During a soccer match, countless movements involving muscular force are performed. While some studies have analyzed the force exerted by soccer players, their results have been divergent, ...particularly when force has been analyzed with respect to field positions. The objective of this study was to compare peak torque, total muscular work, maximum power and isokinetic fatigue index of the knee flexor and extensor muscles of soccer players in a variety of field positions. Seventy-eight under-twenty soccer players were classified according to the position they play: goalkeepers (n=7), full backs (n=14), wingers (n=16), defensive midfielders (n=11), center midfielders (n=14) and forwards (n=16). The concentric isokinetic force of knee flexor and extensor muscles was evaluated using an isokinetic dynamometer, Cybex registered brand Norm 6000 model (CSMI, USA). Data was analyzed in terms of non-parametric statistics and results expressed in medians and semi-interquartile range. The Kruskal-Wallis test was applied and when results were significant to p<0.05, the Mann-Whitney U test was used. Full backs' knee flexor muscles exhibited lower peak torque, total muscular work and maximum power, when compared with the other positions, and defensive midfielders' flexor muscles had a greater fatigue index than the forwards'. Goalkeepers' knee extensor muscles exerted lower peak torque and had a higher fatigue index, when compared to results for the other positions. The results of this study indicate that there are differences in strength between players of different positions, especially full backs, defensive midfielders and goalkeepers. This suggests that the soccer players' field positions have an influence on their levels of isokinetic force.
The mechanical performance, repeatability and comfort of the Quadriso-tester, which assesses isometric knee extensor muscle strength, were examined. Twenty healthy subjects and 20 patients treated ...for unilateral anterior ligamenta cruciata insufficiency were tested. Intra-rater repeatability was determined by the testing and retesting of subjects and calculation of the intra-class correlation coefficient and the mean difference between test and retest values. The comfort level was determined a questionnaire. Measuring time was recorded, and the relationship between knee angle and extension moment was plotted. Strength and stiffness were determined using the finite element method. Intra-rater repeatability was high; the intra-class correlation coefficient of the right and left leg was 0.90 and 0.91, respectively; the coefficient of variation was 6.4 and 6.0%, respectively. The median comfort score of the healthy subjects was 7, and that of the patients was 9. Measuring time remained within 30 min. Misalignment of the knee and sidebar axis disturbed the relationship between knee angle and extension moment Strength and stiffness were higher than required. In conclusion, the Quadriso-tester is a comfortable and fast device to determine quadriceps force with a high repeatability. The knee and sidebar axis should be well aligned.
The objectives of this study were to 1) assess volumetric bone geometry and density at the distal radius of individuals with chronic stroke and 2) assess whether bone strength is associated with ...measures of muscle strength and impairment.
Cross-sectional study of bone and muscle parameters in 15 community-dwelling people living with the residual effects of a stroke (between 1 and 9 years post-incident stroke).
The 4% site of the distal radius had significantly lower bone mineral content and density on the paretic side (p<0.006). There was a significant difference in pQCT measures of bone cortical density (p<0.03), area (p<0.05) and bone strength Stress-Strain Index; SSI (p<0.01) (lower on the paretic side) at the 30%. We found significant correlations between composite muscle strength score of the upper extremities and pQCT-generated bone strength.
This cross-sectional study highlights lower bone strength on the paretic limb and an adaptive response to disuse.
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