2D:4D Digital Length Index in Ball Sports

Abstract

Abstract. The digital ratio length (2D:4D) is a biomarker of the balance between testosterone (T) and fetal estrogens, therefore, it is a predictor of muscular mass and hemoglobin development, associated with sports performance. Although the 2D:4D has been associated with sports, it is required to compare 2D:4D among sports. With the aim of establishing differences of the 2D:4D between athletes of ball sports, 204 Colombian athletes (M_age= 25.9, SD= 10.0) with national and international competence level were observed. Height and body mass were self-reported in order to calculate Body Mass Index (BMI). Also, strength manual pressure and length of index and ring finger of both hands were measured. This study was approved by the bioethics committee. The Anova results indicated that 2D:4D was similar in both hands. The mean 2D:4D of both hands showed differences [F(9, 194)= 2.06, p= .034, η²=.29, 1-β=.82]. The analysis of each finger showed differences: In the right-hand (r), 2Dr [F(9, 194)= 14.8, p= .000, η²=.63, 1-β=.95], 4Dr [F(9, 194)= 12.6, p= .000, η²=.60, 1-β=.99]. In the left-hand (l), 2Dl [F(9, 194)= 18.5, p= .000, η²=.68, 1-β=1.0], 4Di [F(9, 194)= 13.2, p= .000, η²=.61, 1-β=.1.0]. The post-hoc Tukey-B analysis of the 4Dr and 2Dr-4Dl fingers showed four homogenous subsets, while the 2Dr five subsets. In conclusion, differences of the 2D:4D mean of both hands were observed. The fingers length 2D-4Dr-l showed differences among ball sports, mostly, badminton, softball, and squash.