A preclinical study published in Translational Exercise Biomedicine (ISSN: 2942-6812), an official partner journal of International Federation of Sports Medicine (FIMS) , provides the first comprehensive map of how skeletal muscle adapts in the weeks and months following hemorrhagic stroke, revealing that different muscles remodel on different timelines ( DOI: 10.1515/teb 2026 000 8 ). The findings suggest that rehabilitation programs may need to be timed to specific post-stroke windows to effectively leverage the muscle's natural plasticity for functional recovery.
Hemorrhagic stroke accounts for 28% of all strokes worldwide, yet its effects on skeletal muscle remain poorly understood. Previous work by the same research team documented fiber atrophy and a shift from faster to slower muscle fiber types in the rat tibialis anterior (TA) at 2 and 4 weeks post-stroke, with no such changes in the soleus (SOL) muscle. The new study extends that timeline to 8 and 12 weeks, offering the first longitudinal view of spontaneous muscle remodeling during the subacute and chronic phases of recovery.
Led by LaDora V. Thompson at Boston University , the team induced hemorrhagic stroke in the right striatum of young Sprague Dawley rats and evaluated bilateral SOL and TA muscles for fiber cross-sectional area and myosin heavy chain (MHC) composition. The results reveal a complex, muscle-specific plasticity that defies simple explanations. In the SOL, a predominantly slow-twitch muscle, no changes in fiber size or type were observed at either 8 or 12 weeks. The TA, however, told a very different story. In the deep portion of the TA, selective fiber hypertrophy emerged unilaterally by 8 weeks and bilaterally by 12 weeks. The superficial TA, composed largely of fast-twitch fibers, showed no size changes at 8 weeks but developed MHC 2b hypertrophy in the paretic limb by 12 weeks.
Perhaps most striking was the divergent trajectory of fiber type remodeling. The deep TA exhibited a faster-to-slower fiber type shift at 4 weeks that had largely returned to normal by 8 weeks, suggesting a discrete period of heightened plasticity. In contrast, the superficial TA maintained a slower fiber type profile at both 8 and 12 weeks, indicating a more permanent remodeling. " These findings for 8 and 12 weeks extend those from 2 and 4 weeks post-stroke, and demonstrate ongoing muscle plasticity, with timing of adaptations differing between CSA and MHC ," LaDora V. Thompson from Boston University stressed.
The study also confirmed that the collagenase stroke model produces persistent neuromotor deficits through 12 weeks, validating its utility for long-term recovery research. Notably, the ladder test detected subtle motor errors in paretic limbs at both time points, whereas such testing has rarely been documented beyond 28 days in hemorrhagic stroke models.
So what drives these muscle changes? The authors point to multiple factors: central nervous system injury, peripheral nerve alterations, and intrinsic muscle properties. Hemorrhagic stroke triggers a cascade of secondary effects, axonal degeneration, demyelination, and decreased motor unit firing rates, which collectively reshape the neuromuscular landscape. The absence of changes in the SOL further supports a neurogenic rather than purely disuse-driven mechanism.
The clinical implications are profound. Current rehabilitation approaches often apply uniform exercise protocols without accounting for the evolving biology of stroke-affected muscle. " Skeletal muscle fiber type and size are plastic after stroke, " corresponding author LeAnn Snow from University of Minnesota conclude. " Adaptations are muscle-specific and time-specific, and are likely related to neurologic and intrinsic muscle factors. These results suggest that muscle-related rehabilitative therapies require optimal time frames to influence this plasticity for improved function ".
In practical terms, the study identifies distinct windows of opportunity: the deep TA shows peak fiber type plasticity around 4 weeks, while the superficial TA undergoes more sustained remodeling. Fiber size plasticity peaks between 2 and 8 weeks. These staggered timelines suggest that a one-size-fits-all rehabilitation strategy may miss critical opportunities. Power training has shown promise in chronic stroke populations and may be particularly relevant given the observed fiber type shifts.
Translational Exercise Biomedicine
News article
Skeletal muscle adaptations at 8 and 12 weeks post-hemorrhagic stroke
22-Jun-2026