The relationship between the digit ratio (2D:4D) and vertical jump performance in young athletes

Background: Digit ratio (2D:4D), a putative marker of prenatal testosterone, is a negative correlate of sports, athletic, and fitness performance.

Objectives: To describe the relationship between 2D:4D and vertical jump performance in athletes.

Methods: Sixty-one Division I American Football players from a Midwestern U.S. university had their 2D:4D measured digitally and their vertical jump performance measured using jump mechanography. The primary outcome was jump height, with secondary outcomes depicting jump execution also recorded. Linear relationships between 2D:4D and vertical jump performance were quantified using partial correlations adjusted for age, height, mass, and ethnicity.

Results: 2D:4D was a statistically significant weak negative correlate of jump height (partial r [95% confidence interval]: -0.26 [-0.48, -0.01]), indicating that athletes with lower 2D:4Ds (i.e., relatively longer 4th digits) jumped higher. Relationships with jump execution variables were negligible to weak and negative, but not statistically significant.

Conclusions: The significant relationship between 2D:4D and jump height probably reflects both the long-term organizational and short-term activational benefits of testosterone. Therefore, 2D:4D may be a useful indicator of explosive strength among young athletes.