Evaluating the status of the neuromuscular system can provide insight pertaining to fatigue levels and performance potential in athletes. A variety of methods have been used in effort to determine neuromuscular fatigue. For example, jump variations (i.e., squat-jump, countermovement-jump, and drop jump) and short distance sprint speed are popular assessments used by practitioners because they can be evaluated quickly and conveniently on a routine basis. Other coaches rely on technology to derive information pertaining to neuromuscular status, such as direct current from electroencephalogram readings.
Coaches use markers of neuromuscular fatigue to guide training and recovery protocols on a day to day basis. For example, after the warm-up, a quick non-fatiguing performance test can be used to determine athlete readiness for high CNS demanding work. If an athlete’s performance is below average (i.e., using a threshold such as the smallest worthwhile change), training may be modified to less neural intensive work. In contrast, when the performance-indicator is above average, the coach may wish to proceed with the original plan. Coaches may also wish to monitor neuromuscular performance as an indicator of recovery status following competitions. At present, it is unclear which type of non-fatiguing performance tests are the most useful for reflecting neuromuscular fatigue.
A recent study published in the Journal of Strength and Conditioning Research compared the sensitivity of squat-jump, countermovement-jump, and drop jump and short distance sprint speed (20 m) in 11 male team-sport athletes. Reliability of each measure was assessed with intra-session and inter-session coefficient of variations (CV). Subsequent to the reliability testing, subjects underwent exhaustive intermittent exercises to induce fatigue. The performance indicators were re-assessed immediately post-exercise and again at 24 and 72 hours post.
The results showed that Sprint performance was the most reliable (CV = 2%) while drop-jump was the least reliable of all the measures (CV = 4.8%). Sprint times were suppressed immediately post-exercise but returned to baseline by 24 hours. Counter-movement jump and drop jump remained suppressed at 72 hours post. The authors concluded that the countermovement jump may be preferable to the drop-jump given the lower CV. In addition, performance tests that involve the stretch-shortening cycle and thus an eccentric component maybe the most appropriate for detecting neuromuscular fatigue following simulated team-sport competition.
Reference:
Gathercole et al. (2015) Comparison of the Capacity of Different Jump and Sprint Field Tests to Detect Neuromuscular Fatigue. Journal of Strength and Conditioning Research, 29(9): 2522-2531
