Influence of Lower Extremity Strength on Physical Activity in Young Adults

Abstract

Decreased physical activity has been identified as a risk factor for many health related conditions. Lower extremity muscular strength is an important aspect for the completion of physical activity. Differences have been found to exist between males and females with their lower extremity strength. However, limited evidence exists evaluating the influence of strength of the hip and knee muscles on physical activity between sexes. PURPOSE: To explore if a relationship between lower extremity isometric strength and physical activity exists between male and female young adults. METHODS: Isometric strength was recorded on the dominant limb in 47 college aged participants with a handheld dynamometer (30 females and 17 males). Strength was assessed for participant’s hip flexors, extensors, external rotators, internal rotators, abductors, adductors and knee flexors and extensor muscle groups. Strength was normalized as a percentage of body weight. Physical activity was recorded with a commercial activity monitor over 2-weeks, with steps per day being the main outcome. Relationships between lower extremity muscle strength and activity level were explored with pearson product moment correlations, controlling for age and body mass. A linear regression was utilized to explore if lower extremity strength could predict physical activity. RESULTS: Significant correlations were found between activity level and strength in females for their hip flexors (r=.484, p=.007), hip abductors (r=.629, p<.001), hip external rotators (r=.453, p=.012), knee flexors (r=.393, p=.032) and knee extensors (r=.421, p=.020). Isometric hip abductor strength was found to a significant predictor of physical activity when assessed by steps per day (p<.001), accounting for 39% of the variance in the model. No significant correlations were found in males between activity level and strength. CONCLUSIONS: Lower extremity strength appears to play a role in physical activity levels in female college aged individuals, with hip abductor strength significantly predicting activity level. Intervention programs should evaluate strength training for females as one potential approach to improve physical activity.