Localized muscle fatigue and dynamic balance

This investigation was designed for the purpose of ascertaining if one muscle group (dorsi flexors, abdominals, plantar flexors, or knee and hip flexors and extensors) could be identified which most significantly affects dynamic balance. The dependent variable was the dynabalometer. Subjects were 100 male volunteers, between the ages of 19 and 25 yr. Subjects were randomly assigned to a control or 1 of 4 treatment groups. Testing was counterbalanced over time and day. Controls had a practice period and 3 performance trials; other Ss had a practice period, localized fatigue of a muscle group followed by 3 performance trials. Analysis of variance indicated a significant difference between treatment groups (F = 312.09, p less than .01). Multiple comparisons of treatment means showed that only one muscle group, the knee and hip flexors and extensors, differed significantly from all other groups (q = 4.75, p less than .01). Results indicate strongly that the knee and hip flexors and extensors can be considered a most important muscle group for performance by ordinary male college students on the dynabalometer.