Sex performance differences in vertical and horizontal jumping.

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 (θTO), the greater the sex difference observed [range: 17.4-42.1% from TJ to CMJ; regression equation: %Diff = 26.9 (sinθTO)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.