Knee Extension Strength and Hamstrings-to-Quadriceps Imbalances in Elite Soccer Players.

This study examined the relationship between hamstrings-to-quadriceps strength ratio (H:Q) and relative strength of the knee extensors in elite soccer players. Peak torque was measured during isokinetic knee extension/flexion at angular velocities of 60°·s(-1), 180°·s(-1) and 300°·s(-1). 18 professional players were divided into 2 groups, depending on their H:Q at 60°·s(-1). Players in the lower H:Q group (n=7) had significantly smaller H:Q ratios compared with the higher H:Q group (n=11) at all angular velocities (60°·s(-1): 49.2%; 95% CI: 61.3-57.8% vs. 59.5%; 95% CI: 52.2-46.2%, p=0.001). Players in the lower H:Q group had greater knee-extension peak torque compared with the higher H:Q group (60°·s(-1): 313; 95% CI: 335-291 vs. 269; 95% CI: 289-250 N·m, p=0.01). No differences were found in hamstrings' strength between the 2 groups (60°·s(-1): 156; 95% CI: 170-143 vs. 160; 95% CI: 173-148 N·m, p=0.96). Negative correlations between knee extension peak torque and H:Q ratio were observed at all angular velocities (r=-0.65 to -0.67, p<0.01). In conclusion, a low H:Q strength ratio measured during isokinetic strength testing in professional soccer players, is observed mainly in those with strong quadriceps muscles, while players with lower quadriceps strength have H:Q ratios around the recommended values.

Physiological characteristics of elite professional soccer teams of different ranking.

AIM: Few studies have examined the role of physiological characteristics of soccer teams in the finishing position in the league. The purpose of the present study was to investigate whether there are differences in anthropometric characteristics, endurance, isokinetic peak torque, vertical jump height among professional soccer teams with different rank in the Greek championship. METHODS: Three soccer teams that participated in the Greek Championship participated voluntarily in the present study. The B (n=19; 26+/-4 years; 180+/-5 cm; 78+/-4.5 kg) team was among the best three teams of the National Greek league, whereas M (n=15; 24+/-4 years; 178+/-4 cm; 74.8+/-4.2 kg) and L (n=20; 23+/-3 years; 179+/-7 cm; 75.3+/-6.4 kg) teams were in the middle and last of the rank, respectively. All teams were evaluated in body fat (%), peak torque of knee extensors at 1.05 rad/s, running velocity at the lactate threshold (LT) and countermovement jump height. RESULTS: The B team, which was deemed among the best three team of the league, presented significantly (P<0.05) lower body fat (%) values, and higher peak torque of knee extensors, running velocity at the LT, and vertical jump height values in comparison to the middle and last team of the league. CONCLUSIONS: The findings of the present study suggest that the physiological characteristics may play an important role for high soccer performance, as it is reflected from the rank order placed in the Greek championship. Especially, body fat (%), running velocity at the LT, peak torque of knee extensors and vertical jump ability could be differentiating factors for a soccer performance.

Resistance training in older women: effect on vertical jump and functional performance.

AIM: Few studies have determined the effects of a heavy resistance training on vertical jump performance in older adults. The purpose of the present study was to evaluate the effects of a 12 week heavy resistance training in vertical jump and functional performance in healthy, inactive, older women. METHODS: Seventeen sedentary older women (aged 53-69 years) were assigned either to a control (C, n=8), or to a heavy resistance training (RT, n=9). The RT group trained knee extensors and flexors at 80% of 1-repetition maximum (1-RM), 3 days per week for 12 weeks. Both groups were evaluated in 1-RM lower body strength, squat jump (SJ) and countermovement jump (CMJ) height, and chair rising time, before and after the training period. RESULTS: After the training period, RT significantly improved (P<0.001) the 1-RM lower body strength, SJ, CMJ height, and chair rising by 68.9%, 24.5%, 21.7%, and 13%, respectively. Significant correlations were observed among the percent (%) change in 1-RM lower body strength and SJ (r=0.849, P<0.001), CMJ height (r=0.797, P<0.001), and chair rising time (r=-0.917, P<0.001). CONCLUSIONS: Muscle power improved after a short-term heavy resistance training, as measured by vertical jump and chair rising performance, in inactive older adults. The gains in muscle strength may contribute to the gains in chair rising time, SJ and CMJ height.