On the implications of a sex difference in the reaction times of sprinters at the Beijing Olympics

Abstract

Elite sprinters offer insights into the fastest whole body auditory reaction times. When, however, is a reaction so fast that it represents a false start? Currently, a false start is awarded if an athlete increases the force on their starting block above a given threshold before 100 ms has elapsed after the starting gun. To test the hypothesis that the fastest valid reaction times of sprinters really is 100 ms and that no sex difference exists in that time, we analyzed the fastest reaction times achieved by each of the 425 male and female sprinters who competed at the 2008 Beijing Olympics. After power transformation of the skewed data, a fixed effects ANOVA was used to analyze the effects of sex, race, round and lane position. The lower bounds of the 95, 99 and 99.9% confidence intervals were then calculated and back transformed. The mean fastest reaction time recorded by men was significantly faster than women (p<0.001). At the 99.9% confidence level, neither men nor women can react in 100 ms, but they can react in as little as 109 ms and 121 ms, respectively. However, that sex difference in reaction time is likely an artifact caused by using the same force threshold in women as men, and it permits a woman to false start by up to 21 ms without penalty. We estimate that female sprinters would have similar reaction times to male sprinters if the force threshold used at Beijing was lowered by 22% in order to account for their lesser muscle strength.

Figure 1. Sex difference in sprinter reaction times.

Scatter and box-whisker (including median, quartiles, and 95% confidence interval [CI]) plots of the fastest valid reaction times of sprinters at the Beijing Olympics. The lower bounds of the 99% and 99.9% CI are also shown. The numbers of false starts are circled.

Figure 2. Sex difference in rapid plantarflexion moment development.

At time (T₁) the moments produced by men (M_m) and women (M_f) are indicated by points a and b, respectively. The times taken by men (T₁) and women (T₂) to develop the plantarflexion moment, M_m, are indicated by points a and c, respectively. Figure is redrawn from .