Effects of Exercise Intensity on Acute Circulating Molecular Responses Poststroke.
Pierce Boyne, Colleen Meyrose, Jennifer Westover and 8 others
PMID 31976813WHAT IT FOUND
Treadmill high-intensity interval training raised blood markers for brain repair (BDNF, VEGF, IGF1) without raising stress hormones, unlike moderate continuous walking.
However, the study did not measure rehabilitation outcomes, so it is unclear if these acute chemical changes translate to better patient recovery.
Key findings
01High-intensity treadmill training significantly increased serum VEGF and IGF1, while moderate continuous treadmill training did not show significant increases for these markers in the whole sample.
02There were no significant differences between exercise protocols in the primary analysis of molecular responses, although high-intensity treadmill training showed a larger effect size than moderate training for VEGF.
03Participants with slower walking speeds (<0.4 m/s) had significantly greater VEGF responses to high-intensity training compared to those with faster walking speeds.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study measured acute blood chemistry changes, not rehabilitation outcomes like walking speed or motor learning, so it is unknown if these molecular shifts help patients. The sample size was small (n=16), and the subgroup analysis for slow walkers included only three participants, making those findings unstable. The HIT-stepper protocol was modified halfway through the study for safety reasons, creating two different versions of the intervention. Serum levels of these molecules are imperfect proxies for what is happening in the brain, as they do not necessarily reflect central nervous system activity directly.
Declared interests
The authors declare no conflicts of interest. The study was supported by the National Institutes of Health (N.I.H., Extramural) and Non-U.S. Government research support.
The easy way to misread this
Do not assume that the observed increases in BDNF, VEGF, and IGF1 after high-intensity exercise will improve patient recovery. This study only measured acute blood markers and did not assess any functional or cognitive outcomes, so the clinical benefit of these molecular changes remains unproven.