Influence of prolonged intermittent high-intensity exercise on knee flexor strength in male and female soccer players.
This study investigated the effect of an acute, prolonged, intermittent, high-intensity single-leg pedalling exercise task (PIHIET) on the isokinetic leg strength of the knee flexors in six male and seven female collegiate soccer players. Following determination of single-leg VO(2peak), subjects completed a PIHIET designed to simulate the energetics of soccer match play (approximately 90 min in total; approximately 70% single-leg VO(2peak)). Pre-, mid- and post-PIHIET gravity-corrected indices of knee flexion peak torque (PT) and range of motion-relativised torque at 15% of knee flexion (RRT(15%); 0% = full knee extension) were assessed at a lever-arm angular velocity of 1.05 rad.s(-1)for intervention and control limbs using an isokinetic dynamometer. Repeated measures ANOVAs revealed significant condition (PIHIET, control) x time (pre-, mid-, post-PIHIET) interactions for knee flexion PT (F([2,22])=26.2; P<0.001) and RRT(15%) (F([2,22])=20.1; P<0.001). Flexion PT and RRT(15% )were observed to decrease, pre- to post-intervention, from 92.8 (28.7) N.m to 72.1 (28.0) N.m and from 63.8 (17.5) N.m to 47.9 (18.4) N.m respectively, for the intervention limb alone. These data corresponded to 22.3% and 24.9% mean reductions pre-post intervention in PT and RRT(15%). Exploratory post hoc analysis of the pattern of the relative deterioration (%) of PT and RRT(15%), for the intervention limb alone, revealed a three-way interaction [group (male, female) x parameter (PT, RRT(15%)) x assessment phase (pre- to mid-PIHIET, mid- to post-PIHIET)] (F(1,11)=5.2; P<0.05). This interaction characterised a greater deterioration of strength performance during the mid- to post-PIHIET assessment phase, at the extremes of range of motion (RRT(15%)) for the female group. The greater percentage of mid-post phase strength loss observed in women near the end-range extension may potentially be implicated in the higher incidence of knee injury reported in female soccer players.
Centre for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Hassall Road, Alsager, ST7 2HL, UK. t.mercer@mmu.ac.uk
Tom H
TH
Mercer
Nigel P
NP
Gleeson
Karen
K
Wren
D000328:Adult; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012737:Sex Factors; D012916:Soccer / Q000502:physiology*