Two 2026 trials tested exercise against depressive symptoms at opposite ends of life

"Exercise helps depression" is among the better-supported claims in this area and among the least useful, because it does not say which exercise, for whom, or measured against what. Two 2026 secondary analyses are more specific, and their shared design feature is the part worth noticing: neither compared exercise against nothing.

Resistance training in older adults with vascular cognitive impairment

Subcortical vascular cognitive impairment carries a high burden of depressive symptoms, and antidepressant response in this group is often poor.

The trial randomised 91 participants — 45 to progressive resistance training and 46 to a balance and tone control [s1]. Mean age was 75 years (SD 6), 65.2% were female, and mean CESD-10 score at baseline was 7.45 (SD 5.91) [s1].

Depressive symptom scores were significantly lower with resistance training than control at 6 months, an estimated mean difference of −3.17 (95% CI, −6.12 to −0.22; P = 0.036), and at 12 months, −4.25 (95% CI, −7.23 to −1.27; P = 0.006) [s1].

Two features make this more persuasive than a typical exercise trial. The effect grew rather than faded — from −3.17 at 6 months to −4.25 at 12 [s1]. Exercise trials commonly show early gains that decay as adherence drops, and the opposite pattern is harder to explain as novelty or expectation.

And the comparator was balance and tone training, not a waiting list [s1]. Participants in both arms attended sessions, moved, and saw staff. Whatever the difference at 12 months is, it is not the effect of getting out of the house or receiving attention. That is a demanding control, and the trial cleared it.

The limits are the sample and the population. Ninety-one participants, with a confidence interval at 6 months running from −6.12 to −0.22 — very close to zero at one end [s1]. And this is a specific population with cerebrovascular disease and mild-to-moderate cognitive impairment, in whom the authors suggest resistance training should be considered to mitigate depressive symptoms [s1]. It does not generalise to depression at large.

Aerobic exercise in adolescents

The second trial ran at the other end of the age range, in adolescents with subthreshold depressive symptoms — below the diagnostic threshold, but at elevated risk of crossing it.

A total of 206 adolescents aged 12 to 17 were included — 110 males (53%), median age 13 — with 111 in the exercise group and 95 in a psychoeducation control [s2].

The exercise group showed significantly greater reductions: mean PHQ-9 score fell from 9.20 (SE 0.05) at baseline to 7.33 (0.03) after the intervention (t110, −4.49; P < .001), against the control moving from 7.74 (0.04) to 7.28 (0.04) (t94, −1.03; P = .30) [s2].

Again the control was active — psychoeducation, not nothing [s2].

There is a caveat the numbers make plain. The two groups did not start level: 9.20 in the exercise arm against 7.74 in the control [s2]. A group starting higher has more room to fall, and regression to the mean pushes in the same direction as the treatment effect. The trial's own framing is a secondary analysis of a randomised trial, and this is the kind of imbalance that secondary analyses inherit.

The mechanistic half of the paper is where it becomes unusual. Functional connectivity was reduced across 355 alpha-band, 127 beta-band, 30 theta-band and 9 delta-band connections, all significant after correction for false discovery rate, and global network efficiency was enhanced across all frequency bands after the exercise intervention [s2].

Mediation analysis then found two opposing neural pathways, one representing depression reduction (B, −2.28; P < .001) and one depression increase (B, 3.26; P < .001) [s2].

Two opposing pathways, the second larger in absolute terms than the first [s2]. If that holds, the net symptom benefit is a balance between competing processes rather than a single mechanism — which would help explain why exercise trials produce such variable effect sizes across populations. The authors note the finding needs replication in adolescents with clinical rather than subthreshold depression [s2].

What the two share

Both are secondary analyses, so their outcomes were not what the parent trials were primarily designed to detect [s1][s2]. Both are small. Neither enrolled people with severe depression — one studied subthreshold symptoms in adolescents, the other a baseline CESD-10 of 7.45 in older adults with cognitive impairment [s1][s2].

What they add to a crowded literature is the quality of their comparators. A great deal of exercise-and-mood research compares an exercise programme against a waiting list, and then reports a difference that includes attention, structure, social contact and expectation. Balance and tone training and psychoeducation are not perfect controls, but they absorb most of that, and the exercise arms still separated [s1][s2].

What to watch

Whether the growing effect over 12 months in the resistance training trial reproduces in a larger sample, since a benefit that increases with duration would change how these programmes are prescribed [s1]. And whether the opposing-pathway finding survives replication in adolescents with clinical depression [s2].

This article describes published trial results. It is not medical advice, and exercise is not a substitute for treatment of clinical depression.

Sources

• [s1] Resistance training and depressive symptoms in subcortical vascular cognitive impairment: secondary analysis of a randomised controlled trial, British Journal of Sports Medicine, online 2026-09-03.
• [s2] Aerobic Exercise and Subthreshold Depressive Symptoms in Adolescents: Secondary Analysis of a Randomized Clinical Trial, JAMA Network Open, 2026;9(7):e2621568.