Neuromuscular Fatigue After Long-Duration Adventure Racing in Adolescent Athletes

Abstract

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.

Monitoring lower limb biomechanical asymmetry and psychological measures in athletic populations—A scoping review

“…After the removal of duplicate articles, 2484 studies remained for the title and abstract screening. After full‐text screening of 286 articles, 51 articles 14,36–85 were ultimately included in the present scoping review. The rationale for exclusion at the full‐text level can be found in Figure 1.…”

“…73 However, fear of reinjury was also reported to not be related to overall torque production or asymmetry (p > 0.05). 64 As for soreness, higher delayed onset muscle soreness post-training was associated with decreased strength/toque output during subsequent training sessions, 69 but was also found to be associated with improved sport-specific performance as assessed via the agility t-test and game-related statistics (r = 0.59, [0.06; 0.86], p = 0.09, and p < 0.01, respectively). 47 Unfortunately, the limited and inconsistent use of introspective measures outside of pain and RPE appear to preclude the ability to draw strong conclusions regarding the relationships that may exist between lower limb biomechanical asymmetry and self-reported function, fear, or soreness, in addition to a potential variety of other introspective measures not observed here.…”

Neuromuscular Adaptations in Endurance‐Trained Male Adolescents Versus Untrained Peers: A 9‐Month Longitudinal Study

“…As previously done [32], isokinetic contractions were performed at angular velocities of +180° s −1 for KE and −60° s −1 for KF to determine maximal voluntary concentric KE (KE MVC CON ) and eccentric KF (KF MVC ECC ) contraction torques. The functional ratio was calculated as the KF MVC ECC /KE MVC CON ratio to describe the muscle strength balance between quadriceps and hamstrings around the knee joint [33].…”