Towards unravelling the exercise‐induced adaptations in circulating extracellular vesicles

Summary

Exercise training induces a variety of physiological changes in the human body, which can significantly improve exercise performance and/or health status. However, the mechanisms governing these beneficial exercise adaptations are complex, representing an intriguing area of research for exercise physiologists. It is well established that exercise-induced organ crosstalk is mediated through the secretion of humoral factors (e.g. nucleic acids, peptides, and metabolites) into the circulation. Such factors are frequently transported as cargo of lipid-membrane-enclosed vesicular structures called extracellular vesicles (EVs), which can be absorbed by neighbouring or distant cells and thereby exert an effect. In support of this notion, recent EV-related exercise studies have shown an enrichment in small EVs (50–150 nm) in the circulation following acute exercise. Since the beneficial effects of exercise on whole-body metabolism persist after an exercise bout, it is interesting to speculate whether regularly engaging in exercise leads to a certain background level of circulating EVs even in between exercise sessions. However, studies investigating the long-term effects of exercise training history on the abundance of EVs in circulation are limited and employ insufficient methodological approaches or have inadequate control over confounding factors, that is, recent dietary intake and exercise sessions. Consequently, it remains unclear whether exercise training history induces long-term changes in the circulating EV profile in between exercise sessions rather than only being present transiently during and soon after exercise.