The Beneficial Metabolic Adaption Provoked by Consistent Exercise
Consistent exercise produces sweeping changes in metabolism. It is clearly beneficial at any age, and there is a mountain of data to support that assertion. With more modern tools of analysis, greater efforts are being made to catalog the beneficial changes in cellular metabolism that result from exercise, rather than just the improvements to health at a high level. The open access paper noted here is an example of this sort of work.
Exercise provides many health benefits, including weight loss, improved lipid profiles, and improved insulin sensitivity. It is particularly relevant in the era of high-prevalence childhood and adult obesity and cardiometabolic disease. Exercise is a core tenet of all cardiovascular prevention guidelines, and degree of physical fitness is a strong predictor of cardiovascular mortality.
Metabolites are a diverse array of biochemicals that together capture an individual's metabolic state. They are particularly useful in the investigation of cardiometabolic diseases. Furthermore, they can characterize response to both acute and chronic exercise. Several studies have revealed key changes in lipolysis, glycolysis, glycogenolysis, citric acid cycle, and amino acid metabolism after a single/acute aerobic exercise session and identified differences in metabolite substrate use between fit and unfit individuals. However, much less work has been done with respect to metabolic changes following chronic exercise training. These studies reported increases in microbiome-derived tryptophan metabolites and acylcarnitines, and decreases in adenine nucleotides.
We analysed changes in metabolomic profiles at the end of an 80-day exercise intervention compared to baseline, and the association of metabolite changes with changes in clinical parameters. Global metabolism was dramatically shifted after the exercise training programme. Fatty acids and ketone body substrates, key fuels used by exercising muscle, were dramatically decreased in plasma in response to increased aerobic fitness. There were highly significant changes across many classes of metabolic substrates including lipids, ketone bodies, arginine metabolites, endocannabinoids, nucleotides, markers of proteolysis, products of fatty acid oxidation, microbiome-derived metabolites, markers of redox stress, and substrates of coagulation.
For the first time, therefore, we were able to provide an accurate report of the degree of increased consumption of fatty acid and ketone body substrates by trained, energy-efficient muscle. We also captured heretofore unseen, in terms of scale and scope, shifts in metabolism across many different substrates. These findings have important implications in cardiovascular disease prevention and risk reduction regimes.