Lean Mass and Fat Mass as Contributors to Physical Fitness in an Overweight and Obese African American Population.

ABSTRACT

OBJECTIVE: To determine the association of lean vs fat mass with fitness in healthy, overweight and obese African Americans from families with early-onset coronary disease. DESIGN: Cross-sectional study. SETTING: Baltimore, Maryland. PARTICIPANTS: 191 healthy, overweight, sedentary African Americans (69% women; aged 44.8 ± 11 years; body mass index 34 ± 5 kg/m2). MAIN OUTCOME MEASURES: Anthropometrics, smoking, blood pressure, lipids, c-reactive protein, and glucose were assessed with standard methods; body composition was determined by dual energy X-ray absorptiometry; cardiorespiratory fitness was expressed as VO(2peak) attained during a maximal treadmill test. RESULTS: In both men and women, greater lean mass was independently associated with higher VO(2peak) (P < .05) and explained > 21% of the variance in VO(2peak), adjusted for body mass index, fat mass, important covariables, and nonindependence of families. CONCLUSIONS: In this cross-sectional study, lean mass was the key determinant of cardiorespiratory fitness, independent of sex, age, and magnitude of obesity. These data provide a strong rationale for examining whether interventions that increase lean mass may also improve fitness, even among high-risk overweight and obese African Americans.