Relationships between digit ratio (2D:4D) and female competitive rowing performance.

BACKGROUND Digit ratio (2D:4D), a measure of prenatal testosterone exposure, is weakly-to-moderately associated with increased physical performance, although the evidence is far stronger for males than females. OBJECTIVE To examine the relationship between 2D:4D and measured on-water rowing performance in young females competing at the Australian Rowing Championships. METHODS Using an observational, cross-sectional design, female rowers (n = 69, aged 12-30 years) who competed in single sculls events at the Australian Rowing Championships in 2007 and 2008 had numerous physical and digital anthropometric measurements taken, including 2D:4D measurements. Relationships between 2D:4Ds and race times were examined using Pearson's correlations, partial correlations and multiple regression. Partial Least Squares regression analysis determined the strength of the 2D:4D as a predictor of race time relative to 78 body dimensions plus age. RESULTS Overall, weak to strong positive correlations between 2D:4D and race time were found; that is, females with smaller 2D:4Ds had faster race times than females with larger 2D:4Ds. Relationships were weak to moderate for all females (r = 0.29-0.32), moderate-to-strong for senior rowers (aged ≥20 years; r = 0.42-0.55), and weak for junior rowers (aged <20 years; r = 0.13-0.18), with all relationships persisting following adjustment for age. Partial Least Squares regression analysis showed that 2D:4Ds had high predictive importance relative to other body dimensions. CONCLUSIONS Females with smaller 2D:4Ds rowed substantially faster than females with larger 2D:4Ds, with the 2D:4D possibly linked to underlying characteristics that have been optimized over time resulting in better rowing performance.