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Peak power output predicts maximal oxygen uptake and performance time
Abstract
The purposes of this study were firstly to determine the relationship between the peak power output (W
peak) and maximal oxygen uptake (VO2max) attained during a laboratory cycling test to exhaustion, and secondly to assess the relationship betweenW
peak and times in a 20-km cycling trial. One hundred trained cyclists (54 men, 46 women) participated in the first part of this investigation. Each cyclist performed a minimum of one maximal test during whichW
max andVO2max were determined. For the second part of the study 19 cyclists completed a maximal test for the determination ofW
peak, and also a 20-km cycling time trial. Highly significant relationships were obtained betweenW
peak andVO2max (r=0.97,P<0.0001) and betweenW
peak and 20-km cycle time (r= –0.91,P<0.001). Thus,W
peak explained 94% of the variance in measuredVO2max and 82% of the variability in cycle time over 20 km. We concluded that for trained cyclists, theVO2max can be accurately predicted fromW
peak, and thatW
peak is a valid predictor of 20-km cycle time.
... Together with the anaerobic capacity, these performance-related measures largely determine maximal power output during an incremental exercise test to exhaustion (W max ) and the so-called lactate threshold power output (or other surrogates such as critical power [CP] or ventilatory threshold) (1). Of these performance surrogates, threshold power and W max have been shown to predict cycling performance in the laboratory and outdoors (2)(3)(4)(5). In particular, W max has shown very little variation between repeated tests (6), which makes it a very reliable indicator of performance, and it is simple to measure both in the laboratory and on a home trainer. ...
... Power calculations revealed that the required number of cyclists in each group had to be 7 to detect a meaningful difference in 12-and 30-min power output, in which case our six and five junior females was too little. The performance surrogates L 4 , CP, and W max increased from junior age in females and males, and they have been shown to predict cycling performance (2)(3)(4)(5). W max , L 4 , and CP correlated with maximal power output in all test durations (6 s to 30 min) in both sexes, with a gradual increase in correlation coefficient as the test duration increased. Generally, W max showed better prediction values, which probably is due to that fact that W max is influenced by the majority of physiological performance determinants (VO 2max , cycling economy, anaerobic capacity/W`, and neuromuscular characteristics [37]). ...
... Generally, W max showed better prediction values, which probably is due to that fact that W max is influenced by the majority of physiological performance determinants (VO 2max , cycling economy, anaerobic capacity/W`, and neuromuscular characteristics [37]). Furthermore, W max has also been shown to predict endurance performance in cyclists (2,38) and to distinguish endurance performance in well-trained cyclists (38). Additionally, W max is a relatively simple measure to perform both in the laboratory and on a smart home trainer, making it an easy, assessable, low cost, and seemingly good alternative to measure performance potential and track training adaptations. ...
Aim:
This study investigated the development of power profiles and performance-related measures from the junior level (<19 years) via U23 (19-23 years) to senior level (>23 years) in 19 female and 100 male Norwegian national team cyclists.
Methods:
A total of 285 tests were performed in a 3-day laboratory-standardized testing regime. The tests included power profiles with shorter duration (6-60 s) and longer durations (12-30 min) together with performance-related measures: Critical power (CP), work capacity above CP (W'), power output at 4 and 2 mmol·L-1 [BLa-] (L4 and L2), maximal aerobic power (Wmax), and maximal oxygen uptake (VO2max), gross efficiency (GE), and pedalling efficiency.
Results:
Females and males evolve similarly when maturing from junior via U23 to senior categories (all p > 0.07), except for VO2max which increased in females (but not males) from junior to senior level (534 ± 436 ml·min-1, p = 0.013). In general, only performances of longer durations improved with age (12-min and 30-min, p = 0.028, and p = 0.042, respectively). Performance-related measures like Wmax, VO2max, CP, L4, L2, and pedalling efficiency in the fresh state improved with age (all p ≤ 0.025). Importantly, performance in the semi-fatigued state during a 5-min maximal test, was also improved with age (p = 0.045) despite a higher external energy expenditure prior to the test (p = 0.026).
Conclusions:
Junior cyclists show highly developed sprint-abilities, and the primary improvements of absolute power outputs and performance-related measures are seen for durations >60 s when maturing to U23 and senior categories. However, the durability, i.e., the capacity to maintain performance in a semi-fatigued state is improved with age.
... Breath-by-breath V O2 and V CO2 data were obtained throughout the exercise using an online gas analysis system (Quark Cosmed, Rome, Italy). MAP (W) was calculated as per Hawley and Noakes (1992), where Wcompleted is the last completed workload, t is the duration of increment completed, and PI represents the power increase between stages: ...
... Functional Threshold Power (FTP) is defined as the theoretical maximal mean power (MPO) that can be sustained for 60 minutes in a "quasi-steady state" and has been used to predict cycling performance in trained cyclists (Hawley and Noakes, 1992 Initially, participants completed a 15 min warmup of 5 mins at ~50% PPO, followed by a 5 min progressive ramp in intensity before 3 sprints (~80% of perceived max). Participants then completed 20 mins maximal cycling to achieve their highest mean power before an optional 10 min cool down. ...
... Participants completed a standardised warm-up before commencing the test consisting of 2-min stages with 30 W increments until volitional exhaustion with respired gases collected throughout. MAP (W) was calculated per Hawley and Noakes (1992). ...
Endurance athletes have traditionally been advised to consume high carbohydrate intake before, during and after exercise to support high training loads and facilitate recovery. Accumulating evidence suggests periodically training with low carbohydrate availability, termed “train-low”, augments skeletal oxidative adaptations. Comparably, to account for increased carbohydrate utilisation during exercise in hot environmental conditions, nutritional guidelines advocate high carbohydrate intake. Recent evidence suggests heat stress induces oxidative adaptation in skeletal muscle, augmenting mitochondrial adaptation during endurance training. This thesis aimed to assess the efficacy of training with reduced carbohydrate and the impact of elevated ambient temperatures on performance and metabolism. Chapter 4 demonstrated 3 weeks of Sleep Low-Train Low (SL-TL) improves performance when prescribed and completed remotely. Chapter 5 implemented SL-TL in hot and temperate conditions, confirming SL-TL improves performance and substrate metabolism, whilst additional heat stress failed to enhance performance in hot and temperate conditions following the intervention. Chapters 6 and 7 optimised and implemented a novel in vitro skeletal muscle exercise model combining electrical pulse stimulation and heat stress. Metabolomics analysis revealed an ‘exercise-induced metabolic response, with no direct metabolomic impact of heat stress. Chapter 8 characterised the systemic metabolomic response to acute exercise in the heat following SL-TL and heat stress intervention revealing distinct metabolic signatures associated with exercise under heat stress.
In summary, this thesis provides data supporting the application of the SL-TL strategy during endurance training to augment adaptation. Data also highlights the impact of exercise, environmental temperature and substrate availability on skeletal muscle metabolism and the systemic metabolome. Together, these data provide practical support for the efficacy of the SL-TL strategy to improve performance and adaptation whilst casting doubt on the utility of this approach in hot environments in endurance-trained athletes.
... Data are presented as mean ± SD. Normality ( [8], but also with performance in time trials of different durations [4,5,8,9]. For instance, strong correlations (r > 0.8) have been reported between PPO and 16-km [9], 20-km [8], 1-hour [4], or 90-minute time trial performance [7]. ...
... Data are presented as mean ± SD. Normality ( [8], but also with performance in time trials of different durations [4,5,8,9]. For instance, strong correlations (r > 0.8) have been reported between PPO and 16-km [9], 20-km [8], 1-hour [4], or 90-minute time trial performance [7]. ...
... Normality ( [8], but also with performance in time trials of different durations [4,5,8,9]. For instance, strong correlations (r > 0.8) have been reported between PPO and 16-km [9], 20-km [8], 1-hour [4], or 90-minute time trial performance [7]. Of note, PPO has been reported to be more strongly correlated with time trial performance [4,5,7]. ...
Different laboratory-based variables are individually associated with cycling performance, but scarce evidence exists on which of them, when all assessed in combination, could best explain cycling performance. The present study aimed to examine the combined association between laboratory-based endurance, strength/ power and body composition indicators with time trial performance iṅhigh-level cyclists. Ninety-four male cyclists were recruited (age: 20 ± 3.5 years, maximum oxygen uptake [VO2max]: 77.7 ± 5.4 ml · kg−1 · min−1). Participants performed a maximal incremental cycling test for the assessment of endurance indicators (peak power output [PPO], V̇ O2max, ventilatory threshold [VT] and respiratory compensation point [RCP]), and an incremental loading test to assess muscle strength and power-related outcomes (1-repetition maximum, mean maximal power) in the squat, lunge and hip-thrust exercises. Body composition was assessed by dual energy X-ray absorptiometry. On a separate visit, participants performed a simulated 8-minute time trial to assess cycling performance (determined as the mean power output attained). Strong-to-very-strong correlations were found between all endurance indicators and time trial performance (most r-values ranging between 0.68–0.92), whereas weaker correlations were found for strength/power (r-values < 0.5) or body composition (r-values < 0.7) indicators. Multivariate regression analyses revealed that VT, RCP and PPO explained together 92% of the variance in time trial performance (p < 0.001), with no significant contribution of the remaining variables. Although different endurance, strength/power and body composition individually correlate with simulated time trial performance in high-level cyclists, the former (and particularly VT, RCP and PPO) show the strongest association when all studied in combination. These findings underscore the importance of endurance capabilities (above strength/power or body composition) for maximizing time trial performance.
... In addition, previous studies also revealed that the peak power output of the heart or body measured in CPET has a high correlation with VO 2 max in patients with recovering heart failure and athletes (Hawley and Noakes, 1992;Jakovljevic et al., 2011). Physiologically, most oxygen uptake is translated to energy output during peak exercise. ...
... The correlation between the running velocity in a run field test and VO 2 max scaled to body mass in CPET would theoretically result in the optimal result, except that the examinees had a similar level of body mass at baseline. Some reports have shown a moderate-to-high correlation between peak cardiac power output (Watts) and VO 2 max (L/min) not scaled to body mass in CPET in patients with heart failure, in whom the greatest correlation coefficient was 0.85, observed in those with recovering heart function (Jakovljevic et al., 2011), and a high correlation of peak power output with VO 2 max in cycling athletes (correlation coefficient greater than 0.90) (Hawley and Noakes, 1992). The present study is the first report using EPO for a run field test to estimate VO 2 max in CPET in young adults. ...
... The use of the square of the mean velocity was better than the mean velocity in the run field test to correlate with VO 2 max in CPET in adults. This finding is consistent with a previous study on CPET, where peak power output was superior to the cycling speed to estimate VO 2 max in athletes (Hawley and Noakes, 1992). ...
Background: Both cardiopulmonary exercise testing (CPET) and run field tests are recommended by the American Heart Association for assessing the maximal oxygen uptake (VO 2 max) of youth. Power output was highly correlated with VO 2 max in CPET. However, it is unclear regarding the correlations of time and estimated power output (EPO) for a run field test with VO 2 max obtained from CPET in young adults.
Methods: This study included 45 participants, aged 20–40 years, from a sample of 1,120 military personnel who completed a 3,000-m run field test in Taiwan in 2020. The participants subsequently received CPET using the Bruce protocol to assess VO 2 max in the same year. According to the physics rule, EPO (watts) for the run field test was defined as the product of half body mass (kg) and [distance (3000-m)/time (s) for a run field test]. Pearson product–moment correlation analyses were performed.
Results: The Pearson correlation coefficient (r) of time against EPO for the run field test was estimated to be 0.708 ( p <0.001). The correlation coefficient between the time for the run field test and VO 2 max (L/min) in CPET was estimated to be 0.462 ( p = 0.001). In contrast, the correlation coefficient between time for the run field test and VO 2 max scaled to body mass in CPET was estimated to be 0.729 ( p <0.001). The correlation coefficient of EPO for the run field test against VO 2 max in CPET was estimated to be 0.813 ( p <0.001).
Conclusion: In young adults, although the time for a run field test was a reliable estimate of VO 2 max scaled to body mass, EPO proportional to the mean square velocity was found as a superior estimate of VO 2 max.
... Several physiological parameters have been used as performance predictors in top-level cyclists that include: a) maximum oxygen uptake (VO 2MAX ), maximum (W MAX ) and relative (WR MAX ) power output [1,[3][4][5][6][7]; b) oxygen uptake (VO 2VT2 ) and absolute (W VT2 ) and relative (WR VT2 ) power output at ventilatory thresholds 1 and 2 (VT1 and VT2) [4,6,7]; and c) cycling efficiency [8,9]. It has been shown that PRO record high VO 2MAX (70-80 mL⋅kg − 1 ⋅min − 1 ) and W MAX (>500 W or 6-7.5 W/kg) in a maximal incremental test, as well as an optimized VT2 (~90%VO 2MAX ), however, lower VO 2MAX (70-75 mL⋅kg − 1 ⋅min − 1 ), W MAX (300-450 W or 5.0-6.0 ...
... Interestingly, other studies have shown that PRO can reach these power outputs using shorter increments (1-min increments of 25 W) [4,6,7,53]. In the same line, Chicharro et al. [54] found significantly higher VO 2MAX (12.7%; 72.0 vs 63.9 mL⋅kg − 1 ⋅min − 1 ) and W MAX ( Although high levels of VO 2MAX are needed to be competitive in road cycling races at world level, it has been proposed that this parameter is not a good predictor of performance for PRO [7], whereas W MAX is [3]. Hawley and Noakes [3] reported a significant correlation (r = − 0.91) between W MAX in a graded exercise test (25 W every 150 s) and 20 km TT in trained cyclists. ...
... In the same line, Chicharro et al. [54] found significantly higher VO 2MAX (12.7%; 72.0 vs 63.9 mL⋅kg − 1 ⋅min − 1 ) and W MAX ( Although high levels of VO 2MAX are needed to be competitive in road cycling races at world level, it has been proposed that this parameter is not a good predictor of performance for PRO [7], whereas W MAX is [3]. Hawley and Noakes [3] reported a significant correlation (r = − 0.91) between W MAX in a graded exercise test (25 W every 150 s) and 20 km TT in trained cyclists. We found significant correlations between W MAX and VO 2VT1 , VO 2VT2 and VO 2MAX in PRO and AMA. ...
Currently, there are no studies that compares bone condition markers between professional (PRO) and amateur (AMA) cyclists. Amateur cyclists are the ones who practice this sport the most. Therefore, there is an interest in behaving if there is a negative effect at the bone level could be similar than previously described in professional cyclists. The aim of this study was to identify the differences in bone level between professional and amateur road cyclists, and to see if the differences found are related to differences in performance. A parallel trial was carried out with 15 AMA and 10 PRO cyclists. All cyclists performed 2 visits: 1) in a fasted state, body composition with measured by densitometry (DEXA) was analyzed and 2) physiological variables were measured using an incremental test until exhaustion. Significantly lower values were found in bone mineral density, bone mineral content and fat free mass in PRO compared to AMA (p<0.05). In addition, significantly higher power produced in ventilatory thresholds 1 and 2 (VT1 and VT2) and VO2MAX were found in PRO compared to AMA (p<0.05). PRO cyclists present lower values in bone health and muscle mass markers but better results in performance compared to AMA.
... Exercise training enhances physical fitness (muscle strength and aerobic capacity) resulting in marked improvements in metabolic health and functional capacity (1). As such, intense exercise training prior to a period of forced or planned inactivity (i.e., injury or postsurgery) is a common practice as a strategy to augment pre-operative physical fitness and postoperative recovery (2)(3)(4). Pre-operative exercise training prescription is based upon general exercise training guidelines emphasising combined endurance and resistance exercise training (5). However, whether implementation of both exercise modalities reflects optimal programming for all pre-operative settings is questionable (6, 7). ...
... While combined exercise training can induce robust changes in muscle strength and aerobic capacity over extended time periods (≥12 weeks) (8), many individuals have to undergo surgery at short notice, and do not have time to undertake such exercise training regimens (4). As such, it is important to determine the short-term, mode-specific effects of exercise training on multiple components of physical fitness. ...
... Approximately 24-48 h after the VO 2 peak test, maximal upper and lower body muscle strength was assessed via a battery of one-repetition maximum (1RM) tests including bilateral leg press (45º incline), bilateral knee extension and bench press. A series of sets (3)(4)(5)(2)(3)(4)(5)(6)(7)(8) repetitions) at increasing submaximal weights were lifted until the participant reported a rating of perceived exertion (RPE) of ~16 using Borg"s CR6-20 scale. Each 1RM attempt was followed by 5 min of rest. ...
Introduction:
Whether short-term, single-mode exercise training can improve physical fitness prior to a period of reduced physical activity (e.g. post-surgery recovery) is not well characterized in clinical populations nor middle-age adults. We investigated skeletal muscle adaptive responses following endurance exercise training (ENT), high-intensity interval training (HIIT) or resistance exercise training (RET), and a subsequent period of detraining, in sedentary, middle-age men.
Methods:
Thirty-five sedentary, males (39±3 yr) were randomized to parallel groups and undertook six weeks of either ENT (n=12), HIIT (n=12) or RET (n=11) followed by 2.5 weeks of detraining. Skeletal muscle fiber characteristics, body composition, muscle thickness, muscle strength, aerobic capacity, resting energy expenditure and glucose homeostasis were assessed at baseline, and after exercise training and detraining.
Results:
Lean mass increased after RET and HIIT (+3.2±1.6% and +1.6±2.1%, P<0.05). Muscle strength (sum of leg press, leg extension and bench press 1RMs) increased after all training interventions (RET: +25±5%; HIIT: +10±5%; ENT: +7±7%, P<0.05). Aerobic capacity increased only after HIIT and ENT (+14±7% and +11±11%, P<0.05). Type I and II muscle fiber size increased for all groups post-training (main effect of time, P<0.05). Following a period of detraining, the gains in lean mass and maximal muscle strength were maintained in RET and HIIT groups, but maximal aerobic capacity declined below post-training levels in HIIT and ENT (P<0.05).
Conclusion:
Six weeks of HIIT induced widespread adaptations prior to detraining in middle-age men. Exercise training-induced increases in aerobic capacity declined during 2.5 weeks of detraining but gains in lean mass and muscle strength were maintained.
... The VO 2 max is usually being used to describe exercise capacity in healthy individuals [24]. Following, since there is a portion of usage of aerobic metabolites during the WAnT [25], the VO 2 max feature might represent the aerobic contribution during the WAnT [26]. Another example is the VAT features which defines as the point at which changes in gas exchange in the lungs occur during increased exercise intensity (by means of blood lactate accumulation) [25]. ...
... Following, since there is a portion of usage of aerobic metabolites during the WAnT [25], the VO 2 max feature might represent the aerobic contribution during the WAnT [26]. Another example is the VAT features which defines as the point at which changes in gas exchange in the lungs occur during increased exercise intensity (by means of blood lactate accumulation) [25]. Trained athletes accumulate less lactate during a fixed submaximal workload [27], hence this feature change depending on the individual fitness level. ...
We previously were able to predict the anaerobic mechanical power outputs using features taken from a maximal incremental cardiopulmonary exercise stress test (CPET). Since a standard aerobic exercise stress test (with electrocardiogram and blood pressure measurements) has no gas exchange measurement and is more popular than CPET, our goal, in the current paper, was to investigate whether features taken from a clinical exercise stress test (GXT), either submaximal or maximal, can predict the anaerobic mechanical power outputs to the same level as we found with CPET variables. We have used data taken from young healthy subjects undergoing CPET aerobic test and the Wingate anaerobic test, and developed a computational predictive algorithm, based on greedy heuristic multiple linear regression, which enabled the prediction of the anaerobic mechanical power outputs from a corresponding GXT measures (exercise test time, treadmill speed and slope). We found that for submaximal GXT of 85% age predicted HRmax, a combination of 3 and 4 variables produced a correlation of r = 0.93 and r = 0.92 with % error equal to 15 ± 3 and 16 ± 3 on the validation set between real and predicted values of the peak and mean anaerobic mechanical power outputs (p < 0.001), respectively. For maximal GXT (100% of age predicted HRmax), a combination of 4 and 2 variables produced a correlation of r = 0.92 and r = 0.94 with % error equal to 12 ± 2 and 14 ± 3 on the validation set between real and predicted values of the peak and mean anaerobic mechanical power outputs (p < 0.001), respectively. The newly developed model allows to accurately predict the anaerobic mechanical power outputs from a standard, submaximal and maximal GXT. Nevertheless, in the current study the subjects were healthy, normal individuals and therefore the assessment of additional subjects is desirable for the development of a test applicable to other populations.
... Participants commenced cycling at a work-rate of 100 W for 150 s. Work rate increased by 50 W for the next 150 s, and 25 W every 150 s thereafter until volitional exhaustion [11]. Testing was conducted on an Excalibur Sport ergometer (Lode, Groningen, Netherlands) and expiratory gasses analyzed by metabolic cart calibrated to manufacturer's instructions (CosMed, Rome, Italy). ...
... Muscle biopsies were obtained from the vastus lateralis before, and at days 3 and 14 of immobilization. 3RM, 3 repetition maximum testing; Crutch icon, start of immobilization; GET, Graded exercise test[11]; DXA, Dual-energy X-ray absorptiometry; MRI, Magnetic resonance imaging; Muscle icon, muscle biopsy.https://doi.org/10.1371/journal.pone.0273925.g001 ...
Skeletal muscle unloading due to joint immobilization induces muscle atrophy, which has primarily been attributed to reductions in protein synthesis in humans. However, no study has evaluated the skeletal muscle proteome response to limb immobilization using SWATH proteomic methods. This study characterized the shifts in individual muscle protein abundance and corresponding gene sets after 3 and 14 d of unilateral lower limb immobilization in otherwise healthy young men. Eighteen male participants (25.4 ±5.5 y, 81.2 ±11.6 kg) underwent 14 d of unilateral knee-brace immobilization with dietary provision and following four-weeks of training to standardise acute training history. Participant phenotype was characterized before and after 14 days of immobilization, and muscle biopsies were obtained from the vastus lateralis at baseline (pre-immobilization) and at 3 and 14 d of immobilization for analysis by SWATH-MS and subsequent gene-set enrichment analysis (GSEA). Immobilization reduced vastus group cross sectional area (-9.6 ±4.6%, P
... All stages were 2.5 min in length. Peak wattage was calculated as a percentage of the wattage attempted during the final stage of the test along with the time completed at that stage, as used previously [32]. Pulmonary ventilation and expired gas concentrations were analysed in real time using an automated computerised indirect calorimetry system (Ametek S-3A/II and Ametek CD-3A, Pittsburgh, PA, USA). ...
... Notwithstanding, our data demonstrated a 3.8% increase in PV in the heat acclimation group, which is similar to McCleave's study (~3.8%) [31], but slightly less than reported by other studies (+5-6%) [8,32]. Larger responses observed by other studies could be due to the length or type of heat exposure, with participants in the Buchheit study undertaking skills sessions in hot environments (approx. 1 h a day), whereas participants in the Rendell study completed a more controlled isothermal heat strain session for 90 min [8,29]. ...
Background:
Combining the key adaptation of plasma volume (PV) expansion with synergistic physiological effects of other acclimation interventions to maximise endurance performance in the heat has potential. The current study investigated the effects of heat acclimation alone (H), combined with normobaric hypoxia exposure (H+NH), on endurance athletic performance.
Methods:
Well-trained participants completed a heat-stress trial (30 °C, 80% relative humidity (RH), 20.8% fraction of inspired oxygen (FiO2)) of a 75 min steady-state cycling (fixed workload) and a subsequent 15 min cycling time trial for distance before and after intervention. Participants completed 12 consecutive indoor training days with either heat acclimation (H; 60 min·day-1, 30 °C, 80% RH; 20.8% FiO2) or heat acclimation and overnight hypoxic environment (H+NH; ~12 h, 60% RH; 16% FiO2 simulating altitude of ~2500 m). Control (CON) group trained outdoors with average maximum daily temperature of 16.5 °C and 60% RH.
Results:
Both H and H+NH significantly improved time trial cycling distance by ~5.5% compared to CON, with no difference between environmental exposures. PV increased (+3.8%) and decreased (-4.1%) following H and H+NH, respectively, whereas haemoglobin concentration decreased (-2%) and increased (+3%) in H and H+NH, respectively.
Conclusion:
Our results show that despite contrasting physiological adaptations to different environmental acclimation protocols, heat acclimation with or without hypoxic exposure demonstrated similar improvements in short-duration exercise performance in a hot environment.
... Participants were provided with a pre-exercise snack before beginning a cycling familiarisation trial. Subsequently, they completed a 10 min warm-up at self-selected intensity followed by a maximal incremental test to volitional fatigue as described previously (Hawley & Noakes, 1992). Briefly, participants completed a step-test consisting of 150 s stages beginning at 3.33 ...
... Air Liquide Healthcare, Healthcare Corporation America, USA). Peak oxygen uptake (VO2peak) was defined as the highest oxygen uptake attained during two consecutive 30 second sampling periods whilst peak power output (PPO) was calculated using time spent at the final noncompleted workload plus the last fully completed work load (Hawley & Noakes, 1992). ...
The impact of environmental conditions on exercise performance in elite athletes has been explored extensively in the laboratory. Research is yet to determine the effect of the environment on performance in applied settings and novel non-thermally mediated ergogenic aids for endurance exercise in the heat have recently been proposed but are poorly understood and have not been tested in an endurance trained population. The studies in this thesis determined the effect of divergent environmental conditions on outdoor swimming performance in elite swimmers and the effect of paracetamol on the performance of trained triathletes during an endurance cycling bout in hot and humid conditions. There was no effect of the environmental conditions on the core temperature or performance of elite swimmers but skin temperature and thermal sensation differed between conditions. Paracetamol had no effect on endurance time trial performance and core and skin temperature, heart rate and thermal perception was unaffected during steady state and time trial cycling. Overall, the findings reiterate the importance of assessing thermal stress and ergogenic aids in ecologically valid settings using well planned applied study designs. Thermal stress was found to be specific to exercise mode, environmental conditions and exercise intensity and trained endurance athletes should continue to use thermally mediated pre- and per-cooling methods as non-thermally mediating ergogenic aids may not reduce core and skin temperature or thermal perception effectively during endurance exercise bouts.
... In the field of cycling particularly, Ẇ peak is considered a significant performance parameter and even a better predictor of performance than V O 2 max (Balmer et al. 2000;Hawley et al. 1992;Lamberts et al. 2012). The effects of stage duration and stage increment on Ẇ peak are well understood in a qualitative manner, in that a longer (or shorter) stage duration and/or a smaller (or greater) stage increment result in lower (or higher) Ẇ peak (Morton 1994;Zuniga et al. 2012). ...
... Equation 3 is based on average values of the parameters in the oxygen uptake-power output relationships found by Hawley et al. (1992) and Lee et al. (2000). We calibrated the conversion between running speed and cycling power by considering a world class maximum mean running speed ...
Purpose:
Peak power output ([Formula: see text]peak) in an incremental exercise test (EXT) is considered an important predictor of performance for cyclists. However, [Formula: see text]peak is protocol dependent. The purpose of this study was to model the effect of EXT design on [Formula: see text]peak.
Methods:
An adapted version of a previously developed mathematical model was used. For the purpose of validity testing, we compared predicted [Formula: see text]peak differences (predicted Δ[Formula: see text]peak) with actual Δ[Formula: see text]peak found in sports science literature.
Results:
The model quantified Δ[Formula: see text]peak between 36 EXT designs with stage durations in the range 1-5 min and increments in the range 10-50 W. Predicted Δ[Formula: see text]peak and actual Δ[Formula: see text]peak across a wide range of performance levels of cyclists were in good agreement. Depending on the specific combination of increment and stage duration, [Formula: see text]peak may be widely different or equivalent. A minimum difference in increment (5 W) or in stage duration (1 min) already results in significantly different [Formula: see text]peak. In EXTs having the same ratio between increment and stage duration, [Formula: see text]peak in the EXT with the shortest stage duration or the greatest increment is significantly higher. Tests combining 15 W, 25 W or 40 W increments with 2, 3 and 4 min stage durations, respectively, are 'special' in that their [Formula: see text]peak approximates the power output associated with maximal oxygen uptake ([Formula: see text]).
Conclusions:
The modeling results allow comparison of [Formula: see text]peak between widely different EXT designs. Absolute performance level does not affect Δ[Formula: see text]peak. [Formula: see text]peak15/2, [Formula: see text]peak25/3 and [Formula: see text]peak40/4 constitute a practical physiologic reference for performance diagnostics and exercise intensity prescription.
... Significant correlations of a 10 km uphill cycling time trial with PVT and Pmax that have been expressed as relative to the exponent of mass 0.79 have also reported (Pereira Costa et al., 2011). A similar study (Hawley & Noakes, 1992) revealed that a highly significant relationship exists between maximal power output attained during a laboratory test to exhaustion and 20 Km cycling time trial performances. Using a group of amateur, well-trained cyclists, another study (Bishop, Jenkins, & Mackinnon, 1998) reported also that maximal power output was a useful tool in the prediction of endurance cycling performance. ...
... Studying competitive cyclists, for a longer though distance (10km), Pereira Costa et al. (2011), reported similarly low correlations. Other studies (Hawley & Noakes, 1992;Balmer, Davison & Bird, 2000) for longer cycling time trials, reported higher correlations of VO2max with performance time (r=-0.91-0.99). This discrepancy may be the combined influence of VO2max heterogeneity of the subjects used for the earlier studies, as well as the lower contribution of aerobic metabolism to the total energy demands of 3 km time trial, compared to 16 and 20 km time trials. ...
The minimal power that elicits VO2max and the time to exhaustion (tlimit) at this workload appear to determine cyclists’ endurance capabilities, analyze performance and help coaches to design training. Data in the literature are limited so as to elucidate this. The aim of this study was to investigate the tlimit at the power output, which corresponds to 90 (tlimit 90) and 100% VO2max (tlimit 100) in elite endurance cyclists. The contribution of tlimit in 3 km indoor individual time trial was also studied. Subjects were eleven elite male road cyclists (age 17.7 0.5 years, body mass 66.8 4.9 kg, body height 176.3 7.4 cm, VO2max 69.77 2.58 ml.kg-1.min-1). Power output at 90 and 100% VO2max was determined by continuous incremental testing. This protocol had steps of 2 min and increments of 30 W. The exhaustive trials tlimit 90 or tlimit 100 were performed in random order at least five days apart. Five days after the last exhaustive trial, cyclists performed an individual 3 km time trial on an indoor wooden track. Mean sd, tlimit 90 and tlimit 100 were 16:27.73 07:46.6 and 4:48.6 00:53.2 min:sec. Time to exhaustion at tlimit 90 and tlimit 100 ranged between 07:00-30:15 and 03:10-06:00 min:sec, respectively. Tlimit 100, tlimit 90 and VO2max (ml.min-1) did not correlate with 3 km cycling performance (r = 0.08, 0.16 and –0.59, p > 0.05). Tlimit 90 was inversely related (r = –0.49, p = 0.1) with VO2max (ml.min-1). Only power output which corresponded to ventilatory threshold and VO2max correlated significantly with 3 km performance (r = –0.83 and –0.80, p < 0.01). The results of this study indicate that: a) if cyclists’ training intensity is based on %VO2max, individual determination of the tlimit at the %VO2max has to be considered due to a wide range of tlimit to exhaustion; b) 3 km performance directly depends on the power that corresponds with ventilatory threshold and VO2max.
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... The initial visit consisted of anthropometric and body composition measurements, dietary and caffeine intake assessment, while training and health questionnaires were also administered. On Visit 2, cyclists performed an incremental cycle ergometer protocol (Hawley & Noakes, 1992) to determine PPO, followed by a familiarization of the TTE test on the cycle ergometer (CG-04; Inbramed LTDA, Porto Alegre, Brazil). Visits 3 and 4 were for the experimental tests performed under standardized laboratory conditions (23-24°C) between 7:00 and 10:00 a.m. ...
... The incremental cycle ergometer protocol was performed to determine the PPO of each participant. The test started following a 10min warm-up at 100 W. Each stage lasted 150 s, the first performed at 3.3 W/kg, increasing by 50 W for the second stage, followed by 25 W increases per stage until exhaustion (Hawley & Noakes, 1992). Participants received strong verbal encouragement to continue for as long as possible. ...
This study investigated the effects of caffeine mouth rinse on cycling time to exhaustion (TTE) and physiological responses in trained cyclists. In a double-blinded randomized counterbalanced cross-over design, 10 recreationally trained male cyclists (mean ± SD : 32 ± 3 years, 72.8 ± 5.3 kg, 1.78 ± 0.06 m, 13.9% ± 3.3% body fat, peak power output = 289.4 ± 24.7 W) completed two TTE tests cycling at 75% of peak aerobic power following 24 hr of dietary and exercise standardization. Cyclists were administered 25-ml mouth rinses for 5 s containing either 85 mg of caffeine or control (water) every 5 min throughout the exercise tests. No significant improvement in TTE was shown with caffeine mouth rinse compared with control (33:24 ± 12:47 vs. 28:08 ± 10:18 min; Cohen’s dz effect size: 0.51, p = .14). Caffeine mouth rinse had no significant effect on ratings of perceived exertion ( p = .31) or heart rate ( p = .35) throughout the cycling TTE protocol. These data indicate that a repeated dose of caffeinated mouth rinse for 5 s does not improve cycling TTE in recreationally trained male cyclists. However, these findings should be taken with caution due to the small sample size and blinding ineffectiveness, while further well-design studies with larger samples are warranted.
... Para a população em geral, o método de reserva recomendado por essa instituição para a prescrição de exercícios 3 foi validado para a estimativa do VO 2máx 11 em indivíduos ativos, mas não atletas. Em dimensão atlética no ciclismo, dois estudos estabeleceram recomendações objetivas para a determinação do VO 2máx utilizando estratégias indiretas 8,12 . Entretanto, tais abordagens não foram comparadas em conjunto e suas validades preditivas do desempenho atlético não foram investigadas. ...
... Via de regra, os modelos preditivos se utilizam da potência aeróbia máxima (W máx ) 5,8 ou submáxima 11 para estimar o VO 2máx a partir de equações simples ou combinadas. Alguns estudos já demonstraram que a W máx alcançada em um teste aeróbio é um ótimo preditor de desempenho 8,12 . Considerando a característica colinear destas variáveis, é esperado que ocorra uma transferência do poder preditivo do desempenho atlético observado na W máx , ou submáxima, ao VO 2máx , quando estes são utilizados na sua predição. ...
... Runners with greater MLSS running powers displayed greater · VO 2 and running speeds at the MLSS ( Figure 6). As the · VO 2 and running speed associated with the MLSS are strong predictors of running performance [41,42], at least in samples with broad aerobic fitness ranges, it appears that the Stryd running power metric can be used to indicate fitness in a similar manner to that used for cycling PO from constant-intensity exercise [43,44]; however, in contrast to cycling, where the cycling speed at any given PO is primarily dictated by surface area and aerodynamics [45], body mass has a more substantial influence on the relationship between Stryd running power and running speed. Thus, while absolute Stryd running power may be used to estimate fitness in terms of absolute · VO 2 at the MLSS, in order to evaluate fitness from a speed perspective, it is best to interpret Stryd running power relative to body mass or to only interpret the speed-power relationship relative to the individual. ...
We sought to determine the utility of Stryd, a commercially available inertial measurement unit, to quantify running intensity and aerobic fitness. Fifteen (eight male, seven female) runners (age = 30.2 [4.3] years; V·O2max = 54.5 [6.5] ml·kg−1·min−1) performed moderate- and heavy-intensity step transitions, an incremental exercise test, and constant-speed running trials to establish the maximal lactate steady state (MLSS). Stryd running power stability, sensitivity, and reliability were evaluated near the MLSS. Stryd running power was also compared to running speed, V·O2, and metabolic power measures to estimate running mechanical efficiency (EFF) and to determine the efficacy of using Stryd to delineate exercise intensities, quantify aerobic fitness, and estimate running economy (RE). Stryd running power was strongly associated with V·O2 (R2 = 0.84; p < 0.001) and running speed at the MLSS (R2 = 0.91; p < 0.001). Stryd running power measures were strongly correlated with RE at the MLSS when combined with metabolic data (R2 = 0.79; p < 0.001) but not in isolation from the metabolic data (R2 = 0.08; p = 0.313). Measures of running EFF near the MLSS were not different across intensities (~21%; p > 0.05). In conclusion, although Stryd could not quantify RE in isolation, it provided a stable, sensitive, and reliable metric that can estimate aerobic fitness, delineate exercise intensities, and approximate the metabolic requirements of running near the MLSS.
... [14] and a high correlation between power output and VO 2 max in athletes (R > 0.90). [15] Theoretically, most of the oxygen uptake result in energy production, and using estimated power output for a run field test to evaluate VO 2 max is practical for healthy individuals. [16] As far as we know, most prior studies were performed for the VO 2 max correlation in aerobic running exercises, yet no studies assessed the correlation in muscular endurance tests. ...
The American Heart Association recommends a cardiopulmonary exercise test (CPET) and some alternative exercise tests to evaluate maximal oxygen uptake (VO 2 max) of youth. Power output has shown a high correlation with VO 2 max on a CPET. However, the correlations between mean power output (MPO) for muscular endurance exercises and VO 2 max measured from a CPET are not established in young adults. Forty-five volunteers, with an average age of 29.93 ± 7.05 years, from a sample of 1120 military personnel in Taiwan who attended a 2-minute pushup test and a 2-minute sit-up test were included in the current study. These volunteers subsequently underwent a CPET using the Bruce protocol to assess VO 2 max. According to the physics rule, MPO (watts) for the muscular endurance test was defined as a product of moving distance and force: [1/5 × body height (m) × numbers performed × body mass (kg) × gravity (9.8 m/s 2)]. Pearson correlation analyses were performed. For the 2-min pushups, the correlations (r) between pushup numbers and VO 2 max with and without body mass adjustment were 0.541 (P < .01) and 0.188 (P = .21), respectively, while the correlation (r) between MPO and VO 2 max with and without body mass adjustment were 0.410 and 0.557 (both P < .01), respectively. For the 2-minute sit-ups, the correlations (r) between sit-up numbers and VO 2 max with and without body mass adjustment were 0.529 (P < .01) and 0.291 (P = .052), respectively, while the correlations (r) between MPO and VO 2 max with and without body mass adjustment were 0.318 (P = .03) and 0.705 (P < .01), respectively. In military young adults, MPO for both the 2-minute sit-up and the 2-minute pushup tests could be used as alternative field-based methods to estimate VO 2 max. Abbreviations: CHIEF = cardiorespiratory fitness and health in eastern armed forces study, CPET = cardiopulmonary exercise testing, CRF = cardiorespiratory fitness, MPO = mean power output, VO 2 max = maximal oxygen uptake.
... MAP (W) was calculated per Hawley & Noakes. 21 ...
Purpose
Carbohydrate (CHO) intake periodization via the sleep low train low (SL‐TL) diet–exercise model increases fat oxidation during exercise and may enhance endurance‐training adaptation and performance. Conversely, training under environmental heat stress increases CHO oxidation, but the potential of combined SL‐TL and heat stress to enhance metabolic and performance outcomes is unknown.
Methods
Twenty‐three endurance‐trained males were randomly assigned to either control (n = 7, CON), SL‐TL (n = 8, SLTemp) or SL‐TL + heat stress (n = 8, SLHeat) groups and prescribed identical 2‐week cycling training interventions. CON and SLTemp completed all sessions at 20°C, but SLHeat at 35°C. All groups consumed matched CHO intake (6 g·kg⁻¹·day⁻¹) but timed differently to promote low CHO availability overnight and during morning exercise in both SL groups. Submaximal substrate utilization was assessed (at 20°C), and 30‐min performance tests (at 20 and 35°C) were performed Pre‐, Post‐, and 1‐week post‐intervention (Post+1).
Results
SLTemp improved fat oxidation rates at 60% MAP (~66% VO2peak) at Post+1 compared with CON (p < 0.01). Compared with SLTemp, fat oxidation rates were significantly lower in SLHeat at Post (p = 0.02) and Post+1 (p < 0.05). Compared with CON, performance was improved at Post in SLTemp in temperate conditions. Performance was not different between any groups or time points in hot conditions.
Conclusion
SL‐TL enhanced metabolic adaptation and performance compared with CON and combined SL‐TL and heat stress. Additional environmental heat stress may impair positive adaptations associated with SL‐TL.
... Zo blijkt dat de vorm (vast of vloeibaar) van de koolhydraatbron geen verschil in ergogeen effect geeft (Jeukendrup 2004). Er is weinig verschil tussen de effecten van glucose, sacharose en maltodextrine op metabolisme en prestatie wanneer ze worden ingenomen tijdens duurinspanning (Hawley & Noakes 1992;Massicotte et al. 1989;Maughan et al. 1996;Wagenmakers & Brouns 1994). ...
... Peak power output (PPO) was defined as the highest stage the subject successfully completed. PPO, measured in watts, and relative PPO, calculated in watts per kilogram and watts per muscle mass kilogram, were assessed as indicators of rowing performance [31,45]. ...
Maximum oxygen consumption and maximum power output are critical measures for training prescription in endurance sports such as rowing. The objective of this investigation was twofold: to compare the physiological and mechanical responses of female and male traditional rowers during a graded exercise test and to establish reference values in this specific rowing modality that have not yet been documented, unlike in Olympic rowing. Twenty-one highly trained/national level rowers participated in the study: 11 female (age: 30.1 ± 10.6 years, height: 167.3 ± 5.0 cm, body mass: 61.9 ± 4.9 kg) and 10 males (age: 33.5 ± 6.6 years, height: 180.8 ± 6.9 cm, body mass: 74.4 ± 6.9 kg). Significant differences (p < 0.05) were found in rowing performance between sexes, with a very large effect size (d = 7.2). The peak power output for the female rowers was 180.9 ± 11.4 W and 287.0 ± 17.7 W for the male rowers. The female rowers reached a VO2max of 51.2 ± 6.6 mL/kg/min at a mean of 174.5 ± 12.9 W, while the males' VO2max was 62.1 ± 4.7 mL/kg/min at a mean of 280.0 ± 20.5 W. These differences in VO2max and maximal aerobic capacity were significant (p < 0.05), with a large (d = 1.9) and very large (d = 6.2) effect size, respectively. A moderate association between VO2max, and rowing performance expressed in watts per kilogram of muscle mass was observed in the female rowers (r = 0.40, p = 0.228). For the male rowers, the correlation between VO2max and relative peak power output in watts per kilogram of body mass was strong (r = 0.68; p = 0.031). This study highlights the differences in the kinetics of ventilatory and mechanical parameters between female and male rowers and the importance of these differences for specific physical preparation in traditional rowing.
... 66 VO 2 is widely considered one of the major endurance performance determinants (Joyner and 67 Coyle, 2008). Using VO 2max to guide the selection process, prescribing training intensity, assessing 68 training adaptations, or predicting race times is a common practice in high-performance sports 69 (Bassett and Howley, 2000;Bentley et al., 2007;Hawley and Noakes, 1992;Noakes et al., 1990). 70 VO 2max is also one of the critical vital signs. ...
Background: Oxygen uptake (VO2) is one of the most important measures of fitness and critical vital sign. CPET is a valuable method of assessing fitness in sport and clinical settings. This study aimed to: (1) derive prediction models for maximal VO2 (VO2max) based on exercise variables at anaerobic threshold (AT) or respiratory compensation point (RCP) or only somatic and (2) internally validate provided equations.
Methods: 4424 male endurance athletes (EA) underwent maximal symptom-limited CPET on a treadmill (n=3330) or cycle ergometer (n=1094). The cohort was randomly divided between: variables selection (nrunners=1998; ncyclist=656), model building (nrunners=666; ncyclist=219) and validation (nrunners=666; ncyclist=219). Random Forest was used to select the most significant variables. Models were derived and internally validated with Multiple Linear Regression.
Results: Runners were 36.24±8.45 yrs.; BMI=23.94±2.43 kg·m−2; VO2max=53.81±6.67 mL·min−1·kg−1. Cyclists were 37.33±9.13 yr.; BMI=24.34±2.63 kg·m−2; VO2max=51.74±7.99 mL·min−1·kg−1. VO2 at AT and RCP were the most contributing variables to exercise equations. Body mass and body fat had the highest impact on the somatic equation. Model performance for VO2max based on variables at AT was R2=0.81, at RCP was R2=0.91, at AT&RCP was R2=0.91 and for somatic-only was R2=0.43.
Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO2max based on submaximal exercise performance or somatic variables. Presented models are applicable for sport and clinical settling. They are a valuable supplementary method for fitness practitioners to adjust individualised training recommendations.
Funding: The author(s) received no specific funding for this work.
... VO 2max strongly correlates with athlete's aerobic performance, could be applied to prescribe training properly, and is useful to assess adaptation to exercise [7][8][9]. Furthermore, the VO 2max could help in the prediction of a race time [10,11]. Elite athletes achieve varied VO 2max values, dependent on their discipline and training experience [12,13]. ...
In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max by assessing the transferability of the currently available prediction models based on their R2, calibration-in-the-large, and calibration slope. 5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min-1·kg-1, BMI 23.59±2.73 kg·m-2). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and “transition”) and four age subgroups (18–30, 31–45, 46–60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R2 = 0.64), females on CE (Kokkinos R2 = 0.65), males on a treadmill (TE) (Wasserman R2 = 0.26), females on TE (Wasserman R2 = 0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA. All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.
... End-point criteria forV O 2 max being achieved were: (1) heart rate within 10 beats min −1 of age-predicted maximum, (2) respiratory exchange ratio >1.1, and (3) plateau of oxygen consumption despite increased workload. MAP was calculated as per Hawley & Noakes (1992). ...
New findings:
What is the central question of this study? Whole-body substrate utilisation is altered during exercise in hot environments, characterised by increased glycolytic metabolism: does heat stress alter the serum metabolome in response to high intensity exercise? What are the main finding and its importance? Alongside increases in glycolytic metabolite abundance, circulating amino acid concentrations are reduced following exercise under heat stress. Prior research has overlooked the impact of heat stress on protein metabolism during exercise, raising important practical implications for protein intake recommendations in the heat.
Abstract:
Using untargeted metabolomics, we aimed to characterise the systemic impact of environmental heat stress during exercise. Twenty-three trained male triathletes ( V ̇ O 2 peak = 64.8 ± 9.2 ml kg min-1 ) completed a 30-min exercise test in hot (35°C) and temperate (21°C) conditions. Venous blood samples were collected immediately pre- and post-exercise, and the serum fraction was assessed via untargeted 1 H-NMR metabolomics. Data were analysed via uni- and multivariate analyses to identify differences between conditions. Mean power output was higher in temperate (231 ± 36 W) versus hot (223 ± 31 W) conditions (P < 0.001). Mean heart rate (temperate, 162 ± 10 beats min-1 , hot, 167 ± 9 beats min-1 , P < 0.001), peak core temperature (Trec ), core temperature change (ΔTrec ) (P < 0.001) and peak rating of perceived exertion (P = 0.005) were higher in hot versus temperate conditions. Change in metabolite abundance following exercise revealed distinct clustering following multivariate analysis. Six metabolites increased (2-hydroxyvaleric acid, acetate, alanine, glucarate, glucose, lactate) in hot relative to temperate (P < 0.05) conditions. Leucine and lysine decreased in both conditions but to a greater extent in temperate conditions (P < 0.05). Citrate (P = 0.04) was greater in temperate conditions whilst creatinine decreased in hot conditions only (P > 0.05). Environmental heat stress increased glycolytic metabolite abundance and led to distinct alterations in the circulating amino acid availability, including increased alanine, glutamine, leucine and isoleucine. The data highlight the need for additional exercise nutrition and metabolism research, specifically focusing on protein requirements for exercise under heat stress.
... Participants completed a peak power output aerobic exercise test using a Lode Angio CPET armcycle ergometer (ACE, Groningen, The Netherlands) adjusted for their stature and comfort. Participants were provided a heart rate monitor and underwent a graded aerobic exercise test at 55 -65 revolutions per minute (rpm) until exhaustion or for a maximum duration of 30 minutes to determine their peak power output (PPO) which is a predictor of VO2max (17). VO2max was not utilized as PPO was deemed a more practical measure for typical exercising individuals with SCI. ...
Individuals with spinal cord injury (SCI) may experience cardiovascular, musculoskeletal and organ function dysregulation. Sequelae include reduced catecholamine secretion and attenuated immune responses which may impact exercise-induced leukocytosis. The purpose of this study was to characterize major leukocyte subtypes following 30 minutes of acute, submaximal aerobic exercise, in line with updated international SCI exercise guidelines for adults. It was hypothesized that exercise would increase major leukocyte subtypes when compared to fasted baseline. Eight participants with SCI (incomplete n = 6; complete n = 2) completed a 30-minute bout of aerobic exercise on an arm cycle ergometer at 60% of their peak power output followed by 90 minutes of recovery, or a 2-hour seated control condition, in a randomized crossover design, separated by 7-14 days. Blood samples were taken at baseline, post exercise, and 90 minutes after exercise (with time matched control). Leukocyte subtypes were analyzed via flow cytometry and plasma catecholamines by ELISA. Several leukocytes increased from pre- to post-exercise (time X condition interaction; all P < 0.05; mean ± SD), including CD3+ Lymphocytes (19 ± 16%), CD4+ T helper (16 ± 13%), CD8+ T cytotoxic (24 ± 23%), CD3+/CD56+ natural killer T (31 ± 34%), and CD3-/CD56+ natural killer (63 ± 82%). CD16+/CD14dim monocytes decreased by 27 ± 38% following exercise to 90 minutes post-exercise. No changes were observed for catecholamines for either condition. Thirty minutes of acute submaximal aerobic exercise sufficiently increased most lymphocyte subsets with effector functions, while leading to decreased proinflammatory monocytes during the recovery phase. This exercise duration and intensity appear to be an appropriate option for modulating circulating immune cells in individuals with SCI.
... The test was stopped when participants could not maintain a pedaling rate around 70 rpm/min. Peak work capacity (pVO2 peak) was measured and VO2max estimated as the highest 20 s mean value attained before exhaustion (Hawley and Noakes, 1992). ...
Background: Aerobic exercise could produce a positive effect on the brain by releasing brain-derived neurotrophic factor (BDNF). In untrained healthy humans there seems to be a linear correlation between exercise duration and the positive effect of acute aerobic exercise on brain-derived neurotrophic factor levels. Therefore, we performed two different duration of high-intensity interval training protocols (HIIT), both known to improve cardiovascular fitness, to determine whether then have a similar efficacy in affecting brain-derived neurotrophic factor levels.
Methods: 12 untrained young males (aged 23.7 ± 1.8 years), participated in a randomized controlled cross-over trial. They underwent two different work-to-rest ratio high-intensity interval training protocols: high-intensity interval training 1 (30 min, 15 intervals of 1 min efforts at 85%–90% VO2max with 1 min of active recovery at 50%–60% VO2max) and HIIT2 (30 min, 10 intervals of 2 min efforts at 85%–90% VO2max with 1 min of active recovery at 50%–60% VO2max). Serum cortisol, brain-derived neurotrophic factor were collected at baseline, immediately following intervention, and 30 min into recovery for measurements using a Sandwich ELISA method, blood lactate was measured by using a portable lactate analyzer.
Results: Our results showed that the similar serum brain-derived neurotrophic factor change in both high-intensity interval training protocols, with maximal serum brain-derived neurotrophic factor levels being reached toward the end of intervention. There was no significant change in serum brain-derived neurotrophic factor from baseline after 30 min recovery. We then showed that both high-intensity interval training protocols significantly increase blood lactate and serum cortisol compared with baseline value (high-intensity interval training p < 0.01; high-intensity interval training 2 p < 0.01), with high-intensity interval training 2 reaching higher blood lactate levels than high-intensity interval training 1 ( p = 0.027), but no difference was observed in serum cortisol between both protocols. Moreover, changes in serum brain-derived neurotrophic factor did corelate with change in blood lactate (high-intensity interval training 1 r = 0.577, p < 0.05; high-intensity interval training 2 r = 0.635, p < 0.05), but did not correlate with the change in serum cortisol.
Conclusions: brain-derived neurotrophic factor levels in untrained young men are significantly increased in response to different work-to-rest ratio of high-intensity interval training protocols, and the magnitude of increase is exercise duration independent. Moreover, the higher blood lactate did not raise circulating brain-derived neurotrophic factor. Therefore, given that prolonged exercise causes higher levels of cortisol. We suggest that the 1:1work-to-rest ratio of high-intensity interval training protocol might represent a preferred intervention for promoting brain health.
... Previous studies (Bell et al., 2017;Coyle, 1995;Hawley & Noakes, 1992;Lamberts et al., 2012) in elite level cyclists reported a strong relationship between laboratory assessed parameters (PPO, VO 2max , %VO 2max ) and cycling endurance performance. In contrast to our initial hypothesis, laboratory testing did only reveal significant differences for absolute PPO between U23 ELITE (486 ± 38 W) and U23 NON-ELITE (443 ± 33 W), while differences in other laboratory parameters including relative and absolute power output at VT and RCP, and VO 2max did not reach statistical significance. ...
This study investigated the physiological, performance and training characteristics of U23 cyclists and assessed the requirements of stepping up to the elite/international ranks. Twenty highly trained U23 cyclists (age, 22.1 ± 0.8 years; body mass, 69.1 ± 6.8 kg; VO2max, 76.1 ± 3.9 ml·kg⁻¹·min⁻¹) participated in this study. The cyclists were a posteriori divided into two groups based on whether or not they stepped up to elite/international level cycling (U23ELITE vs. U23NON-ELITE). Physiological, performance and training and racing characteristics were determined and compared between groups. U23ELITE demonstrated higher absolute peak power output (p = .016), 2 min (p = .026) 5 min (p = .042) and 12 min (p ≤ .001) power output as well as higher absolute critical power (p = .002). Further, U23ELITE recorded more accumulated hours (p ≤ .001), covered distance (p ≤ .001), climbing metres (p ≤ .001), total sessions (p ≤ .001), total work (p ≤ .001) and scored more UCI points (p ≤ .001). These findings indicate that U23ELITE substantially differed from U23NON-ELITE regarding physiological, performance and training and racing characteristics derived from laboratory and field. These variables should be considered by practitioners supporting young cyclists throughout their development towards the elite/international ranks.
... This is evidenced by the results of the Pearson analyses, which showed a negative correlation of moderate strength between T1 and VO 2 max and ∆HRR2' and ∆HRR3'. The presence of the above correlations may be due to the fact that individuals with higher VO 2 max [41] and greater HRR [42] are able to achieve greater power output in incremental tests and, therefore, also in the 110%Pmax intensity test. During the initial phase of high-power exercise, oxygen deficit and muscle oxygen demand increase rapidly [43], resulting in vasoconstriction in the inactive tissues (including the skin) and redirection of blood towards the active tissues [21]. ...
The aim of this study was to determine whether there are associations between cardiovascular fitness (and aerobic capacity) and changes in temporal skin temperature during and after a single bout of high-intensity exercise. Twenty-three men with varying levels of physical activity (VO2max: 59.03 ± 11.19 (mL/kg/min), body mass 71.5 ± 10.4 (kg), body height 179 ± 8 (cm)) participated in the study. Each subject performed an incremental test and, after a 48-h interval, a 110%Pmax power test combined with an analysis of the thermal parameters, heart rate recovery and heart rate variability. Thermal radiation density from the body surface (temple) was measured using a Sonel KT384 thermal imaging camera immediately after warm-up (Tb), immediately after exercise (Te) and 120 sec after the end of exercise (Tr). The differences between measurements were then calculated. The correlation analysis between the thermal and cardiovascular function parameters during the recovery period showed strong positive associations between the Tr-Te difference and measures of cardiovascular fitness (50 < r < 69, p < 0.05). For example, the correlation coefficient between Tr-Te and VO2max reached 0.55 and between Tr-Te and Pmax reached 0.68. The results obtained indicate that the measurement of temporal temperature during and after an intense 3-min bout of exercise can be used to assess aerobic physical capacity and cardiovascular fitness.
... To ensure validity of the VO 2 max measurement, participants performed a validation bout at 110% of their peak power output achieved in the initial test following at least 15 min rest as described by Poole & Jones (2017). Peak power output was calculated as described by Hawley & Noakes (1992): ...
Endurance athletes frequently employ nutritional strategies to enhance performance. While professional organizations recommend high carbohydrate (HC) diets to maximize performance, many athletes, and researchers have recently shown renewed interest in the ketogenic diet (KD) in hopes to promote “fat adaptation”, which would allow athletes to make use of the essentially unlimited energy resources from stored body fat. This would circumvent one fatigue mechanism, the depletion of muscle glycogen stores, that has been considered central to performance outcomes in endurance events. The present study investigated the effects of participants’ habitual diet (HD), HC, and KD on endurance performance in a 30-km simulated cycling time trial (TT), physiological responses during the TT, and muscle session fuel percentile (SFP) before and after the TT using ultrasonic imaging. Due to the COVID-19 pandemic, data collection ceased after only six recreational cyclists and triathletes (f = 4, m = 6; age: 37.2 ± 12.2; VO2max: 46.8 ± 6.8 ml/kg/min; weekly cycling distance: 225.3 ± 64.2 km). Due to the small sample size, we do not report inferential statistics for our primary outcome measure, cycling performance. Participants completed the KD at the lowest power output. Oxygen consumption (V̇O2), heart rate (HR), and perceived exertion (RPE) during the TT were similar in all conditions. FATox rates were highest in the KD condition and lowest in the HC condition. SFP was lower during KD compared with HD and lower following the TT compared with fasted resting values across all conditions. We discuss methodological considerations into the use of exercise equipment, nutritional interventions, and statistical analysis strategies for study designs like the present. Further research is needed to assess the impact of HC and KD on TT performance in this population. ClinicalTrials.gov Identifier: NCT04097171; OSF preregistration: https://osf.io/ujx6e/
... As with most endurance sports, cycling performance has been reported to be mainly determined by physiological endurance indicators such as maximum oxygen uptake (VO 2max ), the so-called 'lactate threshold' [or other surrogates such as critical power or ventilatory threshold (VT)], and exercise economy (Joyner and Coyle, 2008;van der Zwaard et al., 2021). Indeed, strong evidence supports these laboratory-based indicators as predictors of cycling performance (Hawley and Noakes, 1992;Nichols et al., 1997;Bishop et al., 1998Bishop et al., , 2000Balmer et al., 2000;Bentley et al., 2001;Amann et al., 2006), and some studies have reported that indicators such as maximal aerobic capacity [represented by VO 2max or peak power output (PPO)] might be positively associated with the probability of a junior cyclist reaching the professional category (Svendsen et al., 2018). Controversy exists, however, on whether these endurance indicators can accurately differentiate cyclists of different age categories. ...
Purpose: To compare endurance, strength and body composition indicators between cyclists of three different competition age categories.
Methods: Fifty-one male road cyclists classified as either junior ( n = 13, age 16.4 ± 0.5 years), under-23 [(U23), n = 24, 19.2 ± 1.3 years] or professional ( n = 14, 26.1 ± 4.8 years) were studied. Endurance (assessed through a maximal incremental test and an 8-minute time-trial), strength/power (assessed through incremental loading tests for the squat, lunge and hip thrust exercises) and body composition (assessed through dual energy X-ray absorptiometry) were determined on three different testing sessions.
Results: U23 and, particularly professional, cyclists attained significantly ( p < 0.05) higher values than juniors for most of the analyzed endurance indicators [time-trial performance, maximum oxygen uptake (VO 2max ), peak power output (PPO), respiratory compensation point (RCP), and ventilatory threshold (VT)]. Significant differences ( p < 0.05) between U23 and professionals were also found for time-trial performance, PPO and VT, but not for other markers such as VO 2max or RCP. Professional cyclists also showed significantly ( p < 0.05) lower relative fat mass and higher muscle mass levels than U23 and, particularly, juniors. No consistent differences between age categories were found for muscle strength/power indicators.
Conclusion: Endurance (particularly time-trial performance, PPO and VT) and body composition (fat and muscle mass) appear as factors that best differentiate between cyclists of different age categories, whereas no consistent differences are found for muscle strength/power. These findings might help in performance prediction and/or talent identification and may aid in guiding coaches in the design of training programs focused on improving those variables that appear more determinant.
... VO 2max strongly correlates with athlete's aerobic performance, could be applied to prescribe training properly, and is useful to assess adaptation to exercise [7][8][9]. Furthermore, the VO 2max could help in the prediction of a race time [10,11]. Elite athletes achieve varied VO 2max values, dependent on their discipline and training experience [12,13]. ...
In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max.
5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min⁻¹·kg⁻¹, BMI 23.59±2.73 kg·m⁻²). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and “transition”) and four age subgroups (18-30, 31-45, 46-60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R²=0.64), females on CE (Kokkinos R²=0.65), males on a treadmill (TE) (Wasserman R2 =0.26), females on TE (Wasserman R²=0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA.
All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.
... However, this is difficult given that the equipment for a direct maximum fitness test is expensive and requires qualified and trained staff. 84 Finally, findings on effect sizes should be interpreted with caution given the small sample size and the lack of control group and blinding. Although physical activity was assessed before and after intervention, extraneous activities during intervention such as exercise and treatment was not monitored. ...
The aim was to evaluate feasibility of high-intensity interval training (HIIT) in fatigued adults (20-40 years old) with acquired brain injury (ABI). A prospective pre-post single-arm intervention trial was conducted, including 6-8 months follow-up assessment and interview. Intervention was 18 sessions of intermittent exercise on a cycle ergometer over six weeks. Six out of ten participants without motor impairments completed the intervention (all females, mean age = 30.2 years, months post-injury = 22). On average, participants attended 88% of sessions and achieved high intensity (93% of max heart rate). VO2max improved by 0.53 l/min (SD = 0.29), and participants continued exercising post-intervention. All participants were satisfied with HIIT, were more inclined to exercise, and reported positive effects of exercising for self-management of fatigue. Three sessions a week were demanding to some participants. Findings support feasibility of HIIT as a promising intervention for young adults with post-ABI fatigue.
... Hickson et al. (1981) konnten in ihren Untersuchungen über einen Trainingszeitraum von neun Wochen sogar eine durchschnittliche Steigerung der VO2max von 23 % bei den Probanden nachweisen. Inwiefern sich die maximalen Sauerstoffaufnahmen bei untrainierten Personen und ausdauertrainierten Sportlern unterscheiden, konnten Ogawa et al. (1992) (Hawley & Noakes, 1992;Noakes et al., 1990). Allerdings wird die maximale Geschwindigkeit/Leistung nicht nur durch die VO2max und die Bewegungsökonomie beeinflusst, sondern ebenfalls durch die anaerobe Kapazität, die Muskelkraft und die neuromuskulären Fähigkeiten (Jones & Carter, 2000). ...
High-intensity interval training, characterized by repetitive short to long bouts of high-intensity exercise separated by recovery periods, represents a time-efficient training methodology for improving athlete performance. Previous research indicates that physiological and anatomical differences in men and women may result in divergences in training response. Furthermore, the state of research suggests that changes in skeletal muscle and different functional systems over the course of age may induce different responses to an exercise stimulus. In this regard, the results show that there is a sexual dimorphism in load and recovery during interval exercise. Furthermore, it was found that good trainability is possible in old age, which in turn may counteract age-related changes and their influence on load and recovery behavior.
... Subsequently, they completed a 10-minute warm-up at self-selected intensity followed by a maximal incremental cycling test to volitional fatigue as described previously. 26 Breath-by-breath respiratory gas data were averaged as 30-second epochs throughout the test via metabolic cart (Quark C-PET; COSMED, Rome, Italy). Finally, after a ∼5-minute self-selected cooldown and ∼5-minute passive rest, participants completed a cycling familiarization session, which included a 10-minute steady-state ride at 63% PPO (∼70% VO 2 peak) followed by a short passive recovery (2 min), and the same 7-kJ·kg BM −1 performance TT used in the experimental trial (described subsequently). ...
Purpose:
The effect of acetaminophen (ACT, also known as paracetamol) on endurance performance in hot and humid conditions has been shown previously in recreationally active populations. The aim of this study was to determine the effect of ACT on physiological and perceptual variables during steady-state and time-trial cycling performance of trained triathletes in hot and humid conditions.
Methods:
In a randomized, double-blind crossover design, 11 triathletes completed ∼60 minutes steady-state cycling at 63% peak power output followed by a time trial (7 kJ·kg body mass-1, ∼30 min) in hot and humid conditions (∼30°C, ∼69% relative humidity) 60 minutes after consuming either 20 mg·kg body mass-1 ACT or a color-matched placebo. Time-trial completion time, gastrointestinal temperature, skin temperature, thermal sensation, thermal comfort, rating of perceived exertion, and fluid balance were recorded throughout each session.
Results:
There was no difference in performance in the ACT trial compared with placebo (P = .086, d = 0.57), nor were there differences in gastrointestinal and skin temperature, thermal sensation and comfort, or fluid balance between trials.
Conclusion:
In conclusion, there was no effect of ACT (20 mg·kg body mass-1) ingestion on physiology, perception, and performance of trained triathletes in hot and humid conditions, and existing precooling and percooling strategies appear to be more appropriate for endurance cycling performance in the heat.
... Because measurement of VO 2 peak during the intervention was not possible, peak watts were used as an indication of maximum intensity during the intervention. Changes in power outputs during training will indicate changes in peak power output and accordingly changes in VO 2 peak [43]. ...
Aim
The aim was to assess safety and feasibility of Hybrid High-Intensity Interval Training (HIIT) using Functional Electrical Stimulation (FES) leg cycling and arm ski ergometer in people with Spinal Cord Injuries (SCI).
Method
Eight outpatients (mean age 42.8 years; 7 men) with stable SCI paraplegia (mean 14.5 years since injury) participated in hybrid HIIT (90% peak watts; 4 × 4–min intervals), three times a week (over 8 weeks). Primary outcomes were Adverse Events (AE), participant acceptability, shoulder pain, training intensity (% peak watts), and attendance.
Secondary outcomes were effect on peak oxygen uptake (VO 2 peak) during FES hybrid poling, mean watts, self-reported leisure time physical activity, quality of life, and fatigue.
Results
No serious AE occurred; acceptability with the training modality was high, while shoulder pain increased by 9% ( SD 95.2). During training, 50% of the participants reached > 90% peak watts during the intervals, three with the legs (FES cycle) and one with the arms (Ski-Erg). Overall, mean training intensity (% peak watts) was 92% ( SD 18.9) for legs and 82% ( SD 10.3) for arms. Proportion of fulfilled training minutes was 82% (range 36–100%); one participant dropped out after 6 weeks due to back pain. Mean VO 2 peak increased by 17% ( SD 17.5). Participants reported increased leisure time physical activity and health-related quality of life, besides reduced fatigue.
Conclusion
Hybrid HIIT was safe for people with SCI paraplegia. The majority of the criteria for feasibility were met with acceptable attendance rate, limited drop out, participants enjoyed training, and increased VO 2 peak and mean watts. However, the intensity of 90% peak watts was reached by < 60% of the participants despite high RPE ratings during training. The method of measuring and calculating intensity needs to be studied further before a study using this HIIT protocol is undertaken.
Trial registration
Clinicaltrials.gov , NCT04211311 , registered 12 December 2019 retrospectively registered
... There is limited evidence that PPO is associated with survival in pulmonary fibrosis 18 , but no published study has demonstrated its value in risk prediction for surgery. Studies 19,20 in athletes have shown that PPO strongly correlates with VO 2 peak and with sustained exercise performance, which is in turn associated with AT. If these relationships hold true in patients undergoing major surgery, it may be possible to use a PPO test as a screening tool to rule out CPET abnormalities. ...
Background:
Assessment of exercise capacity is an important component of risk assessment before major surgery. Cardiopulmonary exercise testing (CPET) provides comprehensive assessment but is resource-intensive, limiting widespread adoption. Measurement of a patient's peak power output (PPO) using a simplified test on a cycle ergometer has the potential to identify patients likely to have abnormal CPET findings and to be at increased perioperative risk. The aim of this study was to investigate the potential for PPO to identify those with abnormal CPET and to determine whether PPO predicted the risk of adverse postoperative outcomes.
Methods:
In a retrospective analysis of a single-centre cohort, the ability of PPO to predict a high-risk CPET result in patients undergoing major cancer surgery was analysed. The assessment was validated in patients undergoing major abdominal surgery from a UK national multicentre cohort. The association between PPO and adverse postoperative outcomes to traditional CPET-derived variables were compared.
Results:
In 2262 patients from a single centre, PPO was an excellent discriminator of high-risk CPET, with an area under the receiver operating characteristic curve (AUROC) of 0.901 (95 per cent c.i. 0.888 to 0.913). In the national cohort of 2742 patients, there was excellent discrimination, with an AUROC of 0.856 (0.842 to 0.871). A PPO cut-off of 1.5 W/kg may be appropriate for use in screening, with a sensitivity of 90 per cent in both cohorts. PPO and traditional CPET-derived predictors demonstrated similar discrimination of major postoperative complications and death. The association between PPO and major postoperative complications persisted on multivariable analysis.
Conclusion:
These results suggest a role for the PPO test in preoperative screening and risk stratification for major surgery. Prospective evaluation is recommended.
... Data on high oxygen consumption when performing WAnT by trained cyclists are found by Hawley et al. (1992). They found highly significant relationships between Peak Power (W), VO 2 max (r=.97; ...
Soccer is a high-intensity intermittent team sport where both the aerobic and anaerobic energy systems contribute to the physiological demands of the game. The study aims to search and determine relationships between the values of cardiopulmonary and gas exchange indices during frequently used laboratory tests - the CardioPulmonary Exercise Test (CPET) and the Wingate Anaerobic Test (WAnT), exploring the capacity of the energy systems. Forty-seven soccer players (15.06 ± 0.84 years of age) performed both tests as Oxygen uptake (VO2), Oxygen pulse (O2HR), Pulmonary ventilation (VE), Volume of expired air (VTex), and Breath frequency (BF) were measured online using a breathby-breath cardiopulmonary exercise testing system. Ergometric achievements during WAnT: PP (Peak Power) 662.4 ± 121.2 W; AP (Average Power) 494.67 ± 98.5 W; FI (Fatigue Index) 61.2 ± 28.7%. There was no correlation between WAnT PP and AP and maximum power output in CPET. WAnT VE and VTex correlate significantly with CPET VO2max (r = .676 and r = .772, respectively). The main finding was a presence of approximately identical maximal values of cardiopulmonary parameters achieved in the very different in duration and intensity CPET and WАnT: insignificant differences between CPET versus WAnT: VO2max (55.97 ± 2.02 versus 56.02 ± 17.3 ml.kg.min-1); VEmax (133.96 ± 21.77 versus 126.77 ± 24.77 l.min-1); VTex max (2.19 ± 0.37 l versus 2.06 ± 0.43 l); BFmax (62.20 versus 75.43.min-1). We assume that when conducting WAnT with simultaneous registration of respiration, together with the indices of athletes’ power output, reliable information about the magnitude of VO2max and other cardiopulmonary parameters of players could be obtained. This will greatly facilitate the ongoing control of the exercise conditioning status of athletes.
... When V O 2 max was reported but not W max , we used the equation by Hawley and Noakes [52] to estimate W max (Eq. 3), which is based on the strong correlation between V O 2 max and maximal cycling power output (r = 0.97, standard error of estimate 0.28 L min −1 ). ...
Background
The 5ʹ adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a cellular energy sensor that is activated by increases in the cellular AMP/adenosine diphosphate:adenosine triphosphate (ADP:ATP) ratios and plays a key role in metabolic adaptations to endurance training. The degree of AMPK activation during exercise can be influenced by many factors that impact on cellular energetics, including exercise intensity, exercise duration, muscle glycogen, fitness level, and nutrient availability. However, the relative importance of these factors for inducing AMPK activation remains unclear, and robust relationships between exercise-related variables and indices of AMPK activation have not been established.
Objectives
The purpose of this analysis was to (1) investigate correlations between factors influencing AMPK activation and the magnitude of change in AMPK activity during cycling exercise, (2) investigate correlations between commonly reported measures of AMPK activation (AMPK-α2 activity, phosphorylated (p)-AMPK, and p-acetyl coenzyme A carboxylase (p-ACC), and (3) formulate linear regression models to determine the most important factors for AMPK activation during exercise.
Methods
Data were pooled from 89 studies, including 982 participants (93.8% male, maximal oxygen consumption [𝑉O2max] 51.9 ± 7.8 mL kg−1 min−1). Pearson’s correlation analysis was performed to determine relationships between effect sizes for each of the primary outcome markers (AMPK-α2 activity, p-AMPK, p-ACC) and factors purported to influence AMPK signaling (muscle glycogen, carbohydrate ingestion, exercise duration and intensity, fitness level, and muscle metabolites). General linear mixed-effect models were used to examine which factors influenced AMPK activation.
Results
Significant correlations (r = 0.19–0.55, p < .05) with AMPK activity were found between end-exercise muscle glycogen, exercise intensity, and muscle metabolites phosphocreatine, creatine, and free ADP. All markers of AMPK activation were significantly correlated, with the strongest relationship between AMPK-α2 activity and p-AMPK (r = 0.56, p < 0.001). The most important predictors of AMPK activation were the muscle metabolites and exercise intensity.
Conclusion
Muscle glycogen, fitness level, exercise intensity, and exercise duration each influence AMPK activity during exercise when all other factors are held constant. However, disrupting cellular energy charge is the most influential factor for AMPK activation during endurance exercise.
... FTP (W) was calculated as 95% of the mean power achieved for 20 min [38]. FTP is the highest theoretical steady state power output a cyclist can maintain for approximately 60 min [39] and has been shown to be a positive predictor of cycling performance [40], and a better predictor of mass start cycling performance than VO 2max [41]. In light of this study being completed remotely, all participants completed the test at home, FTP was used to standardise relative exercise intensity for training sessions in place of VO 2max [33]. ...
Background"Sleep Low-Train Low" is a training-nutrition strategy intended to purposefully reduce muscle glycogen availability around specific exercise sessions, potentially amplifying the training stimulus via augmented cell signalling. The aim of this study was to assess the feasibility of a 3-week home-based "sleep low-train low" programme and its effects on cycling performance in trained athletes.Methods
Fifty-five trained athletes (Functional Threshold Power [FTP]: 258 ± 52W) completed a home-based cycling training program consisting of evening high-intensity training (6 × 5 min at 105% FTP), followed by low-intensity training (1 hr at 75% FTP) the next morning, three times weekly for three consecutive weeks. Participant's daily carbohydrate (CHO) intake (6 g·kg-1·d-1) was matched but timed differently to manipulate CHO availability around exercise: no CHO consumption post- HIT until post-LIT sessions [Sleep Low (SL), n = 28] or CHO consumption evenly distributed throughout the day [Control (CON), n = 27]. Sessions were monitored remotely via power data uploaded to an online training platform, with performance tests conducted pre-, post-intervention.ResultsLIT exercise intensity reduced by 3% across week 1, 3 and 2% in week 2 (P < 0.01) with elevated RPE in SL vs. CON (P < 0.01). SL enhanced FTP by +5.5% vs. +1.2% in CON (P < 0.01). Comparable increases in 5-min peak power output (PPO) were observed between groups (P < 0.01) with +2.3% and +2.7% in SL and CON, respectively (P = 0.77). SL 1-min PPO was unchanged (+0.8%) whilst CON improved by +3.9% (P = 0.0144).Conclusion
Despite reduced relative training intensity, our data demonstrate short-term "sleep low-train low" intervention improves FTP compared with typically "normal" CHO availability during exercise. Importantly, training was completed unsupervised at home (during the COVID-19 pandemic), thus demonstrating the feasibility of completing a "sleep low-train low" protocol under non-laboratory conditions.
... The power/speed at OBLA is determined by one's ability to convert oxygen into mechanical energy (i.e., economy of motion) (88) and represents the highest sustainable fraction of VȮ 2 max which an individual can maintain for extended periods (61). The VȮ 2 max, OBLA, and economy of motion have independently (20,23,42,50,51) and collectively (22,126) demonstrated high positive correlations to endurance performance. It is acknowledged that endurance performance is also influenced by a range of internal (e.g., carbohydrate availability (11) and hydration status (34)) and external (e.g., environmental conditions (96), teamwork, and tactics (81)) factors. ...
Smith, NDW, Scott, BR, Girard, O, and Peiffer, JJ. Aerobic training with blood flow restriction for endurance athletes: potential benefits and considerations of implementation. J Strength Cond Res XX(X): 000-000, 2021-Low-intensity aerobic training with blood flow restriction (BFR) can improve maximal oxygen uptake, delay the onset of blood lactate accumulation, and may provide marginal benefits to economy of motion in untrained individuals. Such a training modality could also improve these physiological attributes in well-trained athletes. Indeed, aerobic BFR training could be beneficial for those recovering from injury, those who have limited time for training a specific physiological capacity, or as an adjunct training stimulus to provide variation in a program. However, similarly to endurance training without BFR, using aerobic BFR training to elicit physiological adaptations in endurance athletes will require additional considerations compared with nonendurance athletes. The objective of this narrative review is to discuss the acute and chronic aspects of aerobic BFR exercise for well-trained endurance athletes and highlight considerations for its effective implementation. This review first highlights key physiological capacities of endurance performance. The acute and chronic responses to aerobic BFR exercise and their impact on performance are then discussed. Finally, considerations for prescribing and monitoring aerobic BFR exercise in trained endurance populations are addressed to challenge current views on how BFR exercise is implemented.
... Fitness level (VO 2max in ml/kg/min) was estimated from the highest PPO individuals reached during the exercise tests in W, and body weight (BW) in kg, using the equation of Hawley and Noakes [36]: ...
The environmental conditions during the Tokyo Olympic and Paralympic Games are expected to be challenging, which increases the risk for participating athletes to develop heat-related illnesses and experience performance loss. To allow safe and optimal exercise performance of Dutch elite athletes, the Thermo Tokyo study aimed to determine thermoregulatory responses and performance loss among elite athletes during exercise in the heat, and to identify personal, sports-related, and environmental factors that contribute to the magnitude of these outcomes. For this purpose, Dutch Olympic and Paralympic athletes performed two personalized incremental exercise tests in simulated control (15°C, relative humidity (RH) 50%) and Tokyo (32°C, RH 75%) conditions, during which exercise performance and (thermo)physiological parameters were obtained. Thereafter, athletes were invited for an additional visit to conduct anthropometric, dual-energy X-ray absorptiometry (DXA), and 3D scan measurements. Collected data also served as input for a thermophysiological computer simulation model to estimate the impact of a wider range of environmental conditions on thermoregulatory responses. Findings of this study can be used to inform elite athletes and their coaches on how heat impacts their individual (thermo)physiological responses and, based on these data, advise which personalized countermeasures (i.e. heat acclimation, cooling interventions, rehydration plan) can be taken to allow safe and maximal performance in the challenging environmental conditions of the Tokyo 2020 Olympic and Paralympic Games.
... In cycling, quantifying mechanical power output is straightforward: the cyclist applies a force about some perpendicular distance to the cycling crank, which can be measured at the pedal, crank, bottom bracket, chair, or rear wheel hub (Passfield et al., 2017). There is a strong relationship between mechanical power output and metabolic power and performance (Faria et al., 2005;Hawley & Noakes, 1992). Consequently, measuring mechanical power output provides a more instantaneous, reliable, and sensitive measure of exercise intensity compared to heart rate or speed (Sanders et al., 2017). ...
Active technology (i.e. ‘wearables' and accompanying health tracking apps) is a multi-billion-dollar industry. Nearly one in every 10 people worldwide generates physiological and biomechanical data from wearable devices every day. This data allows users to evaluate their performance over time, to share with friends, to find like-minded training partners and share this data with their primary healthcare providers. Population-based research related to health, wellness, and physical activity is now feasible as a result of data generated from wearables. This chapter will highlight the major current trends and future applications for wearable devices from a user and research-based perspective across the active economy. The authors aim to highlight the practical and clinical utility of wearables to monitor training, fatigue, and performance on the athletic field, the workplace, and the clinical environments. The goal is to improve health, mobility, and quality of life of the end-user.
... PPO was determined to prescribe the exercise intensity for each participant's glycogen depletion protocol. The protocol began at 150 Watts (W) for 2 min and work rate increased by 30 W every minute until exhaustion [22]. Breath by breath analysis (Metamax 3B, CORTEX Biophysik, Leipzig, Germany) was recorded throughout the test. ...
Background:
Previous research has reported that elite Gaelic football players' carbohydrate (CHO) intakes are sub-optimal, especially, in the lead up to competitive matches. Despite clear decrements in running performance across elite Gaelic football matches, there are no studies that have investigated nutrition interventions on match-related Gaelic football performance. The aim of this study was to determine whether a higher-CHO diet in line with sports nutrition guidelines can improve Gaelic football-related performance compared to lower CHO intakes previously observed in Gaelic footballers.
Methods:
Twelve Gaelic football players completed a Gaelic football simulation protocol (GFSP) on two occasions after consuming a high-CHO diet (7 g·kg-1) (HCHO) or an energy-matched lower-CHO diet (3.5 g·kg-1) (L-CHO) for 48 h. Movement demands and heart rate were measured using portable global positioning systems devices. Countermovement jump height (CMJ) and repeated-sprint ability (RSA) were measured throughout each trial. Expired respiratory gases were collected throughout the trial using a portable gas analyser. Blood samples were taken at rest, half-time, and post-simulation.
Results:
There was no significant difference in total distance (p = 0.811; η2 = 0.005) or high-speed running distance (HSRD) covered between both trials. However, in the second half of the HCHO trial, HSRD was significantly greater compared to the second half of the LCHO trial (p = 0.015). Sprint distance covered during GFSP was significantly greater in HCHO (8.1 ± 3.5 m·min-1) compared with LCHO (6.4 ± 3.2 m·min-1) (p = 0.011; η2 = 0.445). RSA performance (p < 0.0001; η2 = 0.735) and lower body power (CMJ) (p < 0.0001; η2 = 0.683) were significantly greater during the HCHO trial compared to LCHO. Overall CHO oxidation rates were significantly greater under HCHO conditions compared to LCHO (3.3 ± 0.5 vs. 2.7 ± 0.6 g·min-1) (p < 0.001; η2 = 0.798). Blood lactate concentrations were significantly higher during HCHO trial versus LCHO (p = 0.026; η2 = 0.375). There were no significant differences in plasma glucose, non-esterified fatty acids (NEFAs), and glycerol concentration between trials. In both trials, all blood metabolites were significantly elevated at half-time and post-trial compared to pre-trial.
Conclusion:
These findings indicate that a higher-CHO diet can reduce declines in physical performance during simulated Gaelic football match play.
Background:
Previous research has identified sex differences in substrate oxidation during submaximal aerobic exercise including a lower respiratory exchange ratio (RER) in females compared to males. These differences may be related to differences in sex hormones. Our purpose was to examine the impact of the natural menstrual cycle (NAT) and 2nd and 3rd generation oral contraceptive pill (OCP2, OCP3) cycle phases on substrate oxidation during rest and submaximal aerobic exercise.
Methods:
Fifty female participants (18 NAT, 17 OCP2, 15 OCP3) performed two experimental trials that coincided with the low (i.e., non-active pill/early follicular) and the high hormone (i.e., active pill/mid-luteal) phase of their cycle. RER and carbohydrate and lipid oxidation rates were determined from gas exchange measurements performed during 10min of supine rest, 5min of seated rest, and two 8min bouts of submaximal cycling exercise at ~40% and ~65% of peak oxygen uptake (V̇O2peak).
Results:
For all groups, there were no differences in RER between the low and high hormone phases during supine rest (0.73±0.05 vs 0.74±0.05), seated rest (0.72±0.04 vs 0.72±0.04), exercise at 40% (0.77±0.04 vs 0.78±0.04) and 65% V̇O2peak (0.85±0.04 vs 0.86±0.03; p>0.19 for all). Similarly, carbohydrate and lipid oxidation rates remained largely unchanged across phases during both rest and exercise, apart from higher carbohydrate oxidation in NAT versus OCP2 at 40% V̇O2peak (p=0.019) and 65% V̇O2peak (p=0.001).
Conclusion:
NAT and OCPs do not appear to largely influence substrate oxidation at rest and during acute submaximal aerobic exercise.
The maximal lactate steady state (MLSS) and critical power (CP) represent the transition from heavy to severe domain and present important relationship with aerobic performance. Due the difficults on determination of these intensities, physiological index derived from incremental tests has been used in estimation. The muscle deoxihemoglobin ([HHb]BP) derivated of near infrared spectroscopy (NIRs) report the muscle oxygen extraction, which present a plateau in response during incremental test, identifying a break point ([HHb]BP), that has been associated with some index of second physiological transition and MLSS. This association, however, has not yet been determined in rowing, sport in which index of second physiological transition overestimated the MLSS. The aim of the present study was to compare the MLSS and CP intensities with the [HHb]BP in vastus lateralis muscle in incremental test with (INC3min) and without (INC1min) recovery in rowing ergometer. In addition, to verify their correlation with performance. Fourteen rowers (age: 26 ± 13 years; body mass: 81.0 ± 7.6 kg; height: 1.82 ± 0.05 m; 2000m time: 415 ± 18 s) performed: I) anthropometric assessment; II) INC3min, with initial load of 130 W and 30 W exercise steps of 3-min and 30 s of passive recovery; III) MLSS determination, through 30-min constant load tests; IV) INC1min, with initial load of 130 W and 30 W exercise steps of 1-min without recovery and V) CP determination through 500, 1000, 2000 and 6000m tests. The vastus lateralis muscle oxygenation was measured by NIRs for determination of [HHb]BP in INC3min ([HHb]BP3min) and INC1min ([HHb]BP1min), that was compared with power of MLSS, CP and first and second physiological transition indexes derivate of blood lactate, heart rate, ventilation and performance tests. The data were expressed as mean and ± SD. The comparison were performed using ANOVA one-way. Pearson correlation with confidence intervals of 95%, mean difference (Δ) and typical error of estimate (TEE) for such indexes with significance level of p < 0.05. The [HHb]BP1min (204 ± 29W) and [HHb]BP3min (207 ± 29W) showed low correspondence from each other (Δ: -3.4%; TEE: 13.2%; r = 0.51), overestimated the MLSS (Δ: 8.4 and 13.1%; TEE: 15.3 and 15.6%) and underestimated the CP (Δ: -20.4% and -17.4%; TEE: 12.3% and 10.5%). The CP was higher than MLSS (Δ: 37.6%; TEE: 10.8%; p < 0.01). The 18 second transition indexes overestimated MLSS (Δ: 12.5 to 44.9%; TEE: 5.6 to 14.3%), while LL2,0 (186 ± 27 W) and VT1 (193 ± 18 W) presented the smallest TEE (11.0 and 9.5%) and Δ (-2.3 and 4.0%), respectively, with magnitudes from trivial to medium. The time (r = -0.87) and mean power (r = 0.86) of 1000m test showed a very large correlation with MLSS. The [HHb]3min and [HHb]1min presented low correlations with performance tests. In conclusion, despite the [HHb]3min and [HHb]1min did not show significant diferences from MLSS, it was observed high variability with high TEE and mean difference that suggest a small correspondence between these indexes. In addition, the CP was higher than [HHb]BP and MLSS. Taking into account the better association of first physiological transition index with the MLSS, which clearly underestimated CP, it is possible that these markers correspond to the lower and the upper boundaries of the heavy domain on rowing exercise.
Background:
Nutrition plays a key role in training and athletic performance and dietary supplements can make a small, but potentially valuable, contribution to achieving peak athletic performance. This study is the first to investigate the effects of supplementation from the combination of BCAAs, L-citrulline, and A-GPC on exercise performance.
Methods:
In this randomized, double-blind, crossover study 30 male trained cyclists (age: 43.7 ± 8.5 years) completed a 20 km cycling time trial (TT) test and a high intensity endurance cycling (HIEC) test following a 7-day supplementation period with either a supplement containing 8 g BCAAs, 6 g L-citrulline, and 300 mg A-GPC or a placebo (15 g maltodextrin). For each trial, mean values for time to completion, peak and average power output, OMNI rating of perceived exertion, and visual analogue scale (VAS) responses on perceived exertion were computed for the 20 km TT test. Mean values for time to fatigue and VAS responses on perceived exertion were computed for the HIEC test. Procedures for dietary intake and exercise patterns were implemented to achieve consistency throughout the study period.
Results:
There was a significant increase (p = .003) in peak power in the 20 km TT (354.27 ± 87.88 and 321.67 ± 63.65, for supplement and placebo trials, respectively) and a significant increase (p = .001) in time to fatigue in the HIEC test (0:19:49 ± 0:11:13 min and 0:14:33 ± 0:09:59 min, for supplement and placebo trials, respectively) with the test supplement compared to the placebo. With the test supplement, there was an average increase in TT peak power of 11% and an average increase in time to fatigue of 36.2% in the HIEC test compared to the placebo. There was no significant improvement in time to completion, average power, OMNI rating of perceived exertion, or VAS responses on perceived exertion in the TT test and no significant improvement in VAS measures of perceived exertion in the HIEC test.
Conclusions:
The combination of BCAAs, L-citrulline, and A-GPC used in this study improves cycling performance and may be useful for individuals seeking to improve athletic performance, particularly in disciplines requiring lower body muscular strength and endurance.
Backround: Oxygen uptake (VO 2 ) is one of the most important measures of fitness and critical vital sign. Cardiopulmonary exercise testing (CPET) is a valuable method of assessing fitness in sport and clinical settings. There is a lack of large studies on athletic populations to predict VO 2max using somatic or submaximal CPET variables. Thus, this study aimed to: (1) derive prediction models for maximal VO 2 (VO 2max ) based on submaximal exercise variables at anaerobic threshold (AT) or respiratory compensation point (RCP) or only somatic and (2) internally validate provided equations.
Methods: 4424 male endurance athletes (EA) underwent maximal symptom-limited CPET on a treadmill (n=3330) or cycle ergometer (n=1094). The cohort was randomly divided between: variables selection (n runners =1998; n cyclist =656), model building (n runners =666; n cyclist =219) and validation (n runners =666; n cyclist =219). Random Forest was used to select the most significant variables. Models were derived and internally validated with Multiple Linear Regression.
Results: Runners were 36.24±8.45 yrs.; BMI=23.94±2.43 kg·m ⁻² ; VO 2max =53.81±6.67 mL·min ⁻¹ ·kg ⁻¹ . Cyclists were 37.33±9.13 yr.; BMI=24.34±2.63 kg·m ⁻² ; VO 2max =51.74±7.99 mL·min ⁻¹ ·kg ⁻¹ . VO 2 at AT and RCP were the most contributing variables to exercise equations. Body mass and body fat had the highest impact on the somatic equation. Model performance for VO 2max based on variables at AT was R ² =0.81, at RCP was R ² =0.91, at AT&RCP was R ² =0.91 and for somatic-only was R ² =0.43.
Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO 2max based on submaximal exercise performance or somatic variables. Presented models are applicable for sport and clinical settling. They are a valuable supplementary method for fitness practitioners to adjust individualised training recommendations.
Funding: No external funding was received for this work.
Die Ausdauerleistungsfähigkeit bezeichnet die Fähigkeit, körperliche Belastungen über einen längeren Zeitraum aufrechtzuerhalten bzw. die Ermüdung hinauszuzögern. Sie ist im Wesentlichen durch die Kapazität des Herz-Kreislauf-Systems und Stoffwechsels determiniert. Eine Ausdauerleistungsdiagnostik ist indiziert, wenn eine generelle Bestimmung des aktuellen Leistungsniveaus erforderlich ist, mit dem Ziel die maximale Kapazität von Herz-Kreislauf-System und/oder Stoffwechsel zu beurteilen. Bei der Auswahl geeigneter Testverfahren sollten Sicherheitsüberlegungen, mögliche Kontraindikationen, eine für den gegebenen Zweck ausreichende Standardisierung und die Einhaltung wissenschaftlicher Testgütekriterien berücksichtigt werden. Zur Verbesserung der Ausdauerleistungsfähigkeit existiert eine Reihe von Trainingsmethoden. Die Auswahl der geeigneten Trainingsmethode hängt vom Leistungsniveau, vom Trainingshintergrund sowie – zumindest teilweise – von individuellen Präferenzen der einzelnen Person ab. Dieser Beitrag ist Teil der Sektion Sportmotorische Fähigkeiten und sportliches Training, herausgegeben vom Teilherausgeber Michael Fröhlich, innerhalb des Handbuchs Sport und Sportwissenschaft, herausgegeben von Arne Güllich und Michael Krüger.
Abstract
Background and Purpose: The increasing process of overreaching in the development
or decline of the athlete's performance acts as a moving that stops in the axis timely will
improve the athlete's performance and achieve the goal. Therefore, the aim of the present
study was investigated the effects of concurrent exercise physical and brain endurance on
overreaching factors in active people.
Methodology: Subjects included 20 active male and female physical education students
(Mean ±SD; age: 22.3 ± 4.4 years, height: 177.56 ± 6.12 cm, BMI: 22± 4.5 kg/m2).
Participants were divided into two groups of concurrent endurance and brain training (BET)
and endurance training (ET), according to the results of the maximum oxygen consumption
test. Physical exercise training was performed on cycle ergometer and brain training using
computer with monitor on front of subjects during cycling. To analyze the results of the
tests, Mix ANOVA. Significance level (P≤0.05) was considered.
Results: The results showed that the maximum oxygen consumption after the training
period, regardless of the type of activity, increased significantly (P = 0.00). Monitoring
resting heart rate. POMS questionnaire indicators and resting cortisol levels did not show a
significant increase indicating non-functional overreaching, respectively (P≤0/51). The
rating of perceived exertion index was higher in the group that did physical endurance
activity along with brain endurance training (P= 0/5).
Conclusion: These findings showed despite the increase stimulant to concurrent physical
and brain endurance training did not cause non-functional overreaching and overtraining,
but also based on the results of performance improvement, it can be said that the subject
achieved functional overreaching and super compensation during the training period, which
was able to experience progress.
Key words: Overreaching, Mental Fatigue, Training Monitoring, Improve Performance,
Amount of Effort Perceived
Purpose:
We investigated whether hepcidin and erythroferrone (ERFE) could complement the Athlete Biological Passport (ABP) in indirectly detecting a 130 mL packed red blood cells (RBCs) autologous blood transfusion. Endurance performance was evaluated.
Methods:
Forty-eight healthy men (n = 24) and women (n = 24) participated. Baseline samples were collected weekly followed by randomization to a blood transfusion (BT, n = 24) or control group (CON, n = 24). Only the BT group donated 450 mL whole blood from which 130 mL RBCs was reinfused four weeks later. Blood samples were collected 3, 7, 14, 21 and 28 days after donation, and 3, 6, and 24 hours and 2, 3, and 6 days following reinfusion. In the CON group samples were collected with the same frequency. Endurance performance was evaluated by a 650-kCal time trial (n = 13) before and one and six days after reinfusion.
Results:
A time×treatment effect existed (P < 0.05) for hepcidin and ERFE. Hepcidin was increased (P < 0.01) ~110 and 89% six and 24 hours after reinfusion. Using an individual approach (99% specificity, e.g. allowing 1:100 false-positive), sensitivities, i.e. true positives, of 30% and 61% was found for hepcidin and ERFE, respectively. For the ABP, the most sensitive marker was Off-hr score ([Hb] (g/L) - 60 × √RET%) (P < 0.05) with a maximal sensitivity of ~58% and ~ 9% following donation and reinfusion, respectively. Combining the findings for hepcidin, ERFE and the ABP yielded a sensitivity across all time-points of 83% following reinfusion in BT. Endurance performance increased 24 hours (+6.4%, P < 0.01) and six days following reinfusion (+5.8%, P < 0.01).
Conclusions:
Hepcidin and ERFE may serve as biomarkers in an anti-doping context following an ergogenic, small-volume blood transfusion.
Introduction
The Propensity to Cycle Tool (PCT) is a widely used free, open source and publicly available tool for modelling cycling uptake and corresponding health and carbon impacts in England and Wales. In this paper we present the methods for our new individual-level modelling representing all commuters in England and Wales.
Methods
Scenario commuter cycling potential in the PCT is modelled as a function of route distance and hilliness between home and work. Our new individual-level approach has allowed us to create an additional “Near Market” scenario where age, gender, ethnicity, car ownership and area level deprivation also affect an individual's likelihood of switching to cycling. For this and other scenarios, we calculate the carbon benefits of cycling uptake based on the trip distance and previous mode, while health benefits are additionally affected by hilliness and baseline average mortality risk. This allows the estimation of how health and carbon benefits differ by demographic group as well as by scenario.
Results
While cycle commuting in England and Wales is demographically skewed towards men and white people, women and people from ethnic minorities have greater cycling potential based on route distance and hilliness. Benefits from cycling uptake are distributed differently again. For example, while increasing female cycling mode share is good for equity, each additional female cyclist generates a smaller average health and carbon benefit than a male cyclist. This is based on women's lower baseline mortality risk, shorter commute travel distances, and lower propensity to commute by car than men.
Conclusion
We have demonstrated a new approach to modelling that allows for more sophisticated and nuanced assessment of cycling uptake and subsequent benefits, under different scenarios. Health and carbon are increasingly incorporated into appraisal of active travel schemes, valuing important outcomes. However, especially with better representation of demographic factors, this can act as a barrier to equity goals.
Intrinsic cardiorespiratory fitness (iCRF) indicates the CRF level in the sedentary state. However, even among sedentary individuals, a wide interindividual variability is observed in the iCRF levels, whose associated molecular characteristics are little understood. This study aimed to investigate whether serum and skeletal muscle metabolomics profiles are associated with iCRF, measured by maximal power output (MPO). Seventy sedentary young adults were submitted to venous blood sampling, a biopsy of the vastus lateralis muscle and iCRF assessment. Blood serum and muscle tissue samples were analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Metabolites related to iCRF were those supported by three levels of evidence: (1) correlation with iCRF, (2) significant difference between individuals with low and high iCRF, and (3) metabolite contribution to significant pathways associated with iCRF. From 43 serum and 70 skeletal muscle analyzed metabolites, iCRF was positively associated with levels of betaine, threonine, proline, ornithine, and glutamine in serum and lactate, fumarate, NADP+, and formate in skeletal muscle. Serum betaine and ornithine and skeletal muscle lactate metabolites explained 31.2 and 16.8%, respectively, of the iCRF variability in addition to body mass. The results suggest that iCRF in young adults is positively associated with serum and skeletal muscle metabolic levels, indicative of the amino acid and carbohydrate metabolism.
The importance of the maximal oxygen uptake (VO2 max) for competitive running performance is established. Although of clear importance, the quantitative association between the volume and intensity of training, and running performance has not been established. The purpose of this investigation was to quantify the relative importance of VO2 max, training volume (miles/week) and intensity for running performance at distances ranging from 1.0 to 26.2 miles. Seventy‐eight well‐trained runners of widely varying ability were studied during uphill treadmill running to determine VO2 max. They provided training records to determine training volume and intensity, and participated in races of 1.0 (n = 31), 2.0 (n = 55), 3.0 (n = 28), 6.0 (n= 17), 10.0 (n = 20) and 26.2 (n = 25) miles. The relationship of VO2 max and training volume and intensity to performance was determined using multiple regression. Performance (running time) was highly correlated with VO2 max (r= ‐0.91, ‐0.92, ‐0.94, ‐0.96, ‐0.95 and ‐0.96 for 1.0, 2.0, 3.0, 6.0, 10.0 and 26.2 miles, respectively). The addition of training measures improved the multiple correlations in some (1.0, 2.0, 3.0 and 6.0 miles) but not all (10.0 and 26.2 miles) events. However, even when addition of one or both training indices improved the multiple correlation, the net reduction in the standard error of estimate was small. The results imply that the volume and intensity of training, per se, are relatively minor determinants of cross‐sectional differences in competitive running performance.
This study presents the finding of a sympathetic innervation of liver parenchymal cells in man. Aspects on the functional role of this innervation in glucose regulation is also given.
Seven men were studied during 30 min of treadmill exercise (approximately 70% VO2 max) to determine the effects of increased availability of plasma free fatty acids (FFA) and elevated plasma insulin on the utilization of muscle glycogen. This elevation of plasma FFA (1.01 mmol/1) with heparin (2,000 units) decreased the rate of muscle glycogen depletion by 40% as compared to the control experiment (FFA = 0.21 mmol/1). The ingestion of 75 g of glucose 45 min before exercise produced a 3.3-fold increase in plasma insulin and a 38% rise in plasma glucose at 0 min of exercise. Subsequent exercise increased muscle glycogen utilization and total carbohydrate (CHO) oxidation 17 and 13%, respectively, when compared to the control trial. This elevation of plasma insulin produced hypoglycemia (less than 3.5 mmol/1) in most subjects throughout the exercise. These data illustrate the regulatory influence of both plasma insulin and FFA on the rate of CHO usage during prolonged severe muscular activity.
The purpose of this study was to determine the relationship between non-invasive laboratory measures of 'muscle power' and swim performance over sprint (50 m) and middle-distance (400 m) events. Twenty-two swimmers performed an upper and lower body Wingate Anaerobic Test (WAT) and a maximal sustained power output test (MPO) for the upper body. Peak power (PP) and mean power (MP) were determined for the WAT, while peak sustained workload (WLpeak) was determined for the MPO. Timed swims over 50 m and 400 m were undertaken by all swimmers during which the number of arm strokes per length was recorded. Highly significant relationships were found between sprint-swim speed (S50) and mean power of the arms (MP(arms)) (r = 0.63, P less than 0.01), between S50 and mean power of the legs (MP(legs)) (r = 0.76, P less than 0.001) and between S50 and the distance covered with each arm stroke (DS) (r = 0.91, P less than 0.001). Multiple regression analyses revealed that WAT power indices for the legs did not significantly increase explained variance in S50 above that of the arms. The relationship between WL(peak) and S400 was highly significant (r = 0.70, P less than 0.001) and indicates the importance of arm power in the longer distance swim events.
Numerous equations exist for predicting VO2max from the duration (an analog of maximal work rate, Wmax) of a treadmill graded exercise test (GXT). Since a similar equation for cycle ergometry (CE) was not available, we saw the need to develop such an equation, hypothesizing that CE VO2max could be accurately predicted due to its more direct relationship with W. Thus, healthy, sedentary males (N = 115) and females (N = 116), aged 20-70 yr, were given a 15 W.min-1 CE GXT. The following multiple linear regression equations which predict VO2max (ml.min-1) from the independent variables of Wmax (W), body weight (kg), and age (yr) were derived from our subjects: Males: Y = 10.51 (W) + 6.35 (kg) - 10.49 (yr) + 519.3 ml.min-1; R = 0.939, SEE = 212 ml.min-1. Females: Y = 9.39 (W) + 7.7 (kg) - 5.88 (yr) + 136.7 ml.min-1; R = 0.932, SEE = 147 ml.min-1 Using the 95% confidence limits as examples of worst case errors, our equations predict VO2max to within 10% of its true value. Internal (double cross-validation) and external cross-validation analyses yielded r values ranging between 0.920 and 0.950 for the male and female regression equations. These results indicate that use of the equations generated in this study for a 15 W.min-1 CE GXT provides accurate estimates of VO2max.
The failure of oxygen uptake to increase with increasing work has been considered a marker of the limits of the cardiopulmonary system for many years. However, the concept has suffered from inconsistencies in definition, criteria, and data sampling, all of which affect the interpretation of the relation between changes in work and oxygen uptake. To evaluate the response and reproducibility of the slope in oxygen uptake at peak exercise, six subjects (mean age, 33 +/- 6 years) performed two individualized ramp treadmill tests on separate days. During exercise, oxygen uptake (for a given sample of 30 eight-breath running averages) was regressed with time and the slope was calculated. Maximal oxygen uptake, maximal heart rate and maximal perceived exertion were reproducible from day 1 to day 2 (mean difference, 0.4 ml/kg/min, 1.0 beats per minute, and 0.2 for maximal oxygen uptake, heart rate, and maximal perceived exertion, respectively [not significant]). Considerable variability in the slopes was observed during each test and from day to day. This occurred despite the use of large gas exchange samples, averaging techniques, and constant, consistent changes in external work. A plateau, defined as the slope of an oxygen uptake sample at peak exercise that did not differ significantly from a slope of zero, was not a consistent finding within subjects between days. We conclude that marked variability in the slope of the change in oxygen uptake occurs throughout progressive exercise, despite the use of large samples and a linear change in external work. These findings appear to preclude the determination of a plateau by common definitions.
The classical "oxygen debt" hypothesis formulated by Hill and associates in the 1920s was an attempt to link the metabolism of lactic acid with the O2 consumption in excess of resting that occurs after exercise. The O2 debt was hypothesized to represent the oxidation of a minor fraction (1/5) of the lactate formed during exercise, to provide the energy to reconvert the remainder (4/5) of the lactate to glycogen during recovery. In 1933 Margaria et al. modified this hypothesis by distinguishing between initial, fast ("alactacid"), and second, slow ("lactacid"), O2-debt curve components. They hypothesized that the fast phase of the post-exercise O2 consumption curve was due to the restoration of phosphagen (ATP + CP). It is now probable that the original lactic acid explanation of the O2 debt was too simplistic. Numerous studies on several species have provided evidence demonstrating a dissociation between the kinetics of lactate removal and the slow component of the post-exercise VO2. The metabolism of lactate, a readily oxidizable substrate, following exercise appears to be directed primarily toward energy production in mitochondria. The elevated concentration of lactate present at the end of exercise may be viewed as a "reservoir of carbon," which may serve as a source of oxidative ATP production or as a source of carbon skeletons for the synthesis of glucose, glycogen, amino acids, and TCA cycle intermediates. The metabolic basis of the elevated post-exercise VO2 may be understood in terms of those factors which directly or indirectly influence mitochondrial O2 consumption. Included among these factors are catecholamines, thyroxine, glucocorticoids, fatty acids, calcium ions, and temperature. Of these, elevated temperature is perhaps the most important. As no complete explanation of the post-exercise metabolism exists, it is recommended that the term "O2 debt" be used to describe a set of phenomena during recovery from exercise. The terms "alactacid debt" and "lactacid debt," which suggest a mechanism, are inappropriate. Use of alternative terms, e.g., "excess post-exercise oxygen consumption" (EPOC) and "recovery O2," will avoid implication of causality in describing the elevation in metabolic rate above resting levels after exercise.
UNDER this heading Robinson, Edwards and Dill1 published in
1937 results of investigations of five young men of international renown
in distance running. Lash, who held the world's record for the 2-mile
race, running on a treadmill at 21.6 km./hr. with no gradient, attained
an oxygen intake of 5.35 l./min. or 81.5 ml. per kgm. of body-weight per
min.2.
The effect of training on the skeletal muscle metabolism of 11-to 13-year-old boys was examined. In one experiment changes in blood lactate, and muscle lactate, CP, ATP, and glycogen were determined at rest and following exercise before and after 4 months of training. The concentrations of glycogen, CP and ATP at rest were higher (P<0.01) following training. Blood and muscle lactate were 23 and 56 % higher after maximal work following training. A greater reduction in muscle glycogen occurred during maximal work after training but the pattern for ATP and CP depletion was unchanged. In a second experiment boys trained by pedalling a bicycle ergometer an average of 30 min 3 times a week for 6 weeks. Biopsy samples of the vastus lateralis were examined for oxidative (succinate dehydrogenase) and anaerobic (phosphofructokinase) capacity before and after training. The fiber composition and relative oxidative capacity in the fibers was determined histochemically. Succinate dehydrogenase and phosphofructokinase activities increased 30 and 83 %, respectively, following training. Fiber distribution was unchanged by training but the oxidative capacity of both fiber types appeared to increase.
Seven male sedentary human subjects were studied during intense muscular work (80% of maximal oxygen uptake) performed either for 15 min or until exhaustion (mean duration: 47±2 min).
Plasma catecholamines were estimated before and after the experiment by means of an original fluorimetric assay. Epinephrine and norepinephrine were individually isolated from plasma and assayed in single extracts by a highly sensitive fluorimetric method. Epinephrine or norepinephrine levels as low as 15 ng per liter were detectable by this procedure in human plasma.
The adrenergic pattern was found to be greatly different from one subject to another and related to emotivity: the effect of this factor was revealed by the predominance of epinephrine in plasma at rest or under exercise (ratio NA/A <1).
In nonemotive subjects (ratio NA/A>1 at rest) plasma epinephrine and norepinephrine increased progressively during exercise. Increments after exercise were higher for norepinephrine changes; however, the fact that epinephrine concentrations correlated significantly with norepinephrine suggests a simultaneous and coordinated stimulation of adrenal glands and orthosympathetic nervous system.
In emotive subjects (ratio NA/A<1 at rest) the apprehension of muscular work promoted a difference in catecholamine responses: norepinephrine release was not affected by subject's anxiety, while epinephrine secretion, already elevated before the test, reached a high degree of magnitude in the first minutes of muscular work, remaining nearly constant until exhaustion.
Physical training of nonemotive subjects, during 2 months with two intense exercises by a week, reduced strongly norepinephrine release after exhaustive muscular work. In the same conditions, the adrenal-medullary response was not significantly modified when compared with untrained subjects.
Our results suggest that the adrenergic behaviour during exercise is a function of effort intensity to be supplied; catecholamines seem to be important factors in regulating body homeostasy during muscular work in man. In addition, emotive subjects exhibit amplified adrenal-medullary response, which may be related to psychological stimuli.
Adrenaline, noradrenaline, lactate and glucose levels in the blood, together with the heart rate and oxygen intake were examined in eight boys (12.8±0.8 years) and seven adults (27.8±2.9 years) during a graduated treadmill exercise. At rest, noradrenaline is higher in the adults, while adrenaline, lactate, glucose, heart rate and relative oxygen intake show no differences between the groups. At the same exercise levels, adrenaline (+90–180%), noradrenaline (+28–77%) and the heart rate are higher in boys, corresponding to a higher relative exercise load, and glucose, lactate and the relative oxygen intake show no differences. During maximum treadmill exercise adrenaline, glucose and the relative oxygen intake show no differences between the groups, whereas the noradrenaline (−30%) and lactate levels (−25%) are lower and the heart rate is 4% higher in the boys. There is an identical increase in lactate and catecholamine levels (r=0.92 and 0.87) with a lower correlation with high intensity “anaerobic” physical exercise, which shows no age dependent difference until about the age of 40. The maximum catecholamine (adrenaline and noradrenaline) and lactate concentration is 25% lower in the boys; an indication of reduced maximum sympathetic activity and reduced maximum anaerobic capacity is seen. The constant relationship between adrenaline and noradrenaline during physical work (r=0.90 and 0.85), also with a lower correlation at high intensiv physical exercise, changes from 1∶3.5 (boys) to 1∶5.5 (adults) (p<0.001), based on higher noradrenaline levels in the adults at rest, at submaximum exercise levels and during maximum ergometric work; these changes are seen to be the cause of an age dependent negative chronotropic effect.
Elf ausdauertrainierte Knaben (12,81,2 Jahre) und 12 Jugendliche (17,70,5 Jahre) wurden einer stufenweisen Laufbandergometrie und einem 10 000-m-Lauf unterzogen. Im Laborversuch wurde das Sauerstoffaufnahmevermgen, die maximale Lactatazidose sowie die anaerobe Schwelle, die Herzfrequenz und der Glucosespiegel im Blut, whrend des Feldversuches die Catecholaminausscheidung, das Verhalten des Glucose-, Lactat-, Glycerinspiegels und der freien Fettsuren untersucht.Das Sauerstoffaufnahmevermgen der Jugendlichen und das absolute Herzvolumen ist gr\er, unterscheidet sich aber gewichtsbezogen nicht von den Knaben. Die maximale Lactatezidose der Knaben ist niedriger, unterscheidet sich aber auf submaximalen Stufen, bezogen auf die relative Sauerstoffaufnahme nicht von den Jugendlichen. Die Sauerstoffaufnahme im Bereich der anaeroben Schwelle als Ausdruck der Gte der Ausdauertrainiertheit betrgt bei beiden Gruppen bereinstimmend ca. 55 ml/kgmin und entspricht ca. 80–90% des Sauerstoffaufnahmevermgens. Die Herzfrequenz der Knaben liegt auf gleichen submaximalen Stufen und bei maximaler Ergometerarbeit hher und bleibt auch in bezug auf die relative Sauerstoffaufnahme und im Bereich der anaeroben Schwelle 5–10 Schlge/min hher. Der Glucosespiegel nimmt bei Knaben und Jugendlichen gleicherma\en whrend der Ergometerarbeit 20–25% zu. Die Basisexkretion freier Catecholamine zeigt keinen Unterschied zwischen beiden Gruppen; sie steigt whrend des 10 000-m-Laufes vier- bis fnffach an und zeigt gewichtsbezogen keinen Unterschied zwischen beiden Gruppen; der Lactatspiegel nimmt 217% (Knaben) und 338% (Jugendliche), der Glucosespiegel 36 und 61%, die freien Fettsuren 131 und 69% und Glycerin ca. 300% zu. Die Differenzen zwischen beiden Gruppen sind nicht signifikant. Hinsichtlich der Trainierbarkeit und der Ausdauerleistungsfhigkeit, kenntlich an der relativen Herzgr\e, dem gewichtsbezogenen Sauerstoffaufnahmevermgen, der relativen Catecholaminexkretion (ng/minkg) sowie der relativen Sauerstoffaufnahme im Bereich der anaeroben Schwelle und der Vernderung energiereicher Substrate ist keine Unterlegenheit der Knaben gegenber Jugendlichen anzunehmen. Aus Grnden der Vergleichbarkeit wird vorgeschlagen, die Catecholaminausscheidung auf das Krpergewicht zu beziehen.Eleven endurance trained young boys and 12 adolescents were examined during a graduated treadmill ergometric test and one week later during a 10,000m race. Aerobic capacity (oxygen intake), anaerobic capacity (lactate), anaerobic threshold, heart rate, and blood glucose levels were determined during laboratory testing. The sympathoadrenergic activity (excretion of free adrenaline and noradrenaline in urine), and the influence of prolonged submaximum exercise on carbohydrate- (glucose, lactate) and lipid metabolism (glycerine, free fatty acids) were determined during the field experiment. Aerobic capacity in adolescents, like the absolute heart volume, is larger than in young boys but shows no weight related differences. Anaerobic capacity of young boys is shown to be lower, but shows no difference to the adolescents at the same submaximum levels related to the relative oxygen intake. Oxygen intake at the anaerobic threshold is a sign of the endurance condition and reaches approx 55 ml/kgmin in both groups, and corresponds to about 80–90% of aerobic capacity. Heart rate in the young boys is higher at the same submaximum levels and during maximum ergometric exercise; also in relation to the relative oxygen intake and at the anaerobic threshold the heart rate remains 5–10 beats/min higher. The glucose level increases 20–25% in both the young boys and the adolescents during ergometric exercise. The excretion at rest of free catecholamine shows no difference between the groups. The average excretion during the 10,000 m race increases four to five times and shows no weight related differences between the groups. The lactate level increases 217% (young boys) and 338% (adolescents), the glucose level 36 and 61%, the free fatty acids 131 and 69%, and glycerine about 300%. The differences between both groups are not significant. In regard to trainability and endurance capacity, recognizable by the rleative heart volume, the relative aerobic capacity and the relative catecholamine excretion as well as the relative oxygen intake at the anaerobic threshold and changes of the energy rich substrates, the young boys show no disadvantage to the adolescents. For reasons of comparison it is suggested that catecholamine excretion be refered to body weight.
Maximal oxygen uptake (V̇O2 max) has been described as an important characteristic of endurance athletes. Early investigations by Robinson, Edwards, and Dill, and Saltin and Astrand reported V̇O2 max values above 80 ml/kg.min for distance runners and cross-country skiers. Saltin and Astrand further documented a differentiation in V̇O2 max in a variety of athletic types. A more recent study showed that although V̇O2 max differentiated well in endurance athletes of diverse abilities, there was a limitation of using V̇O2 max to predict distance running performance of good runners. Costill et al. and Costill, Thomason, and Roberts found that the fractional utilization of VO2 at a standard running speed to be an important measure in predicting V̇O2 capacity in good distance runners. Running efficiency from the standpoint of energy expenditure may also be an important factor in differentiating distance runners. It has been suggested that differences may exist in some metabolic variables between elite marathon runners (26.2 miles or 42 km) and other elite types of middle-long distance runners (1-6 miles or 1,500-10,000 m). As metabolic and efficiency differences may prove more predictive in differentiating among elite runners, it was the purpose of this investigation to study the submaximal and maximal metabolic characteristics of a large sample of elite runners to observe if specific differentiation into the types of runner could be made.
The present study was designed to investigate the isokinetic peak torque at the highest speed of muscle shortening (210 degrees/second) related to age, sex, and physical performance. The subjects were 569 normal boys and girls, 13 to 17 years of age, and 35 swimmers, 11 to 21 years of age. Peak torque of knee extensor muscles increased linearly with age for boys from 13 to 17 years, while it remained relatively constant for girls 14 to 17 years of age. The relationship (boys r = .688, p < .001; girls r = .373, p < .01) between peak torque of knee extensors and mean speed in meters per second of 50 meters maximal run was significant. Significant correlations (boys r = .728, p < .001; girls r = .515, p < .05) were also obtained between peak torque of arm pull muscles and the best record in time of 100 meters free style swimming.
Bipsies were obtained from the gastrocnemius muscle of 13 male and 12 female distance runners and analyzed for [14C]palmitoyl-CoA oxidation, fiber composition, and the activities of selected enzymes. The male and female runners were similar in terms of maximal oxygen uptake (VO2max), training mileage, fiber compositions, and data collected during a 60-min treadmill run at 70% VO2max. Muscle succinate dehydrogenase and carnitine palmitoyl transferase activities were, however, significantly greater (P less than 0.05) in the male than in female runners. In addition, the male runners' muscle also showed a greater capacity to oxidize palmitoyl CoA. Little relationship, however, was found between muscle lipid metabolism, enzyme activities, and the calculated (respiratory exchange) fraction of energy derived from fat during 60 min of running at 70% VO2max. Although these data support the concept that endurance training (80-115 km/wk) markedly enhances the capacity of muscles to metabolize fats, the factors that regulate the usage of lipids during prolonged exercise do not appear to be limited by the capacity of the fibers to oxidize fatty acids, as determined by in vitro measurements.
A major problem in administering the Astrand-Ryhming Test to low-fit individuals is their inability to maintain a workload sufficient to produce exercise heart rates. Since differences in perceived exertion have been observed at different pedalling speeds, the use of a higher pedalling speed might be preferred. The purpose of this study was to determine the validity of the Astrand-Ryhming Test administered at 50 and 80 rpm. Thirty male volunteer subjects were randomly assigned to test order groups. The tests consisted of: Astrand-Ryhming Test administered at 50 rpm; Astrand-Ryhming test administered at 80 rpm; and maximum oxygen intake determined at the end of a graded exercise test. The results revealed relatively low validity coefficients of r(xy) = 0.64 and r(xy) equals 0.63 for Astrand-Ryhming Tests administered at 50 and 80 rpm, respectively. The correlation between the 50 and 80 rpm tests was r=0.85. One-way analysis of variance for repeated measures, and subsequent Duncan's New Multiple Range Test, revealed that the criterion maximal oxygen intake values were significantly higher than those predicted by the Astrand-Ryhming Test. No differences were observed between the 50 and 80 rpm Astrand-Ryhming protocols. It was concluded that the administration of Astrand-Ryhming Tests at 80 rpm is acceptable, and the resultant predictions of maximal oxygen intake are clinically accurate. It was suggested that use of the Astrand-Ryhming Tests be limited to general fitness screening situations where more sophisticated techniques are unavailable.
Cardiopulmonary and metabolic variables were investigated at maximal and submaximal bicycle ergometer exercises in 41 swimmers of both sexes, 8–18 years old. \(\dot V\)O2 max and \(\dot V\)O2 max·HR−1 were higher in boys than in girls and increased with maturity, while \(\dot V\)O2 max·kg−1 and HVE were not influenced by this. The HV increased clearly during this growth period, the pubertal and postpubertal subjects showing 16 and 17% higher values for HV and HV·kg−1 than those reported in normal schoolchildren populations. During the submaximal exercise at 70% \(\dot V\)O2 max the highest HR values were found in the prepubertal group, whilst the lowest were observed in the postpubertal subjects. These findings suggest that a given percentage of \(\dot V\)O2 max as a reference unit, is more reliable than a certain HR to obtain comparable results in subjects with different ages.
Blood samples were collected before, during, and after the submaximal exercise. Blood glucose and FFA did not differ in relation to the stages of maturity. During exercise, insulin decreased in prepubertal children, did not alter in pubertal adolescents, and increased in postpubertal subjects. The lactate concentration, during exercise, increased in relation to maturity. The same results were found for HGH, but no differences were found with regard to sex. Since the pattern of HGH secretion during exercise is similar to that found after arginine and insulin administration it is assumed that the same mechanism (i.e., sex hormones) triggers the HGH release.
Maximal aerobic capacity of 66 ten year old ice hockey players was measured on a treadmill twice over a 4 to 5 month period. This time approximated mid (T1) to post (T2) competitive season. The results of these VO2 max tests were grouped according to the presence or absence of a plateau in the oxygen uptake (less than 2.1 ml/kg-min) during the last work loads before fatigue. The mean values for T1 and T2 were not significantly different for any of the measurements made; the reproducibility was considered to be high. The reliability of the measures varied with the presence or absence of a plateau at maximum, for example; VO2 max, plateau r = 0.74, no plateau r = 0.27; heart rate, plateau r = 0.92, no plateau r = 0.40. The differences between the mean values for the "double plateau" group when compared to the "no plateau" group were not significant for VO2 max, HR or VE. The differences were significant for the post-exercise blood lactate and respiratory exchange values at T2 only; the "double plateau" group reached higher values in each case (R = 1.00 vs 0.92; blood lactate 6.5 vs 5.4 mM/1).