Posted on 7 September 2022
Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.
Why is this research important: When human cells divide, they are unable to replicate the entirety of the chromosomes that make up the genome. Instead, a small segment of DNA is lost from the ends of each chromosome. To avoid the loss of important genetic information, chromosomes are ‘capped’ by segments of DNA called telomeres. Telomeres don’t encode any information, and serve only to protect the rest of the DNA from damage. When a cell’s telomeres become too short, it may stop dividing permanently or self destruct in order to prevent critical damage to the genetic code.
Telomere shortening is considered by many to be one of the hallmarks of ageing. However, telomere shortening occurs at different rates in different people, and there’s good evidence to suggest that it can be slowed down through lifestyle practices. Whether this actually translates to improved longevity is still a matter of some debate.
What did the researchers do: In this study, researchers performed a meta-analysis of 43 studies investigating the relationship between physical activity and telomere length or the activity of telomerase, an enzyme that preserves telomere length. Eight of these studies were trials in which participants were randomised to an exercise group or a control group. This is the ideal study design for testing whether an intervention (in this case exercise) causes an outcome (in this case a reduction in telomere shortening). The other studies were either categorised as interventional (participants were assigned exercise, but there was either no control group or exercise wasn’t assigned randomly) or as observational studies (researchers looked at the telomeres of people who were already physically active – there was no intervention).
Key takeaway(s) from this research: Overall, studies supported a relationship between exercise and slower telomere shortening, with 33 out of 43 studies suggesting positive benefits. However, when looking at the results from different types of study, the picture is less clear. Observational studies, which made up the majority of the supportive studies, are only able to demonstrate a correlation between exercise and telomere length, not causation. That’s because people who exercise may also engage in other healthy activities that could influence their telomeres. Only studies in which participants are randomly assigned exercise or no exercise can support a causal link. Of the 8 such studies, only 5 found a significant relationship between exercise and telomere length.
Why the inconsistency? Different randomised trials included participants of different ages, genders and health status, and used different exercise regimes with varying durations. All of these factors could have influenced the effects of physical activity on participants’ telomeres, so we need more studies to figure out exactly how exercise interacts with telomere shortening.
Based on the available data, aerobic exercise appeared to be more effective than anaerobic exercise for preserving telomere length. Evidence about exercise intensity was conflicting, with some studies suggesting that moderate exercise was optimal for telomere length, while others suggested that high intensity exercise was better. Some studies also suggest that the benefits of exercise may be greatest beyond the age of 40.
So, while the majority of the evidence suggests that exercise helps to preserve telomere length, there are still many unanswered questions about the specifics. One thing is for certain, however: exercise is a powerful way to protect against almost all age-related diseases.
Physical Activity on Telomere Length as a Biomarker for Aging: A Systematic Review: https://doi.org/10.1186/s40798-022-00503-1