ECSS Paris 2023: OP-AP26
INTRODUCTION: Work efficiency, critical power, and cardiorespiratory fitness are the key determinants in assessing endurance performance. Cardiorespiratory fitness is commonly measured as the highest oxygen uptake (VO2peak) during an incremental ramp test (RT). However, such protocols provide limited insight into sport-specific performance parameters. In contrast, Time Trials (TT) provide insight into pacing and aerobic capacity while critical power or short-duration All Out Tests (AOT) provide data on anaerobic work capacity, peak power, and fatigue index. Protocols that capture such performance parameters as well as VO2peak would thus improve endurance performance assessment and increase testing efficiency. Previous studies have thus compared VO2peak achieved during RT with TT and/or AOT. However, most studies used group mean comparisons using t-test or correlation analyses which are clearly not suitable to evaluate validity of a method. Those few studies correctly using Bland-Altman analyses, however, did not pre-specify an acceptable range which is essential for subsequent interpretation. METHODS: Two studies were conducted. First, 18 males and 13 females well-trained endurance athletes performed two RT and two 4-minute TT on four different days, while measuring gas exchange parameters with a metabolic cart. In the second study, 23 males and 17 females semi-professional and professional athletes performed one RT followed by a 3-minute AOT with an intervening 20-min recovery. The a priori defined tolerance limits for delta-VO2peak between the exercise tests was set to ±0.13 L/min (approximately ±3.3%). This value derived from the day-to-day variation in VO2peak measured in a previous study [1]. RESULTS: Participants’ mean (standard deviation) age (years) was 23 (4) years in the first and 30 (4) years in the second study. The mean differences when comparing the first RT with the first TT and comparing the second RT with the second TT were 0.02 L/min (p=0.93) and 0.03 L/min (p=0.87), respectively, which indicates no significant differences as presented in previous studies. However, the respective tolerance limit for these comparisons were -0.35 to 0.31 L/min and -0.36 to 0.42 L/min and thus outside of the a priori defined limit. Likewise, for the comparison of RT and AOT the mean difference was 0.08 L/min (p=0.64), but the tolerance limit was -0.42 to 0.58 L/min. The respective Lin’s concordance correlation coefficient for RT VO2peak was 0.98 (95% CI: 0.96 to 0.99) for TT, and 0.95 (95% CI: 0.92 to 0.97) for AOT. CONCLUSION: The TT and AOT show limited agreement with RT VO2peak. However, considering the lack of systematic deviations in VO2peak and the determination of further performance parameters emphasize the potential value of incorporating VO2peak measurements during TT and/or AOT for investigating aspects of performance. References: Knaier R, et al. Frontiers in Physiology 10 (2019): 219.
Read CV Jonathan WagnerECSS Paris 2023: OP-AP26
INTRODUCTION: Performance in cross-country mountain biking (MTB) is primarily determined by athletes’ aerobic capacity. However, with the reduction of race duration to 80 minutes, anaerobic capacity, along with muscle strength and power gained importance as key performance determinants. Adequate trunk muscle strength (TMS) is needed in MTB to facilitate force transfer between the lower and upper extremities, particularly during the start, inclines and finish sprints. There is preliminary evidence indicating that TMS training of the global, large and superficial trunk muscles can improve cycling economy (CE). Here, we examined the effects of global TMS training on TMS and CE in MTB athletes. METHODS: Twenty-four female trained (Tier 2-3) mountain bikers aged 14-22 years participated in this study. They were paired by age and randomly assigned to a TMS training or an active control (CON) group. The training took place during the off-season, lasted for eight weeks with three weekly sessions. While TMS performed 30 minutes of TMS training targeting the global trunk muscles, CON did their regular upper- and lower-body strength training excluding trunk muscle exercises. Both groups had similar training volumes. Pre- and post-training, maximal isometric TMS and TMS endurance for ventral, dorsal and lateral trunk muscles were tested. Physiological CE (i.e., O2/CO2 per min/kg) and mechanical CE (e.g., lateral oscillations of the bike frame, torque effectiveness during pedalling) were assessed while performing a MTB racecourse simulation for twelve minutes on a 3x5-m treadmill. RESULTS: Group-by-time interactions were found for maximal isometric flexor (p<0.0001, d=1.1) and extensor (p<0.0001, d=1.7) TMS. Post-hoc tests revealed greater improvements for flexors (p<0.001, d=2.2, +32.2%) and extensors (p<0.001, d=2.0, +28.4%) following TMS training. Interaction effects were also observed for lateral TMS endurance (p=0.03, d=0.47), with post-hoc tests indicating greater progress in the TMS group (p=0.03, d=0.74, +18.2%). For mechanical CE, an interaction effect was found for bike oscillation (p<0.001, d=0.8) in favour of the TMS group (p=0.01, d=0.9, -24.4%). CONCLUSION: TMS training improved maximal isometric flexor and extensor TMS, lateral TMS endurance and mechanical CE. Off-season global TMS training is a suitable recommendation for female MTB athletes.
Read CV Roland BlechschmiedECSS Paris 2023: OP-AP26
INTRODUCTION: Repeated sprint training in hypoxic conditions has been shown to improve repeated sprint ability (RSA). Moreover, repeated sprint training with voluntary hypoventilation at low lung volume (VHL) is gaining attention as an alternative method for establishing a hypoxic environment in the body. Training with VHL has previously demonstrated a further increase in RSA compared to the same training with normal breathing [1]. However, a direct comparison between “repeated sprint training in hypoxia” and “repeated sprint training with VHL” has not yet been conducted. The purpose of the present study was to compare the training adaptations between “repeated sprint training with VHL” and “repeated sprint training in hypoxia”. METHODS: Twenty-four healthy, physically active males (age, 21.9 ± 0.4 years; height, 172.9 ± 1.2 cm; weight, 71.0 ± 21.9 kg) performed repeated cycling sprints (two sets of 6-8 × 6-s maximal sprints with 24-s rest periods between sprints) twice per week for three weeks (six sessions in total). Subjects were randomly assigned to one of three different groups: (1) training in normoxia with normal breathing (NOR group; 23°C, FiO2 = 20.9%), (2) training in hypoxia with normal breathing (HYP group; 23°C, FiO2 = 16.4%), or (3) training in normoxia with breath holding (VHL group; 23°C, FiO2 = 20.9%). Before and after the training periods, subjects performed RSA test (12 × 6-s maximal sprints with 24-s rest periods between sprints) and maximal oxygen uptake (VO2max) test. Power output, systemic oxygen uptake, and cardiac function were monitored during the training and performance tests. Muscle oxygenation variables in vastus lateralis and respiratory muscles were also evaluated using near-infrared spectroscopy. RESULTS: Over six training sessions, the minimum arterial oxygen saturation was significantly lower in the VHL and HYP than in the NOR (VHL; 84.8±1.6%, HYP: 82.8±1.0%, NOR: 92.1±0.7%, P < 0.05). Peak power output and mean power output did not differ significantly among the groups (P > 0.05). In the VHL, cardiac output (including the 24-s recovery between sprints) was significantly increased in session 6 compared with session 1 (P < 0.05), but not in the HYP and NOR (P > 0.05). Power output during RSA test was significantly increased in the VHL and HYP (VHL, 575±21 W vs. 659±30 W, P < 0.05; HYP, 604±26 W vs. 671±35 W, P < 0.05), whereas the NOR did not show significant changes after the training period (592±32 W vs. 623±30 W, P > 0.05). Additionally, VO2max during the incremental pedaling test was significantly increased in the VHL (P < 0.05), but not in the HYP and NOR (P > 0.05). CONCLUSION: Three weeks of repeated sprint training with VHL and repeated sprint training in hypoxia caused comparable decreases in arterial oxygen saturation during the training session and enhanced RSA performance. Furthermore, the increase in VO2max observed after the training with VHL suggests that the physiological mechanisms for enhancing RSA may differ from those of hypoxic training.
Read CV Ayano ImaiECSS Paris 2023: OP-AP26