Does exercise help your immune system as you age?
Regular, moderate exercise helps your immune system by reducing smouldering inflammation. Suddenly training very hard without a gradual build-up can actually temporarily lower your immune defences.
Yes, regular exercise helps your immune system as you get older. It suppresses the smouldering, chronic low-grade inflammation that comes with ageing. That persistent inflammation increases the risk of age-related diseases and early death. Exercise is one of the few non-pharmaceutical ways to counter this, with few side effects1.
The picture is not black and white. Moderate, regular exercise has an anti-inflammatory effect and lowers the risk of metabolic and cardiopulmonary diseases, through favourable changes in immune cells and signalling molecules. But heavy, exhausting exertion tells a different story: after such effort your immune defences temporarily dip, leaving you briefly more susceptible to infections. That effect passes, but it is worth keeping in mind if you suddenly start exercising very intensely later in life2,3.
A less well-known mechanism has to do with the energy factories inside your cells. Exercise activates the process by which damaged energy factories are cleared away and replaced by healthier ones. When that system functions less well, it is associated with age-related diseases and a weaker immune defence. Exactly how large this effect is in older people has not yet been properly quantified4.
There is also an early, intriguing finding about exercise, gut bacteria, and cancer immunity. In studies in mice and cell cultures, exercise was found to stimulate, via gut bacteria, the production of a substance that made immune cells attacking cancer cells more active and made immunotherapy more effective. In humans, this substance has so far only been identified as a potential signalling molecule, not as a proven active agent. This research is still in its early stages5.
Finally, exercise has been linked to changes in a metabolic pathway that plays a role in energy production and immune regulation. Whether this concretely improves immune defence in older people cannot be established on the basis of the available studies; what we have here is an association, not a demonstrated effect6.
Based on multiple studies in humans and in animal research (PMID 38052484, 32342473, 10893431, 38036770, 40639377, 30980044, 36356628). The evidence for anti-inflammatory effects of regular exercise is reasonably strong. The findings regarding energy factories, gut bacteria, and the metabolic pathway mentioned come largely from animal research or limited human research. No large randomised trials or meta-analyses are available as a direct source.