The Power Of Exercise: The Effect Of Age And Activity Level On Muscular Power

Abstract

Muscle, strength, and power decline as we age, and power is critical for functional independence. This dissertation tested additional factors such as the amount and type of PA, muscular fatigue, movement mechanics, and muscle fiber type, which are known to affect power, in older adults, including masters athletes. The study involved PA questionnaires, biomechanical assessment of functional tasks including countermovement jumps (CMJ) with lower-body motion capture and a custom apparatus with embedded force plates, and MRI Dixon and DTI of the lower limb musculature and lumbar spine region. Age, sex and PA level predicted lower-body power during CMJ, with activity level demonstrating a protective effect (r=0.540) similar in magnitude to the effect of age (r=-0.654). Athletics discipline also predicted lower-body power during CMJ (r=0.389) with short distance athletes having the highest predicted power but also the most negative slope. Greater trunk flexion was associated with greater lower-body power, but older adults did not tend to use this strategy. MRI diffusion parameters weakly predicted ankle power and also differed in short distance athletes. Activity level and athletic discipline showed positive, protective effects on lower-body and joint power during the CMJ with a strength of effect comparable to that of age. Trunk flexion angle was associated with greater lower-body power output in the CMJ and was a strategy adopted only by younger adults potentially confounding the measurement of power in older adults. Overall, high levels of PA, and participation in high power track and field events is protective of muscular power and likely functional independence in older adults.