SEX DIFFERENCES IN RECOVERY FROM SPRINT INTERVAL EXERCISE

The purpose of the study was to examine whether there were differences between males and females in energy metabolism following a bout of sprint interval training (SIT). Sixteen males (mean ± SD [95% CI] for age, stature, body mass and fat-free mass [FFM] of 25.4 ± 5.9 [22.3, 28.6] years, 181.3 ± 7.0 [177.6, 185.0] cm, 82.7 ± 13.3 [75.6, 89.8] kg, and 69.0 ±10.6 [63.4, 74.6] kgFFM, respectively) and 16 eumenorrheic females (26.1 ± 5.5 [23.1, 29.8] years, 164.1 ± 8.7 [159.5, 168.7] cm, 72.0 ± 15.4 [63.8, 80.2] kg, and 51.6 ± 8.5 [47.0, 56.1] kgFFM), tested in the mid-luteal phase of their menstrual cycle, completed a SIT protocol, consisting of 4 x 30-s Wingate sprints at 0.065% FFM. Respiratory variables were used to estimate energy metabolism following (post-SIT) and 24 h following the bout of SIT (24 h post-SIT). Compared to females, males had significantly higher post-SIT mean fat oxidation rates (0.10 g.min-1 and 0.17 g.min-1, respectively, F(1,30) = 34.82, p < 0.001, ƞp2 = 0.54), energy expenditure (1.28 ± 0.26 and 1.82 ± 0.40 kcal.min-1, respectively, F(1,30) = 20.759, p <0.001, ƞp2 = 0.41), excess post-exercise oxygen consumption values (1.91 ± 0.60 and 3.02 ± 1.58 L, F(1,30) = 6.882, p <0.014, ƞp2 = 0.19), and lower relative carbohydrate oxidation rates (0.0007±0.0013 and 0.0018±0.0007 g.min-1 per kgFFM, respectively, F(1,30) = 10.506, p < 0.003, ƞp2 = 0.26). The higher metabolic values post-SIT for the males compared to the females might be explained by the males having a greater FFM and having exercised at a higher exercise intensity. Practically, these findings could mean that, if prescribing SIT as a strength and conditioning professional, males and females could respond differently in terms of energy expenditure post-exercise.