Blood pressure and cerebral oxygenation responses to skeletal muscle tension: a comparison of two physical maneuvers to prevent vasovagal reactions C. R. France, J. L. France and S. M. Patterson Department of Psychology, Porter Hall, Ohio University, Athens, OH, USA Correspondence C. R. France, 245 Porter Hall, Ohio University, Athens, OH 45701, USA E-mail: France@ohio.edu Accepted for publication Received 11 July 2005; accepted 6 September 2005 Key words cerebral oxygenation; muscle tension; orthostatic challenge; vasovagal syncope Summary Aim: The present study compared blood pressure, heart rate, and cerebral oxygen- ation responses to two manipulations used to prevent vasovagal reaction – skeletal muscle tensing alone and skeletal muscle tensing with leg crossing. Methods and Results: Using a repeated measures within-subjects design, healthy young adults engaged in a brief laboratory protocol that included an initial 3 min resting baseline, 3 min of muscle tensing (or no-tensing control), and a 1 min orthostatic challenge. This sequence was repeated three times for each participant to allow for a direct comparison of physiological responses to two different muscle-tensing manipulations as compared to the no-tensing control condition. Results indicated that, relative to the no-tensing, both muscle tensing manipulations elicited significant increases in systolic blood pressure (8Æ7±1Æ1 mmHg), diastolic blood pressure (4Æ9±0Æ6 mmHg), and heart rate (10Æ9±0Æ9 bpm), while a significant increase in cerebral oxygenation was only observed in response to muscle tensing with legs crossed (0Æ8±0Æ2%). Blood pressure and heart rate responses to orthostatic challenge did not differ between the two tensing manipulations, although muscle tensing with legs crossed was followed by a more rapid recovery of cerebral oxygenation levels. Conclusion: These findings suggest that muscle tensing elicits physiological adaptations that may help reduce the risk of vasovagal reactions; however, the combination of lower body tension with the legs crossed is likely to be most effective as it was uniquely associated with significant increases in the flow of oxygenated blood to the brain. Introduction A variety of physical procedures have been developed to reduce the risk of vasovagal reactions among patients prone to vasovagal syncope, individuals with blood and injury phobia, and volunteer blood donors (van Dijk et al., 2000; Wieling et al., 2004). Some of the most commonly reported techniques have included leg crossing (van Lieshout et al., 1992), squatting (van Lieshout et al., 1992; Wieling et al., 2004; van Dijk et al., 2005), skeletal muscle tensing (Ost & Sterner, 1987; Ost et al., 1989; Foulds et al., 1990; Ost et al., 1991; Brignole et al., 2002; Ditto et al., 2003,2004; Croci et al., 2004) and a combination of leg crossing and muscle tensing (van Dijk et al., 2000; Krediet et al., 2002; Wieling et al., 2004; van Dijk et al., 2005). Although individual laboratory studies have shown that such techniques can effectively avert vasovagal reactions by producing acute increases in blood pressure and central blood flow (Foulds et al., 1990; Krediet et al., 2002; Wieling et al., 2004; van Dijk et al., 2005), to the authors’ knowledge there are currently no published reports that directly compare physiological respond- ing to the different muscle tensing techniques. As a result, it is difficult to determine which technique is likely to be most effective at eliciting the cardiovascular adjustments required to prevent vasovagal reactions. The present study compared blood pressure and cerebral oxygenation responses to two of the most common physical procedures to prevent vasovagal reaction – skeletal muscle tensing alone and skeletal muscle tensing with leg crossing. Because our primary aim was to examine the potential benefit of tensing in the blood donation context, we chose to apply the muscle tensing technique in a manner that has previously been shown to reduce vasovagal reactions in volunteer blood donors Clin Physiol Funct Imaging (2006) 26, pp21–25 Ó 2006 Blackwell Publishing Ltd • Clinical Physiology and Functional Imaging 26, 1, 21–25 21