Direct and indirect measurement of neuromuscular fatigue in Canadian football players

This study assessed the effects of a fatiguing game simulation (G-Sim) on the balance of collegiate Canadian football players. The purpose of the study was to evaluate postural control as a potential tool for monitoring neuromuscular fatigue (NMF) in collision-based team sports. Fifteen male Canadian football players were recruited (mean +/- SD: age 21.8 +/- 1.6 years, weight 97.6 +/- 14.7 kg). Indirect NMF measures (postural sway and countermovement jump (CMJ)) were performed 24 h before (T-Base), immediately before (T-Pre) and after (T-Post), and 24 h (T24) and 48 h after (T48) a Canadian football G-Sim. Peak isometric knee extensor torque of a maximal voluntary contraction (MVC) and electrically evoked tetani at 20 Hz (P20) and 80 Hz (P80) were also recorded as direct NMF measures at T-Base, T-Pre, T-Post, and T48. At T-Post, we observed significant declines in MVC, P20, and the MVC/P80 ratio (-15.3%, -15.7%, and -12.1%, respectively; n = 12) along with reductions in CMJ takeoff velocity and peak power (-6.9% and -6.5%, respectively; n = 12) and larger area of the center of pressure trajectory (95.2%; n = 10) during a 60-s postural sway task. All variables were no longer different than baseline by T48. Acute neuromuscular impairment in this cohort is likely attributable to alterations in excitation-contraction coupling due to structural damage and central activation failure. Congruency between the direct and indirect measures of NMF suggests monitoring postural sway has the potential to identify both neuromuscular and somatosensory alterations induced by acute game-induced fatigue in collision-based team sports players.