The effect of sex differences in percentage of body fat on speed and endurance running performance

Abstract Purpose – Technological developments over the past two decades induced lifestyle changes such as high TV-viewing and high computer/tablet/smartphone and increase population physical inactivity. This change in lifestyle can affect young people and adults of both sexes differently and modify or reverse the well-known male-female morphological and physical differences. The aim of this study is to compare the effect of sex differences in percentage of body fat on speed and endurance running performance. Methods − 72 male and 64 female students aged 20 to 23 years participated in this study. After assessing their morphological characteristics, running performances during 30 m and 400 m, and maximum aerobic velocity (MAV) and maximal oxygen consumption (VO2max) during a 20 m shuttle running test have been estimated for each subject. Male students were re-tested after being overweighed down with a weight equivalent to the mean differences in body fat recorded between the two sexes in the form of a loaded worn vest. Results – Male are 15,7% heavier and 7,4% taller (p < 0.001) and presented a percentage of fat mass (17.2 ± 2%) significantly (p < 0.001) lower than that of women subject (25.0 ± 2.5%) (difference male vs female for body fat mass: 45.34%). Running performances during 30 m and 400 m, MAV and VO2max were significantly (p < 0.001) better in males (4.81 ± 0.11 sec, 61.97 ± 2.63 sec, 12.53 ± 0.54 km/h and 49.67 ± 3.3 ml/min/kg, respectively) than in females (5.58 ± 0.31 sec, 87.95 ± 8.93 sec, 10.38 ± 0.57 km/h and 37.22 ± 3.31 ml/min/kg, respectively) In the weighted condition, male performances during 30 m and 400 m, MAV and VO2max were attenuated by 6.89%, 14.16%, 6.48% and 10.07%, respectively) but remain significantly better than those of female students. Conclusion - Excess body fat in female students has a detrimental effect (range ≈ -7 to -14%) on 30 m, 400 m, MAV and VO2max performances. The persistence of sex differences after overweighting male students indicates that body fat could be responsible for ≈ 50 to 70% of the observed differences between sexes performances during short and long sprints, and 20 m shuttle running test.