Mary Jo Reiling

Blood pressure reductions with exercise and sodium restriction in postmenopausal women with elevated systolic pressure: Role of arterial stiffness

OBJECTIVES This study determined the relative efficacy of aerobic exercise (daily walking) and moderate dietary sodium restriction (sodium intake <100 mmol/day) for reducing systolic blood pressure (SBP) and pulse pressure (PP) in postmenopausal women with elevated initial levels, and the potential role of reductions in large artery stiffness in these changes. BACKGROUND Lifestyle behaviors are recommended for lowering blood pressure (BP) in adults with elevated baseline levels, but there is little information as to the relative efficacy of different interventions or the mechanisms underlying their potential beneficial effects. METHODS After baseline measurements and random assignment, 35 nonmedicated healthy postmenopausal women with SBP between 130 and 159 mm Hg completed three months of either aerobic (walking) exercise (n = 18; 62 +/- 9 years, mean +/- SD) or moderate dietary sodium restriction (SR) (n = 17; 65 +/- 10 years, mean +/- SD). RESULTS Body mass and composition, plasma volume, and fasting concentrations of metabolic coronary risk factors did not differ between the groups at baseline or change with intervention. Systolic BP and PP at rest decreased with both exercise and SR (p < 0.05); however, the reductions were three- to fourfold greater with SR (p < 0.05). Sodium restriction, but not exercise, also reduced 24-h SBP and PP (p < 0.05). Aortic pulse wave velocity (PWV) and carotid augmentation index were reduced only with SR (p < 0.05). Changes in SBP and PP at rest and over 24 h correlated with the corresponding changes in aortic PWV (r = 0.53 to 0.61, p < 0.01). CONCLUSIONS Moderate SR lowers SBP and PP in postmenopausal women with elevated baseline levels more than does daily walking. The greater blood pressure reductions with SR may be mediated in part by a decrease in the stiffness of the large elastic arteries.

Effect of regular aerobic exercise on elevated blood pressure in postmenopausal women

The efficacy of aerobic exercise for lowering arterial blood pressure (BP) in postmenopausal women with elevations of 130 to 159/85 to 99 mm Hg has not been established. To determine this, 10 postmenopausal women with high normal resting BP or stage I essential hypertension were studied throughout a 12-week lead-in period (no exercise, n = 5) and/or 12 weeks of moderate-intensity aerobic exercise (walking, n = 9). There were no significant time effects during the lead-in period (all p >0.4). Maximal aerobic capacity (as assessed by maximal oxygen consumption) was unchanged after 12 weeks of exercise, but exercise tolerance (treadmill walking time) increased by approximately 10% (p <0.05). Body weight, dietary intake and composition, and urinary sodium excretion were unchanged before versus after exercise training. After 12 weeks of exercise, systolic and diastolic BP at rest were significantly lowered by 10/7 and 12/5 mm Hg, respectively, in the sitting and standing positions (p <0.001); some (> or = 3 to 5 mm Hg) decrease in BP was observed in every subject. On average, subjects with stage I hypertension had a reduction in BP into the high normal range, whereas subjects with high-normal initial levels had a reduction in BP into the normal range. Borderline significant (p = 0.06 to 0.07) reductions in systolic and diastolic BP were observed by the end of the second and tenth weeks of training, respectively. Ambulatory determined 24-hour levels of BP were unchanged with training, but significant reductions in BP during submaximal exercise occurred. Our results demonstrate that regular aerobic exercise can produce clinically important reductions in resting BP in Caucasian postmenopausal women with mild to moderately elevated initial levels. This effect of exercise is observed in the absence of changes in maximal aerobic capacity, body weight, or dietary intake.

Regular walking increases peak limb vasodilatory capacity of older hypertensive humans: Implications for arterial structure

Background Although regular aerobic exercise has been shown to lower arterial blood pressure in older adult humans with essential hypertension, the mechanisms responsible for this hypotensive effect remain largely unknown. Objective To examine the hypothesis that the reduction in arterial blood pressure in older hypertensive humans with regular exercise is accompanied by evidence of a change in arterial structure. Methods We measured peak limb vascular conductance, a well-established noninvasive measure of arterial structure, both in the forearm (untrained limb) and in the calf (exercise-trained limb) of 22 older adults (aged 51–74 years) with stage 1 or 2 essential hypertension. Eleven subjects walked 3–4 days/week at a mild exercise intensity (45% of heart rate reserve) for 6 months. Eleven other subjects served as nonexercising controls. Results Maximal oxygen consumption of subjects in the exercise group increased by 17% (P < 0.05) with no change in body mass and body fat. Systolic and diastolic arterial blood pressures at rest were reduced by 7 ± 4 and 5 ± 2 mmHg, respectively (P < 0.05). There were roughly 20% increases in peak forearm blood flow and peak forearm vascular conductance (both P < 0.05). Similar increases in peak calf blood flow and vascular conductance were observed (both P < 0.01). There were no significant changes in any of these variables over the same time period for the nonexercising controls. Conclusions The decrease in resting blood pressure in older adults with stage 1 or 2 essential hypertension in response to regular aerobic exercise is associated with an increase in peak limb vascular conductance, which could be due in part to favorable changes in arterial structure. These exercise-induced functional and, possibly, structural changes are not confined to the exercise-trained limbs, but rather are more systemic in nature. These apparent beneficial changes in limb vasodilatory capacity and vascular structure can be produced with a mode, intensity, and frequency of aerobic exercise that can be tolerated and is commonly performed by older adults.

Lack of age-associated elevations in 24-h systolic and pulse pressures in women who exercise regularly

We tested the hypothesis that the elevations in 24-h arterial systolic (SBP) and pulse (PP) pressures with age in sedentary adult females are absent or smaller in women who exercise regularly. Four groups of healthy normotensive women were studied: premenopausal (n = 12; 29 +/- 1 yr, mean +/- SE) and postmenopausal (n = 20; 62 +/- 1) sedentary, and premenopausal (n = 14; 30 +/- 1) and postmenopausal (n = 12; 58 +/- 1) endurance-exercise trained (distance runners). In the sedentary group, 24-h SBP and PP (Spacelabs ambulatory monitor 90207) were approximately 10 mmHg higher (P < 0.05) in the postmenopausal women than in the premenopausal controls; this was because of higher daytime and nighttime SBP and PP levels in the postmenopausal women. In contrast, 24-h, daytime and nighttime SBP and PP were not different with age in the endurance-trained women. SBP variability and SBP load (% of all recordings > 140 mmHg) generally were greater with age in the sedentary women (e.g., SBP load = 14 +/- 4 vs. 3 +/- 1%, P < 0.05) but not in the endurance-trained women. In the pooled population, 24-h SBP and PP were related to waist-to-hip ratio (measure of abdominal adiposity) (r = 0.48 and 0.49, respectively, P < 0.001) and carotid augmentation index (measure of arterial stiffness) (r = 0.43 and 0.53, P < 0.005). In the sedentary women, accounting for the influence of either of these factors eliminated the significant age-associated differences in 24-h SBP and PP (P > 0.3). Our results suggest that the elevations in 24-h SBP and PP with age in sedentary adult females may not occur in women who regularly perform endurance exercise. This appears to be related to the absence of age-associated increases in abdominal adiposity and arterial stiffness in the exercising women.We tested the hypothesis that the elevations in 24-h arterial systolic (SBP) and pulse (PP) pressures with age in sedentary adult females are absent or smaller in women who exercise regularly. Four groups of healthy normotensive women were studied: premenopausal ( n = 12; 29 ± 1 yr, mean ± SE) and postmenopausal ( n = 20; 62 ± 1) sedentary, and premenopausal ( n = 14; 30 ± 1) and postmenopausal ( n= 12; 58 ± 1) endurance-exercise trained (distance runners). In the sedentary group, 24-h SBP and PP (Spacelabs ambulatory monitor 90207) were ∼10 mmHg higher ( P < 0.05) in the postmenopausal women than in the premenopausal controls; this was because of higher daytime and nighttime SBP and PP levels in the postmenopausal women. In contrast, 24-h, daytime and nighttime SBP and PP were not different with age in the endurance-trained women. SBP variability and SBP load (% of all recordings > 140 mmHg) generally were greater with age in the sedentary women (e.g., SBP load = 14 ± 4 vs. 3 ± 1%, P < 0.05) but not in the endurance-trained women. In the pooled population, 24-h SBP and PP were related to waist-to-hip ratio (measure of abdominal adiposity) ( r = 0.48 and 0.49, respectively, P < 0.001) and carotid augmentation index (measure of arterial stiffness) ( r = 0.43 and 0.53, P < 0.005). In the sedentary women, accounting for the influence of either of these factors eliminated the significant age-associated differences in 24-h SBP and PP ( P > 0.3). Our results suggest that the elevations in 24-h SBP and PP with age in sedentary adult females may not occur in women who regularly perform endurance exercise. This appears to be related to the absence of age-associated increases in abdominal adiposity and arterial stiffness in the exercising women.

Role of central circulatory factors in the fat-free mass-maximal aerobic capacity relation across age

Fat-free mass (FFM) (primarily skeletal muscle mass) is related to maximal aerobic capacity among healthy humans across the adult age range. The basis for this physiological association is assumed to be a direct relation between skeletal muscle mass and its capacity to consume oxygen. We tested the alternative hypothesis that FFM exerts its influence on maximal aerobic capacity in part via an association with central circulatory function. To do so, we analyzed data from 103 healthy sedentary adults aged 18-75 yr. FFM was strongly and positively related to maximal oxygen consumption ( r = 0.80, P < 0.001). FFM was also strongly and positively related to supine resting levels of blood volume ( r = 0.79, P < 0.001) and stroke volume ( r = 0.75, P < 0.001). Statistically controlling for the collective influences of blood volume and stroke volume abolished the tight relation between FFM and maximal oxygen consumption ( r = 0.12, not significant). These results indicate that 1) FFM may be an important physiological determinant of blood volume and stroke volume among healthy sedentary adult humans of varying age; and 2) this relation between FFM and central circulatory function appears to represent the primary physiological basis for the strong association between FFM and maximal aerobic capacity in this population. Our findings suggest that sarcopenia (loss of skeletal muscle mass with aging) may contribute to the age-related decline in maximal aerobic capacity primarily via reductions in blood volume and stroke volume rather than a direct effect on the oxygen-consuming potential of muscle per se.Fat-free mass (FFM) (primarily skeletal muscle mass) is related to maximal aerobic capacity among healthy humans across the adult age range. The basis for this physiological association is assumed to be a direct relation between skeletal muscle mass and its capacity to consume oxygen. We tested the alternative hypothesis that FFM exerts its influence on maximal aerobic capacity in part via an association with central circulatory function. To do so, we analyzed data from 103 healthy sedentary adults aged 18-75 yr. FFM was strongly and positively related to maximal oxygen consumption (r = 0.80, P < 0. 001). FFM was also strongly and positively related to supine resting levels of blood volume (r = 0.79, P < 0.001) and stroke volume (r = 0.75, P < 0.001). Statistically controlling for the collective influences of blood volume and stroke volume abolished the tight relation between FFM and maximal oxygen consumption (r = 0.12, not significant). These results indicate that 1) FFM may be an important physiological determinant of blood volume and stroke volume among healthy sedentary adult humans of varying age; and 2) this relation between FFM and central circulatory function appears to represent the primary physiological basis for the strong association between FFM and maximal aerobic capacity in this population. Our findings suggest that sarcopenia (loss of skeletal muscle mass with aging) may contribute to the age-related decline in maximal aerobic capacity primarily via reductions in blood volume and stroke volume rather than a direct effect on the oxygen-consuming potential of muscle per se.