Resistance training reduces symptoms of anxiety and depression

This meta-analysis of 32 clinical trials found that exercise was associated with reduced depression and anxiety symptoms in people with a clinical diagnosis of these conditions. However, only 3 trials tested resistance training alone, and results were highly inconsistent across studies.

• The resistance training evidence is thin: only 3 studies tested it alone; the analysis groups resistance with 'mixed' exercise
• 90% of depression variation and 86% of anxiety variation came from differences between studies
• Blinding was impossible; participants always knew whether they were exercising
• Many trials were very small (18 of 32 had <=50 participants)

This study found that 8 weeks of supervised weight training significantly reduced anxiety symptoms in young adults who did not already have an anxiety disorder, with no serious side effects. However, it did not measure depression at all, so it cannot say anything about whether weight training reduces depression.

• The study enrolled only 28 people — too few to draw firm conclusions, and the benefit found for anxiety is statistically borderline when accounting for the number of outcomes tested
• Depression was never measured, so the paper cannot support or contradict that part of the claim
• The training group received one-on-one personal supervision for every session, meaning it is unclear how much of the benefit came from the exercise itself versus the extra human attention and social contact
• Participants were specifically selected for low anxiety levels, limiting how much the results apply to people who actually struggle with anxiety
• Worry — a closely related symptom — did not improve more with training than with just waiting, which tempers enthusiasm for the broader claim