Training-induced alterations of the in vivo force-velocity relationship of human muscle

Abstract

Seventeen male and female subjects (ages 20-38 yr) were tested pre- and posttraining for maximal knee extension torque at seven specific velocities (0, 0.84, 1.68, 2.51, 3.35, 4.19, and 5.03 rad . s-1) with an isokinetic dynamometer. Maximal knee extension torques were recorded at a specific joint angle (0.52 rad below the horizontal plane) for all test speeds. Subjects were randomly assigned to one of three experimental groups: group A, control, n = 7; group B, training at 1.68 rad . s-1, n = 5; or group C, training at 4.19 rad . s-1, n = 5. Subjects trained the knee extensors by performing two sets of 10 single maximal voluntary efforts three times a week for 4 wk. Before training, each training group exhibited a leveling-off of muscular tension in the slow velocity-high force region of the in vivo force-velocity relationship. Training at 1.68 rad . s-1 resulted in significant (P less than 0.05) improvements at all velocities except for 5.03 rad . s-1 and markedly affected the leveling-off in the slow velocity-high force region. Training at 4.19 rad . s-1 did not affect the leveling-off phenomenon but brought about significant improvements (P less than 0.05) at velocities of 2.51, 3.35, and 4.19 rad . s-1. The changes seen in the leveling-off phenomenon suggest that training at 1.68 rad . s-1 might have brought about an enhancement of motoneuron activation.

Evaluation of Muscle Strength Among Different Sports Disciplines: Relevance for Improving Sports Performance

“…Peak torque may be measured as the greatest torque developed during a contraction, regardless of where in the contraction (and range of movement) it occurs [10][11][12]. Alternatively, strength may be measured as the greatest torque achieved at a particular point in the range of movement [13][14][15][16]. Sometimes both measurements have been made [17][18][19].…”

The Physiological Determinants of Load Bearing Performance at Different March Distances

“…al1 (2). For knee extension, subjects were seated in the Cybex chair with the N dominant leg strapped to the lever arm of the dynamometer so that the machine's axis of rotation was in alignment with the subject's knee joint.…”

The Influence of Velocity-Specific Resistance Training on the In Vivo Torque-Velocity Relationship and the Cross-Sectional Area of Quadriceps Femoris

“…However, these results are not confidently offered as explanation for the enhanced performance and there is evidence to suggest that much of the training effect may be mediated by neurological adaptation (5,7,11,21). This would be reasonable considering the apparent untrained state of the subjects utilized in the majority of the investigations.…”

“…The question of velocity-specific training effects has been addressed by a number of investigators (5,7,10,13,16) and has been discussed in review articles (18,21). However, in spite of this attention, the nature of, or even the existence of such velocityspecific adaptations has not been sufficiently clar-' Thi s work was supparted by Sport Canada end Hydra-Fitness Indus- Sectms of the American Physical Therapy Assodation ified.…”