Background: Rhythmic tensing of the muscles of the core and lower extremities (applied muscle tension, or AMT) has been associated with decreased rates and severity of whole blood donor reactions. A possible mechanism by which this occurs is via increased availability of oxygen in the brain. The purpose of this study was to examine the effects of applied muscle tensing on changes in cerebral oxygenation during blood donation.
Methods: Seventy-two female blood donors were recruited at mobile blood drives in the American Red Cross Blood Services - Central Ohio Region. Participants were randomly assigned to engage in either AMT during donation, or a distraction-control condition in which donors engaged in a repeated, gentle foot flexion movement. Cerebral oxygenation was monitored throughout the donation process using near infrared spectroscopy.
Results: Participants who engaged in applied muscle tensing were shown to have attenuated decreases in cerebral oxygenation across the three intervals of the blood draw relative to the distraction manipulation, F(1, 70) = 8.144, p = 0.006. Whereas cerebral oxygenation decreased 1.42% (SD = 2.09) for those in the distraction-control group, oxygenation levels increased 0.13% (SD = 2.56) in the applied muscle tension group.
Conclusion: Applied muscle tension is associated with an attenuated decrease in cerebral oxygenation compared to a distraction-control group. This suggests that the salutary effect of AMT may be in part due to an increase in oxygen available to the brain.