Growth hormone 1 (GH1) gene and performance and post-race rectal temperature during the South African Ironman triathlon.
BACKGROUND
Some studies have suggested that the insertion allele of the ACE gene is associated with endurance performance, including the Ironman triathlon. It is possible that this association is due to genetic linkage between the ACE I/D locus and the T/A variant in intron 4 of the neighbouring GH1 gene. The A variant is associated with lower levels of growth hormone production. Growth hormone has multiple effects, especially on metabolism during exercise and recovery from exercise. Its production during exercise has also been shown to stimulate sweat rate and heat loss.


OBJECTIVE
To determine whether the GH1 gene is associated with the performance and/or post-race rectal temperatures of competitors in the South African Ironman triathlon.


METHODS
A total of 169 of the fastest finishing white male triathletes who completed the 2000 and/or 2001 South African Ironman triathlon and 155 control subjects were genotyped for the T/A variant in the GH1 gene. Post-race rectal temperature was also determined in 103 of these triathletes.


RESULTS
There was no significant difference in the frequency of this polymorphism in the GH1 gene when the fastest finishing triathletes were compared with the control subjects. Post-race rectal temperatures were, however, significantly higher in those triathletes with an AA genotype (mean (SD) 37.7 (0.8) degrees C) compared with those with a TT genotype (37.2 (0.8) degrees C) (p = 0.019).


CONCLUSIONS
The T/A polymorphism in intron 4 of the GH1 gene was not associated with performance of the fastest finishers of the South African Ironman triathlon. Post-race rectal temperatures were, however, significantly higher in the fastest finishing athletes, who were homozygous for a GH1 genotype associated with lower growth hormone production.
Walpole
B
B
UCT/MRC Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa.
Noakes
T D
TD
Collins
M
M
D000328:Adult; D000483:Alleles; D001642:Bicycling / Q000502:physiology; D001833:Body Temperature Regulation / Q000235:genetics* / Q000502:physiology; D004247:DNA / Q000235:genetics; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000235:genetics*; D012420:Running / Q000502:physiology; D013019:South Africa; D013177:Sports / Q000502:physiology*; D013550:Swimming / Q000502:physiology
D013006:Growth Hormone; D004247:DNA