Digit Ratio (2D:4D) and lactate response during a football-specific intermittent field fitness test in women.

BACKGROUND

Lactate, an important respiratory substrate, is generated during exercise. Digit ratio (2D:4D) is strongly associated with lactate in men over a range of exercise intensities, but in women the association has been reported as weaker and restricted to high running speeds. Here we report a replication of this finding in women employing the 30-15 Intermittent Fitness Test (30-15 IFT).

METHOD: The participants were amateur female football players. Digit lengths, height, body composition and VO2max were measured. The 30-15 IFT involves 30-s shuttle runs between lines positioned 40 m apart. Audio signals determine the pace, starting at 10 km/h and increasing by 0.5 km/h to a maximum of 18 km/h.

RESULTS

Mean lactate levels (mmol/L) rose with running speed, ranging from 2.13 (±0.78) to 13.63 (±2.83). At running speeds 12 km/h to 16 km/h (n = 28 and 26 respectively) there were positive correlations between lactate and weight and BMI and negative associations with VO2max. At 18 km/h (n = 16) right 2D:4D was positively related and height negatively related to lactate. The former remained significant after the effect of height was removed.

CONCLUSION

Our findings from the 30-15 IFT in the field are similar to those reported from a laboratory treadmill test. The digit ratio, especially right 2D:4D, is positively associated with lactate levels during running in women, independent of height. In contrast previous findings in men the association applies to high running speeds only.