Do you know the best timing to do exercise? I did not. Therefore, I tried to find it as a graduate thesis; Effect of acute exercise on mitochondrial biogenesis in epididymal adipose tissue and solues muscle:detection of effective exercise timing.
Introduction
All of the life on the earth has circadian rhythm affected by clock genes. The expressions of genes related to mitochondrial biogenesis are also up and down-regulated by clock genes. It is widely known that exercise training increases mitochondrial biogenesis. Then, I hypothesize that the expressions of mRNAs related to mitochondrial biogenesis and beneficial effect of exercise might be altered depending on the time to carry out exercise.
Training protocol and methods
The effect of acute moderate treadmill exercise at a 5° inclination at 17m/min for 60 min on several genes related to mitochondrial biogenesis were examined in the rats (each group n=3). The exercise was conducted either at the beginning of dark phase (clock time, 20:00~21:00) or at the end of dark phase (clock time, 6:30~7:30). The expression level of Bmal-1, which is one of clock genes, was peak at the end of dark phase and bottom at the beginning of dark phase. Both exercises were performed during the dark phase under dim light to prevent light-induced phase shifts in the rats. I measured mRNAs expressions of transcriptional factors in epididymal adipose tissue and soleus muscle. The examination was conducted with positive reverse transcriptase polymerase chain reaction (RT-PCR).
Results
An acute exercise up-regulated the expression of pgc-1α, which is considered as a master regulator of mitochondria biogenesis, epididymal adipose tissue at the beginning of dark phase, but not at the end of dark phase (Fig. 1). On the other hand, in skeletal muscle, an acute exercise resulted in no significant changes in the expressions of pgc-1α at both time points.
Conclusion
This study shows that because dark phase means active phase for rats, compared with acute exercise at the end of active phase, acute exercise at the beginning of active phase could have a possibility promoting mitochondrial biogenesis in white adipose tissue. The beneficial effect on mitochondrial biogenesis in adipose tissue and skeletal muscle, thus, might be altered by the time to carry out exercise.
Figure1. pgc-1α mRNA expression of resting state (control group) and exercise group in epididymal adipose tissue and soleus muscle at the end of dark phase (ED) and the beginning of the dark phase (BD), respectively. Exercise group were dissected immediately after (0h), 3 (3h), 24 (24h) hours after an acute exercise. Data are normalized per S18 rRNA. Values are means ± SE; n = 3 in each group. * p < 0.05 or less. $ p < 0.05 or less, vs 3h.
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