Impact of Muscle Material Properties on the Hypertrophic Response of Aged Women to Resistance Exercise

Abstract

All of the reports that comprise this dissertation center around the overarching hypothesis that the attenuated response to resistance exercise observed in older adults is caused by an impaired ability of the muscle to sense mechanical stimuli as a result of increased muscle stiffness. In the first study we investigated the difference in the response of young and aged women to a single bout of resistance exercise. We hypothesized that there would be a less robust hypertrophic response to the exercise bout in the older adults than the young adults. The results of this study showed that young and aged women have a different response to acute exercise. The aged women had an attenuated response when compared to their young counterparts. It was also found that p70S6k phosphorylation is a robust marker that can be used to quantify hypertrophic response to acute resistance exercise. In the second study we investigated the impact of a long-term stretching intervention on the response of aged women to an acute bout of resistance exercise. The stretching was used as a means to modulate muscle stiffness to test they hypothesis that stiffness is related to hypertrophic response to exercise. The results of this study showed that stretching did improve response to an acute bout of resistance exercise. However, while there was a trend toward a reduction in muscle stiffness the change in muscle material properties was not significant. In the third study we investigated the impact of a long-term stretching intervention on the hypertrophic response of aged women to a long-term resistance exercise intervention. We hypothesized that having older women participate in a stretching intervention prior to beginning a resistance training intervention would improve their response to the resistance training program. The results of this study showed that performing a stretching intervention prior to beginning a resistance exercise intervention improved the hypertrophic response to resistance exercise. Taken together, these studies indicate that stretching does appear to be an effective means to improve response to both an acute bout of exercise and a long-term resistance exercise intervention.