steps in excitation-contraction coupling, and exercise-induced cell signaling regulating training adaptation. The present review provides both a historical and contemporary overview of the effects of exercise on muscle glycogen metabolism, addressing factors affecting glycogen use during exercise as well as the evolving concepts of how glycogen and glycolysis are integrated with cell function, skeletal muscle fatigue, and training adaptation.KeywordsGlycogenolysis, glycogen particleDietExerciseE-C coupling, fatigue, performance

Is the maximal lactate steady state concept really relevant to predict endurance performance?

Article

Full-text available

Jul 2022
EUR J APPL PHYSIOL

Purpose There is no convincing evidence for the idea that a high power output at the maximal lactate steady state (PO_MLSS) and a high fraction of 𝑉˙O2max at MLSS (%𝑉˙O2_MLSS) are decisive for endurance performance. We tested the hypotheses that (1) %𝑉˙O2_MLSS is positively correlated with the ability to sustain a high fraction of 𝑉˙O2max for a given competition duration (%𝑉˙O2_TT); (2) %𝑉˙O2_MLSS improves the prediction of the average power output of a time trial (PO_TT) in addition to 𝑉˙O2max and gross efficiency (GE); (3) PO_MLSS improves the prediction of PO_TT in addition to 𝑉˙O2max and GE. Methods Twenty-one recreationally active participants performed stepwise incremental tests on the first and final testing day to measure GE and check for potential test-related training effects in terms of changes in the minimal lactate equivalent power output (∆PO_LEmin), 30-min constant load tests to determine MLSS, a ramp test and verification bout for 𝑉˙O2max, and 20-min time trials for %𝑉˙O2_TT and PO_TT. Hypothesis 1 was tested via bivariate and partial correlations between %𝑉˙O2_MLSS and %𝑉˙O2_TT. Multiple regression models with 𝑉˙O2max, GE, ∆PO_LEmin, and %𝑉˙O2_MLSS (Hypothesis 2) or PO_MLSS instead of %𝑉˙O2_MLSS (Hypothesis 3), respectively, as predictors, and PO_TT as the dependent variable were used to test the hypotheses. Results %𝑉˙O2_MLSS was not correlated with %𝑉˙O2_TT (r = 0.17, p = 0.583). Neither %𝑉˙O2_MLSS (p = 0.424) nor PO_MLSS (p = 0.208) did improve the prediction of PO_TT in addition to 𝑉˙O2max and GE. Conclusion These results challenge the assumption that PO_MLSS or %𝑉˙O2_MLSS are independent predictors of supra-MLSS PO_TT and %V˙O2_TT.

Factors Influencing Substrate Oxidation During Submaximal Cycling: A Modelling Analysis

Article

Full-text available

Jul 2022
SPORTS MED

Background: Multiple factors influence substrate oxidation during exercise including exercise duration and intensity, sex, and dietary intake before and during exercise. However, the relative influence and interaction between these factors is unclear. Objectives: Our aim was to investigate factors influencing the respiratory exchange ratio (RER) during continuous exercise and formulate multivariable regression models to determine which factors best explain RER during exercise, as well as their relative influence. Methods: Data were extracted from 434 studies reporting RER during continuous cycling exercise. General linear mixed-effect models were used to determine relationships between RER and factors purported to influence RER (e.g., exercise duration and intensity, muscle glycogen, dietary intake, age, and sex), and to examine which factors influenced RER, with standardized coefficients used to assess their relative influence. Results: The RER decreases with exercise duration, dietary fat intake, age, VO2max, and percentage of type I muscle fibers, and increases with dietary carbohydrate intake, exercise intensity, male sex, and carbohydrate intake before and during exercise. The modelling could explain up to 59% of the variation in RER, and a model using exclusively easily modified factors (exercise duration and intensity, and dietary intake before and during exercise) could only explain 36% of the variation in RER. Variables with the largest effect on RER were sex, dietary intake, and exercise duration. Among the diet-related factors, daily fat and carbohydrate intake have a larger influence than carbohydrate ingestion during exercise. Conclusion: Variability in RER during exercise cannot be fully accounted for by models incorporating a range of participant, diet, exercise, and physiological characteristics. To better understand what influences substrate oxidation during exercise further research is required on older subjects and females, and on other factors that could explain additional variability in RER.

Research publications linked with the analysis of time to exhaustion in cycling and the importance of laboratory tests

Article

Full-text available

Jun 2022

Jose Ramon Lillo-Bevia

It seems sensible to establish that TTE in laboratories for each cyclist and for each specific physiologic event, involves a very high cost in human resources, time, and materials, as well as been highly demanding for cyclists from the physiological and physiological point of view. These facts preclude its widespread use for most of them. However, it is also evident that although the use of potentiometers in the field and the analysis of power profiles based on specific times represent the future, it must be recognized that, without the basic research carried out in laboratories around the world during the last three decades, this future would lack of the sufficient scientific support

Spaceflight and sport science: Physiological monitoring and countermeasures for the astronaut–athlete on Mars exploration missions

Article

Full-text available

Apr 2025
EXP PHYSIOL

Long‐duration spaceflight impacts essentially every system in the human body, resulting in multisystem deconditioning that might impair the health and performance of crewmembers, particularly on long‐duration exploration missions to Mars. In this review, we apply the sport science model of athlete monitoring, testing and training to astronauts; tactical athletes, whose occupation includes physically demanding tasks. We discuss exploration‐specific physiological monitoring modalities and provide a brief historical overview of physiological countermeasures to spaceflight. Finally, we suggest countermeasures to protect exploration crew health and performance, including targeted preflight and in‐flight exercise training, in‐flight exercise hardware and adjunct individualized nutrition and sleep considerations. Mars exploration missions will be exemplars of the astronaut–athlete paradigm. An integrated approach to physiological monitoring and countermeasures will maximize the likelihood of exploration mission success.

Antioxidant supplementation blunts the proteome response to three weeks of sprint interval training preferentially in human type 2 muscle fibres

Preprint

Jan 2025

Sprint interval training (SIT) is a time-efficient type of endurance training that involves large type 2 muscle fibre recruitment. Effiective antioxidant supplementation may mitigate positive training adaptations by limiting the oxidant challenge. Our aim was to test whether SIT affiects type 2 more than type 1 muscle fibres, and whether the training response is mitigated by antioxidant treatment. Young men performed three SIT sessions (6 × 30 s all-out cycling) per week for three weeks while treated with antioxidants (vitamin C, 1 g/day; vitamin E, 235 mg/day) or placebo. Vastus lateralis biopsies were taken to measure (i) activation of genes for reactive oxygen/nitrogen species (ROS) sensors and inflammatory mediators with quantitative RT PCR and (ii) fibre type-specific proteome adaptations using mass spectrometry-based proteomics. Vitamin treatment decreased the upregulation of genes for ROS sensors and inflammatory regulators during the first SIT session. The three weeks of SIT caused generally larger proteome adaptations in type 2 than in type 1 fibres, and this included larger increases in abundance of proteins involved in mitochondrial energy production. Vitamin treatment blunted the SIT-induced proteome adaptations, whereas it did not affiect the training-induced improvement in maximal cycling performance. In conclusion, (i) the large type 2 fibre recruitment and resulting proteome adaptations are instrumental to the effiectiveness of SIT, and (ii) antioxidant supplementation counteracts positive muscular adaptations to SIT, which would blunt any improvement in submaximal endurance performance, whereas it does not affiect the improvement in maximal cycling performance, where O2 delivery to muscle would be limiting.

The MDM2 SNP309 differentially impacts cardiorespiratory fitness in young healthy women and men

Article

Full-text available

Dec 2024
EUR J APPL PHYSIOL

Purpose Maximal oxygen consumption (VO2max), the predominant index of cardiorespiratory fitness (CRF), is a predictor of whole-body function and longevity in humans. The central cardiac function and the skeletal muscle’s capacity to use oxygen are key determinants of VO2max. Murine Double Minute 2 (MDM2), mainly known as an oncogene, could regulate myocardial hypertrophy, skeletal muscle angiogenesis, and oxidative phosphorylation. A prevalent single nucleotide polymorphism in the MDM2 promoter (SNP309) substitutes a T for a G, supporting a greater transcriptional activity. We aim to assess whether SNP309 impacts intrinsic CRF. Methods 82 young healthy nonathletic male and female adults aged 23 ± 2 years performed cardiorespiratory exercise testing to determine their VO2max (mL kg⁻¹ min⁻¹). The genomic DNAs isolated from saliva were genotyped using Taqman-based qPCR. Results A one-way ANOVA showed that SNP309 influenced relative VO2max in the whole cohort (p = 0.044) and in men (p = 0.009), remaining non-significant in women (p = 0.133). VO2max was higher in TT homozygotes than in GT heterozygotes (whole cohort, 47 ± 12 vs. 42 ± 6 mL kg⁻¹ min⁻¹, p = 0.030; men, 53 ± 8 vs. 45 ± 6 mL kg⁻¹ min⁻¹, p = 0.011). A contingency analysis revealed a positive association between SNP309 in men in which the TT genotype was more frequent in the high VO2max group (p = 0.006). When considering G as the dominant allele, men bearing a G allele had lower relative VO2max than TT homozygotes (47 ± 7 vs. 53 ± 8, GG/GT vs. TT, p = 0.010). Conversely, women bearing a G allele had a higher relative VO2max than TT homozygotes (39 ± 5 vs. 34 ± 7, GG/GT vs. TT, p = 0.047). Conclusion SNP309 impacts VO2max in a sex-dependent manner in our cohort. Graphical abstract Created using Biorender software.

From Tissue to System: What Constitutes an Appropriate Response to Loading?

Article

Full-text available

Nov 2024
SPORTS MED

Optimal loading involves the prescription of an exercise stimulus that promotes positive tissue adaptation, restoring function in patients undergoing rehabilitation and improving performance in healthy athletes. Implicit in optimal loading is the need to monitor the response to load, but what constitutes a normal response to loading? And does it differ among tissues (e.g., muscle, tendon, bone, cartilage) and systems? In this paper, we discuss the “normal” tissue response to loading schema and demonstrate the complex interaction among training intensity, volume, and frequency, as well as the impact of these training variables on the recovery of specific tissues and systems. Although the response to training stress follows a predictable time course, the recovery of individual tissues to training load (defined herein as the readiness to receive a similar training stimulus without deleterious local and/or systemic effects) varies markedly, with as little as 30 min (e.g., cartilage reformation after walking and running) or 72 h or longer (e.g., eccentric exercise-induced muscle damage) required between loading sessions of similar magnitude. Hyperhydrated and reactive tendons that have undergone high stretch–shorten cycle activity benefit from a 48-h refractory period before receiving a similar training dose. In contrast, bone cells desensitize quickly to repetitive loading, with almost all mechanosensitivity lost after as few as 20 loading cycles. To optimize loading, an additional dose (≤ 60 loading cycles) of bone-centric exercise (e.g., plyometrics) can be performed following a 4–8 h refractory period. Low-stress (i.e., predominantly aerobic) activity can be repeated following a short (≤ 24 h) refractory period, while greater recovery is needed (≥ 72 h) between repeated doses of high stress (i.e., predominantly anaerobic) activity. The response of specific tissues and systems to training load is complex; at any time, it is possible that practitioners may be optimally loading one tissue or system while suboptimally loading another. The consideration of recovery timeframes of different tissues and systems allows practitioners to determine the “normal” response to load. Importantly, we encourage practitioners to interpret training within an athlete monitoring framework that considers external and internal load, athlete-reported responses, and objective markers, to contextualize load–response data.

Role of the ACE I/D Polymorphism in Selected Public Health-Associated Sporting Modalities: An Updated Systematic Review and Meta-Analysis

Article

Full-text available

Oct 2024
Int J Environ Res Publ Health

Background: The ACE I/D polymorphism has been suggested to be associated with multiple chronic diseases and sports modalities, which has public health implications for global populations and sport performance. This updated review aims to strengthen the association and identify sporting disciplines that are most influenced by the ACE gene polymorphism using a meta-analysis approach. Methods: Published studies on the association between the ACE I/D polymorphism and elite endurance and power were collected until 15 June 2024. The studies on public health-associated sports like running, swimming, and cycling were systematically reviewed following pre-agreed criteria, and a meta-analysis was carried out using different genetic models. Results: A total of 137 studies were identified in the literature search and screened. There was a significant association between elite endurance and the ACE II genotype compared with healthy inactive controls (OR, 1.54; 95%CI, 1.24–1.91) and elite power athletes (OR = 1.56; 95%CI = 1.07–2.28). Specifically, runners and triathletes were associated with the II genotype compared with controls (OR = 1.76; 95%CI = 1.26–2.47; p-value = 0.001 and OR = 2.69; 95%CI = 1.15–6.32, p-value = 0.023, respectively). Additionally, endurance swimmers were associated with the II genotype compared with short-distance, power swimmers (OR = 2.27; 95%CI = 1.49–3.45; p-value < 0.001). Conclusion: The meta-analysis results confirm and strengthen the association between elite endurance and the ACE I/D polymorphism in different sporting modalities, which may have implications for public health and sports participation.

Aerobic capacity and respiratory indices of junior cross-country skiers and biathletes during incremental exercise testing

Article

Full-text available

Sep 2024

The present study compared the isocapnic buffering phase (ICB), hypocapnic hyperventilation phase, ventilatory threshold (VT), respiratory compensation point (RCP), and maximum oxygen uptake (VO2max) among biathlon and cross-country ski athletes during an incremental exercise test. 37 male and 33 female Turkish National Team athletes volunteered to participate in the research. Body fat percentage, lean mass, and fat mass values of athletes were measured using the bioelectrical impedance analysis method, and oxygen consumption (VO2) was measured with a portable cardiopulmonary exercise test system with a ramp protocol on the treadmill. In VT, RCP, and VO2max phases, male athletes had higher VO2 and speed values than female athletes (p < 0.05). In contrast, they had similar values across different categories of sports (biathlon and cross-country skiing) (p > 0.05). Additionally, XC skiers and males had higher absolute (Abs) VO2 and mass-normalized (Rel) VO2 values than biathletes and females in exhaustion times and ICBs (p < 0.05). In contrast, they had similar Abs VO2 and Rel VO2 values in hypocapnic hyperventilation phases (p > 0.05). In addition, XC skiers and males had higher absolute (Abs) VO2 and relative (Rel) VO2 values than biathletes and females in exhaustion times and ICBs (p < 0.05). In contrast, they had similar Abs VO2 and Rel VO2 values in hypocapnic hyperventilation phases (p > 0.05). These results indicate significant differences in physiological profiles between male and female athletes and between XC skiers and biathletes.

The highest work rate associated with a predominantly aerobic contribution coincides with the highest work rate at which VO2max can be attained

Article

Full-text available

Jul 2024
EUR J APPL PHYSIOL

Purpose To estimate the highest power output at which predominant energy contribution is derived from the aerobic system (aerobic limit power: ALP) and to compare ALP with the upper boundary of the severe intensity exercise domain. Methods Fifteen male individuals participated in this study. The upper boundary was estimated using i) linear relationship between time to achieve

\dot{\text{V}}

O2max and time to task failure (PUPPERBOUND), ii) hyperbolic relationships between time to achieve

\dot{\text{V}}

O2max vs. power output, and time to task failure vs. power output (PUPPERBOUND´), and iii) precalculated

\dot{\text{V}}

O2max demand (IHIGH). ALP was estimated by aerobic, lactic, and phospholytic energy contributions using

\dot{\text{V}}

O2 response, blood [lactate] response, and fast component of recovery

\dot{\text{V}}

O2 kinetics, respectively. Results ALP was determined as the highest power output providing predominant aerobic contribution; however, anaerobic pathways became the predominant energy source when ALP was exceeded by 5% (ALP + 5%) (from 46 to 52%; p = 0.003; ES:0.69). The

\dot{\text{V}}

O2 during exercise at ALP was not statistically different from

\dot{\text{V}}

O2max (p > 0.05), but

\dot{\text{V}}

O2max could not be attained at ALP + 5% (p < 0.01; ES:0.63). ALP was similar to PUPPERBOUND and PUPPERBOUND´ (383 vs. 379 and 384 W; p > 0.05). There was a close agreement between ALP and PUPPERBOUND (r: 0.99; Bias: − 3 W; SEE: 6 W; TE: 8 W; LoA: − 17 to 10 W) and PUPPERBOUND´ (r: 0.98; Bias: 1 W; SEE: 8 W; TE: 8 W; LoA: − 15 to 17 W). ALP, PUPPERBOUND, and PUPPERBOUND´ were greater than IHIGH (339 ± 53 W; p < 0.001). Conclusion ALP may provide a new perspective to intensity domain framework.

Differences between indoor and outdoor field cycling tests in triathletes are associated with training environment history and BMI: analysis and prediction formula

Article

Jun 2024
J SPORT MED PHYS FIT

BACKGROUND: Cyclists and triathletes test, train, and race both indoors and outdoors. However, the differences between indoor and outdoor performance remain understudied. This study aimed to analyze the relationship between indoor and outdoor performance in cycling. We investigated the influence of training environment history (indoor vs. outdoor) and application of e-sport platform on the aforementioned relationship. METHODS: Forty-three well-trained triathletes performed indoor and outdoor field tests to establish maximum sprint power (MSP) and functional threshold power (FTP). The main effects for FTP and MSP were assessed by repeated-measures ANOVA to analyze the differences between power output obtained indoors and outdoors. Multiple covariates, including training environment history and application of ZWIFT e-sport platform, were applied. Multiple linear regression was performed to investigate outdoor FTP prediction based on indoor testing. RESULTS: No significant differences were found for MSP and FTP obtained indoors and outdoors. However, the high individual variability in the disparity between indoor and outdoor power output (PO) in triathletes was observed. There was a statistically significant interaction between FTP and training environment history (P<0.001 for FTP expressed in W*kg-1 and W) and FTP and BMI (P=0.042 and P=0.034 for FTP expressed in W*kg-1 and W, respectively). The prediction formulas to establish outdoor FTP based on indoor testing had high accuracy (R2 0.80 and 0.68 for full and simple model, respectively). CONCLUSIONS: The study underlines the crucial role of the appropriate testing environment, corresponding to the training environment and racing demands. A high individual variability in the disparity between indoor and outdoor PO at FTP is associated with training environment history and BMI. No such interactions were found for MSP.

A obtenção direta do VO2máx não é influenciada pela característica dos protocolos de teste de esforço máximo

Article

Full-text available

Feb 2024

The values of maximum oxygen consumption (VO2max) obtained indirectly are influenced by the characteristic or exercise protocol configuration. However, it is unclear in the literature if this prerogative is true when VO2max is measured directly. The objective was to compare the values of VO2max and maximal heart rate (HRmax) obtained through a maximum incremental protocol (Tmax) and a continuous time to exhaustion (TLim) protocol, based on the power of the VO2max. Twelve males cyclists (Age = 36,0 ± 9,3 years; height = 173,2 ± 5,9 cm; mass = 78,5 ± 10,7 kg), trained for regional proves of long distance participated in the study. A Tmax was performed on the cycle ergometer with increments of 22.5 W every minute, with an initial load of 157.5 W maintaining a standard rotation of 90 RPM. TLim was performed at the same rotation until exhaustion from the lowest occurrence power of VO2max (PVO2max). Student's t-test was used to compare the dependent variables (p≤0.05). There was no significant difference in the obtained values of VO2max and HRmax (TMax = 45.02 ± 7.21 ml · kg-1 · min-1 vs. TLim = 44.17 ± 7.21 ml · kg-1 · min-1) e (HRTmax = 182.9 ± 9.2 bpm vs. HRTLim = 181.3 ± 7.5 bpm), respectively, when compared both tests. The TLim on PVO2Max provided reliable values of VO2max and HRmax, and a shorter total test time performed, compared to a maximal incremental protocol.

Ergophysiological evaluation of heart failure patients with reduced ejection fraction undergoing exercise-based cardiac rehabilitation: A systematic review and meta-analysis

Article

Full-text available

Jan 2024

Comprehensive measurement of muscle maximal oxygen uptake determinants: insights and application

Article

Full-text available

Jan 2024
J PHYSIOL-LONDON

Multifactorial Approach to the Determinants of sprint performance in Road Cycling

Research

Full-text available

Jun 2023

The physiological and mechanical determinants of sprint performance in road cycling have been the subject of various studies. However, given the specificity of a cycling sprint, no study has attempted to jointly analyse the physiological and mechanical, cognitive and psychological determinants of sprint performance. The aim of this study is therefore to determine which of the physiological, cognitive and psychological markers are most relevant for predicting sprint performance.

Impact of physical fitness and exercise training on subcutaneous adipose tissue beiging markers in humans with and without diabetes and a high‐fat diet‐fed mouse model

Article

Oct 2023

Aims Exercise training induces white adipose tissue (WAT) beiging and improves glucose homeostasis and mitochondrial function in rodents. This could be relevant for type 2 diabetes in humans, but the effect of physical fitness on beiging of subcutaneous WAT (scWAT) remains unclear. This translational study investigates if beiging of scWAT associates with physical fitness in healthy humans and recent‐onset type 2 diabetes and if a voluntary running wheel intervention is sufficient to induce beiging in mice. Materials and Methods Gene expression levels of established beiging markers were measured in scWAT biopsies of humans with (n = 28) or without type 2 diabetes (n = 28), stratified by spiroergometry into low (L‐FIT; n = 14 each) and high physical fitness (H‐FIT; n = 14 each). High‐fat diet‐fed FVB/N mice underwent voluntary wheel running, treadmill training or no training (n = 8 each group). Following the training intervention, mitochondrial respiration and content of scWAT were assessed by high‐resolution respirometry and citrate synthase activity, respectively. Results Secreted CD137 antigen ( Tnfrsf9/Cd137 ) expression was three‐fold higher in glucose‐tolerant H‐FIT than in L‐FIT, but not different between H‐FIT and L‐FIT with type 2 diabetes. In mice, both training modalities increased Cd137 expression and enhanced mitochondrial content without changing respiration in scWAT. Treadmill but not voluntary wheel running led to improved whole‐body insulin sensitivity. Conclusions Higher physical fitness and different exercise interventions associated with higher gene expression levels of the beiging marker CD137 in healthy humans and mice on a high‐fat diet. Humans with recent‐onset type 2 diabetes show an impaired adipose tissue‐specific response to physical activity.

Limited Effects of Inorganic Nitrate Supplementation on Exercise Training Responses: A Systematic Review and Meta-analysis

Article

Full-text available

Sep 2023

Background Inorganic nitrate (NO3⁻) supplementation is purported to benefit short-term exercise performance, but it is unclear whether NO3⁻ improves longer-term exercise training responses (such as improvements in VO2peak or time to exhaustion (TTE)) versus exercise training alone. The purpose of this systematic review and meta-analysis was to determine the effects of NO3⁻ supplementation combined with exercise training on VO2peak and TTE, and to identify potential factors that may impact outcomes. Methods Electronic databases (PubMed, Medscape, and Web of Science) were searched for articles published through June 2022 with article inclusion determined a priori as: (1) randomized placebo-controlled trials, (2) exercise training lasted at least three weeks, (3) treatment groups received identical exercise training, (4) treatment groups had matched VO2peak at baseline. Study quality was assessed using the Cochrane Risk-of-Bias 2 tool. Standardized mean difference (SMD) with 95% confidence intervals (CI) were calculated using restricted maximum likelihood estimation between pre- and post-training differences in outcomes. Moderator subgroup and meta-regression analyses were completed to determine whether the overall effect was influenced by age, sex, NO3⁻ dosage, baseline VO2peak, health status, NO3⁻ administration route, and training conditions. Results Nine studies consisting of eleven trials were included: n = 228 (72 females); age = 37.7 ± 21 years; VO2peak: 40 ± 18 ml/kg/min. NO3⁻ supplementation did not enhance exercise training with respect to VO2peak (SMD: 0.18; 95% CI: -0.09, 0.44; p = 0.19) or TTE (SMD: 0.08; 95% CI: − 0.21, 0.37; p = 0.58). No significant moderators were revealed on either outcome. Subset analysis on healthy participants who consumed beetroot juice (BRJ) revealed stronger trends for NO3⁻ improving VO2peak (p = 0.08) compared with TTE (p = 0.19), with no significant moderators. Sunset funnel plot revealed low statistical power in all trials. Conclusions NO3⁻ supplementation combined with exercise training may not enhance exercise outcomes such as VO2peak or TTE. A trend for greater improvement in VO2peak in healthy participants supplemented with BRJ may exist (p = 0.08). Overall, future studies in this area need increased sample sizes, more unified methodologies, longer training interventions, and examination of sex as a biological variable to strengthen conclusions.

Alterations in aerobic fitness and muscle deoxygenation during ramp incremental exercise in trained youth cyclists: a ~3-year longitudinal study

Article

Apr 2023

Alterations of aerobic fitness and muscle deoxygenation during a ramp incremental exercise test (GXT) were assessed on two occasions within a time-frame of 2.9 ± 0.1y in competitive youth cyclists. Nine cyclists (age, 14.5 ± 1.1y; peak oxygen uptake (_ VO 2peak), 62.6 ± 4.2 mL.min −1 .kg −1) participated in this investigation. _ VO 2peak , the gas exchange threshold (GET) and the respiratory compensation point (RCP), as well as the muscle deoxygenation response pattern were determined during a GXT using open circuit spirometry and near-infrared spectroscopy, respectively. T-tests and Pearson's correlations were used to assess effects of time on the dependent variables and relationships between changes of parameter estimates of aerobic fitness and the muscle deoxygenation response, respectively. Workrate and metabolic rate at GET (33 ± 20 and 42 ± 23%) and RCP (36 ± 20 and 40 ± 22%), and _ V O 2peak (30 ± 18%) significantly increased throughout the study (P < 0.05). The muscle deoxygenation response showed a significant rightward shift from occasion one to two (P < 0.05). Alterations in the workrate/metabolic rate at RCP, and _ VO 2peak , were correlated with alterations of the muscle deoxy-genation response (R = 0.71-0.89, P < 0.05). Together, this is thought to indicate a superior muscle perfusion within the tissue of interrogation at the same metabolic rate on occasion two vs. one, which partially contributed to the improved aerobic fitness in the cyclists herein. ARTICLE HISTORY

Exercise-induced skeletal muscle angiogenesis: impact of age, sex, angiocrines and cellular mediators

Article

Full-text available

Jan 2023
EUR J APPL PHYSIOL

Exercise-induced skeletal muscle angiogenesis is a well-known physiological adaptation that occurs in humans in response to exercise training and can lead to endurance performance benefits, as well as improvements in cardiovascular and skeletal tissue health. An increase in capillary density in skeletal muscle improves diffusive oxygen exchange and waste extraction, and thus greater fatigue resistance, which has application to athletes but also to the general population. Exercise-induced angiogenesis can significantly contribute to improvements in cardiovascular and metabolic health, such as the increase in muscle glucose uptake, important for the prevention of diabetes. Recently, our understanding of the mechanisms by which angiogenesis occurs with exercise has grown substantially. This review will detail the biochemical, cellular and biomechanical signals for exercise-induced skeletal muscle angiogenesis, including recent work on extracellular vesicles and circulating angiogenic cells. In addition, the influence of age, sex, exercise intensity/duration, as well as recent observations with the use of blood flow restricted exercise, will also be discussed in detail. This review will provide academics and practitioners with mechanistic and applied evidence for optimising training interventions to promote physical performance through manipulating capillarisation in skeletal muscle.

Functional threshold power is an estimate of critical power

Conference Paper

Nov 2019

Introduction: Functional threshold power (FTP) is the endurance performance measure adopted by cyclists which estimates maximum power output for one hour. Training zones are derived as fractions of FTP with supposed correlations to blood lactate ([bLa]). However, little physiological evidence exists to support FTP and its training zones. Methods: Ten recreationally to moderately trained cyclists performed a maximal test to determine peak oxygen uptake (V̇ O2peak: 51.9 ± 7.4 ml·min-1 ·kg-1 ) and maximal aerobic power (MAP; 335 ± 59 W), three time trials (TT - 3, 8 and 12 min) and three constant-load trials to exhaustion (TTE) for determination of critical power (CP) from two trial formats (TT: 240 ± 41 W; TTE: 251 ± 49 W). A sub-maximal test determined lactate threshold (LT; 192 ± 41 W) and [bLa] = 4.0 mmol.L-1 ([bLa]4; 229 ± 43 W), and a 20 min TT provided the FTP estimate (236 ± 45 W). Participants performed one final TTE trial at FTP (45 ± 12 min). Results: FTP was not different to CP-TT (P = 1.000), CP-TTE (P = 0.216), or [bLa]4 (P = 1.000), and positively correlated to CP-TT (r = 0.98, P < 0.01), CP-TTE (r = 0.97, P < 0.01), and [bLa]4 (r = 0.85, P < 0.01). Discussion: These data reveal strong positive correlations of FTP with CP and [bLa]4 which substantiates previous literature supporting FTP as a single test estimate of endurance performance and CP. Take home message: An alternative model of FTP training zones based on LT, CP, and MAP was created with increased physiological validity.

Anthropometric characteristics according to the role performed by World Tour road cyclists for their team: Anthropometric characteristics in elite cyclists

Article

Oct 2022

Purpose Certain anthropometric characteristics are required for athletes to successfully perform in elite endurance sports. The present study aims to analyse the anthropometric characteristics of professional cyclists according to their specialty. Method Anthropometric measurements were conducted of the body composition of seventy-six male professional road cyclists in line with International Society for Advancement of Kinanthropometry protocol. Results Fat mass did not differ (p > 0.05) between climbers, all-rounders and flat specialists, although the following anthropometric variables did differ according to the role played within the team (p < 0.05): Body mass (climbers: 63.8 ± 3.6, all-rounders: 68.8 ± 5.3, flat specialists: 74.5 ± 5.6 kg) skeletal body mass (climbers: 29.7 ± 1.6, all-rounders: 31.4 ± 1.9, flat specialists: 33.5 ± 2.4 kg); body surface area (climbers: 1.78 ± 0.07, all-rounders: 1.89 ± 0.10, flat specialists: 1.96 ± 0.1 m²); frontal area (climbers: 0.33 ± 0.01, all-rounders: 0.35 ± 0.02, flat specialists: 0.36 ± 0.02 m²). Conclusions Anthropometric characteristic differ between world-class cyclists depending on their specialty. These differences could influence performance in relation to different types of road cycling competitions. The present study identified characteristics which could be used by coaches to evaluate their athletes in the context of elite or professional road cycling.

Impairment in maximal lactate steady state after carbon monoxide inhalation is related to training status

Article

Aug 2022

New findings: What is the central question of this study? What is the effect of an elevated COHb concentration following carbon monoxide inhalation on the maximal lactate steady state (MLSS) in humans and is this effect dependent on aerobic fitness? What is the main finding and its importance? An elevated COHb concentration intensified physiological responses to exercise at the MLSS- including heart rate, ventilation, and peripheral fatigue-in all participants and reduced the MLSS (i.e., destabilized the blood lactate concentration) in trained but not untrained males and females. Abstract: This study investigated whether a lower effective [Hb], induced by carbon monoxide (CO) inhalation, reduces the peak oxygen uptake (V̇O2 peak) and the maximal lactate steady state (MLSS) and whether training status explains individual variation in these impairments. Healthy young participants completed two ramp incremental tests (n = 20 [10 female]) and two trials at MLSS (n = 16 [8 female]) following CO rebreathe tests and sham procedures (SHAM) in random orders. All fitness variables were normalized to fat-free mass (FFM) to account for sex-related differences in body composition, and males and females were matched for aerobic fitness. The V̇O2 peak (mean [SD]: -4.2 [3.7]%), peak power output (-3.3 [2.2]%), and respiratory compensation point (-6.3 [4.5]%) were reduced in CO compared with SHAM (P < 0.001 for all), but the gas exchange threshold (-3.3 [7.1]%) was not (P = 0.077). Decreases in V̇O2 peak (r = -0.45; P = 0.047) and peak power output (r = -0.49; P = 0.029) in CO were correlated with baseline aerobic fitness. Compared to SHAM, physiological and perceptual indicators of exercise-related stress were exacerbated by CO while cycling at MLSS. Notably, the mean blood lactate concentration ([La]) increased (i.e., Δ[La] > 1.0 mM) between 10 min (5.5 [1.4] mM) and 30 min (6.8 [1.3] mM; P = 0.026) in CO, with 9/16 participants classified as unstable. These unstable participants had a higher V̇O2 peak (66.2 [8.5] vs. 56.4 [8.8] mL·kg FFM-1 ·min-1 , P = 0.042) and V̇O2 at MLSS (55.8 vs. 44.3 mL·kg FFM-1 ·min-1 , P = 0.006) compared to the stable group. In conclusion, a reduced O2 -carrying capacity decreased maximal and submaximal exercise performance, with higher aerobic fitness associated with greater impairments in both. This article is protected by copyright. All rights reserved.

A three-minute all-out test performed in a remote setting does not provide a valid estimate of the maximum metabolic steady state

Article

Full-text available

Aug 2022
EUR J APPL PHYSIOL

Purpose: The three-minute all-out test (3MT), when performed on a laboratory ergometer in a linear mode, can be used to estimate the heavy-severe-intensity transition, or maximum metabolic steady state (MMSS), using the end-test power output. As the 3MT only requires accurate measurement of power output and time, it is possible the 3MT could be used in remote settings using personal equipment without supervision for quantification of MMSS. Methods: The aim of the present investigation was to determine the reliability and validity of remotely performed 3MTs (3MTR) for estimation of MMSS. Accordingly, 53 trained cyclists and triathletes were recruited to perform one familiarisation and two experimental 3MTR trials to determine its reliability. A sub-group (N = 10) was recruited to perform three-to-five 30 min laboratory-based constant-work rate trials following completion of one familiarisation and two experimental 3MTR trials. Expired gases were collected throughout constant-work rate trials and blood lactate concentration was measured at 10 and 30 min to determine the highest power output at which steady-state [Formula: see text] (MMSS-[Formula: see text]) and blood lactate (MMSS-[La-]) were achieved. Results: The 3MTR end-test power (EPremote) was reliable (coefficient of variation, 4.5% [95% confidence limits, 3.7, 5.5%]), but overestimated MMSS (EPremote, 283 ± 51 W; MMSS-[Formula: see text], 241 ± 46 W, P = 0.0003; MMSS-[La-], 237 ± 47 W, P = 0.0003). This may have been due to failure to deplete the finite work capacity above MMSS during the 3MTR. Conclusion: These results suggest that the 3MTR should not be used to estimate MMSS in endurance-trained cyclists.

Effects of Exercise Training Intensity and Duration on Skeletal Muscle Capillarization in Healthy Subjects: A Meta-analysis

Article

Full-text available

May 2022

Purpose: To investigate the effect of intensity and duration of continuous and interval exercise training on capillarization in skeletal muscle of healthy adults. Methods: PubMed and Web of Science were searched from inception to June 2021. Eligibility criteria for studies were: endurance exercise training >2 wks in healthy adults, and capillary to fiber ratio (C:F) and/or capillary density (CD) reported. Meta-analyses were performed and subsequent subgroup analyses were conducted by the characteristics of participants and training scheme. Results: 57 trials from 38 studies were included (10/90%, athletic/sedentary). C:F was measured in 391 subjects from 47 trials while CD was measured in 428 subjects from 50 trials. Exercise training increased C:F (Mean difference (MD) 0.33 [0.30-0.37; 95% CI]) with low heterogeneity (I2 = 45.08 %) and CD (MD 49.8 [36.9-62.6] Cap/mm2) with moderate heterogeneity (I2 = 68.82%). Compared to low intensity training (LOW, <50% of VO2max), 21% higher relative change in C:F ratio was observed after continuous moderate intensity training (CON, 50-80%VO2max) and 54% higher change after interval training with high intensity (INT, 80-100% of VO2max) in sedentary subjects. The magnitude of capillary growth was not dependent on training intervention duration. In already trained subjects, no additional increase in capillarization was observed with various types of training. Conclusions: In sedentary subjects, CON and INT leads to increases in capillarization, whereas LOW has less effect. Within the timeframe studied, no effect on capillarization was established regarding training duration in sedentary subjects. The meta-analysis highlights the need for further studies in athlete groups to discern if increased capillarization can be obtained, and if so, which combination is optimal (time vs intensity).

The Performance, Physiology and Morphology of Female and Male Olympic-Distance Triathletes

Article

Full-text available

Apr 2022

Sex differences in triathlon performance have been decreasing in recent decades and little information is available to explain it. Thirty-nine male and eighteen female amateur triathletes were evaluated for fat mass, lean mass, maximal oxygen uptake (VO2 max), ventilatory threshold (VT), respiratory compensation point (RCP), and performance in a national Olympic triathlon race. Female athletes presented higher fat mass (p = 0.02, d = 0.84, power = 0.78) and lower lean mass (p < 0.01, d = 3.11, power = 0.99). VO2 max (p < 0.01, d = 1.46, power = 0.99), maximal aerobic velocity (MAV) (p < 0.01, d = 2.05, power = 0.99), velocities in VT (p < 0.01, d = 1.26, power = 0.97), and RCP (p < 0.01, d = 1.53, power = 0.99) were significantly worse in the female group. VT (%VO2 max) (p = 0.012, d = 0.73, power = 0.58) and RCP (%VO2 max) (p = 0.005, d = 0.85, power = 0.89) were higher in the female group. Female athletes presented lower VO2 max value, lower lean mass, and higher fat mass. However, females presented higher values of aerobic endurance (%VO2 max), which can attenuate sex differences in triathlon performance. Coaches and athletes should consider that female athletes can maintain a higher percentage of MAV values than males during the running split to prescribe individual training.

Physiological and Somatic Principal Components Determining VO2max in the Annual Training Cycle of Endurance Athletes

Article

Full-text available

Mar 2022
Int J Environ Res Publ Health

The purpose of the study was to assess the impact of training on the physiological variables achieved during the test effort in the macrocycle of road cyclists and their use in the maximal oxygen uptake (VO2max) prediction at individual training stages in the VO2max test. Nine well-trained male cyclists (age 25.6 ± 5.2 years and body weight 72.4 ± 7.35 kg) participated in the study and each phase of the macrocycle was followed by a time to exhaustion test (TTE) on the bicycle ergometer. The research showed that training loads significantly influence the maximum power (PPO), ventilation (VE) in the preparatory period (T1), time of the test (TTmax) at the start of the competition period (T2), percentage of body fat in total body weight (%FAT) and skeletal muscle mass (MMS) during the competition period (T3). Of the 16 variables taken for the analysis of the principal components (PC), the regression model determined one principal variable responsible for VO2max in the training macrocycle of cyclists, the relative value of maximum power (PPORV) and the accompanying variables in individual periods: breathing frequency (BF), delta blood lactate concentration (ΔLA), body fat (FAT) and MMS. Determining PC influencing the exercise capacity can be crucial in achieving the intended goals by athletes. Monitoring these indicators can help protect the health of professional athletes and provide guidelines in the training process, stimulate the body properly while protecting against overtraining.

Viewpoint: Using VO 2max as a marker of training status in athletes - can we do better?

Article

Full-text available

Feb 2022

The disturbance of desire‐goal motivational dynamics during different exercise intensity domains

Article

Full-text available

Jan 2022
SCAND J MED SCI SPOR

Purpose The desire-goal motivational conflict helps explain endurance performance, however, the physiological concomitants are unknown. The present study examined disturbances in desire to reduce effort and performance goal value across moderate, heavy, and severe exercise intensity domains, demarcated by the first (LT1) and second (LT2) lactate thresholds. In addition, the within-person relationships between blood lactate concentration, heart rate and desire-goal conflict were examined. Methods Thirty participants (53% female, Mage = 21.03 years; SD = 2.06 years) completed an incremental cycling exercise test, in which work-rate was increased by 25 watts every four minutes, until voluntary exhaustion or sufficient data from the severe intensity domain had been collected. Desire to reduce effort, performance goal value, blood lactate concentration (for determination of LT1 and LT2) and heart rate were measured at the end of each stage and analyzed using multilevel models. Results The desire to reduce effort increased over the exercise test with additional shifts and accelerations after each lactate threshold. The performance goal did not show general declines, nor did it shift at LT1. However, the performance goal value shifted at LT2, and the rate of change increased at both thresholds. Within-person variation in blood lactate concentration positively correlated with the desire to reduce effort and negatively correlated with the performance goal. Within-person variation in heart rate correlated with desire to reduce effort but not the performance goal. Conclusion Transitioning through both lactate thresholds are important phases for motivation during progressive exercise, particularly for the desire to reduce effort. Within-person variation in blood lactate concentration is more influential for motivation, compared to heart rate.

Links between Exercise Capacity, Exercise Training, and Metabolism

Article

Sep 2023

Exercise capacity of an individual describes the ability to perform physical activity. This exercise capacity is influenced by intrinsic factors such as genetic constitution and extrinsic factors such as exercise training. On the metabolic level exercise and metabolism are linked. As an important site of metabolism and the main source for ATP needed for muscle contraction, mitochondrial function can determine exercise capacity, and exercise inversely influences mitochondrial function. It has been suggested that exercise mediates many of its effects due to such metabolic changes. Although extrinsic factors affect exercise capacity, a major part of an individual's exercise capacity is genetically determined, and extrinsic factors can only improve on this baseline. Looking at the effect of exercise capacity on and with disease, the two go hand in hand. On one hand, disease is negatively affecting an individual's exercise capacity; on the other hand, exercise offers an effective treatment option. Combining these factors, exercise capacity is an often‐ignored prognostic variable for life expectancy as well as morbidity and mortality. In this review, we aim to provide the current knowledge on the links between inherited and acquired exercise capacity, as well as the mechanisms in which metabolism interacts with exercise capacity. © 2023 American Physiological Society. Compr Physiol 13:5115‐5155, 2023.

Durability as an index of endurance exercise performance: Methodological considerations

Article

Full-text available

Mar 2025
EXP PHYSIOL

Endurance athletes routinely complete physiological assessments to predict performance, inform training programmes and monitor subsequent training adaptations. This profiling is typically performed with the athlete in a ‘fresh’ (i.e., rested) condition, but physiological profiling variables deteriorate during prolonged exercise. Durability has been defined as the resilience to the deterioration of physiological variables and performance during or following prolonged exercise. Herein, we review the current approaches to measure durability. The construction of the fatiguing protocol affects durability profiles, with greater relative intensity and duration resulting in more marked deterioration of baseline measures. The design of durability assessments should control for factors that could impact durability measurements, such as nutrition and environmental characteristics, to ensure that outcomes are repeatable and can be compared between athletes or over time in the same athlete. The selection of these parameters should be based on the proposed research question or applied context and take account of the training status of the athlete. Accordingly, this review highlights important considerations to ensure that protocols for profiling durability in research and applied practice are appropriate.

The effect of performing mental exertion during cycling endurance exercise on fatigue indices: sex dependent differences

Article

Full-text available

Mar 2025

Introduction Men and women have different performance abilities, where women have greater tolerance for fatigue in long-distance exercise. Part of this greater tolerance may be due, in part, differences in men’s and women’s mental fatigue capacity during exercise. Thus, the aim of this study was to examine the effect of cycling endurance exercise, along with mental fatigue, on the sex dependent differences in exercise tolerance. Methods Twenty-five (15 women and 10 men) cyclists in a randomized, controlled, and crossover protocol performed three experimental sessions. In the first session, the cycling peak power output (PPO) was determined and 65% of PPO was used for intensity of the experimental sessions. In sessions 2 and 3, participants performed Cycling + Mental Exertion (ME) (cycling endurance exercise with a ME-stroop task) and Cycling + Movie (cycling endurance exercise while watching a movie). Serum cortisol concentration and a psychomotor vigilance task (PVT) were measured pre‐ and post-sessions. During the experimental sessions rate of perceived exertion (RPE) and heart rate (HR) were recorded every 10 min and participants completed the NASA‐TLX questionnaire directly following the post- PVT. Results Performing Cycling + ME was associated with a longer time to exhaustion (p < 0.05) and higher RPE following 40‐70 min in women than men (p < 0.05). Cycling + ME increased HR following 40-70 min in women (p < 0.05). For both men and women cortisol concentration level was higher pre‐ to post‐Cycling + ME with no difference between sexes. Women exhibited faster reaction times compared to men in both pre‐ and post‐sessions. Discussion Performing mental exertion with cycling endurance exercise impairs endurance performance. While our findings align with some previous research, we suggest that men may be more prone to mental fatigue; however, further research needed to confirm this.

Der Zusammenhang zwischen Laktat- Leistungskurve, Aerober-und Ausdauerkapazität

Presentation

Full-text available

Jan 2018

In dieser Präsentation wurde der Zusammenhang (n=24) zwischen der Laktat-Leistungskurve (LLK), der Aerober- und Ausdauerkapazität gezeigt. Die aerobe Kapazität (AEC) wurde durch die Belastung in einem Stufentest und die Ausdauerkapazität (EC) durch die Belastung in einem Dauertest bei 80% der Pmax ermittelt. Anhand von Fallbeispielen wird eine "erwartete" Leistung mit unseren Daten abgeglichen.

Effects of Eight Week Supplementation of Ashwagandha and Amalaki Churna as a Rasayana w.r.t General Physical Fitness and Cardio-respiratory Endurance

Article

Full-text available

Sep 2024

In India and around the world, people are spending more and more time enjoying sedentary lifestyle. This type of lifestyle decreases our physical fitness and compromises our cardio respiratory endurance. Under such circumstances along with a dynamic change in lifestyle and enhanced physical activity, there arises a need of drugs which can improve the physical fitness and cardio respiratory endurances among the youngsters and the adults. Purpose: The aim of the present study was to evaluate the efficacy of Ashwagandha and Amalaki Churna as a Rasayana with respect to general physical fitness and cardio-respiratory endurance. Material and Methods: 60 healthy individuals were registered for the present study. The individuals were divided into four groups. Each group comprised of 15 individuals. Group-I individuals were given Amalaki Churna, group-II individuals were given Ashwagandha Churna, group-III individuals were given both Ashwagandha and Amalaki Churna and group-IV individuals were given starch capsules as placebo therapy. The Ashwagandha and Amalaki Churna were given in the dose of 5gm each. Outcome measures: The study subjects were asked to perform tread mill test and TMT related parameters like exercise time, work load attained in terms of Mets, VO2 max, heart rate reserve index and rate pressure product were measured both before and after the completion of 8 weeks of therapy. Apart from this vital capacity and BMI were also measured. Results: After the therapy there was a statistically significant improvement in general physical fitness and cardiorespiratory endurance on various parameters in group-I, group-II, group-III, whereas placebo group did not show any statistically significant improvement. Conclusion: Ashwagandha and Amalaki improved the general physical fitness and cardiorespiratory endurance of the individuals.

Predicting Future Athletic Performance in Young Female Road Cyclists Based on Aerobic Fitness and Hematological Variables

Article

Jul 2024
Int J Sports Physiol Perform

Purpose : This study aimed to determine whether the initial levels of aerobic fitness and hematological variables in young female road cyclists are related to their athletic performance development during their careers. Methods : Results of graded exercise tests on a cycle ergometer and total hemoglobin mass (tHb-mass) measurements were analyzed in 34 female road cyclists (age 18.6 [1.9] y). Among them, 2 groups were distinguished based on their competitive performance (Union Cycliste Internationale world ranking) over the following 8 years. Areas under the curve in receiver-operating-characteristic curves were calculated as indicators of elite-performance prediction. Results : Initial graded exercise test variables (peak power, peak oxygen uptake, and power at 4 mmol/L blood lactate) were not significantly different in elite (n = 13) versus nonelite (n = 21) riders. In contrast, elite riders had higher tHb-mass expressed either in absolute measures (664 [75] vs 596 [59] g, P = .006) or normalized to body mass (11.2 [0.8] vs 10.3 [0.7] g/kg, P = .001) and fat-free mass (14.4 [0.9] vs 13.1 [0.9] g/kg, P < .001). Absolute and relative erythrocyte volumes were significantly higher in elite subjects ( P ranged from < .001 to .006). Of all the variables analyzed, the relative tHb-mass had the highest predictive ability to reach the elite level (area under the curve ranged from .82 to .85). Conclusion : Measurement of tHb-mass can be a helpful tool in talent detection to identify young female road cyclists with the potential to reach the elite level in the future.

Standing on the Shoulders of Giants: Essential Papers in Sports and Exercise Physiology

Article

Full-text available

Jun 2024

Purpose : The purpose of this survey was to create a list of essential historical and contemporary readings for undergraduate and graduate students in the field of exercise physiology. Methods : Fifty-two exercise physiologists/sport scientists served as referees, and each nominated ∼25 papers for inclusion in the list. In total, 396 papers were nominated by the referees. This list was then sent back to the referees, with the instructions to nominate the “100 essential papers in sports and exercise physiology.” Results : The referees cast 4722 votes. The 100 papers with the highest number of votes received 51% (2406) of the total number of votes. A total of 37 papers in the list of “100 essential papers” were published >50 years ago, and 63 papers were published since 1973. Conclusions : This list of essential studies will provide a perspective on contemporary studies, the “ giant’s shoulders ” to enable young scholars to “see further” or to understand where they have “come from.” This compilation is also meant to impress on students that, given the (lack of) technology available in the past, some of the early science required enormous intuitive leaps on the part of historical scientists.

Effects of Time-Restricted Eating on Aerobic Capacity, Body Composition, and Markers of Metabolic Health in Healthy Male Recreational Runners: A Randomized Crossover Trial

Article

Jan 2024

Telling Stories with Data: With Applications in R

Book

Jun 2023

Rohan Alexander

Belastungs-EKG

Chapter

Jun 2023

Aspectos fisiológicos do ciclismo: da avaliação ao treinamento

Book

Feb 2023

Celso José Marcelino Júnior

Descrever com o apoio da literatura científica durante pesquisa de Pós-graduação na UNIFESP, estudos e artigos científicos sobre os aspectos da fisiologia do exercício e o ciclismo. O objetivo deste trabalho é fornecer maior entendimento e atualizar sobre a natureza fisiológica do ciclismo. Uma revisão sistemática da literatura resultou em 38 estudos específicos para o ciclismo. https://loja.uiclap.com/titulo/ua29052/

Factors contributing to the change in thermoneutral maximal oxygen consumption after iso-intensity heat acclimation programmes

Article

Dec 2022
EUR J SPORT SCI

The factors explaining variance in thermoneutral maximal oxygen uptake (V˙O2max) adaptation to heat acclimation (HA) were evaluated, with consideration of HA programme parameters, biophysical variables and thermo-physiological responses. Seventy-one participants consented to perform iso-intensity training (range: 45%-55% V˙O2max) in the heat (range: 30°C-38°C; 20%-60% relative humidity) on consecutive days (range: 5-days-14-days) for between 50-min and-90 min. The participants were evaluated for their thermoneutral V˙O2max change pre-to-post HA. Participants' whole-body sweat rate, heart rate, core temperature, perceived exertion and thermal sensation and plasma volume were measured, and changes in these responses across the programme determined. Partial least squares regression was used to explain variance in the change in V˙O2max across the programme using 24 variables. Sixty-three percent of the participants increased V˙O2max more than the test error, with a mean ± SD improvement of 2.6 ± 7.9%. A two-component model minimised the root mean squared error and explained the greatest variance (R2; 65%) in V˙O2max change. Eight variables positively contributed (P < 0.05) to the model: exercise intensity (%V˙O2max), ambient temperature, HA training days, total exposure time, baseline body mass, thermal sensation, whole-body mass losses and the number of days between the final day of HA and the post-testing day. Within the ranges evaluated, iso-intensity HA improved V˙O2max 63% of the time, with intensity- and volume-based parameters, alongside sufficient delays in post-testing being important considerations for V˙O2max maximisation. Monitoring of thermal sensation and body mass losses during the programme offers an accessible way to gauge the degree of potential adaptation.

A Cloth Facemask Causes No Major Respiratory or Cardiovascular Perturbations During Moderate to Heavy Exercise

Article

Dec 2022

Purpose: Investigate whether a cloth facemask could affect physiological and perceptual responses to exercise at distinct exercise intensities in untrained individuals. Methods: Healthy participants (n = 35; 17 men, age 30 [4] y, and 18 women, age 28 [5] y) underwent a progressive square wave test at 4 intensities: (1) 80% of ventilatory anaerobic threshold; (2) ventilatory anaerobic threshold; (3) respiratory compensation point; and (4) exercise peak (Peak) to exhaustion, 5-minute stages, with or without a triple-layered cloth facemask (Mask or No-Mask). Several physiological and perceptual measures were analyzed. Results: Mask reduced inspiratory capacity at all exercise intensities (P < .0001). Mask reduced respiratory frequency (P = .001) at Peak (-8.3 breaths·min-1; 95% confidence interval [CI], -5.8 to -10.8), respiratory compensation point (-6.9 breaths·min-1; 95% CI, -4.6 to -9.2), and ventilatory anaerobic threshold (-6.5 breaths·min-1; 95% CI, -4.1 to -8.8), but not at Baseline or 80% of ventilatory anaerobic threshold. Mask reduced tidal volume (P < .0001) only at respiratory compensation point (-0.5 L; 95% CI, -0.3 to -0.6) and Peak (-0.8 L; 95% CI, -0.6 to -0.9). Shallow breathing index was increased with Mask only at Peak (11.3; 95% CI, 7.5 to 15.1). Mask did not change HR, lactate, ratings of perceived exertion, blood pressure, or oxygen saturation. Conclusions: A cloth facemask reduced time to exhaustion but had no major impact on cardiorespiratory parameters and had a slight but clinically meaningless impact on respiratory variables at higher intensities. Moderate to heavy activity is safe and tolerable for healthy individuals while wearing a cloth facemask. Clinicaltrials: gov: NCT04887714.

Relationship of BMI with Proteinuria and Hematuria after One Session of Intense Continuous and Interval Exercise in Girls

Article

Full-text available

Jul 2022

Introduction: Obesity effects on kidney function. Urinary disorders after exercise are also common, and probably due to transient hemodynamic problems in the glomerular and tubular renal function. The purpose of this research is to investigate the relationship of BMI with proteinuria and hematuria after one session of intense continuous and interval exercise in girls. Methods: In this quasi-experimental research, 45 hostelry high school girl students with a mean age of 15.18 ± 0.39 years were randomly selected and in three groups of 15, they ran 1600 meters in a continuous and interval manner. Urine test collected before, one and 24 hours after activity. The results were analyzed by SPSS version 16 software and one way ANOVA and Pearson correlation coefficient. Results: Increased proteinuria was significant one hour (P = 0.002) and 24 hours after activity (P = 0.001) in the continuous group. In the continuous group, the relationship between fat percentage (P=0.017) and body mass index (P=0.001) with protein excretion 24 hours after activity was positive and significant. One hour after activity, protein excretion with fat percentage and Body mass index (BMI) had no significant relationship. Hematuria was also not significant after activity. Conclusion: Body mass index (BMI) and fat percentage were effective on protein excretion after one session of intense physical activity and had no significant effect on hematuria. Therefore, overweight people were advised to participate in interval exercise to lose weight.

Exercise Stress Testing in Athletes

Article

Jul 2022
CLIN SPORT MED

Exercise stress testing (EST) is indicated for diagnostic and prognostic purposes in the general population. In athletes, stress tests can also be useful to inform the risk of high-intensity training and competition, to assess athletic conditioning, and to refine training regimens. Many specific indications for EST are unique to athletes. Treadmill and cycle ergometer protocols each have their strengths and disadvantages; extensive protocol customization may be necessary to answer the clinical question at hand. A comprehensive understanding of the available tools for exercise testing, their strengths, and their limitations is crucial to providing cardiovascular care to athletic individuals.

The Relationship Between Aerobic Capacity and Academic Performance and Cognitive Performance in Medicine Students

Thesis

Full-text available

Feb 2019

Zeynep Bayramlar

OBJECTIVE. The aim of this study was to investigate the relationship between the aerobic capacity (VO2max) and academic performance and the different components of the cognitive functions of the brain, including spatial memory, attention, problem solving, flexibility, mathematics in medicine students. METHODS. Aerobic capacity measurement was performed by cardiopulmonary exercise test and VO2max measurement in Exercise Physiology Laboratory at Göztepe EAH Merdivenköy Polyclinic in İstanbul Medeniyet University. The measurement of body composition was performed in the Student Physiology Laboratory of the Medical Faculty of Istanbul Medeniyet University. To evaluate cognitive performance, In the Student Computer Laboratory, with Lumosity programme 6 categories of cognitive tests related to speed, memory, attention, flexibility, problem solving and mathematics were applied and evaluated. To assess the academic performance, The final exam grade point averages and weighted grade point averages and LYS entry points of the students who will participate in the study were taken from the student affairs department. The relationships between brain cognitive functions and academic performance and aerobic capacity were evaluated by correlation and regression analysis. RESULTS. When the relationship between aerobic capacity and cognitive performance was examined; Flexibility (r = 0,332 p = 0,007), Problem Solving (r = 0,248 p = 0,047) and Attention (r = 0,248 p = 0,047) from the cognitive performance test categories with aerobic capacity (VO2max) a positive linear relationship was found between them. There was no significant relationship between aerobic capacity and school success. vii Abstract CONCLUSION. As a result of this study, it was found that there is a relationship between aerobic capacity and some of cognitive performance tests in medical school students. However is was not found any relationship between aerobic capacity and school success. This situation may be caused by other factors affecting the success of the school. Keywords: VO2max, aerobic capacity, cognitive performance, academic performance

A Coaching Perspective on Modern Training Metrics and Return from Injury and Illness

Article

Oct 2021
Phys Med Rehabil Clin

Kolie Moore

Guiding cyclists in their return from illness and injury can be managed in many ways. Understanding how cyclists use power-derived training metrics can give care providers a common language to aid in this return. A general understanding of these metrics may be used to monitor cyclists for signs of nonfunctional overreaching or overtraining. Understanding aspects of training and detraining, particularly hematological, is helpful in communicating fitness expectations. Three populations of cyclists are discussed in terms of their expected knowledge of these metrics, typical training volume and intensity, and relationship with a coach or coaches.

Changes VO2max and running performance with training

Article

Full-text available

Nov 1978
Eur J Appl Physiol Occup Physiol

This study was undertaken to determine the response of

\dot V

O2 max and of running performance (805 and 3218 m) to the onset of training in untrained individuals and to an increase in the volume and intensity of training in well trained individuals. In series A,

\dot V

O2 max and performances of 12 previously untrained individuals were determined before and after 4 and 8 weeks of training. In series B, performances,

\dot V

O2 max and

\dot V

O2 submax of 15 previously well trained runners were determined before and after 4 and 8 weeks of controlled training. In series A,

\dot V

O2 max increased during the first 4 weeks of training but failed to increase further even in the presence of an increased training load (80 total km for the first 4 weeks, 130 total km for the second 4 weeks). Running performances improved throughout the training period. In series B, neither

\dot V

O2 max nor

\dot V

O2 submax changed but running performance improved throughout the experimental period. The results indicated that not all of the improvement in running performance subsequent to training is attributable to changes in

\dot V

O2 max. Further the results indicate that changes in running economy are not a likely explanation for performance improvement among previously well trained runners. It is suggested that physiological adaptations not integrated in the test of

\dot V

O2 max, or improvement in pacing contribute to training induced improvements in running performance.

Applied Physiology of Marathon Running

Article

Full-text available

Mar 1985

Performance in marathon running is influenced by a variety of factors, most of which are of a physiological nature. Accordingly, the marathon runner must rely to a large extent on a high aerobic capacity. But great variations in maximal oxygen uptake (VO2 max) have been observed among runners with a similar performance capacity, indicating complementary factors are of importance for performance. The oxygen cost of running or the running economy (expressed, e.g. as VO2 15 at 15 km/h) as well as the fractional utilisation of VO2 max at marathon race pace (%VO2 Ma X VO2 max-1) [where Ma = mean marathon velocity] are additional factors which are known to affect the performance capacity. Together VO2 max, VO2 15 and %VO2 Ma X VO2 max-1 can almost entirely explain the variation in marathon performance. To a similar degree, these variables have also been found to explain the variations in the 'anaerobic threshold'. This factor, which is closely related to the metabolic response to increasing exercise intensities, is the single variable that has the highest predictive power for marathon performance. But a major limiting factor to marathon performance is probably the choice of fuels for the exercising muscles, which factor is related to the %VO2 Ma X VO2 max-1. Present indications are that marathon runners, compared with normal individuals, have a higher turnover rate in fat metabolism at given high exercise intensities expressed both in absolute (m/sec) and relative (%VO2 max) terms. The selection of fat for oxidation by the muscles is important since the stores of the most efficient fuel, the carbohydrates, are limited. The large amount of endurance training done by marathon runners is probably responsible for similar metabolic adaptations, which contribute to a delayed onset of fatigue and raise the VO2 Ma X VO2max-1. There is probably an upper limit in training kilometrage above which there are no improvements in the fractional utilisation of VO2 max at the marathon race pace. The influence of training on VO2 max and, to some extent, on the running economy appears, however, to be limited by genetic factors.

Changes in onset of blood lactate accumulation (OBLA) and muscle enzymes after training at OBLA

Article

Full-text available

Feb 1982
Eur J Appl Physiol Occup Physiol

Eight well-trained middle and long distance male runners added to their regular training program a weekly 20-min treadmill run at a velocity calculated to elicit a blood lactate concentration of 4 mmol X 1-1. VO2 max, the running velocity eliciting 4 mmol X 1-1 blood lactate (VOBLA), and the activities of citrate synthase (CS), phosphofructokinase (PFK), lactate dehydrogenase (LDH) and LDH isozymes in the M. vastus lateralis were determined before and after 14 weeks of this training. Significant increases were observed in VOBLA and the relative fraction of heart-specific LDH, while the activity of PFK and the ratio of PFK/CS decreased after training. The change in VOBLA was negatively correlated to the mean rate of blood lactate accumulation during the last 15 min of the treadmill training runs, and positively correlated to the percentage of slow twitch fibers in the M. vastus lateralis. The data support the hypothesis that a steady state training intensity which approximates VOBLA will increase VOBLA, and will result in measureable local metabolic adaptations in the active skeletal muscles of well-trained runners without a significant change in maximal aerobic power. Muscle fiber type composition may be an indicator of the "trainability" of the musculature.

Measurement of pedal loading in bicycling: II. Analysis and results

Article

Full-text available

Feb 1981
J BIOMECH

A computer-based instrumentation system was used to accurately measure the six foot-pedal load components and the absolute pedal position during bicycling. The instrumentation system is the first of its kind and enables extensive and meaningful biomechanical analysis of bicycling. With test subjects riding on rollers which simulate actual bicycling, pedalling data were recorded to explore four separate hypotheses. Experiments yielded the following major conclusions: (1) Using cleated shoes retards fatigue of the quadriceps muscle group. By allowing more flexor muscle utilization during the backstroke, cleated shoes distribute the workload and alleviate the peak load demand on the quadriceps group; (2) overall pedalling efficiency increases with power level; (3) non-motive load components which apply adverse moments on the knee joint are of significant magnitude; (4) analysis of pedalling is an invaluable training aid. One test subject reduced his leg exertion at the pedal by 24 per cent.

Muscle respiratory capacity and fiber type as determinant of the lactate threshold

Article

Full-text available

Apr 1980

This study examined the relationship between the respiratory capacity of an individual's skeletal muscle and the work rate at which blood lactate accumulation begins (lactate threshold). Comparisons were also made among fiber type, VO2max, and the lactate threshold. Muscle biopsies were taken from the vastus lateralis muscle for determination of respiratory capacity and fiber type (myosin ATPase). The lactate threshold was assessed in terms of both the absolute work rate (VO2) and relative work rate (%VO2max). The capacity of muscle homogenates to oxidize pyruvate was significantly (P less than 0.01) related to the absolute (r = 0.94) and relative (r = 0.83) lactate thresholds. Significant positive correlations (P less than 0.01) were also found between the percent of slow-twitch fibers and absolute (r = 0.74) and relative (r = 0.70) lactate thresholds. The results suggest that the muscle's respiratory capacity is of primary importance in determining the work rate at which blood lactate accumulation begins. They also suggest that the proportion of slow-twitch fibers may play an important role in determining the relative lactate threshold.

Running economy and distance running performance of highly trained athletes

Article

Full-text available

Jan 1980

The purpose of the study was to determine the relationship between running economy and distance running performance in highly trained and experienced distance runners of comparable ability. Oxygen uptake (Vo2) during steady-state and maximal aerobic power (Vo2max) were measured during treadmill running using the open-circuit method. Distance running performance was determined in a nationally prominent 10 km race; all subjects (12 males) placed among the top 19 finishers. The subjects averaged 32.1 min on the 10 km run, 71.7 ml.kg-1.min-1 for Vo2max, and 44.7, 50.3, and 55.9 ml.kg-1.min-1 for steady-state Vo2 at three running paces (241, 268, and 295 m.min-1). The relationship between Vo2max and distance running performance was r = -0.12 (p = 0.35). The relationship between steady-state Vo2 at 241, 268 and 295 m.min-1 and 10 km time were r = 0.83, 0.82, and 0.79 (p < 0.01), respectively. Within this elite cluster of finishers, 65.4% of the variation observed in race performance time on the 10 km run could be explained by variation in running economy. It was concluded that among highly trained and experienced runners of comparable ability and similar Vo2max, running economy accounts for a large and significant amount of the variation observed in performance on a 10 km race.

RUNNING PERFORMANCE FROM THE VIEWPOINT OF AEROBIC POWER

Chapter

Dec 1978

Metabolic Differentiation of Distinct Muscle Types at the Level of Enzymatic Organization

Article

Jan 1971
ADV EXP MED BIOL

Dirk Pette

Metabolic differentiation of muscle tissue may be understood from the viewpoints of quantitative and qualitative adaptation. Quantitatively, it is the consequence of a balance of input of chemical energy and output of mechanical work in the myofibrillar apparatus. Qualitatively, it is the expression of an adjustment to the functional characteristics of the muscle, such as the quality and temporal pattern of energy expenditure (e.g. steady and continuous, steady and discontinuous or dicontinuous performance of work. The kinds of metabolic differentiation possible are based on the fact that muscle cells may draw energy from the oxidation of various fuels. The caloric values of the various fuels determine their different theoretical maximum energy-yields. The nature of the fuel also determines the type of its metabolism, especially with regard to an obligatory or nonobligatory aerobic catabolism. Energy-output in cell metabolism depends finally on the catabolic rate. Nature of the fuel, type of metabolism and catabolic rate thus represent fundamental elements in metabolic differentiation.

Physiological Measurement of Metabolic Functions in Man

Article

Jan 1963

A Flexible System Of Enzymatic Analysis

Article

Jan 1972

Characteristics of skeletal muscle in competitive cyclists

Article

Feb 1977
Med Sci Sports

Muscle samples from the vastus lateralis and maximal oxygen uptakes were obtained from 22 male and 7 female competitive cyclists. 19 untrained males, and 10 untrained females. Eleven of the 22 male cyclists were designated elite cyclists (Group A) on the basis of their success in national and/or international competition. The remaining 11 male cyclists (Group B) were also trained but had not achieved the same level of competitive success. Significant mean differences (P less than 0.05) between Groups A and B were found for VO2 max (67 and 57 ml/kg/min), malate dehydrogenase (MDH) and phosphorylase (PH), in biopsied muscle. No differences were evident between Groups A and B for % slow twitch (ST) and % fast twitch (FT) fibers, or in area FT or ST. Nor was there any difference in the mean activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) between the groups. Significant correlations were found between VO2 max and SDH, VO2 max and MDH, and between SDH and MDH. These data also indicate that an extremely high percentage of FT or ST fibers may not be a requirement for success in competitive cycling as has been found in earlier studies on sprint or endurance running.

Effect of detraining on responses to submaximal exercise

Article

Oct 1985

Seven endurance-trained subjects were studied 12, 21, 56, and 84 days after cessation of training. Heart rate, ventilation, respiratory exchange ratio, and blood lactate concentration during submaximal exercise of the same absolute intensity increased (P less than 0.05) progressively during the first 56 days of detraining, after which a stabilization occurred. These changes paralleled a 40% decline (P less than 0.001) in mitochondrial enzyme activity levels and a 21% increase in total lactate dehydrogenase (LDH) activity (P less than 0.05) in trained skeletal muscle. After 84 days of detraining, the experimental subjects' muscle mitochondrial enzyme levels were still 50% above, and LDH activity was 22% below, sedentary control levels. The blood lactate threshold of the detrained subjects occurred at higher absolute and relative (i.e., 75 +/- 2% vs. 62 +/- 3% of maximal O2 uptake) exercise intensities in the subjects after 84 days of detraining than in untrained controls (P less than 0.05). Thus it appears that a portion of the adaptation to prolonged and intense endurance training that is responsible for the higher lactate threshold in the trained state persists for a long time (greater than 85 days) after training is stopped.

Muscle fiber type and size in trained and untrained muscle of elite athletes

Article

Jan 1986

Tissue samples were obtained from vastus lateralis and deltoid muscles of physical education students (n = 12), Greco-Roman wrestlers (n = 8), flat-water kayakers (n = 9), middle- and long-distance runners (n = 9), and olympic weight and power lifters (n = 7). Histochemical stainings for myofibrillar adenosinetriphosphatase and NADH-tetrazolium reductase were applied to assess the relative distribution of fast-twitch and slow-twitch (ST) muscle fiber types and fiber size. The %ST was not different in the vastus (mean SD 48 +/- 14) and deltoid (56 +/- 13) muscles. The %ST was higher (P less than 0.001), however, in the deltoid compared with vastus muscle of kayakers. This pattern was reversed in runners (P less than 0.001). The %ST of the vastus was higher (P less than 0.001) in runners than in any of the other groups. The %ST of the deltoid muscle was higher in kayakers than in students, runners (P less than 0.001), and lifters (P less than 0.05). The mean fiber area and the area of ST fibers were greater (P less than 0.01) in the vastus than the deltoid muscle. Our data show a difference in fiber type distribution between the trained and nontrained muscles of endurance athletes. This pattern may reflect the adaptive response to long-term endurance training.

Three "myosin adenosine triphosphatase" systems: the nature of their pH lability and sulfhydryl dependence

Article

Oct 1970

Metabolic Differentiation of Distinct Muscle Types at the Level of Enzymatic Organization

Article

Oct 1969

Activity levels of glycogen phosphorylase, hexokinase, triosephosphate dehydrogenase, lactate dehydrogenase, citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, glycerolphosphate dehydrogenase (mitochondrial), and hexosediphosphatase have been determined in white (fast) muscles, red (slow) muscles, heart and smooth muscle of higher animals. The activities of these enzymes are taken as relative measures of metabolic capacities. Their ratios are interpreted as representing relations of different metabolic pathways or systems. In all muscles investigated comparable ratios exist for phosphorylase/triosephosphate dehydrogenase (glycogenolysis/glycolysis), glycerolphosphate dehydrogenase/triosephosphate dehydrogenase (mitochondrial glycerolphosphate oxidation/glycolysis), triosephosphate dehydrogenase/lactate dehydrogenase (glycolysis/lactate fermentation), hexokinase/citrate synthase (glucose phosphorylation/citric acid cycle) and 3-hydroxyacyl-CoA dehydrogenase/citrate synthase (fatty acid oxidation/citric acid cycle). With respect to the constancy of these ratios, consistent characteristics exist in the organization of the enzyme activity pattern. It is suggested that the more or less invariable coordination of these metabolic systems is not subject to metabolic differentiation. On the contrary, metabolic differentiation is reflected by extreme variations of the following ratios: triose-phosphate dehydrogenase/3-hydroxyacyl-CoA dehydrogenase (glycolysis/fatty acid oxidation), triosephosphate dehydrogenase/citrate synthase (glycolysis/citric acid cycle), lactate dehydrogenase/citrate synthase (lactate fermentation/citric acid cycle), phosphorylase/hexokinase (glycogenolysis/glucose phosphorylation), and hexosediphosphatase/hexokinase (gluconeogenesis/glucose phosphorylation). These variable enzyme activity ratios are discriminative magnitudes and make it possible to discern distinct metabolic types of muscle. White (fast) muscle is characterized by high capacities of glycogenolysis, glycolysis and lactate fermentation, whereas the capacities of glucose phosphorylation, citric acid cycle and fatty acid oxidation are low. Red (slow) muscles, heart and smooth muscle show inverse characteristics. In white (fast) muscle, high activities of hexosediphosphatase and of mitochondrial glycerolphosphate dehydrogenase indicate that gluconeogenesis starting from glycerolphosphate or triosephosphate is probably important in this muscle type, and compensates for its low capacity of glucose phosphorylation.

Perceived exertion: a note on "history" and methods

Article

Feb 1973
Med Sci Sports

Gunnar Borg

Early studies of subjective force estimates for short time work on a bicycle ergometer are reviewed. Results showed that perceived pedal resistance followed a positively accelerating function with an exponent of 1.6. A model for inter individual comparisons using subjective range as a frame of reference is explained. Results of two experiments comparing four different rating methods are reported. Two methods involved the original Borg Scale, and a variation, one graded from 1 to 21 and the other from 6 to 20. The third method utilized a line scale while the fourth scale was graded from 1 to 9 with 2 anchored by the expression 'Not At All Stressful' and 8 with 'Very, Very Stressful'. These two experiments show that good correlations between heart rates and ratings are obtained independent of which scale is used. Since the Borg (6 to 20) Scale is the one most often used and gives values that grow fairly linear with work load and heart rate it is proposed that this scale be used in most cases.

Onset of Blood Lactate Accumulation and Enzyme Activities in M. Vastus Lateralis in Man

Article

Sep 1981

In an earlier study, we reported close relationships between marathon running performance and the running velocity (V) at which the "onset of blood lactate accumulation" (VOBLA) occurs in a group of marathon runners. Using biopsy material from the m. vastus lateralis of the same subjects (n = 19), we have evaluated the relationship of VOBLA to different muscle enzyme activities together with muscle fiber composition and capillary density in the present study. The activities of lactate dehydrogenase (LDH EC 1.1.1.27), phosphofructokinase (PFK EC 2.7.1.11), and citrate synthase (CS EC 4.1.3.7) were determined. VOBLA was negatively correlated to LDH (r = -0.54) and PFK/CS (r = -0.68). Using multiple regression analysis, the PFK/CS ratio together with the capillary density accounted for 61% of the variation in VOBLA. Absolute training kilometrage was the most significant variable measured and accounted for 77% of the variation in VOBLA. Subjects were divided into elite runners (n = 6) and nonelite runners (n = 13) for an additional analysis of the relationship between VOBLA and the ratios of PFK/CS or LDH/CS. Significant relationships between VOBLA and the ratios were observed only in the nonelite runners (r = -0.77 and -0.66, respectively). The vertical distances between the regression lines for these two subject groups could not be explained only on the basis of the enzyme activity ratios. A greater adaptation to fat combustion in the elite runners might explain the disproportionally high VOBLA in relation to the PFK/CS or LDH/CS activity ratios.

Physiological determinants of endurance performance as studied in competitive racewalkers

Article

Feb 1983

The physiological factors that relate to 20-km performance were studied in eight competitive racewalkers. The racewalking velocity at the blood lactate threshold (LT) during steady-state exercise was highly correlated to racewalking pace (r = 0.94) and predicted performance times to within 0.6%, which agrees with previous observations on runners. The two factors that contribute to velocity at LT are O2 uptake at LT (VO2 at LT) and submaximal racewalking economy (measured as the VO2 at a standard velocity). Oxygen uptake at LT was significantly correlated (r = 0.89) to performance in the racewalkers in the present investigation, which agrees with previous observations of runners. Submaximal economy was significantly correlated to performance in the racewalkers (r = -0.82). Maximal oxygen uptake measured during racewalking was not significantly correlated (r = 0.62) to performance. These data indicate that the velocity at LT correlates closely to performance in racewalkers and that the factor of submaximal economy, which partly determines velocity at LT, is related more to performance ability in racewalking than was previously observed in running.

Recovery from short term intense exercise: Its relation to capillary supply and blood lactate concentration

Article

Feb 1983
Eur J Appl Physiol Occup Physiol

Muscle force recovery from short term intense exercise was examined in 16 physically active men. They performed 50 consecutive maximal voluntary knee extensions. Following a 40-s rest period five additional maximal contractions were executed. The decrease in torque during the 50 contractions and the peak torque during the five contractions relative to initial torque were used as indices for fatigue and recovery, respectively. Venous blood samples were collected repeatedly up to 8 min post exercise for subsequent lactate analyses. Muscle biopsies were obtained from m. vastus lateralis and analysed for fiber type composition, fiber area, and capillary density. Peak torque decreased 67 (range 47-82%) as a result of the repeated contractions. Following recovery, peak torque averaged 70 (47-86%) of the initial value. Lactate concentration after the 50 contractions was 2.9 +/- 1.3 mmol X 1(-1) and the peak post exercise value averaged 8.7 +/- 2.1 mmol X 1(-1). Fatigue and recovery respectively were correlated with capillary density (r = -0.71 and 0.69) but not with fiber type distribution. A relationship was demonstrated between capillary density and post exercise/peak post exercise blood lactate concentration (r = 0.64). Based on the present findings it is suggested that lactate elimination from the exercising muscle is partly dependent upon the capillary supply and subsequently influences the rate of muscle force recovery.

Effect of training on blood lactate levels during submaximal exercise

Article

Jun 1984

Eight men were studied before and after a 12-wk exercise program to determine the effect of training on blood lactate levels during submaximal exercise. The training elicited a 26% increase in maximum O2 uptake (VO2max). Lactate concentrations at the same relative exercise intensities in the 55-75% of VO2max range were significantly lower after training. A significantly higher relative exercise intensity was needed to elicit a given lactate level in the 1.5- to 3.0-mM range after training. O2 uptake at the work rate required to raise blood lactate to 2.5 mM was 39% higher after training. A blood lactate of 2.5 mM was attained at 68 +/- 4% VO2max before and 75 +/- 3% of VO2max after training. Eight competitive runners required an even higher relative work rate (83 +/- 2% of VO2max) to attain a blood lactate of 2.5 mM. These data provide evidence that the adaptations to training that result in an increase in VO2max are, to some degree, independent of those responsible for the lower blood lactate levels during submaximal exercise.

Blood lactate threshold in some well-trained ischemic heart disease patients

Article

Feb 1983

Six patients with ischemic heart disease who had exercised intensely for longer than 1 yr appeared to have a disproportionately high capacity for endurance exercise relative to VO2 max. They were compared with healthy runners of the same age (mean 55 yr) with similar training programs (6-12 km/day, 5 day/wk). The trained patients had a significantly (P less than 0.05) lower maximal cardiac output (-17%) and VO2 max (-18%, 37 vs. 45 ml . kg-1 . min-1). Despite their lower VO2 max, the trained patients were able to run 8 km at the same speed as the normal runners (approximately 189 m/min). The trained patients' ability to keep pace with the normal subjects was apparently due to a very high lactate threshold (LT) relative to VO2 max. The patients' LT (lactate 1 mM above base line) occurred at a treadmill running speed of 176 m/min, which elicited 100% of their VO2 max, compared with a LT at 178 m/min and 84% of VO2 max in the normal subjects (P less than 0.01). Our results show that some individuals with VO2 max limited by impaired cardiac function can undergo adaptations to training that enable them to maintain close to a metabolic steady state during exercise that elicits VO2 max.

The maximal steady state versus selected running events

Article

Feb 1981

To investigate the relationship between the maximal steady state (MSS) and selected running events, seven males (mean = 37.6 years) who were experienced competitive distance runners were studied. From a series of 10-min steady-state treadmill runs, MSS (treadmill velocity, VO2, or heart rate where lactic acid concentration was 2.2 mM/L of venous blood) was determined for all subjects. Treadmill velocity at MSS averaged 258.9 +/- 29.0 m/min. The subjects subsequently performed maximal time trials or races at 13.7 m (15 yd), 45.7 m (50 yd), 402.3 m (440 yd), 3.22 km (2 miles), 8.05 km (5 miles), 16.09 km (10 miles), and 20 km (12.44 miles). Running paces for the 402.3-m, 3.22-km, 8.05-km, 16.09-km, and 20-km distances were all correlated significantly with the treadmill pace at MSS (r = 0.84 to 0.995). The highest correlation was between the MSS treadmill velocity and the 8.05-km pace. The mean for a 6.44-km (4 miles) flat section of the 16.09-km run was identical to the mean treadmill velocity at MSS (258.9 m/min). These data indicate that the pace for essentially aerobic events (3.22 km to 20 km) can be closely approximated by knowledge of a runner's MSS, or conversely that the MSS can be predicted very closely from the pace during an all-out 3.22-km, 8.05 km, 16.09-km, or 20-km run.

Longitudinal study of aerobic power in superior junior athletes

Article

Feb 1981

The effects of endurance training on aerobic power, and the relationship between aerobic power and running performance were investigated in 11 junior runners over a period of 5-to-7 years, starting from the age of 14. Aerobic power was measured using treadmill running and a protocol that involved increasing speed. The six subjects who comprised group I were those who continued competitive training, while the five in group II had stopped training by the age of 18. The subjects in group I demonstrated greater aerobic power (l x min-1) and better running performance than those in group II. Aerobic power for group I increased from 3.54 l x min-1 (65.4 ml x kg-1 x min-1) to 4.49 l x min-1 (75.5 ml x kg-1 x min-1) between the ages of 14.8 and 18.8 yr. The increase in l x min-1 and ml x kg-1 x min-1 was statistically significant (p less than 0.01, p less than 0.05). The greatest aerobic power found in subject A corresponds to the data from world-class runners: 3.63 l x min-1 (61.5 ml x kg-1 x min-1) at age 14.7 yr; 4.67 l x min-1 (74.6 ml x kg-1 x min-1) at 17.8 yr; and 5.04 l x min-1 (76.3 ml x kg-1 x min-1) at 20.7 yr. After their training was discontinued, aerobic power for those in group II decreased to the level of ordinary schoolboys. Improvement in running performance was closely related to the increase of aerobic power in l x min-1. Superior running performance seems to be associated with high aerobic power in l x min-1, rather than in ml x kg-1 x min-1 for junior runners.

Onset of Blood Lactate Accumulation and Marathon Running Performance

Article

Mar 1981

This study was designed to examine the interrelationships among endurance running performance (marathon), the exercise intensity at which the "onset of blood lactate accumulation" (OBLA) occurs training volume, and muscle fiber characteristics. In conjunction with Stockholm's Marathon (1979), 18 male subjects underwent a test to determine the relationship between treadmill running velocity and blood lactate accumulation. The velocity at which a blood lactate accumulation of 4 mmol x l-1 occurred was referred to as the VOBLA. The m. vastus lateralis was biopsied and muscle fiber type distribution (% slow twitch, ST) and capillary density determined. With marathon running velocity (VM) as the dependent variable, multiple regression analysis showed that VOBLA accounted for 92% of the variation in VM, and VOBLA plus training volume prior to the marathon accounted for 96% of this variation. All performance variables were positively correlated to % ST muscle fiber distribution (r = 0.55-0.69) and capillary density (r = 052-0.63). Thus, marathon running performance was closely related to VOBLA and to the ability to run at a pace close to that velocity during the race. These properties were in turn related to % ST, capillary density, and training volume.

Plasma lactate accumulation and distance running performance

Article

Nov 1993

Laboratory and field assessments were made on eighteen male distance runners. Performance data were obtained for distances of 3.2, 9.7, 15, 19.3 km (n = 18) and the marathon (n = 13). Muscle fiber composition expressed as percent of slow twitch fibers (%ST), maximal oxygen consumption (VO2max), running economy (VO2 for a treadmill velocity of 268 m/min), and the VO2 and treadmill velocity corresponding to the onset of plasma lactate accumulation (OPLA) were determined for each subject. %ST (R > or equal to .47), VO2max (r > or equal to .83), running economy (r > or equal to .49), VO2 in ml/kg min corresponding to the OPLA (r > or equal to .91) and the treadmill velocity corresponding to OPLA (r > or equal to .91) were significantly (p < .05) related to performance at all distances. Multiple regression analysis showed that the treadmill velocity corresponding to the OPLA was most closely related to performance and the addition of other factors did not significantly raise the multiple R values suggesting that these other variables may interact with the purpose of keeping plasma lactates low during distance races. The slowest and fastest marathoners ran their marathons 7 and 3 m/min faster than their treadmill velocities corresponding to their OPLA which indicates that this relationship is independent of the competitive level of the runner. Runners appear to set a race pace which allows the utilization of the largest possible VO2 which just avoids the exponential rise in plasma lactate.

Physiological measurements. For use in the study of metabolic functions.

Article

Aug 1959

Perceived exertion: a note on history and methods Three "myosin ATPase" systems: the nature of their pH lability and sulfhydryl dependence

90-93

G A Borg
M H Brooke

BORG, G. A. Perceived exertion: a note on history and methods. Med. Sci. Sports 5: 90-93, 1973. 5. BROOKE, M. H., AND K. K. KAISER. Three "myosin ATPase" systems: the nature of their pH lability and sulfhydryl dependence. J. Hi&o&m. Cytochem. 18: 670-672,197O.

Glycogen utilization in leg muscles of men during level and uphill running Fractional utilization of the aerobic capacity during distance running

475-481

D L Costill
P D Gollnick
B Saltin
H Thomason

COSTILL, D. L., E. JANSSON, P. D. GOLLNICK, AND B. SALTIN. Glycogen utilization in leg muscles of men during level and uphill running. Acta Physiol. Stand. 91: 475-481,1974. 11. COSTILL, D. L., H. THOMASON, AND E. ROBERTS. Fractional utilization of the aerobic capacity during distance running. Med. Sci. Sports 5: 248-252,1973.

Changes in VOW, and running performance Physiol

249-254

J T Daniels
R A Yarbrough

DANIELS, J. T., R. A. YARBROUGH, AND C. FOSTER. Changes in VOW, and running performance Physiol. Occup. Physiol. 39: 249-254,1978.

lactate threshold in some well-trained tients

E F Coyle
W H Martin
A A Ehsani
A Bloomfield

COYLE, E. F., W. H. MARTIN, A. A. EHSANI, A. BLOOMFIELD, D. R. SINACORE, lactate threshold in some well-trained tients. J. AppZ. Physiol. 54: l&23,1983.

Plasma lactate accumulation and distance running 37 Muscle fiber types and size in performance trained and untrained muscles of elite athletes

Jan 1979
338-344

D L Costill
I A Tesch
And J Karlsson

D. L. COSTILL. Plasma lactate accumulation and distance running 37. TESCH, I? A., AND J. KARLSSON. Muscle fiber types and size in performance. Med. Sci. Sports 11: 338-344, 1979. trained and untrained muscles of elite athletes. J. Appl. Physiol.

(+)-lactate. Determination with lactate dehydrogenase and NAD

Jan 1974
1464-1468

J H Wilmore
E F Coyle
J E Billing

FARRELL, P. A., J. H. WILMORE, E. F. COYLE, J. E. BILLING, AND 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. GUTMAN, I., AND A. W. WAHLEFELD. L-(+)-lactate. Determination with lactate dehydrogenase and NAD. In: Methods of Enzymatic Analysis (2nd ed.), edited by H. U. Bergmeyer. New York: Academic, 1974, p. 1464-1468.

Capillary density in skeletal muscle of man

Jan 1975
203-205

ANDERSEN, P. Capillary density in skeletal muscle of man. Actu Physiol. &and. 95: 203-205,1975.

Glycogen utilization in leg muscles of men during level and uphill running

Jan 1974
475-481

H Thomason
And E Roberts

Glycogen utilization in leg muscles of men during level and uphill running. Acta Physiol. Stand. 91: 475-481,1974. 11. COSTILL, D. L., H. THOMASON, AND E. ROBERTS. Fractional utilization of the aerobic capacity during distance running. Med.

Blood lactate: implications for training and sport performance

Jan 1986
10-25

JACOBS, I. Blood lactate: implications for training and sport performance. &orts Med. 3: 10-25, 1986.

The use of laboratory test results with long distance runners

Jan 1986
213

LONDEREE, B. R. The use of laboratory test results with long distance runners. Sports Med. 3: ZOl-213,1986.

Mean arterial pressure, O,-uptake, and muscle force time during dynamic and rhythmic-static exercise in men with high percentages of fast and slow twitch fibers

Jan 1980
143-155

SUZUKI, Y. Mean arterial pressure, O,-uptake, and muscle force time during dynamic and rhythmic-static exercise in men with high percentages of fast and slow twitch fibers. Eur. J. AppZ. Physiol. Occup. Physiol. 43: 143-155, 1980.

Determinants of endurance in well-trained cyclists

Abstract

No full-text available

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