Purpose / Abstract
The purpose is to examine the acute effects of moderate intensity continuous (MOD) and high intensity interval (HI) exercise on central BP and arterial stiffness in premenopausal women.
While exercise is generally positively associated with cardiovascular health, exercise mode and intensity have divergent effects on central blood pressure (cBP) and arterial stiffness. High intensity interval (HI) exercise is increasing in popularity due to its profound effects on aerobic capacity and markers of health, however it is unclear how this form of exercise acutely influences cBP and arterial stiffness.
Introduction / Background
- Peripheral BP measurement via the brachial artery is the most common method to assess hypertension.
- However, the central BP value (BP in the aorta) may better predict risk of CVD attributed to the impact of a returning waveform. (Figure 1)
- Arterial stiffness is a component that corresponds to the impact of the returning waveform, which can be influenced by exercise.
- Aerobic exercise appears to decrease arterial stiffness while resistance exercise may have little affect or increases arterial stiffness. (Figure 2, Figure 3)
- High intensity interval exercise is a common practice that improves numerous risk factors for CVD, but it is unclear what influence it would have on central BP.
Ten, recreationally active, pre-menopausal women (Age 44±1 yr; BMI 25.4±1.0 kg/m2; VO2max 29±2 ml/kg/min) performed two experimental trials in a randomized order. Trials differed only in the exercise performed. Exercise was performed on a treadmill and trials were matched for energy expenditure and consisted of either 40 min at 70% HRR (MOD) or four four-minute intervals at 90% HRR separated by three-minute intervals at 70% HRR (HI). Measurements of cBP and arterial stiffness were performed in duplicate at rest and 15 (Post15) and 30 (Post30) min post-exercise. Brachial blood pressure was obtained manually via the auscultatory method while parameters of cBP were derived using pulse wave analysis via applanation tonometry at the radial artery. Central (carotid to femoral artery) and peripheral (femoral to dorsalis pedis artery) arterial stiffness were measured as pulse wave velocity (PWV) via applanation tonometry.
- A maximal exercise test on a treadmill was conducted to determine maximum heart rate (HRmax) and aerobic capacity (VO2max).
- Subjects (Table 1) performed two randomized, isocaloric exercise trials: one moderate continuous (MOD) and the other high intensity interval (HI) separated by 36 hours. (Figure 2)
- Duplicate measurements of HR, BP, Pulse Wave Analysis (PWA), and Pulse Wave Velocity (PWV) were assessed at rest and 15 and 30 minutes post exercise.
- A two-way (trial x time) ANOVA with repeated measures on time (pre, post15, and post30) was employed to assess statistical significance (P <0.05).
Central systolic blood pressure (cSBP), augmentation pressure (AP), augmentation index (AIx), central pulse pressure (cPP), and peripheral PWV were lower (P<0.05) after exercise, independent of exercise trial. The change in cSBP and AIx was greater (P<0.05) in HI at both Post15 and Post30 while the change in AP and peripheral PWV was greater (P<0.05) in HI at Post15 only. No changes were observed for AIx normalized to HR75 or central PWV in response to exercise or between trials.
High intensity interval exercise elicited more robust positive effects on central blood pressure and peripheral arterial stiffness compared to a moderate-intensity continuous exercise session matched for energy expenditure. These data support the use of HI as an effective modality to improve vascular health in pre-menopausal women.
- HI exercise significantly reduced cSBP, AIx, AP, cPP, and pPWV Post 15 and 30 compared to MOD exercise.
- These results indicate that an acute HI exercise bout improves markers of vascular health more than an isocaloric MOD exercise bout.
- Further research into the chronic effect of HI compared to MOD on markers of vascular health should be conducted.
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