Strength training and anxiety: what the science actually says

The first change often does not show in the mirror

People who start training usually do it for their body, but research has begun to ask whether exercise also affects anxiety and mood, and it has done so with controlled, randomised studies. In this article we look at three recent syntheses of the scientific literature: what they actually measured, in which people and with what limits. The numbers are interesting, but they need to be read carefully and must not be mistaken for a promise of results.

Three syntheses of studies, three different populations

The first is a systematic review with meta-analysis published in 2025 in the International Journal of Mental Health Nursing (Banyard and colleagues). It included 32 randomised controlled trials with 3,243 adult participants diagnosed with depression or anxiety; 26 studies (2,681 people) entered the meta-analyses. For depressive symptoms, across 25 studies, the pooled standardised mean difference (SMD) was -0.97 (95% confidence interval -1.28 to -0.66), an effect the authors describe as large; for anxiety, across 11 studies, it was -0.66 (-1.09 to -0.23), a moderate effect. The negative sign indicates fewer symptoms in the group that exercised. The interventions were aerobic, strength-based or a combination of the two, and the review concludes that all three modes are beneficial.

The second, published in 2024 in Early Intervention in Psychiatry (Marinelli and colleagues), is specifically about strength training in young people. It considered 10 randomised trials involving 376 participants aged 26 or younger with clinically elevated anxiety and depression symptoms, in interventions lasting at least four weeks. Resistance training was associated with a reduction in depressive symptoms (Hedges' g -1.06; interval -1.61 to -0.51) and anxiety symptoms (-1.02; -1.50 to -0.54) compared with control groups. The authors report substantial heterogeneity between studies, with an I² of 79% for depression and 66% for anxiety: this means the results of individual studies differed considerably from one another.

The third is a review of reviews, with a meta-meta-analysis, published in 2025 in the Journal of the American Academy of Child and Adolescent Psychiatry (Singh and colleagues) and focused on children and adolescents aged 5 to 18. It brought together 21 systematic reviews, 375 randomised trials and 38,117 participants, including people with clinical conditions (depression, psychosocial disorders, obesity, cancer) and healthy people. The effects were moderate: SMD -0.45 (-0.59 to -0.31) for depression, across 180 trials, and -0.39 (-0.61 to -0.17) for anxiety, across 55 trials. Resistance exercise was the most effective for anxiety symptoms; for depression, mixed exercise modes and moderate intensity showed the largest effects, and interventions shorter than 12 weeks worked better than those of 12 weeks or more.

How to read these numbers

The values in the chart are standardised mean differences (SMD, including Hedges' g): they measure by how many standard deviations symptoms change compared with the control group, and they are neither kilograms nor percentages. This makes it possible to compare different measurement scales, but it does not by itself tell you how much better someone feels in daily life. Moreover, the three studies concern different groups, namely adults with a diagnosis, young people with elevated symptoms, and children and adolescents, using different methods: their values should not be ranked as if they had been measured on the same people.

Specialists' own reading is cautious too. In the editorial accompanying Singh's study in the same journal (Cortese and colleagues), the effects are described as small, with confidence intervals ranging from very small to medium, and the reminder that details matter. As for the strength of the evidence, Marinelli and colleagues rated it high for depression and moderate for anxiety, while Singh and colleagues rated it moderate for depression and low to moderate for anxiety. Marinelli and colleagues also call for studies with longer follow-up, because the available research does not show how long the benefits last.

What this means for people who train

The most solid message is that structured exercise, strength training included, is associated with an average reduction in anxiety and depression symptoms in populations who have them. Extreme programmes are not needed: in Singh's study, moderate intensity gave the largest effects on depression. These studies do not, however, establish the ideal dose for an individual, nor how long the benefits last after the intervention ends.

It must be said clearly that these are group averages, observed in research settings and, in most cases, in people with clinically relevant symptoms, not individual promises. Training does not replace treatment when it is needed: if anxiety or low mood interfere with daily life, talk to your family doctor or a specialist and consider training as a possible complement, not an alternative. Likewise, before starting a weight-training programme it makes sense to review any health conditions or pain with your doctor.

In a personal training programme the practical aim is to make training sustainable: correct technique, appropriate loads and gradual progression reduce the risk of quitting because of discomfort or frustration. This is a matter of method, not a treatment, and it is not something the studies cited examined.