Digit ratio (2D:4D), testosterone, cortisol, aggression, personality and hand-grip strength: Evidence for prenatal effects on strength

• Published in: Early human development Vol. 100; pp. 21 - 25
• Main Authors: Ribeiro, Evaldo, Neave, Nick, Morais, Rosana Nogueiro, Kilduff, Liam, Taylor, Suzan R., Butovskaya, Marina, Fink, Bernhard, Manning, John T.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.09.2016
• Subjects: Adolescent; Adult; Advanced Basic Science; Aggression; Aggression - physiology; Athletic Performance; Cross-Over Studies; Digit ratio; Fetal Development - physiology; Fingers - anatomy & histology; Hand Strength - physiology; Hand-grip strength; Humans; Hydrocortisone - analysis; Male; Neonatal and Perinatal Medicine; Personality - physiology; Saliva - chemistry; Sex Characteristics; Testosterone; Testosterone - analysis; United Kingdom; Young Adult; Hand-grip strength; Testosterone; Aggression; Digit ratio
• ISSN: 0378-3782; 1872-6232; 1872-6232
• DOI: 10.1016/j.earlhumdev.2016.04.003

Digit ratio (2D:4D) is a putative marker for prenatal testosterone and is correlated with performance in many sports. Low 2D:4D has been linked to strength but the evidence is mixed and strength is also influenced by mass, testosterone, and behavioural factors. It has been hypothesised that the 2D:4D-strength correlation may be strongest in challenge conditions when short-term changes occur in steroid hormones. We tested this suggestion in men. We used a cross-over study design with a challenge (an aggressive video of rugby tackles) and control (a blank screen) condition. 89 healthy men. Finger lengths (2nd and 4th for both hands), hand-grip strength (HGS), testosterone (T), cortisol (C), aggression (Buss-Perry Aggression Questionnaire) and personality type (Ten Item Personality Measure). In both conditions participants provided saliva samples (for hormone assays). In the challenge condition there was a highly significant increase in HGS, and modest changes in T, physical aggression and emotional stability. HGS correlated negatively with left hand 2D:4D. In a multiple regression, left hand 2D:4D was negatively related to HGS and emotional stability was positively related to HGS. In the control condition HGS was not correlated with 2D:4D. In a multiple regression, BMI, physical aggression, and emotional stability were significantly related to HGS. 2D:4D is a negative correlate of strength in challenge situations. This finding may in part explain associations between 2D:4D and sports performance.