The health benefits of resistance training across age demographics, in particular ageing populations, is well known. Even in those who take up the activity later in life, weight training has been found to have a positive physiological impact on inflammation, muscle mass, fat mass, insulin sensitivity and more. The mechanisms with which weight training exerts these effects, however, is not as well understood.
What are micro RNAs (miRNA)?
Thanks to COVID-19, or more specifically the Pfizer and Moderna vaccines, we’ve all become familiar with the term mRNA or messenger RNA.
The lesser known but related and similar-sounding miRNA is a small type of RNA that is of specific interest to scientist for the role they play in the onset of a number of health problems and diseases, particularly age-related conditions.
miRNAs are involved in regulating gene expression, by interacting with mRNAs to induce mRNA degradation and translation repression.
By either initiating or down-regulating certain genetic mechanism, miRNAs are believed to impact the onset of a number of health conditions, including inflammation, heart disease, Alzheimer’s disease and cancer. A number of miRNAs are also believed to be associated with age-related obesity and muscle loss.
Exercise has been shown to positively impact circulating miRNAs in healthy persons and patients, indicating miRNAs play a role in physiological adaptations to exercise and the subsequent and related health benefits as well.
Previous research has explored the impact of aerobic exercise on circulating miRNA molecules. A more recent study explored the miRNA response to a resistance training program in the ageing population.
The specific focus was on whether resistance training, through its impact on the circulating numbers and balance of varying miRNAs, can prevent age-related weight gain, muscle loss and inflammation. From here, the hypothesis is that this will see a reduction in the subsequent and related health impacts as well.
Ten healthy older adults (67.6 years of age ± 2.2 years; 7 women and 3 men) with little to no resistance training experience embarked on a 12-week resistance training program.
Participants performed three training sessions per week, with at least one rest day between sessions. The workouts were supervised by instructors, and both free weights and machines were employed.
Ten full body exercises were performed across the three workouts. They were a chest pressing movement, a shoulder press, seated row, squat, bridge, bicep and tricep movement, abdominal curl, lower back extension, and calf raise. Each training session included three sets of each exercise.
Blood samples were collected at baseline and following the 12-week program with 14 fat tissue-associated miRNAs (11 adipogenesis and 3 anti-adipogenesis), nine muscular tissue-related miRNAs (myogenesis), and five inflammation-associated miRNAs measured.
Compared to baseline, there was a significant decrease in miRNAs associated with weight gain (adipogenesis related miRNAs) and a significant increase in the miRNAs associated with inhibiting weight gain (anti-adipogenesis related miRNAs), as a result of the 12-week resistance training program. This indicates that weight training has a down-regulating impact on adipogenic genes.
Additionally, the miRNAs that act as negative regulators of skeletal muscle growth via inhibiting the insulin/ IGF-1 signaling pathway all significantly decreased after resistance training, serving to maintain muscle mass and function in older adults.
Finally, there was evidence to suggest that resistance training had a significant inhibitory effect on miRNAs that mediate pro-inflammatory markers, in particular, TNFα.
Although more research is needed, this study not only provides further evidence for the benefits of resistance training in the ageing population, but further uncovers some of the mechanisms involved in this type of exercise, that serve to protect muscle mass and prevent fat cell proliferation during ageing.
All of these impacts were found in participants regardless of physiological adaptations to the training program, such as significant changes in skinfold tests and muscle mass measures.
Therefore, even when we are not seeing the physical benefits of our weight training efforts on the surface, there is evidence to suggest that important health protecting benefits of weight training are still taking place, through mechanisms associated with miRNAs and gene expression.
No matter what stage of life you’re in, embracing a weight training regime into your weekly routine can not only make you look and feel good, but as we uncover the underlying mechanisms at play, may help to prevent many common age-related health conditions as well. And it’s never too late to start.
Liu H., Cheng H., Tsai S., and Sun W. Effect of Progressive Resistance Training on Circulating Adipogenesis-, Myogenesis-, and Inflammation-Related microRNAs in Healthy Older Adults: An Exploratory Study. Gerontology. 2020;66(6):562-570. doi: 10.1159/000510148. Epub 2020 Oct 6. PMID: 33022678.
Mohamed, B., Verma, N., Prina-Mello, A., Williams, Y., Davies, A., Bakos, G., Tormey, L., Edwards, C., Hanrahan, J., Salvati, A., Lynch, I., Dawson, K., Kelleher, D., and Volkov, Y. Activation of stress-related signalling pathway in human cells upon SiO2 nanoparticles exposure as an early indicator of cytotoxicity. Journal of Nanobiotechnology. 2011;9:29. doi:10.1186/1477-3155-9-29