Influence of resistance training on telomere length
For more than twenty years, research into biological aging has focused on a discreet but fundamental marker: telomere length. These small segments of DNA that cap our chromosomes play an essential protective role, preventing errors and damage during each cell division. But with each replication, telomeres shorten slightly until they reach a critical threshold where the cell can no longer divide properly. This process, called cellular senescence, is at the heart of biological aging and many chronic diseases.
In addition to genetic inheritance, we now know that certain lifestyles accelerate this shortening. Smoking, alcohol, obesity, oxidative stress, diabetes, a sedentary lifestyle and physical inactivity, and even a low socioeconomic status are all predictors of short telomeres in adults. Conversely, healthy behaviors (a good diet, restful sleep, stress management, and regular physical activity) seem to slow this erosion and even increase their length. Most studies have focused on the effects of endurance, showing that regular exercise can preserve telomere length and delay cellular aging. But what about resistance training?
The study
To answer this question, American researchers analyzed data collected from 4,814 American women and men, representative of the adult population in the United States. This information was taken from the NHANES (National Health and Nutrition Examination Survey), a national survey conducted in the United States since the 1960s by the Centers for Disease Control and Prevention (CDC). This program combines interviews, biological measurements, and samples to assess the health and behaviors of the American population.
Between 1999 and 2002, researchers collected blood samples to measure telomere length, as well as detailed information on the physical activity habits of participants aged 20 to 69. Leukocyte telomeres (those found in white blood cells) were measured using polymerase chain reaction (PCR) in the research laboratory of biologist Elizabeth Blackburn (Nobel Prize winner in medicine for her work on telomeres). At the same time, participants reported how often they had done resistance training in the previous 30 days, with sufficient accuracy to calculate the average number of minutes per week spent on muscle resistance training.
Based on this information, the researchers created three categories:
- non-exercisers (less than 10 minutes of resistance training per week)
- moderate exercisers (10 to 50 minutes per week)
- regular exercisers (at least 60 minutes per week)
To isolate the specific effect of resistance training, the analyses incorporated a large number of confounding variables: age, gender, ethnicity, income level, household size, body mass index, smoking, and participation in other forms of physical activity (47 types identified). All of this data was statistically weighted to allow for extrapolation to the national level.
The objective was to determine whether weekly resistance training time was associated with longer telomeres, a direct indicator of slower biological aging.
Results & Analysis
The main results show that people who report regularly doing resistance training have significantly longer telomeres than those who report not doing so, even after adjusting for all demographic and lifestyle factors.
Men and women who did at least one hour of resistance training per week (regular exercisers) had telomeres that were on average 225 to 238 base pairs longer than those who did not exercise. Those who exercised moderately (between 10 and 50 minutes per week, moderate exercisers) had telomeres that were on average 120 to 140 base pairs longer, reflecting a dose-dependent effect.
After adjusting for differences between all covariates, for every 10 minutes of resistance training per week, telomeres were on average 6.7 base pairs longer. Therefore, 90 minutes of resistance training per week would predict telomeres that are 60.3 base pairs longer on average. Given that each year of chronological age was associated with telomeres that were 15.47 base pairs shorter in this national sample, 90 minutes per week of resistance training would be associated with an average biological age that is 3.9 years younger. This interpretation suggests that one hour of resistance training three times per week (180 minutes total) could be associated with 7.8 fewer years of biological aging.
The results also confirmed several known associations: smokers had shorter telomeres, as did obese individuals, while individuals of normal weight or those who engaged in other forms of physical activity had higher values. Surprisingly, the MET-minute volume of physical activities other than resistance training (running, walking, cycling, swimming, etc.) was not significantly correlated with telomere length after adjusting for other factors. This could suggest that strength training has a distinct effect on cellular aging, potentially via mechanisms specific to muscle mass, hormonal signaling, and/or oxidative stress regulation. That said, other studies have reported a positive effect of endurance activities on telomere length.
Physiologically, several mechanisms may explain these observations. Resistance training stimulates protein synthesis and muscle regeneration, two processes that require high mitochondrial activity and better glucose utilization. It reduces chronic inflammation and oxidative stress, two major enemies of telomeres. It improves insulin sensitivity, increases resting metabolism, and promotes the reduction of visceral fat, whose pro-inflammatory effects are well documented. Finally, it stimulates the release of myokines (cytokines secreted by muscles during exercise) that act remotely on organs, in particular by modulating the immune response and protecting cells against premature aging.
Practical applications
Resistance training is far from being a simple tool for developing strength and muscle mass; it plays a central role in metabolic regulation, immunity, and cell signaling. Preserving your muscles therefore means preserving your biological health potential and longevity.
On a practical level, the study shows that it is not necessary to adopt extreme training volumes to reap measurable benefits. One to two hours of resistance training per week would be enough to slow down cellular aging by several years. This volume corresponds, for example, to two to three sessions of 30 to 45 minutes, with a full-body workout. Of course, consistency is key. Only continuous stimulation, week after week, will maintain metabolic adaptations and protect telomeres.
These results also have an important preventive dimension. In a society where aging is often accompanied by a loss of muscle function (sarcopenia), an increase in diabetes and cardiovascular disease, resistance training appears to be an effective, accessible, and inexpensive non-pharmacological therapy. It strengthens bone density, regulates blood pressure, reduces visceral fat, protects cognitive function and, now, has been proven to slow down the aging of our cells.
Of course, due to its protocol, the results of this study do not allow us to establish a cause-and-effect relationship. Even though the time spent resistance training was strongly linked to lower levels of biological aging, it is not possible to say that regular weight training led to longer telomeres. Perhaps those who reported doing the most resistance training were those who naturally had longer telomeres (?)…
Furthermore, the time spent resistance training was reported by the participants themselves, which suggests a possible margin of error. Participants may have underestimated or overestimated the time spent exercising. In addition, the questionnaire focused on training over the past 30 days, so information on long-term resistance training could not be evaluated.
Finally, participants with high or moderate levels of resistance training may have had other lifestyle behaviors specific to their subgroup that influenced favorable results. Not all possible covariates could be measured and statistically controlled for.
That said, the fact remains that out of more than 4,800 people surveyed, those who reported regularly doing resistance training had longer telomeres. Whether this is a statistical fluke or biological truth, regular resistance training has so many health benefits that it would be foolish not to do it.
Reference
Tucker LA & Bates CJ. Telomere Length and Biological Aging: The Role of Strength Training in 4814 US Men and Women. Biology 2024, 13, 883.
