This study further establishes that TFAM protein levels are higher in conditions with enhanced oxidative capacity. The mRNA levels of TFB1M and TFB2M are influenced by endurance training, possibly suggesting a role for these factors in the regulation of exercise-induced mitochondrial biogenesis.

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The aim of the present study was to investigate mRNA and protein levels of mitochondrial transcription factors Tfam, TFB1M and TFB2M in individuals with high oxidative capacity (elite athletes) compared to normally trained individuals, as well as the effect of 5 weeks of exercise in healthy males.Method: Skeletal muscle biopsies were obtained from the vastus lateralis muscle at rest from 12 males with high oxidative capacity, 9 moderately trained male controls and 12 healthy males before and after 10 days and 5 weeks of one‐legged knee extension exercise. One leg exercised with restricted blood flow (R‐leg), the other with non‐restricted blood (NR‐leg) flow.Results: mRNA expression of TFB1M and TFB2M was increased after 10 days and 5 weeks of exercise in the R‐leg. Moreover, higher mRNA expression of both TFB1M and TFB2M was detected in elite athletes compared to moderately active individuals. No differences in TFAM mRNA were observed.Conclusion: This suggests that metabolic perturbation, induced by regular contractile activity, or a higher oxidative status have long‐term effects on steady state mRNA expression of TFB1M and TFB2M but not on Tfam. Protein analyses could not detect any differences in TFB1M and TFB2M between elite athletes and moderately active individuals. However, TFAM protein expression was significantly higher in the elite athletes.