Introduction:
Stroke is one of the leading causes of death and long-term disability worldwide, with a growing number of survivors living with cognitive impairment. Aerobic exercise is recognised as a promising non-pharmacological intervention supporting neuroplasticity and functional recovery after stroke. Brain-derived neurotrophic factor (BDNF) plays a key role in activity-dependent plasticity and has been proposed as a potential biomarker of rehabilitation success; however, clinical evidence regarding exercise-induced changes in BDNF remains inconsistent.

Aim:
This clinical narrative review summarises clinical studies evaluating the effects of structured aerobic training on circulating BDNF levels and cognitive outcomes in stroke survivors.

Materials and methods:
A literature search identified five eligible clinical trials.

Results:
Across these studies, aerobic exercise interventions consistently improved cognitive performance or related functional outcomes. Moderate-intensity aerobic training, corresponding to approximately 50–60% of heart rate reserve, was associated with the most consistent cognitive benefits. In contrast, high-intensity exercise protocols were linked to increases in circulating BDNF concentrations but did not demonstrate clearly superior cognitive outcomes compared with moderate-intensity training. Chronic BDNF responses to aerobic training were heterogeneous. One study reported an increase in resting BDNF levels, two studies observed no significant change, one study reported a decrease, and one study demonstrated BDNF increases only following high-intensity interval training. In most trials, changes in circulating BDNF were not associated with improvements in cognitive or clinical outcomes.

Conclusions:
These findings indicate that aerobic exercise is an effective component of post-stroke rehabilitation aimed at improving cognitive function. However, resting circulating BDNF shows substantial variability and does not consistently reflect cognitive recovery, suggesting that BDNF alone is not a reliable long-term biomarker of exercise-induced cognitive improvement after stroke. Moderate-intensity aerobic training remains the most practical and clinically beneficial strategy.