Drop punt kicking induces eccentric knee flexor weakness associated with reductions in hamstring electromyographic activity

Drop punt kicking induces eccentric knee flexor weakness associated with reductions in hamstring electromyographic activity

Objectives: To examine the effect of 100 drop punt kicks on isokinetic knee flexor strength and surface electromyographic activity of bicep femoris and medial hamstrings.

Design: Randomized control study.

Methods: Thirty-six recreational footballers were randomly assigned to kicking or control groups. Dynamometry was conducted immediately before and after the kicking or 10 min of sitting (control). Results: Eccentric strength declined more in the kicking than the control group (p < 0.001; d = 1.60), with greater reductions in eccentric than concentric strength after kicking (p=0.001; d=0.92). No signifi- cant between group differences in concentric strength change were observed (p = 0.089; d = 0.60). The decline in normalized eccentric hamstring surface electromyographic (bicep femoris and medial ham- strings combined) was greater in the kicking than the control group (p < 0.001; d = 1.78), while changes in concentric hamstring surface electromyographic did not differ between groups (p = 0.863; d = 0.04). Post-kicking reductions in surface electromyographic were greater in eccentric than concentric actions for both bicep femoris (p = 0.008; d = 0.77) and medial hamstrings (p < 0.001; d = 1.11). In contrast, the control group exhibited smaller reductions in eccentric than concentric hamstring surface electromyo- graphic for bicep femoris (p=0.026; d=0.64) and medial hamstrings (p=0.032; d=0.53). Reductions in bicep femoris surface electromyographic were correlated with eccentric strength decline (R = 0.645; p = 0.007).

Conclusions: Reductions in knee flexor strength and hamstring surface electromyographic are largely limited to eccentric contractions and this should be considered when planning training loads in Australian Football.

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