Sunday, August 17, 2008
The forces produced by an athlete during the support phase of a sprint run are a vital determinant of the outcome of the performance. The purpose of this study was to improve the understanding of sprint technique in well-trained sprinters through the comprehensive analysis of joint kinetics during the support phase of a maximum-velocity sprint.
It was found that the knee moment did not contribute substantially to power generation during the latter part of the support phase. This may be explained in part by the specific technical requirements of the maximum-velocity phase of the sprint. However, major periods of power generation of the hip extensors in early stance and of the plantar flexors in late stance were observed. The knee extensors played a negligible role in positive work generation throughout stance. The action of the knee joint during the support phase may therefore have been more of a facilitator for the radial transfer of power from the hip through the ankle on to the track. (Bezodis IN. Kerwin DG. Salo AI. Lower-limb mechanics during the support phase of maximum-velocity sprint running . Medicine & Science in Sports & Exercise. 40(4):707-15, 2008 Apr).
Another study showed that (1) the difference in leg stiffness between endurance-trained and power-trained athletes is best attributed to increased joint stiffness, and (2) the difference in joint stiffness between the two groups may be attributed to a lack of similarity in the intrinsic stiffness of the muscle-tendon complex rather than in altered neural activity. (Hobara H. Kimura K. Omuro K. Gomi K. Muraoka T. Iso S. Kanosue K. Determinants of difference in leg stiffness between endurance- and power-trained athletes. Journal of Biomechanics. 41(3):506-14, 2008).
This study showed that the ability to produce force quickly, as measured by the time to achieve 60% of maximum voluntary contraction is related to sprinting performance, with the coefficient of determination accounting for 53% of the variance in the data. These data also show that sprinting ability is linked with drop jump performance, especially the drop jump from a height of 30 cm. It is suggested that the above tests may prove useful in preparing and testing the sprinting ability and sprint specific strength levels. (Bissas AI. Havenetidis K. The use of various strength-power tests as predictors of sprint running performance. Journal of Sports Medicine & Physical Fitness. 48(1):49-54, 2008 Mar.)
In a study to investigate the effects of performing heavy back squats and heavy front squats on the average speed during each 10-m interval of 40-m sprint trials. Heavy back squats produced significantly greater speeds compared with the heavy front squats treatment. It is suggested that coaches could incorporate heavy back squats into the warm-up procedure of athletes to improve sprinting performance. (Yetter M. Moir GL. The acute effects of heavy back and front squats on speed during forty-meter sprint trials. Journal of Strength & Conditioning Research. 22(1):159-65, 2008 ).
lower body topics ,
muscles ,
performance ,
sprinting
Sunday, August 17, 2008
The forces produced by an athlete during the support phase of a sprint run are a vital determinant of the outcome of the performance. The purpose of this study was to improve the understanding of sprint technique in well-trained sprinters through the comprehensive analysis of joint kinetics during the support phase of a maximum-velocity sprint.
It was found that the knee moment did not contribute substantially to power generation during the latter part of the support phase. This may be explained in part by the specific technical requirements of the maximum-velocity phase of the sprint. However, major periods of power generation of the hip extensors in early stance and of the plantar flexors in late stance were observed. The knee extensors played a negligible role in positive work generation throughout stance. The action of the knee joint during the support phase may therefore have been more of a facilitator for the radial transfer of power from the hip through the ankle on to the track. (Bezodis IN. Kerwin DG. Salo AI. Lower-limb mechanics during the support phase of maximum-velocity sprint running . Medicine & Science in Sports & Exercise. 40(4):707-15, 2008 Apr).
Another study showed that (1) the difference in leg stiffness between endurance-trained and power-trained athletes is best attributed to increased joint stiffness, and (2) the difference in joint stiffness between the two groups may be attributed to a lack of similarity in the intrinsic stiffness of the muscle-tendon complex rather than in altered neural activity. (Hobara H. Kimura K. Omuro K. Gomi K. Muraoka T. Iso S. Kanosue K. Determinants of difference in leg stiffness between endurance- and power-trained athletes. Journal of Biomechanics. 41(3):506-14, 2008).
This study showed that the ability to produce force quickly, as measured by the time to achieve 60% of maximum voluntary contraction is related to sprinting performance, with the coefficient of determination accounting for 53% of the variance in the data. These data also show that sprinting ability is linked with drop jump performance, especially the drop jump from a height of 30 cm. It is suggested that the above tests may prove useful in preparing and testing the sprinting ability and sprint specific strength levels. (Bissas AI. Havenetidis K. The use of various strength-power tests as predictors of sprint running performance. Journal of Sports Medicine & Physical Fitness. 48(1):49-54, 2008 Mar.)
In a study to investigate the effects of performing heavy back squats and heavy front squats on the average speed during each 10-m interval of 40-m sprint trials. Heavy back squats produced significantly greater speeds compared with the heavy front squats treatment. It is suggested that coaches could incorporate heavy back squats into the warm-up procedure of athletes to improve sprinting performance. (Yetter M. Moir GL. The acute effects of heavy back and front squats on speed during forty-meter sprint trials. Journal of Strength & Conditioning Research. 22(1):159-65, 2008 ).
lower body topics , muscles , performance , sprinting