HR Dynamic To Exercise And CRF Of Young Women At High Familial Risk Of Hypertension: Effects Of Interval Versus Continuous Training

Abstract

BACKGROUND AND PURPOSE: Offspring of essential hypertensive parents (FH+) are at high risk for hypertension and subsequent cardiovascular disease (CVD). Poor cardiac autonomic control of the nervous system, evaluated by the heart rate (HR) dynamic during graded exercise test (GXT), and cardiorespiratory fitness (CRF) are risk factors for hypertension, CVD, and both all-cause and CVD mortality. Physical exercise to improve autonomic control and CRF is thus strongly recommended, however evidence regarding the most efficient training intensity for FH+ is still lacking. Our purpose was therefore to assess the effects of high intensity aerobic interval training (AIT) compared to continuous moderate intensity training (CMT), representing the same total training load, in the HR dynamic to exercise and CRF of FH+. METHODS: Fifty-nine healthy young women FH+ were randomized to AIT (85% of VO2PEAK; n = 16), CMT (65% of VO2PEAK; n = 16), or control group (n = 12). Exercise training was performed three times a week. A GXT was performed before and after 16 weeks of follow-up to evaluate resting, peak, reserve and recovery HR (difference between HR at peak and one minute after termination of exercise), and CRF. RESULTS: Resting, peak and reserve HR did not change after the follow-up in all groups. Recovery HR improved only after AIT (11.8 ± 4.9 × 20.6 ± 5.8 bpm; P < 0.01). VO2PEAK increased more after AIT than CMT group (15.8% × 8.0%; P = 0.036). The first and second ventilatory threshold increased in both AIT and CMT group, but the second ventilatory threshold also increased more after AIT than CMT (22.1% × 8.8%; P = 0.008). With these improvements, AIT group displayed higher post-exercise time to exhaustion (P < 0.008), time to reach first ventilatory threshold (P < 0.008), and time to reach second ventilatory threshold (P < 0.001) when compared to both CMT and Con group. CRF did not change in the control group. CONCLUSIONS: AIT was more effective than CMT for improving recovery HR (a marker of cardiac autonomic control of the nervous system) and CRF of healthy young women offspring of essential hypertensive parents. These finds may have important implications for designing exercise training programs for the prevention of an inherited hypertensive disorder.