Abstract

Objective: The crucial role of haemoglobin in endurance performance has been well documented. We examined whether polymorphisms in the HBB gene modified aerobic capacity.

Methods: 102 recruits were trained by running 5000 m three times per week for 18 weeks. Exercise intensity progressively increased from an initial heart rate corresponding to 95% of the individual baseline ventilatory threshold during the first 10 weeks to 105% during the last 8 weeks. The phenotypes measured were running economy and VO₂max. Running economy was determined by measuring submaximal VO₂ for 5 min at a constant running speed of 12 km·h⁻¹ and VO₂max was obtained during an incremental test to exhaustion. Genomic DNA was extracted from white cells of peripheral blood and the −551C/T, intron2,+16C/G and +340 A/T genotypes were examined relative to the TAA site variants by PCR-RFLP.

Results: Genotype distributions were in Hardy-Weinberg equilibrium at three loci. None of the running economy and VO₂max-related traits were associated with the three polymorphisms or haplotypes at baseline, while the training response of running economy was associated with −551C/T and intron2,+16C/G polymorphisms. Subjects homozygous for intron2,+16C/C or −551C/C had decreased oxygen cost of running compared to the other individuals.

Discussion: It was concluded that the −551C/C or intron2,+16C/C genotype might explain part of the individual variation in the cardiorespiratory adaptation to endurance training.