Neurology · Medical Literature
Effects of Single-Bout Endurance Exercise Intensity on Peripheral Neurotrophic Factors in Patients With Ischemic Stroke During the Subacute Phase of Rehabilitation.
Abstract
BACKGROUND Strong evidence suggests that a single session of aerobic exercise can alter serum neurotrophin concentrations and induce neural adaptations. This study aimed to analyze the effects of exercise intensity during a single exercise session on serum neurotrophin concentrations in patients after a first ischemic stroke. MATERIAL AND METHODS Thirty participants (mean age: 65.64±9.34 years) were randomly assigned to either the low-intensity continuous exercise group (n=15) or the moderate-intensity continuous exercise group (n=15). Serum neurotrophin concentrations were measured using an enzyme-linked immunosorbent assay. Cognitive function was assessed with the Addenbrooke's Cognitive Examination III; functional ability with the Rivermead Motor Assessment; depressive symptoms with the Beck Depression Inventory; and exercise intensity with the Graded Cycling Test with the Talk Test. RESULTS Descriptively, a single session of aerobic exercise in the moderate-intensity continuous exercise group was associated with a substantial increase in serum brain-derived neurotrophic factor concentration (median change=1.9 ng/mL, 95% bootstrap confidence interval [0.7, 2.8]) and a decrease in serum irisin concentration (median change=-257.4 ng/mL, 95% bootstrap confidence interval [-490.1, -206.8]). Mean-based inferential analyses using 2-way repeated-measures analysis of variance revealed no significant Group×Time interactions for serum neurotrophins, except for lactate concentration. CONCLUSIONS A single session of aerobic exercise in patients after ischemic stroke was associated with changes in circulating lactate concentrations. Descriptive median-based analyses indicated exercise-related shifts in selected biomarkers, whereas mean-based analyses suggested broadly similar neurotrophin responses across exercise intensities.
Clinical relevance
This study addresses a critical gap in stroke rehabilitation by examining whether exercise intensity modulates acute neurotrophin responses — specifically BDNF and irisin — in ischemic stroke patients during the subacute recovery phase, a period of heightened neuroplasticity. The target population is first-ever ischemic stroke survivors (mean age ~65 years), for whom optimizing neurorecovery through exercise prescription is a pressing clinical priority. Understanding the neurobiological dose-response relationship of aerobic exercise informs evidence-based rehabilitation protocols aimed at enhancing neural repair and cognitive recovery.
Key findings
1. A single session of moderate-intensity continuous exercise (MICE) was associated with a descriptive increase in serum BDNF concentration (median change = +1.9 ng/mL, 95% bootstrap CI [0.7, 2.8]), suggesting a potentially clinically meaningful acute neurotrophin response. 2. Serum irisin concentration decreased in the MICE group following a single exercise bout (median change = −257.4 ng/mL, 95% bootstrap CI [−490.1, −206.8]), an unexpected direction that warrants further mechanistic investigation. 3. Two-way repeated-measures ANOVA revealed no statistically significant Group×Time interactions for serum neurotrophins (BDNF or irisin), indicating that mean-based inferential analyses did not confirm a differential intensity-dependent neurotrophin response. 4. The only biomarker demonstrating a statistically significant Group×Time interaction by mean-based ANOVA was serum lactate concentration, confirming the physiological validity of the intensity manipulation between low- and moderate-intensity groups. 5. The study was conducted in n=30 participants (low-intensity n=15, MICE n=15; mean age 65.64 ± 9.34 years), limiting statistical power to detect moderate effect sizes and precluding definitive inferential conclusions. 6. Cognitive function (Addenbrooke's Cognitive Examination III), functional ability (Rivermead Motor Assessment), and depressive symptoms (Beck Depression Inventory) were assessed as secondary outcomes, though intensity-stratified results for these endpoints are not reported in the abstract.
Practice implications
Clinicians prescribing exercise during subacute stroke rehabilitation should note that while moderate-intensity continuous exercise appears descriptively associated with acute BDNF elevation, mean-based analyses do not confirm a statistically significant intensity-dependent advantage over low-intensity exercise for neurotrophin modulation, suggesting that lower-intensity protocols may yield broadly comparable acute neurobiological responses in this population. Given that lactate — but not BDNF or irisin — showed a significant group-by-time interaction, the Talk Test-guided Graded Cycling Test appears to be a valid, low-burden tool for titrating exercise intensity in post-stroke patients who may have limited capacity for standard cardiopulmonary exercise testing. Future rehabilitation trials should employ larger sample sizes, explore chronic (multi-session) exercise effects on neurotrophins, and evaluate whether acute BDNF shifts in the magnitude observed (≈1.9 ng/mL) translate into measurable gains in motor or cognitive recovery endpoints.