Accelerometer load: a new way to measure fatigue during repeated sprint training?

Purpose:Prescribing the appropriate dose of repeated sprint training to a large number of players in a team sports environment presents a challenge to practitioners. Players experience fatigue and performance decrements at different rates, and so a means of monitoring this would be of interest to coaches. This study aimed to identify if accelerometer load could be used to detect the performance decrement during repeated sprints. Materials and Methods:Nine male semi-professional and amateur soccer players performed 25 m sprints (2 x 12.5 m with 180 degrees change of direction) interspersed with 20 s passive recovery until a 5% performance decrement in sprint time was reached. Trunk segmental accelerations were measured at the thoracic spine using a triaxial accelerometer worn in a tight-fitting vest. Results:Sprint time increased by 8.5% (range 5-13%) from the first to the last sprint. Accelerometer load demonstrated a mean decrease of 15% (range 11-23%) from the first to the last sprint. Least squares linear regression revealed accelerometer decrement to be two to threefold greater than the sprint performance decrement. Additionally, strong within-participant associations between accelerometer load and sprint decrement with very large to nearly perfect correlations were observed (Pearson'sr = 0.84-0.99,P < 0.03). Conclusion:Practitioners may be able to utilize this concept to monitor the fatigue induced by repeated sprinting or high-intensity efforts in team sports training in order to prescribe sprint training relative to individual fatigue profiles.