Exercise cools chronic inflammation, but only if your fitness actually improves

Carrying excess weight is linked with chronic low-grade inflammation, which is implicated in the development of cardiometabolic disease. Exercise is often described as anti-inflammatory, but previous systematic reviews on the question have been inconclusive, largely because they did not account for factors that could distort the picture, such as age, sex, body composition and how long the training lasted. This review set out to compare aerobic, resistance and combined training, plus spontaneous physical activity, while explicitly handling those potential confounders. The aim was to establish not just whether exercise reduces inflammatory markers, but which kind works and under what conditions.

The researchers systematically searched the Medline, Cochrane and Embase databases from January 2000 to July 2022 for randomised trials of long-term training interventions in people with overweight or obesity, with or without cardiometabolic disease. The inclusion criteria retrieved 106 full texts covering 8,642 individuals with BMIs ranging from 25.1 to 43.8. They compared aerobic training, resistance training, combined training and spontaneous physical activity, then ran a meta-analysis and meta-regression, treating sex, age, body composition and trial length as moderators of the effects on circulating cytokines and adipokines.

Independently of training mode, exercise reduced circulating levels of adiponectin, C-reactive protein, IL-6, IL-18, IL-20, leptin, sICAM and TNF-α. Comparing modes head to head, combined training outperformed aerobic training for regulating CRP, with no differences between modes on the remaining biomarkers. The meta-regression added the most interesting wrinkle: changes in maximal oxygen uptake, or VO2max, influenced the effects on CRP, IL-6 and TNF-α, while IL-10 was influenced by changes in body fat. Spontaneous physical activity was the exception, showing no effectiveness in lessening inflammatory status.

Earlier reviews of exercise and inflammation in this population were inconclusive, so this analysis extends the evidence by addressing the confounders they left open. It also complicates the simple message that any movement is anti-inflammatory: the results suggest benefits appear provided that exercise actually raises VO2max, and that casual unstructured activity does not deliver the same result. Open questions remain about the ideal training dose, why combined training edged out aerobic work for CRP specifically, and whether these biomarker changes translate into fewer actual disease events over time.

This is a reason to think that structured training which measurably improves your fitness matters more for inflammatory status than the particular mode you choose: aerobic, resistance and combined approaches all moved the markers. It is also a reason to be sceptical that light incidental movement alone will shift inflammation for people carrying extra weight, at least on these measures. The finding applies to circulating biomarkers, not to disease outcomes, so it describes a plausible pathway rather than a guaranteed health result.