Key result
Electrical muscle stimulation significantly increased internal carotid artery blood flow from 330 to 371 mL/min (Cohen's d 0.55) but did not change vertebral artery blood flow in healthy young men.
Why the study?
Although electrical muscle stimulation has potential as an alternative to voluntary exercise, its effects on cerebral blood flow when applied to large lower limb muscles are poorly understood.
Does electrical muscle stimulation of large lower limb muscles increase cerebral blood flow in healthy males?
RCT (n=9)
Randomized crossover
No
Does electrical muscle stimulation of large lower limb muscles increase cerebral blood flow in healthy males?
Standardized Mean Difference: 0.55
Absolute Event Rate: 371% vs 330%
p-value: p=0.001
Electrical muscle stimulation of large lower limb muscles acutely increases internal carotid artery blood flow but not vertebral artery blood flow, likely due to differences in cerebrovascular CO2 reactivity.
EMS may selectively boost carotid flow in healthy young men; leaves open effects in older or cerebrovascular disease populations.
A bstract Background Electrical muscle stimulation (EMS) induces involuntary muscle contraction. Several studies have suggested that EMS has the potential to be an alternative method of voluntary exercise; however, its effects on cerebral blood flow (CBF) when applied to large lower limb muscles are poorly understood. Thus, the purpose of this study was to examine the effects of EMS on CBF, focusing on whether the effects differ between the internal carotid (ICA) and vertebral (VA) arteries. Methods The participants performed the experiments under EMS and control (rest) conditions in a randomized crossover design. The ICA and VA blood flow were measured before and during EMS or control. Heart rate, blood pressure, minute ventilation, oxygen uptake, and end-tidal partial pressure of carbon dioxide (P ET CO 2 ) were monitored and measured as well. Results The ICA blood flow increased during EMS [Pre: 330 ± 69 mL min −1 ; EMS: 371 ± 81 mL min −1 , P = 0.001, effect size (Cohen’s d) = 0.55]. In contrast, the VA blood flow did not change during EMS (Pre: 125 ± 47 mL min −1 ; EMS: 130 ± 45 mL min −1 , P = 0.26, effect size = 0.12). In the EMS condition, there was a significant positive linear correlation between ΔP ET CO 2 and ΔICA blood flow (R = 0.74, P = 0.02). No relationships were observed between ΔP ET CO 2 and ΔVA blood flow (linear: R = − 0.17, P = 0.66; quadratic: R = 0.43, P = 0.55). Conclusions The present results indicate that EMS increased ICA blood flow but not VA blood flow, suggesting that the effects of EMS on cerebral perfusion differ between anterior and posterior cerebral circulation, primarily due to the differences in cerebrovascular response to CO 2 .
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Ando et al. (2021) conducted an RCT in Healthy (n=9). Electrical muscle stimulation (EMS) vs. Rest (control) was evaluated on Internal carotid artery (ICA) blood flow (Cohen's d 0.55, p=0.001). Electrical muscle stimulation significantly increased internal carotid artery blood flow from 330 to 371 mL/min (Cohen's d 0.55) but did not change vertebral artery blood flow in healthy young men.
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