The effects of muscle relaxation and stress on the blood pressure levels of normotensives

Shoemaker and Tasto (1975) found that progressive muscle relaxation lowers the blood pressure levels of essential hypertensives to within a normal range under laboratory conditions. As a sequel to this study the effects of muscle relaxation and stress on the blood pressure levels of normotensives were studied. One group was taught relaxation, one group was stressed, one group read, and one group did nothing. Blood pressure measurements taken immediately after the completion of these tasks indicated that muscle relaxation does not lower the blood pressure levels of normotensives but that stress significantly raises both the systolic and diastolic levels.Level of arousal can, at least in one sense, be viewed as occurring on a dimension defined by extreme anxiety at one end and extreme relaxation at the other. Research on the physiological correlates and/or defining properties of arousal has produced inconsistent and equivocal results. Little work has been done relating blood pressure levels to arousal, however. Shoemaker and Tasto (1975) found a consistent and predictable drop in the blood pressure levels of essential hypertensives as a result of progressive muscle relaxation. In their study those subjects with the highest blood pressure levels showed the greatest drop while those with moderately high levels showed moderate drops and those with the lowest levels (yet still above normal) showed the least amount of change. The amount by which blood pressure dropped as a result of progressive relaxation was positively correlated with the pretreatment level of blood pressure. The result of progressive relaxation was to lower blood pressure levels to within a normal range, with all subjects appearing to approach a lower asymptotic level. Because of the consistent picture which began to emerge, the question arose as to whether blood pressure might be a reliable physiological correlate of the relaxation-anxiety dimension.The more specific questions emanating from this issue were: what effect does progressive relaxation have on the blood pressure levels of normotensives; what effect does stress have on the blood pressure levels of normotensives; and, what effect does stress have on the blood pressure levels of essential hypertensives? Since we could not immediately foresee the benefits that would outweigh the potential harm that might arise by placing hypertensives under stress, this study was limited to addressing the first two questions.Since the blood pressure levels of normotensives are probably at an optimal level for the physiological functioning of the organism, lower levels would be physiologically nonadaptive. and thus progressive relaxation should not lower the blood pressure levels of normotensives as it does those of essential hypertensives. On the other hand, if the elevated blood pressure levels of essential hypertensives are at least in part the result of a stress reaction, it would be expected that the blood pressure levels of normotensives might rise under stress conditions.