Effects of Structured Exercise Training on MiRNA Expression in Previously Sedentary Individuals

Introduction: Micro ribonucleic acids (miRNA) respond to acute bouts of vigorous exercise, such as maximal cardiopulmonary exercise tests (CPET), by expressing an anti-atherogenic, anti-inflammatory and hence probably ergogenic profile. However, the impact of long-term engagement in physical exercise on CPET-induced miRNA response in sedentary individuals, with subsequent increased risk for cardiovascular diseases, remains unclear.

Methods: Thirty-four sedentary participants underwent CPET before and after a four-month app-assisted exercise intervention, during which the moderate to vigorous physical activity (MVPA) was increased to over 150 min/week. Capillary blood samples were collected before and after CPET at baseline and after the exercise intervention. Twenty target miRNAs previously reported to be responsive to exercise and exercise adaptive pathways, or linked to atherogenic properties as inflammation, or previously identified upregulated following exercise in subjects with coronary artery disease versus healthy subjects were analyzed via real-time polymerase chain reaction.

Results: Physical activity increased from 64 ± 48 to 354 ± 332 min/week of MVPA (p<0.001, +553%), accompanied by an improvement in maximal power output during CPET (ΔWattmax: 19 ± 13, p<0.001, +9%). Eleven of the selected twenty miRNAs showed significant responses to CPETs at either the beginning or end of the study. We found a significant increase both times for miR-103a (glycolysis, %change base: +12%, post +17%), miR-146a (inflammation, %change base: +20%, post +21%), and miR-222 (cardiac remodeling, %change base: +10%, post +21%), while miR-30a (inflammation, %change base: -27%, post: -38%) decreased significantly (all p≤0.043).

Conclusion: Increased physical activity led to a significant CPET-induced change in three miRNAs from an atherogenic profile to a healthier one, indicating improved metabolic health and reduced inflammation.