Abstract
Intermittent hypoxic exposure with exercisetraining is based on the assumption that brief exposure tohypoxia is suYcient to induce beneWcial muscular adaptationsmediated via hypoxia-inducible transcription factors(HIF). We previously demonstrated (Mounier et al. MedSci Sports Exerc 38:1410–1417, 2006) that leukocytesrespond to hypoxia with a marked inter-individual variabilityin HIF-1 mRNA. This study compared the eVects of3 weeks of intermittent hypoxic training on hif gene expressionin both skeletal muscle and leukocytes. Male enduranceathletes (n = 19) were divided into an Intermittent HypoxicExposure group (IHE) and a Normoxic Training group(NT) with each group following a similar 3-week exercisetraining program. After training, the amount of HIF-1mRNA in muscle decreased only in IHE group (¡24.7%,P < 0.05) whereas it remained unchanged in leukocytes inboth groups. The levels of vEGF121 and vEGF165 mRNA inskeletal muscle increased signiWcantly after training only inthe NT group (+82.5%, P < 0.05 for vEGF121; +41.2%,P < 0.05 for vEGF165). In leukocytes, only the IHE groupshowed a signiWcant change in vEGF165 (¡28.2%,P < 0.05). The signiWcant decrease in HIF-1 mRNA inskeletal muscle after hypoxic training suggests that transcriptionaland post-transcriptional regulations of the hif-1gene are diVerent in muscle and leukocytes.