Exercise shows a small-to-moderate telomere benefit overall

Across pooled analyses, exercise produced a small-to-moderate positive effect on telomere length — a meaningful signal given how difficult telomere studies are to run. High-intensity interval training outperformed aerobic and endurance exercise, a gap that had not been consistently reported in individual studies before. The earlier disagreements across the literature turned out to stem largely from differences in exercise type and how long participants trained, not from random measurement noise. Picture telomeres as the plastic caps on shoelaces: exercise does not regrow them once they have worn down, but it slows the rate at which they fray, and the intensity of the workout influences how much protection you get.