Micro-RNAs, Exercise and Cellular Plasticity in Humans: The Impact of Dietary Factors and Hypoxia.

Physical exercise is a stress that modulates a plethora of cellular mechanisms to promote morphological and metabolic adaptations. Substantial efforts have been made to better understand the modulation of pathways involved in cell plasticity during exercise, but human explorations may be limited because invasive procedures are often required. In recent years, minimally invasive methods for the analysis of microRNAs (miRNAs) modulation in response to exercise have been developed. miRNAs are small molecules that belong to a family of non-coding RNAs. miRNAs have a significant biological impact as they control more than 60% of human genome by targeting specific messenger RNAs. Recent studies conducted in human showed that miRNAs are detectable in a variety of biological fluids such as serum, plasma, saliva, urine and tears. Both endurance and strength exercises modulate the expression of miRNAs coding for actors involved in several cellular processes related to training adaptation. In this review, we discuss recent advances on the development of methods for miRNAs detection and the impact of acute and chronic exercise on their modulation in humans. We especially highlight the most recent studies on the factors that can impact miRNAs modulation during exercise, including the mode of exercise, the nutritional status, the use of ergogenic aids, and hypoxic exposure, and present recent findings on the potential to use miRNAs as biomarkers for anti-doping control. We finally discuss the importance of considering recent data on organelle turnover-related pathways, and current limitations in order to encourage further investigations on this area.