Thigh tissue composition exhibits a curvilinear relationship with aging: A cross-sectional study

OBJECTIVES: To explore whether quadratic model will better estimate the relationship between aging and thigh tissue composition in a cohort that range in age from young to older adults. METHODS: 51 healthy subjects participated in this investigation. All subjects underwent CT imaging for the thigh. Cross-sectional area of the fat and muscular tissues in the thigh were quantified. Hierarchical regression models were created. Age was entered first into the models to estimate its linear relationship with the thigh tissues. Then the squared value of the age variable was entered second to identify whether a quadratic model would better estimate the relationship between the variables. RESULTS: The linear model was significant for thigh muscular tissue. Quadratic models were able to account for additional significant prediction of the cross-sectional area of thigh tissues. Muscular area decreased with aging until 60 years after that it didn’t change. Fat areas increased with aging until 45-50 years and then it decreased. CONCLUSIONS: The cross-sectional area of different thigh tissues exhibit a curvilinear pattern with aging. Muscular tissue area may not change after 60 years; this could be explained by the reduction in fat that may infiltrate inside the muscles and offset the muscular reduction.