Physical exercise, both aerobic training and strength training, demonstrably reduces depression and anxiety in people with a confirmed diagnosis and is likely to be causally effective. For mild to moderate depression the effect is comparable to antidepressants; for anxiety disorders it is effective but generally less potent than medication.
Yes, exercise really does help with depression and anxiety. This is not hype: several large overviews of randomised trials show that physical activity reduces depressive symptoms with a large effect (SMD -0.97) and anxiety symptoms with a moderate to large effect (SMD -0.66). These effects were measured in people with a confirmed diagnosis, not merely in people who feel a bit down. Taken together, these findings are based on tens of thousands of participants across dozens of studies worldwide.
For mild to moderate depression, exercise is comparable to antidepressants as a first-line treatment. For anxiety disorders, exercise is demonstrably effective, but generally does not reach the level of pharmacological treatment. That does not mean you have to choose one or the other: exercise can be combined well with other treatments. A broad scientific review further concludes that exercise can be prescribed as a fully-fledged medical treatment for depression, anxiety and stress, with specific recommendations for type and dosage.
Both aerobic training (such as running or cycling) and strength training work. A small but well-designed study (n=28) showed that eight weeks of strength training strongly reduced anxiety symptoms in young adults, although it had no measurable effect on rumination or worrying. The small size of that study calls for caution when interpreting the results.
There are also findings for specific groups. In older cancer patients, both yoga and tai chi and regular physical exercise helped against depression and anxiety, with mind-body movement (yoga, tai chi) scoring slightly better. In people with Parkinson's disease, mindfulness yoga turned out to reduce anxiety and depression significantly more than conventional stretching and strength training. And for pregnant women, it has been shown that regular exercise helps prevent anxiety and prenatal depression, without demonstrable risk to mother or child, provided the type and intensity are tailored to the individual situation.
One important point to note: exercise is not a miracle cure and does not replace professional care for severe or persistent complaints. For some conditions, such as anxiety disorders, the effect is smaller than for depression, and for rumination problems specifically the effect appears limited. In cancer patients it is explicitly advised to avoid inactivity, but the intensity and type of training must be matched to the medical situation. In short: for virtually everyone, exercise is a meaningful, safe addition to the treatment and prevention of depression and anxiety.
Claims are based on 8 PMIDs, including multiple meta-analyses and systematic reviews of randomised trials (including PMID 40432290, 21495519, 26606383, 31626055, 39903465) and several smaller RCTs. The total number of participants is difficult to establish precisely; the largest meta-analysis alone covers more than 3,200 participants (PMID 40432290). Estimated total across all studies: >10,000.