Purpose: To characterize the acute effects of a long-duration adventure race on knee extensor (KE) fatigue and the knee functional ratio in adolescent athletes. Methods: Twenty trained male adolescents (aged 14–17 y) performed an adventure race of 68.5 km. Maximal voluntary isometric contraction (MVIC) KE and knee flexor torques were measured before and immediately after the race. Central and peripheral components of neuromuscular fatigue were quantified from the maximal voluntary activation level and the doublet peak torque (Tw100), respectively. The peak eccentric knee flexor torque to concentric KE torque ratio was also measured to determine functional ratio. Results: The race completion time was 05:38 (00:20) hours. Significant reductions in MVICKE (−14.7%, P < .001) and MVICKF (−17.0%, P < .01) were observed after the race. Voluntary activation level decreased by 8.3% (P < .001) while Tw100 remained unchanged. Peak eccentric knee flexor torque decreased 16.0% (P < .001) while peak concentric KE torque did not change. This resulted in a significant reduction in functional ratio (−12.0%, P < .01). Conclusion: The adventure race induced a moderate fatigue, which was mainly explained by central factors without significant peripheral fatigue. However, particular attention should be paid to the knee muscular imbalance incurred by the race, which could increase the risk of ligament injury in adolescent athletes.

Purpose This study tested the hypothesis that prepubertal boys, but not untrained men, would exhibit a similar post-exercise parasympathetic reactivation as well-trained adult male endurance athletes. Methods Twelve prepubertal boys (12.3 ± 1.6 years), 14 untrained men (21.8 ± 2.2 years) and 16 well-trained adult male endurance athletes (24.5 ± 4.8 years) completed an incremental maximal run field test on a track. Immediately after exercise completion, heart rate recovery (HRR) was assessed in the supine position for 5 min. Heart rate variability was analyzed in the time domain, and log-transformed values of the root mean square of successive differences in heart beats (Ln RMSSD 30 ) were calculated over consecutive 30 s windows. Results Prepubertal children and well-trained adult endurance athletes showed significantly faster HRR than untrained adults from 30 s post-exercise until the end of recovery ( p < 0.05). Ln RMSSD 30 was significantly higher in prepubertal children and athletes than untrained adults over the post-exercise time interval 60–150 s ( p < 0.05). No significant differences were observed for HRR and Ln RMSSD 30 between prepubertal children and athletes. Conclusion Prepubertal children and well-trained adult endurance athletes exhibited comparable and faster HRR and parasympathetic reactivation than untrained adults following maximal exercise. This indirectly suggests that oxidative profile may be preserved by exercise training during growth and maturation to offset the decline in post-exercise HRR, parasympathetic reactivation and aspects of metabolic health.

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Objective: The present study investigated the acute effects of a mixed-modality, long-duration adventure race on pulmonary function in adolescent athletes. Methods: Twenty male adolescents aged 14 to 17 years volunteered to participate in a simulated competitive wilderness adventure race of 68.5-km. Expiratory function was evaluated by spirometry with an Ergocard CPX Clinical system before, immediately after, and 24 h after race completion. Measurements included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), forced expiratory flows at 25%, 50% and 75% of FVC (FEF25, FEF50, FEF75, respectively) and peak expiratory flow (PEF). Maximal inspiratory and expiratory mouth static pressures (MIP and MEP, respectively) were also measured using a portable hand-held mouth pressure meter across the same time points. Results: The mean completion time of the race was 05:38 ± 00:20 hours. A significant post-race decrease in FVC was observed immediately after the race (-5.2%, p < 0.05). However, no significant changes were observed for FEV1, PEF or the FEV1/FVC and FEV1/PEF ratios. The results also showed no significant modifications in the maximal expiratory flow-volume curves irrespectively of FVC percentages (FEF25, FEF50, FEF75). In addition, estimates of respiratory muscle strength (MIP and MEP) were unaffected by the race. Conclusion: The long-duration adventure race induced no substantial reduction in expiratory pulmonary function and this response was associated with no apparent respiratory muscle fatigue. Therefore, the pulmonary system of trained adolescent athletes was sufficiently robust to endure the mixed-modality, long-duration adventure race of ∼5-6 h.