Estimated Prestroke Peak VO2 Is Related to Circulating IGF-1 Levels During Acute Stroke.
Anna E Mattlage, Michael A Rippee, Michael G Abraham and 2 others
PMID 27377914WHAT IT FOUND
In 15 acute stroke patients, estimated pre-stroke aerobic fitness correlated with circulating IGF-1 levels but not with IGFBP-3.
Patients with higher IGF-1 had significantly higher estimated fitness. This small observational study links a biomarker to a calculated fitness estimate, offering no evidence that changing fitness alters stroke recovery.
Key findings
01Estimated pre-stroke peak VO2 was significantly and positively related to IGF-1 levels (r = .60; p = .02), but not to IGFBP-3 (r = −.09; p = .75).
02Individuals with higher-than-median IGF-1 had significantly better estimated peak VO2 (32.4 ± 6.9 mL*kg−1*min−1) compared to those with lower-than-median levels (20.7 ± 7.8 mL*kg−1*min−1; p = .03).
03There were no significant differences in estimated peak VO2 between higher- and lower-than-median levels of IGFBP-3 (p = .24).
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The sample size was extremely small (n=15), which limits the reliability of the findings. Pre-stroke aerobic fitness was estimated using a mathematical formula based on self-reported activity and resting heart rate, not measured directly via exercise testing. The study is cross-sectional and observational; it cannot prove that higher fitness causes higher IGF-1 levels or that either factor influences stroke recovery. Physical activity levels were reported by patients or surrogates, which may be inaccurate due to recall bias or the patient's acute condition. The study did not measure functional recovery or patient outcomes, so the clinical significance of the IGF-1 association remains unknown.
Declared interests
The paper reports support from the National Institutes of Health (Extramural) and the University of Kansas Medical Center. No commercial funding or conflicts of interest related to the biomarkers or prediction equations are declared.
The easy way to misread this
Do not interpret the correlation between estimated fitness and IGF-1 as evidence that prescribing exercise will raise IGF-1 or improve stroke recovery. The fitness measure was a calculated estimate based on pre-stroke history, not a measured response to therapy, and the study did not assess clinical outcomes.