Original Research Article
Endurance running and digit ratio (2D:4D): Implications for fetal testosterone effects on running speed and vascular health
Article first published online: 9 APR 2007
Copyright © 2007 Wiley-Liss, Inc.
American Journal of Human Biology
Volume 19, Issue 3, pages 416–421, May/June 2007
How to Cite
Manning, J. T., Morris, L. and Caswell, N. (2007), Endurance running and digit ratio (2D:4D): Implications for fetal testosterone effects on running speed and vascular health. Am. J. Hum. Biol., 19: 416–421. doi: 10.1002/ajhb.20603
- Issue published online: 9 APR 2007
- Article first published online: 9 APR 2007
- Manuscript Accepted: 19 OCT 2006
- Manuscript Revised: 12 OCT 2006
- Manuscript Received: 17 AUG 2006
There is anatomical and physiological evidence that endurance running (ER), i.e., running one or more kilometers using aerobic metabolism, originated early in the evolution of Homo, and the consequences of early selection for ER may be important in modern Homo. Here we examine ER performance in competitive ER. ER is sex dependent such that men tend to run faster than women, and the influence of sex on ER suggests that it may be modified by testosterone (T). It is shown that a putative proxy for prenatal T, the ratio of the length of the 2nd and 4th digits (2D:4D), is correlated with ER. Thus performance in training for ER was associated with high prenatal T, as measured by low 2D:4D, in both men and women. In cross-country races from 1 to 4 miles, 2D:4D explained about 25% of the variance in both male and female ER. Therefore, speed in ER was dependent on a proxy for prenatal T. 2D:4D correlates with performance in sport and exercises, which test a mix of strength and fitness, but the associations are in general quite weak with 2D:4D accounting for less than 10% of the variance in performance. Our finding that 2D:4D explains about 25% of the variance in ER suggests that prenatal T is important in determining efficiency in aerobic exercise. Early populations of Homo may have been strongly selected for ER and high prenatal T. The implications of this for patterns of predisposition to cardiovascular disease in modern Homo are discussed.Am. J. Hum. Biol. 19:416–421, 2007. © 2007 Wiley-Liss, Inc.