Effect of exercise training on total peripheral resistance, heart rate variability, and prehypertension in apparently healthy African American women

Exercise training has consistently been shown, in the research literature, to be an effective non-pharmacological alternative to treat hypertension (HTN). However, the underlying mechanism that accounts for the reductive and possible preventive effects, induced by exercise have not been clearly established. To our knowledge, no study has examined the effect of an aerobic exercise-training program on prehypertension (resting blood pressure between 120/80--139/89 mm Hg) and the underlying variables that may exacerbate the disease's development in apparently healthy African American women. Therefore, the aim of the present study was to investigate the effects of a 10-week aerobic exercise-training regimen on total peripheral resistance (TPR), heart rate variability (HRV), and prehypertensive blood pressure status in apparently healthy African American women. Twenty-three prehypertensive African American women served as study participants (12 exercised trained and 11 controls). Each participant was required to meet all inclusionary criteria which included: being an African American woman between the ages of 30--45 years, a sedentary lifestyle, non-smoking status, body mass index between 25--35 (kg· m-2), and a prehypertensive blood pressure status. A VO2 peak and submaximal exercise test were conducted on the cycle ergometer. HRV was assessed using power spectral analysis of beat-to-beat measurements in various frequency domains. Results revealed a significant reduction in TPR in the trained group from pre to post intervention periods (pre 35.3 +/- 5.1 mm Hg·L·min -1 vs. post 26.9 +/- 4.3 mm Hg·L ·min-1) (p < .05). The trained group also increased in VO2 peak and absolute workload achieved (19.0 +/- 1.1 vs. 23.0 +/- 1.1 ml·kg· min-1; 116 +/- 4.7 vs. 133 +/- 8.3 watts, respectively) (p < .05). There were no observed significant changes in systolic, diastolic, or mean arterial blood pressure from pre to post-exercise periods in either group. However, the absolute change in resting SBP from pre to post when comparing the exercise and control group was statistically significant (4.75 and -4.45 mm Hg, respectively)(negative numbers indicate a increase from pre to post measurement periods) (p < .05). The findings of this investigation suggests that a 10-week aerobic exercise training protocol is sufficient enough to elicit changes in TPR, but was not a strong enough stimulus to reduce associated blood pressure levels in African American women with prehypertension.