Effect of applied muscle tension on cerebral oxygenation in female blood donors

BACKGROUND: Applied muscle tension (AMT), which involves rhythmic tensing of the muscles of the core and lower extremities, has been associated with attenuation of presyncopal reactions among whole blood donors. This study was designed to examine whether the salutary effects of AMT may be mediated by increases in cerebral oxygenation during blood donation.

STUDY DESIGN AND 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 or repeated gentle foot flexions (i.e., distraction control) during whole blood donation. Cerebral oxygenation was monitored throughout the donation using near infrared spectroscopy.

RESULTS: Participants who engaged in AMT 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 AMT group.

CONCLUSION: AMT is associated with an attenuated decrease in cerebral oxygenation compared to a distraction-control group. Further studies are necessary to establish if the salutary effect of AMT during blood donation may be in part due to an increase in oxygen available to the brain.