Date of Award

January 2013

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Exercise and Sport Science

First Advisor

Matthew J. Sabin

Department Affiliation

Exercise and Sport Science

Abstract

Low ratios of the length of the second finger to the length of the fourth finger in the right (right 2D:4D) and the left hand (left 2D:4D) have been linked to high prenatal testosterone concentrations. Low R-L 2D:4D (subtracting left 2D:4D from right 2D:4D) has been associated with high androgen sensitivity as indicated by low numbers of cytosine-adenine-guanine (CAG) triplet repeats on exon-1 of the androgen receptor gene. Endurance training has led to higher increases in maximal oxygen uptake capacity (VO2max) in men with relatively low numbers of CAG triplet repeats, suggesting a relationship between R-L 2D:4D and VO2max. Moreover, Low right and left 2D:4D are associated with superior performances in sports such as fencing, rugby, soccer, basketball, and sumo wrestling. The strongest associations, however, have been found between right 2D:4D and endurance running performance (r² = 0.25). An inverse relationship between R-L 2D:4D and VO2max, running velocity at V̇O₂max, and peak lactate concentration in pubertal boys has been reported.

The purpose of the present investigation was to examine the relationships between measures of digit ratios and performance variables (VO2max, maximal respiratory exchange ratio (RERmax), absolute running economy (REabs), relative running economy (RErel), and total time on the treadmill (ToT)) in post-pubertal sedentary populations and in trained endurance runners. The relationship between digit ratios and endurance running performance in the form of personal records (PRs) over different race distances in the trained runners was also examined in order to explore which performance variable moderates the relationship between prenatal testosterone and/or testosterone sensitivity and endurance running performance. A significant negative relationship between left 2D:4D and VO2max (r = 0.49) was found only in the female sedentary group after removing the effects of weight using first order partial correlation analyses. In both the male and female trained runners, measures of digit ratio and VO2max showed a trend to be positively related. REabs related negatively to digit ratios in the male and female sedentary groups, while RErel was negatively related to digit ratios in only the male sedentary group. All other relationships between digit ratios and performance variables were highly inconsistent across groups and often within groups. We found fairly consistent and moderately strong positive relationships between digit ratios and PRs which do not seem to be moderated by VO2max. However, The associations between 2D:4D and endurance running performance seemed be mediated by RERmax in male endurance runners, indicating that the capacity to buffer and/or clear lactic acid moderates the relationship between prenatal testosterone stimulation and endurance running capabilities. We recommend the investigation of the relationships among lactate threshold, endurance running performance and 2D:4D.

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