Could aerobic exercise applied before constraint-induced movement therapy change circulating molecular biomarkers in chronic post-stroke?

Background: Integrating aerobic exercise (AE) into rehabilitation programs for post-stroke individuals could enhance motor recovery and cardiovascular health by increasing brain-derived neurotrophic factor (BDNF) and the myokine irisin. Chronic stroke survivors typically exhibit elevated matrix metalloproteinase-9 (MMP-9) activity, which is negatively correlated with steps and time in medium cadence, although the impact of AE on this biomarker remains unclear.
Objective: To evaluate the effect of high-intensity AE training prior to modified constraint-induced movement therapy (mCIMT) on BDNF and irisin concentration, and on MMP-2 and MMP-9 activity in chronic post-stroke individuals and to associate these results with functional improvements.
Methods: Nine participants received AE combined with mCIMT for two weeks, while the control group ( n  = 7) received mCIMT alone. Manual dexterity and functional capacity were assessed before and after the intervention. Serum samples were analyzed for BDNF, irisin, MMP-2 and MMP-9.
Results: There were no significant main effects of assessment, group or interaction on molecular biomarkers. However, the AE group had a significant increase in MMP-9 activity post-intervention ( p  = .033; d  = 0.67). For the Box and Block Test, there were significant main effects of assessment ( F [1, 14] = 33.27, p  = .000, η _p ²  = 0.70) and group ( F [1, 14] = 5.43, p  = .035, η _p ²  = .28). No correlations were found between biomarkers and clinical assessments.
Conclusion: AE prior to mCIMT did not influence circulating BDNF and irisin levels but did induce an acute rise in MMP-9 activity, suggesting potential effects on cardiovascular remodeling in this population.