Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Kinesiology and Health Science

Committee Chair(s)

Eadric Bressel


Eadric Bressel


David Bolton


Chris Dakin


Brennan Thompson


Jeffrey Mason


Obesity is a common, costly, and critical disease that increases the risk of disability and premature death. Most commonly, obesity is caused by an increased consumption of energy dense foods and decreased time spent being physically active. The greater weight with obesity interrupts normal musculoskeletal function which can lead to physical adaptations such as decreased lower-extremity muscle strength and abnormal walking patterns, both of which are among top risk factors for falls in older individuals. However, the effects of obesity on walking and lower-extremity muscle strength have not previously been examined by incorporating the results of all existing studies in a comprehensive systematic review and meta-analysis. Therefore, the purpose of this dissertation was to (1) determine the effect of obesity on measures of walking in adults, and to (2) determine the effect of obesity on knee extensor strength, muscle size, and muscle quality in children, adolescents, adults and older adults. In the first study, there were 47 studies included in the systematic review and 44 in the meta-analyses. Study two included 35 studies in the systematic review and 29 in the meta-analyses. The results suggest that (1) obesity reduces self-selected walking speed and step length, but increases step width and the amount of time spent with both feet in contact with the ground, and (2) obesity increases absolute maximal measures of knee extensor strength and muscle size, but decreases relative maximal measures of knee extensor strength and muscle quality. However, the effect of obesity on knee extensor size, quality, and strength appears to diminish with age. The results of this dissertation will improve our understanding of how obesity influences walking and knee extensor function, which will allow the design of better treatments for those suffering from obesity as well as a basis of knowledge to guide researchers going forward.