Muscle distribution: Variations with body weight, gender, and age

Little is known about skeletal muscle distribution in healthy adults. Data were collected on 132 healthy, ambulatory, Caucasian women and men, aged 20–89 yr. Appendicular skeletal muscle mass multiple regression models were developed to assess the relationships between regional skeletal muscle and height, weight, age, ethnicity, and extremity lengths. Results: (1) with an increase in body weight there is a greater relative increase in upper muscle distribution; (2) women have less upper muscle mass compared to men; (3) with increasing age there is a relative reduction in upper muscle distribution. The present results indicate that skeletal muscle is not a homogenous component, but has at least three independent factors, gender, weight, and age, influencing distribution.