PROQUEST: 302917072
The purpose of this study was to investigate the endurance characteristics of selected muscle groups throughout the body in normal physically healthy young adult males. It was hypothesized that the static contractile endurance characteristics of selected muscle groups in the upper and lower extremities of the body are unique, indicating endurance is not common to a particular muscle group. This hypothesis was drawn from the research literature which indicates that there are histological and physiological differences between muscle groups to provide each with its own unique endurance capabilities. The hypothesis was established counter to the conception that an individual has over all muscular endurance determined by such centralized factors as cardiac output and central neural control. It was also postulated that the manner in which a static task is accomplished, that is, continuous contraction as opposed to intermittent contraction would contribute to differences in muscular endurance. This postulation was based on the fact that blood flow to a muscle is an important factor in the endurance performance of a muscle and that a continuous contraction tends to Impair blood flow to the muscle whereas intermittent contractions may facilitate it.
The study was conducted in the Physical Fitness Research Laboratory at the University of Illinois in the spring semester, 1978. Thirtynine male volunteers from the University of Illinois between the ages of 18 and 28 years served as subjects for the study. Five muscle groups were studied, the finger flexors, forearm extensors, forearm flexors, dorsal flexors of the foot and plantar flexors of the foot, and two types of maximal static contractions, continuous and intermittent (3 sec. contraction x 3 sec. rest), lasting for a total of sixty-three seconds. The dependent variables in this study were maximal muscular strength, total force output, percent total work and percent final contraction.
Analysis of the data revealed nine important findings. Consistent with previous research, endurance measures obtained independently of strength exhibited low to medium between day reliability. The two endurance varaibles used in this study, percent total work (%TW) and percent final contraction (%FC) demonstrated primarily low, negative relationships with strength. This same relationship was reported by researchers who measured endurance as the time a muscle could retain a percent of its maximal force; thus,validating the method of quantifying endurance in this study. Strength of the muscles of the upper extremity were related, as were the strength measures of the lower extremity, supporting previous conclusions reported in the literature. Endurance of muscle groups were generally independent of each other as were the endurance measures obtained from muscle groups performing continuous and intermittent contractions. Of the two endurance variables, percent total work was more sensitive to differences in endurance of muscle groups for intermittent contraction. Percent total work revealed grip as having the lowest endurance of the five muscle groups performing intermittent contraction. Endurance differences between muscle groups for continuous plantar and dorsal flexors of the foot proved to have the greatest endurance of the five muscle groups for continuous exercise. Endurance curves exhibited one and two-component curves which differed in configuration for each muscle group and each type of contraction.
The following conclusions were drawn in support of the hypothesis: