The second to fourth digit ratio: a measure of hand grip strength?

Abstract

Background: The ratio of the lengths of the index and the ring finger (2D:4D ratio) is generally different between men and women. This has often been used as an indicator of the levels of prenatal androgen exposure. It has hence been suggested to have a role in many gender differences including performance in sports. Men generally outperform women in most physical abilities. However, reports in various studies have been inconclusive, depending upon the physical ability tested. Hand Grip Strength (HGS) is a good measure of overall strength of an individual. Hence, we decided to determine the relationship between 2D:4D and HGS of both hands in men and women.Methods: Scanned images of both hands of young volunteers were analysed and the 2D:4D ratio calculated. HGS was measured and results correlated with 2D:4D.Results: 2D:4D ratio of men was significantly less than of women for the right (p<0.001) and the left hand (p<0.001). HGS of men was significantly greater than that of women for the right (p<0.0001) and for the left hand (p<0.0001). 2D:4D ratio in men showed a weak but significant positive correlation with HGS of right(p<0.05) and left hand(p<0.05). A weak but significant positive correlation was also seen for the left hand in females. However, 2D:4D ratios did not show any significant correlation with HGS for the right hand in women.Conclusions: We conclude that 2D:4D ratio is a measure of Hand Grip Strength in men, but is not a robust measure of HGS in women.