Anthropometrics, Performance, and Psychological Outcomes in Mixed Martial Arts Athletes

SIMPLE SUMMARY: The digit ratio is a prenatal testosterone biomarker and it is related to sports performance. Few investigations have explored the digit ratio in determining the potential performance of an individual in power-based sports, specifically, combat sports. This biomarker, in conjunction with other measures, might be valuable in determining the potential athleticism of an individual. In the present study, we compared the digit ratios between mixed martial arts athletes and non-athletes. Moreover, we investigated the association between (1) handgrip strength and the digit ratio in mixed martial arts athletes and (2) psychometric variables and digit ratios in mixed martial arts athletes and non-athletes. Athletes presented lower digit ratios than the control group in both hands. Moreover, athletes presented less agreeableness, more openness, and less anger than the controls. We observed that the left hand 2D:4D was negatively correlated with handgrip strength and lean body mass in professional athletes. However, we did not observe an association between psychometric variables or wins with 2D:4D. To conclude, the prior digit ratio might provide efficient data for analyses and important feedback to determine key performance predictors in a particular competition, but it does not explain the full sports performance; it needs to be included with other performance measures. ABSTRACT: The digit ratio (2D:4D) is related to prenatal testosterone (T) and sports performance. Few investigations have explored 2D:4D in determining the potential performance of individuals in power-based sports, specifically combat sports. This study compared 2D:4D between mixed martial arts (MMA) athletes and non-athletes and investigated the association between (1) handgrip strength (HGS) and lean body mass (LBM) with 2D:4D in MMA athletes and (2) psychometric variables and 2D:4D in MMA athletes and non-athletes. In total, 122 men participated in this study (53 non-athletes, 45 professionals, and 24 amateur fighters). The 2D:4D was measured using a caliper, HGS was assessed with a dynamometer, and psychometric variables were evaluated using questionnaires. Athletes displayed significantly (p < 0.05) lower median values of right (0.95 ± 0.04) and left (0.96 ± 0.03) 2D:4D in comparison with non-athletes, (0.97 ± 0.03) and (0.99 ± 0.03), respectively. We observed that left hand 2D:4D was negatively correlated with HGS (r = −0.43; p < 0.05) and lean body mass (r = −0.49; p < 0.05) in professional athletes. Professional athletes also displayed significant differences (* p < 0.05; ** p < 0.001) in psychometric variables compared to non-athletes for (1) agreeableness **, median values (interquartile range) = −0.11 (−0.19–0.07) and 0.2 (−0.09–0.33), respectively; (2) anger **, mean ± standard error = 2.40 ± 0.12 and 2.89 ± 0.89, respectively; and (3) openness *, mean ± standard error = 0.17 ± 0.04 and −0.006 ± 0.04, respectively. However, we did not observe an association between psychometric variables or wins with 2D:4D. In conjunction with other measures, 2D:4D is valuable in determining the potential athleticism of an MMA athlete.