Associations between 2D:4D digit ratio and handgrip strength in a Central European population.

The 2D:4D ratio refers to the relative lengths of the second (2D) and fourth (4D) fingers and represents a sexually dimorphic trait that is established during prenatal development. It is widely regarded as an indirect marker of fetal androgen exposure, particularly testosterone. Elevated testosterone levels in utero are associated with increased growth of the ring finger compared to the index finger, which leads to a lower 2D:4D ratio. Similarly, handgrip strength is influenced by prenatal testosterone levels and reflects an individual's overall physical fitness and muscle mass. The present study investigated the relationship between 2D:4D ratios and handgrip strength in an age-homogeneous sample of Central European university students aged 18 to 32 years (n = 203; 99 males, 104 females). Statistical analyses confirmed that females exhibited significantly higher digit ratios than males on both hands, supporting established sex differences likely shaped by prenatal hormonal influences. Males demonstrated substantially greater handgrip strength compared to women, reflecting an established sex-based physical dimorphism in physical strength. The findings of this study additionally support the hypothesis that a lower left and right 2D:4D ratio, considered an indicator of increased prenatal testosterone exposure, is associated with greater handgrip strength. This correlation was most pronounced in the right hand, particularly among male and right-handed participants. The pattern of the relationship between digit ratio and physical strength differed by sex, with males exhibiting a U-shaped association and females showing an inverted U-shaped relationship. Overall, this study replicates and extends previous findings and thereby contributes to a better understanding of digit ratio as a potential biomarker for androgen-related traits, especially in connection with physical strength.