Influence of prolonged intermittent high-intensity exercise on knee flexor strength in male and female soccer players

Abstract

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.

Isokinetic and isometric muscle function of the knee extensors and flexors during simulated soccer activity: Effect of exercise and dehydration

“…Mercer et al (2003) reported a 22% decline in peak torque of the knee flexors following 90 min intermittent cycling. Using a treadmill-based exercise protocol to induce fatigue, Rahnama et al (2003) showed that strength performance of both quadriceps and hamstrings of college level players were significantly reduced from pre-exercise to half-time and from half-time to post-exercise at all angular velocities.…”

“…A number of studies have attempted to describe the temporal aspects of the decay in muscle strength during soccer-simulation studies (Greig, 2008;Mercer, Gleeson, & Wren, 2003;Rahnama, Reilly, Lees, & Graham-Smith, 2003). Mercer et al (2003) reported a 22% decline in peak torque of the knee flexors following 90 min intermittent cycling.…”

“…Therefore, the use of cycling (Mercer et al, 2003) or treadmill-running (Greig, 2008;Rahnama et al, 2003) protocols to simulate the complex demands of soccer may not be wholly appropriate. The Loughborough Intermittent Shuttle Test (LIST; Nicholas, Nuttall, & Williams, 2000) has been shown to be a valid and reliable method of replicating the physiological demands experienced by soccer players during a competitive game and may offer a more ecologically valid method of inducing fatigue to examine aspects of muscle strength during soccer.…”

Soccer-Specific Fatigue and Eccentric Hamstrings Muscle Strength

“…With regard to data analysis, investigators using soccerspecific fatiguing protocols might consider the angle at which peak torque is attained and, in more detail, the torque curve time-history, as others 26 have shown discrepancies among angles with single-leg pedaling exercises. The relevance of peak torque to injury incidence data should naturally be treated with some caution.…”

Hip-Abductor Fatigue and Single-Leg Landing Mechanics in Women Athletes

“…[1][2][3] Many of these injuries are believed to occur during single-leg landings, with no direct blow to the knee. [4][5][6] Although the causes of these injuries are not known, they are widely believed to include some combination of environmental, biomechanical, neuromuscular, structural, and hormonal factors. [7][8][9] Authors 10-12 studying biomechanical and neuromuscular risk factors for ACL injury have suggested that weakness of muscles that abduct the hip, such as the gluteus medius, may predispose an individual to greater hip adduction or internal-rotation excursion during weight-bearing activities such as jumping or landing.…”