Background. Both the high body fatness and low aerobic fitness have been shown to be risk factors for cardiovascular disease and type 2 diabetes. It is still unclear, whether these factors are related to each other or if they are independent risk factors. The objective of this study was to assess the influence of body composition on aspects of aerobic fitness in obese women. Methods and Results. Relative body fat was measured in a group of 31 obese women differing in age (25-54 years) by dual energy X-ray absorbtiometry (DEXA), in range of 40,8-58,8% of the body fat. Intracellular and extracellular fractions of the fat free mass were assessed by bioimpedance analysis. Maximal power output and maximal oxygen consumptionweremeasured by stepwise load test on bicycle ergometer.Mean values of absolute and relativeVO2max expressed per kg bodymass and per kg fat-freemasswere 2,09±0,38 l.min-1, 22,82±3,79ml.min-1 kg-1, and 44,05±7,03 ml.min-1.kg-1, respectively. Absolute VO2max was positively related to body weight (R=0,4758; P<0,01), BMI (R=0,5004; P<0,01), fat-free mass (R=0,5138; P<0,01) and body cell mass (R=0,4983; P<0,01). No significant dependence of relative VO2max per kg body mass on the body fat was identified. Conclusions. Aerobic fitness, expressed by relative maximal oxygen consumption per kg of body weight, is not influenced by the percent of body fat in obese women. Body cellmass ismarkedly related to aerobic fitness, expressed by absolute maximal oxygen consumption in obese women.

        Key words: body composition, aerobic fitness, oxygen consumption, obesity.