Exercise and Biological Age: What the Research Now Tells Us About How Much Is Enough

We have always known that exercise is good for us. The evidence for that is not in question. What has been less clear — until recently — is the mechanism by which movement slows biological ageing, which specific types of exercise move which clocks, and how much is actually enough.

Two papers published in May and June 2026 give us more precision than we have had before. The first, a systematic review and meta-analysis by Shan and colleagues published in The Lancet Healthy Longevity in May 2026, pooled data from 44 studies across 145,465 adults to examine the relationship between physical activity and biological age as measured by DNA methylation clocks. The second, published in the British Journal of Sports Medicine on 2 June 2026, examined long-term resistance training and all-cause mortality in nearly 150,000 adults tracked for up to 30 years. Together, they tell a specific, actionable story — and it is particularly relevant for women in perimenopause.

What the Lancet meta-analysis found

Shan et al. examined physical activity against four major epigenetic clocks: Horvath, Hannum, PhenoAge, and GrimAge. The findings were not uniform across all four — which is itself informative.

Higher physical activity was significantly associated with lower biological age on the Horvath EAA (epigenetic age acceleration) and GrimAge EAA measures. The association was not significant for Hannum or PhenoAge. This is not a contradiction — it reflects the fact that different clocks measure different biology. Horvath’s clock measures cellular ageing across multiple tissue types. GrimAge is trained on mortality risk and reflects the pace of physiological ageing most closely linked to actual healthspan. The clocks that responded to exercise are the ones most predictive of how long and how well you live.

The honest caveat: most of the data came from cross-sectional studies — snapshots in time rather than longitudinal tracking. This means we can observe that more active people have younger biological ages on these clocks, but the evidence does not yet conclusively establish that increasing exercise causes the difference rather than correlates with it. The authors are clear about this limitation. What we can say is that the association is consistent, meaningful, and biologically plausible given everything else we know about exercise and epigenetic regulation.

Which clock does exercise move — and why

As discussed in the Five Clocks post, biological ageing runs on multiple independent systems simultaneously. Exercise primarily acts on two of them.

The transcriptomic clock — which measures gene expression patterns in tissue — is the clock most directly moved by physical activity, particularly resistance training. As we age, genes involved in mitochondrial biogenesis and protein synthesis in muscle tissue decline in expression; genes involved in inflammation increase. Resistance training demonstrably reverses this pattern in skeletal muscle. A 2026 biorxiv preprint examining the skeletal muscle methylome after exercise training found significant shifts in both the epigenetic and transcriptomic signatures of muscle tissue — essentially, exercised muscle expresses a younger gene pattern than sedentary muscle of the same chronological age.

The immune clock is the second system exercise addresses, primarily through aerobic activity. Regular moderate-intensity aerobic exercise reduces the accumulation of exhausted and senescent T cells, maintains naïve immune cell populations for longer, and reduces the chronic low-grade inflammation — inflammaging — that accelerates immune clock ageing. This is one mechanism behind the consistent finding that physically active older adults have immune profiles more characteristic of people a decade younger.

The epigenetic clock (methylation) is influenced indirectly: exercise improves mitochondrial efficiency, reduces oxidative stress, and modulates inflammatory signalling — all of which affect the methylation patterns that epigenetic clocks read. But this is more indirect than the transcriptomic and immune effects, which may partly explain why the Lancet meta-analysis found clock-specific rather than universal results.

How much resistance training is actually enough

The British Journal of Sports Medicine paper provides the clearest answer to this question yet. Across nearly 150,000 adults tracked for up to 30 years, the researchers found a clear dose-response relationship between resistance training and all-cause mortality — with a specific sweet spot.

Doing 90 to 119 minutes of resistance training per week was associated with a 13% lower risk of dying from any cause compared to no resistance training. Beyond two hours per week, no additional mortality benefit was observed — the curve flattened. The maximum risk reduction of approximately 27% appeared at around 60 minutes per week, suggesting that even relatively modest amounts of strength work confer meaningful benefit, and that two 30-minute sessions weekly is a genuinely effective target rather than an undersell.

Combining resistance training with aerobic exercise produced the largest mortality reduction overall — the two modalities are complementary, not interchangeable. Resistance training addresses the transcriptomic clock via muscle gene expression; aerobic exercise addresses the immune and metabolic clocks via different mechanisms. This is the multi-lever argument again: different exercise types move different biological systems.

Why perimenopause changes the exercise equation

Oestrogen is anabolic. It directly supports muscle protein synthesis, protects against muscle breakdown, and maintains mitochondrial efficiency in muscle cells. As oestrogen begins to fluctuate and decline in perimenopause, the biological cost of not doing resistance training rises significantly.

Muscle mass naturally declines from the late 30s — a process called sarcopenia — at roughly 3 to 5% per decade. In perimenopause, the withdrawal of oestrogen’s protective effect on muscle accelerates this decline. Women who enter perimenopause with a strong muscle mass baseline are meaningfully better placed: they have more physiological reserve, better insulin sensitivity (because muscle is the body’s primary site of glucose uptake), a more metabolically active body composition, and a lower risk of the falls and fractures that become increasingly consequential in later life.

The cortisol post explored how stress hormones interact with body composition in perimenopause — and the exercise equation connects directly: cortisol is catabolic, breaking down muscle tissue. Women under chronic stress who are not doing resistance training are losing muscle mass through two routes simultaneously. Managing cortisol through vagus nerve regulation and adequate sleep, while building the muscle base through resistance training, addresses both pathways.

Protein intake becomes more important in perimenopause for the same reason: oestrogen’s anabolic support for muscle synthesis declines, so dietary protein needs to compensate. The post-workout window — the 30 to 60 minutes after resistance training — is when muscle cells are most responsive to protein for synthesis and repair. A meal containing 25 to 35 grams of complete protein in this window is not an optional extra; for perimenopausal women doing resistance training, it is the mechanism by which the session actually builds the tissue.

What a practical week looks like

Based on the evidence from both papers, the minimum effective dose for perimenopausal women looks something like this:

Two resistance training sessions per week of 30 to 45 minutes each. Compound movements — squats, deadlifts, rows, presses — that recruit multiple muscle groups and produce the greatest metabolic and transcriptomic response. Progressive overload: gradually increasing the challenge over weeks and months, because the adaptation signal requires a stimulus that remains slightly above your current capacity.

Two to three aerobic sessions per week of 20 to 40 minutes at moderate intensity — brisk walking, cycling, swimming, dancing. These do not need to be intense. The immune clock benefits from sustained moderate-intensity aerobic activity, not from high-intensity intervals specifically (though those have their own benefits and can be incorporated).

Recovery is not optional. Sleep is when the transcriptomic repair that exercise stimulates is actually carried out. As explored in the sleep-fasting post, slow-wave sleep is the cellular maintenance window. Training without adequate sleep is the equivalent of renovating a room and then not applying the paint — the stimulus is there, the follow-through is not.

Adaptogens — particularly ashwagandha (KSM-66) — have the most robust evidence base for supporting HPA axis regulation and reducing the cortisol-driven muscle catabolism that impairs recovery from training. This is not a replacement for adequate sleep and stress management, but it is a meaningful complement for women whose cortisol patterns are dysregulated during perimenopause.

Two sessions a week. Two hours total. The transcriptomic clock responds. The immune clock responds. The metabolic clock responds. It is not complicated — it just needs to be consistent, and it needs to start in perimenopause rather than after it.

The Five Clocks post made the case that no single lever moves every biological clock. Exercise is the closest thing we have to a multi-clock intervention. The evidence from 145,000 people now makes the dose clearer. Two 30-minute sessions weekly. Combined with aerobic movement. Supported by protein, sleep, and stress management. That is the minimum effective prescription — and it is well within reach.

Key references: Shan J et al., “Physical activity and biological age measured by DNA methylation clocks: a systematic review and meta-analysis” — The Lancet Healthy Longevity, May 2026 (DOI: 10.1016/j.lanhl.2026.100835). BJSM, “Long-term resistance training and all-cause and cardiovascular mortality” — British Journal of Sports Medicine, 2 June 2026 (DOI: 10.1136/bjsports-2025-110503).

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