Absence of Sex Difference in Digit Ratio (2D:4D) Among the Elite Sportspersons: Further Evidence Among the Polish Swimmers.

The control group showed a significant sex difference in right hand 2D:4D, with females showing a higher ratio than males.

• t = 2.17, p < 0.05 for the right hand 2D:4D sex difference in the control group
• Control group consisted of 54 males and 34 females
• This pattern is consistent with the typical sexually dimorphic pattern reported in the general population

No sex difference in 2D:4D was evident in any of the swimmers' groups.

• The absence of sex difference was found in both the national team swimmers and other higher level swimmers
• This contrasts with the significant sex difference observed in the non-sporting control group
• The finding applied to both right and left hand measurements in the swimming groups

Female swimmers showed significantly lower right 2D:4D than control females.

• The difference was significant for right 2D:4D in females across the three study groups
• Both national team and general higher level female swimmers showed lower right 2D:4D than control females
• Lower 2D:4D indicates higher prenatal testosterone exposure

Male swimmers showed significantly lower left 2D:4D than control males.

• The difference in 2D:4D among the three study groups was significant only for the left 2D:4D in males
• The laterality pattern differed between sexes, with females showing the effect in the right hand and males in the left hand
• This suggests sport-level related variation in prenatal androgen exposure among male swimmers

Top level swimmers had the lowest 2D:4D compared to lower level swimmers and non-sporting controls.

• A gradient was observed whereby swimmers overall had lower 2D:4D than non-sporting individuals
• Among swimmers, the national team (top level) had the lowest 2D:4D values
• This pattern was observed across the three study groups examined in the cross-sectional design

Female elite swimmers showed 'masculine' 2D:4D similar to their male counterparts, suggesting positive selection for masculinised digit ratio in competitive female sports.

• The female swimmers, particularly the elite group, showed digit ratios comparable to male swimmers
• The authors hypothesized 'a plausible positive selection for a masculinised digit ratio (higher prenatal testosterone exposure) among the females in highly competitive professional sports'
• This finding aligns with the concept that higher prenatal testosterone exposure confers athletic advantages in swimming

The study design was cross-sectional and measured height, weight, and lengths of the second and fourth digits in Polish swimmers and controls.

• Two groups of swimmers were assessed: Polish national team swimmers and other higher level swimmers
• A control group of non-sporting individuals (54 males and 34 females) was included
• Physical measurements included height, weight, and lengths of 2D (index finger) and 4D (ring finger) for both hands