How quickly can you change your biological age with exercise?

One year of regular aerobic training can make measurable brain regions younger. In a randomised study of 120 older adults, the hippocampus (the brain's memory centre) grew by 2% after twelve months. That sounds modest, but it roughly compensates for 1 to 2 years of age-related brain shrinkage. The control group actually lost volume. Spatial memory improved at the same time.

At the DNA level, an 8-week combination of exercise, healthy nutrition, better sleep and relaxation lowered biological age by an average of 3 years on the so-called 'epigenetic clock' (a measure of how old your DNA modifications look). That sounds impressive, but it comes from a small study of just 43 men between the ages of 50 and 72. More importantly, exercise was one component of a complete package -- you cannot conclude from this research how much of the work the physical activity itself did. In addition, two of the authors had a financial interest in the programme, which warrants a note of caution when interpreting the findings.

There are also interesting signals involving taurine, a substance that naturally declines with age. A single exercise session raises taurine levels in the blood in humans. In animal research, higher taurine levels are linked to a longer, healthier lifespan. Whether this temporary effect in humans actually slows the clock has not yet been demonstrated.

In brief: measurable changes in the brain are visible after one year of regular training. Broader effects on biological age are suggested by early and small-scale research, but no study has yet isolated exercise as a standalone variable and shown that it is sufficient to structurally turn back the biological clock. The signals are positive enough to make exercise a central part of your daily routine.