Abstract
Performance differences between males and females are substantially greater when humans jump for maximal height versus distance. We postulated that the lower muscle mass/body mass fractions of females would cause sex differences in performance to increase as jump take-off angle and the force required to elevate body mass against gravity (force/body weight) increased. We tested this idea using triple jump (TJ), long jump (LJ) and high jump (HJ) data from World Athletics best-performers lists (n = 40 per sex) and countermovement jump (CMJ) data acquired from collegiate athletes (n = 19 per sex) jumping from force platforms. Across the four jumps, the more vertically oriented the take-off angle (θ(TO)), the greater the sex difference observed [range: 17.4-42.1% from TJ to CMJ; regression equation: %Diff = 26.9 (sinθ(TO))(2) + 14.2, R (2) = 0.98]. For the strictly vertical CMJ, between-sex differences in jump height (∆ = 42.1%) were eight times larger than the differences in ground-phase force application (∆force/body mass = 5.1%). We conclude that (i) small differences in mass-specific ground force application result in much larger differences in performance for more vertically oriented and gravity-opposed jumps, and (ii) lower muscle mass/body mass fractions require females to use more of their available force to offset gravity, thereby leaving them with less remaining force to elevate body mass.