Adiposity and age explain most of the association between physical activity and fitness in physically active men

Abstract

Background: To determine if there is an association between physical activity assessed by the short version of the International Physical Activity Questionnaire (IPAQ) and cardiorespiratory and muscular fitness. Methodology/Principal Findings: One hundred and eighty-two young males (age range: 20-55 years) completed the short form of the IPAQ to assess physical activity. Body composition (dual-energy X-Ray absorptiometry), muscular fitness (static and dynamic muscle force and power, vertical jump height, running speed [30 m sprint], anaerobic capacity [300 m running test]) and cardiorespiratory fitness (estimated VO2max: 20 m shuttle run test) were also determined in all subjects. Activity-related energy expenditure of moderate and vigorous intensity (EEPAmoderate and EEPAvigorous, respectively) was inversely associated with indices of adiposity (r =20.21 to 20.37, P<0.05). Cardiorespiratory fitness (VO2max) was positively associated with LogEEPAmoderate (r = 0.26, P<0.05) and LogEEPAvigorous (r = 0.27). However, no association between VO2max with LogEEPAmoderate, LogEPPAvigorous and LogEEPAtotal was observed after adjusting for the percentage of body fat. Multiple stepwise regression analysis to predict VO2max from LogEEPAwalking, LogEEPAmoderate, LogEEPAvigorous, LogEEPAtotal, age and percentage of body fat (%fat) showed that the %fat alone explained 62% of the variance in VO2max and that the age added another 10%, while the other variables did not add predictive value to the model [VO2max = 129.62-(25.16 x Log %fat) - (34.06 x Log age); SEE: 4.3 ml.kg-1. min-1; R2 = 0.72 (P<0.05)]. No positive association between muscular fitness-related variables and physical activity was observed, even after adjusting for body fat or body fat and age. Conclusions/Significance: Adiposity and age are the strongest predictors of VO2max in healthy men. The energy expended in moderate and vigorous physical activities is inversely associated with adiposity. Muscular fitness does not appear to be associated with physical activity as assessed by the IPAQ. © 2010 Serrano-Sánchez et al.