Association between Digital Finger Ratio (2D:4D) and Salivary Testosterone level in Combative Sports and Non-Sportsmen

Abstract

The second to fourth-digit-ratio (2D:4D), a putative marker of prenatal androgen action and a sexually dimorphic trait, has been suggested to be related with fitness and sports performance. But there very few studies which has evaluated the association between 2D:4D and the circulating levels of testosterone hormone. The objectives of the study were to examine the difference between 2d:4d and salivary testosterone hormone in 107 male combative sportsmen (42 = boxers, 37 = wrestlers & 28 = judokas) and 150 non-sportsmen (NSM) Length of index finger and ring finger of both left and right hand was measured with the help of digital vernier caliper. We found a significant difference in the digital finger ratio 2d:4d between the combative sportsmen and non sportsmen (Boxers v/s NSM t value -7.73, P < 0.01, Wrestlers v/s NSM t value – 5.60, P < 0.01 & Judokas t value – 4.75, P < 0.01). Further significant difference (Boxers v/s NSM t value -17.59, P < 0.01, Wrestlers v/s NSM t value – 18.03, P < 0.01 & Judokas t value – 13.75, P < 0.01) in the level of salivary testosterone hormone (pg/ml) between the combative sportsmen and non sportsmen was found. We suggest that low right-left 2D:4D is a predictive marker of testosterone receptiveness in men trained for the combative sports and this association is programmed by the action of prenatal testosterone.