Post-match changes in neuromuscular function and the relationship to match demands in amateur rugby league matches

Objectives: The current study investigated the change in neuromuscular contractile properties following competitive rugby league matches and the relationship with physical match demands.

Design: Eleven trained, male rugby league players participated in 2-3 amateur, competitive matches (n = 30).

Methods: Prior to, immediately (within 15-min) and 2h post-match, players performed repeated counter-movement jumps (CMJ) followed by isometric tests on the right knee extensors for maximal voluntary contraction (MVC), voluntary activation (VA) and evoked twitch contractile properties of peak twitch force (Pt), rate of torque development (RTD), contraction duration (CD) and relaxation rate (RR). During each match, players wore 1 Hz Global Positioning Satellite devices to record distance and speeds of matches. Further, matches were filmed and underwent notational analysis for number of total body collisions.

Results: Total, high-intensity, very-high intensity distances covered and mean speed were 5585 ± 1078 m, 661 ± 265, 216 ± 121 m and 75 ± 14 m min(-1), respectively. MVC was significantly reduced immediately and 2h post-match by 8 ± 11 and 12 ± 13% from pre-match (p<0.05). Moreover, twitch contractile properties indicated a suppression of Pt, RTD and RR immediately post-match (p<0.05). However, VA was not significantly altered from pre-match (90 ± 9%), immediately-post (89 ± 9%) or 2h post (89 ± 8%), (p>0.05). Correlation analyses indicated that total playing time (r = -0.50) and mean speed (r = -0.40) were moderately associated to the change in post-match MVC, while mean speed (r = 0.35) was moderately associated to VA.

Conclusions: The present study highlights the physical demands of competitive amateur rugby league result in interruption of peripheral contractile function, and post-match voluntary torque suppression may be associated with match playing time and mean speeds.