Epigenetic modifications, such as DNA methylation, are important for cellular development and function, and aberrant DNA methylation profiles are exhibited by patients with chronic diseases. Physical exercise attenuates the risk of many cardio-metabolic diseases and mortality; an effect enhanced with higher exercise intensities. High-intensity interval training (HIT) induces similar, if not greater, health and fitness benefits quicker than traditional exercise training and requires significantly less training volume. To aid our understanding of the molecular mechanisms of the health benefits gained from HIT, we analysed DNA methylation changes after 4 weeks of HIT.
12 healthy, young men (18–24yrs) performed 3 times a week HIT for 4 weeks. DNA and RNA was extracted from circulating blood samples donated by participants at rest, before and three days after their final HIT session. Whole-genome DNA methylation was quantified using the Infinium HumanMethylation 450k BeadChip (Illumina).
HIT increased cardiorespiratory fitness (VO2max) by 2ml.kg.min-1 (P = 0.05). HIT induced DNA methylation changes (0.1–62.8%) at 205,987 sites (q < 0.05) relating to 32,445 transcripts. While 124,411 CpG sites corresponding to 27,263 transcripts were de-methylated after HIT, 81,576 CpG sites relating to 16,256 transcripts became more methylated. CpG island, N shore and S shore DNA methylation decreased whilst N shelf methylation increased (P < 0.001). Pathways involving metabolism, stem cell proliferation and transcription factor activity were significantly modulated after HIT.
Relatively short-term exercise training profoundly modulates the leukocyte methylome. Whether these epigenetic changes are required for or are a result of the phenotypic health and fitness adaptations to exercise requires further study.