How does exercise help our mitochondria?
T
he current world marathon record is set by Eilud Kipchoge, a Kenyan marathoner who finished a full 42.195 km in only 2:01:09 in the 2022 Berlin Marathon. I, on the other hand, who follows a stereotypical sedentary lifestyle, probably would go less than 10 kms within the same time and would already be exhausted. For a long time, researchers have wondered what is responsible for such dramatic differences in the physical abilities of elite athletes and ordinary people. The first clue, of course, was the difference in muscle compositions. In 1945, it was experimentally established that exercise and training induce biochemical differences in skeletal muscles. Soon after in 1967, science pin-pointed that exercise could also affect mitochondrial respiration in skeletal muscles. Mitochondria have two membranes. The inner membrane surrounds a partition called cristae. Earlier studies showed no evidence of plasticity in the physical structure of cristae upon exercise. Therefore, it had been long assumed that exercise affects the plasticity of mitochondria, and not of the cristae, towards an increase in the mitochondrial volume and respiration.
In general, density of cristae predicted the maximal oxygen uptake better than the overall volume of mitochondria. All these results suggest that it is the cristae within our mitochondria that have a certain plasticity that appears to correlate with exercise and the activity levels in our lifestyle. Exercise impacts not only the structure of mitochondrial cristae, but also the overall health of mitochondria. This is measured by how effectively mitochondria maintain or re-establish metabolic homeostasis upon changes in metabolic needs. The importance of mitochondrial health is highlighted over the course of aging. Sarcopenia, progressive decrease in muscle mass, is a hallmark of aging responsible for various health implications for the elderly population. Dysfunctional mitochondria, such as those with fragmented morphology or mutations in the mtDNA, are significant contributors to sarcopenia. It is important to note that the mitochondrial functions of elderly people who exercise regularly are similar to those from younger counterparts, suggesting that exercise is key in preserving mitochondrial health over the process of aging.
Mitochondrial Health
This assumption was questioned in a more recent study by a group of Danish and Swedish scientists. They recruited volNearly 1.5% of all medical publications are related to unteers who were either 1) obese with a sedentary lifestyle, mitochondria. This is far higher than any other organelles 2) recreationally active, or 3) elite including the nucleus in the second athletes. All of them donated their place at around 1%. Further, the inGrowth & Adulthood Aging leg muscle biopsy samples before terest in mitochondria has only been Development and after participating in a short increasing since 1980. While the role 10-week exercise schedule. Interestof mitochondria has been and coningly, the surface area of the cristae tinues to be highlighted in various asPh y Ac sical of athletes was 150% greater than pects of health and disease, exercise tive ly those of obese sedentary individuremains the most potent behavioral als. Also, the density of cristae sigtherapeutic approach for enhancing Se den nificantly increased in recreationally mitochondrial health and overall intar y active participants after exercise. dividual longevity. Age - Steve Lee IMMpress Vol. 11 No. 2 2023
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