| Abstract: | Comparison of male and female performance trends in athletics and swimming over the last decade shows that women tend to improve their results less rapidly than men. Does this divergence reflect unequal physical capacities? Measuring performance implies the determination of numerous (biological, psychological, sociological) elements. For most authors, physical capacities are decisive in explaining performance levels, as expressed by energetic and biochemical factors. The latter are analysed in this study in order to compare performances in both sexes. Energy expenditure may be assessed through the study of maximum aerobic power and aerobic endurance. During tests which required a significant amount of aerobic power, female were observed to be lower than male performances. These differences may be explained by the lower maximal oxygen uptake (O2 max) in women. Absolute O2 max values, expressed in 1·min−1 are typically 30 to 50% higher in men than in women. Using the relative expression of O2 max, in ml of oxygen per kg of body weight, the apparent sex difference in maximal aerobic power is reduced to approximately 20%. Thus, part of the sex difference in O2 max is related to the difference in body size and weight. One factor known to influence O2 max is relative body fat. If O2 max is expressed relative to fat-free weight, the sex difference in O2 max is further reduced and, in some cases, ceases to exist. A smaller heart size and a lower hemoglobin concentration are two factors which are proposed as a possible hypothesis to explain this variation. The sex differential in O2 max between trained men and women was less than for untrained subjects. On the other hand, during exercise involving moderate speed, women displayed better endurance properties than men. This observation indicates that females depend upon aerobic energy turnover and fat combustion to a larger extent than males. A higher lipid contribution to energy metabolism was explained in women compared to men via the lower values of respiratory exchange ratios obtained in women for oxygen uptake values below 75 to 80% of maximal oxygen uptake.The biochemical component takes into consideration the strength characteristics are produced by muscle and the conditions under which thus strength is manifested, assessed through efficiency study. Men are usually stronger than women because they have more muscle mass. However, when muscular strength is expressed relative to lean body mass or to cross-sectional area of muscle, sexual differences are reduced significantly. Signifaicant differences in gross energy expenditure are apparent between men and women but when expressed in relation to body weight, the difference in energy cost is decreased. These differences are also dependent upon activity and training level.In general, women have a significantly lower capacity to perform physical work than men. The effects of physical fitness training do not alter these differences. |
