The Effects Of High Intensity Interval Training On Mean Arterial Pressure And C-reactive Protein A BSTRACT B ACKGROUND M ETHODS R ESULTS S UMMARY Essential hypertension (HTN) is associated with low-grade systemic inflammation (LGSI) and is reduced by aerobic exercise training (ET). In recent years, high-intensity interval training (HIIT) has been shown to elicit similar cardiorespiratory adaptations as ET while requiring less time exercising. PURPOSE: To determine if HIIT is more effective than ET in controlling hypertension and LGSI. METHODS: Eight healthy inactive subjects; 33.0 ± 4.8 yrs with mild HTN (resting mean arterial pressure (MAP) ± 5.4 mmHg), were recruited. Subjects initially completed a cycle VO2max test (23.0 ± 3.7 mL/kg/min), while resting BP, heart rate (HR), and LGSI (via C-reactive protein (CRP)) were assessed. Subsequently, subjects were randomly assigned to four weeks of exercise training on a cycle ergometer at either 40% VO2 reserve for 30 minutes (ET; n=4) or 60% Wmax for 10 1 minute with 1 minute rest between bouts (HIIT; n=4). RESULTS: Following ET, VO2max increased from 22.8 ± 1.9 to 27.1 ± 4.3 mL/kg/min (p 0.05) on VO2max, resting MAP or systolic blood pressure. Diastolic blood pressure and CRP did not change (p>0.05) with either form of training. Resting HR significantly decreased in both groups ± CONCLUSIONS: These preliminary data suggest that with four weeks of exercise training, ET was more effective than HIT in reducing blood pressure in subjects with mild hypertension; while neither form of training was effective in reducing LGSI. 1.Cornelissen, Véronique A., and Robert H. Fagard. Effects of endurance training on blood pressure, blood pressure–regulating mechanisms, and cardiovascular risk factors. 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Harms, FACSM Dept of Kinesiology, Kansas State University, Manhattan, KS S UBJECTS 12 subjects (men= 2, women=10) completed the experiments None of the subjects were participating in regularly scheduled activities or taking any medication that affects their cardiovascular function No history of cardiovascular, respiratory or metabolic diseases determined via questionnaire B ASELINE M EASUREMENTS Resting blood pressure (BP rest ) was assessed via manual plethysmography of the brachial artery following ≥10 min seated rest. Systemic inflammation was evaluated using measurements high sensitivity C-reactive protein (hs-CRP) via whole blood sample from a finger stick (Alere Cholestech LDX, Alere San Diego, Inc. San Diego, CA). Maximal oxygen uptake was measured during an incremental cycle ergometer test with metabolic and ventilatory data being analyzed continuously breath-by-breath (Sensormedics 229 Metabolic Cart, Sensormedics Corp., Yorba Linda, CA). E XERCISE T RAINING : Subjects were randomly assigned to either an interval training group (HIIT) or a continuous endurance group (ET) for 8 weeks of training. VO2max was reassessed after 4-weeks of training ET exercise trained 30 minutes, cycling at 40% VO 2 reserve (60 rpm) for four days a week HIIT exercise trained 20 minutes, cycling at 60% Power peak (100 rpm) for 3 days a week Intervals were set to a 1:1 work-to-rest ratio, each day consisting of a total of 10 minutes cycling and 10 minutes resting Prior to exercise, three days each week, BP rest was assessed H IGH B LOOD P RESSURE High blood pressure is recognized as systolic (SBP) or diastolic (DBP) blood pressure above 119 and 79 mmHg, respectively. Hypertension (HTN) is clinically diagnosed at or above SBP of 140 or DBP of 90 mmHg In 2008, USDHHS reported 29% of all Americans 18 years and older were hypertensive 4 Prehypertension is classified as SBP between mmHg and DBP between mmHg In 2008, an additional 28% of American adults were prehypertensive 4 If left uncontrolled, subjects have a 26-90% of becoming hypertensive 4 S YSTEMIC I NFLAMMATION The systemic inflammatory response involves a cascade of cytokine activity ultimately resulting in increased levels of circulating C-reactive Protein (CRP) 5 C-reactive protein is a hepatically derived protein that is, at elevated levels, a primary indicator of risk for cardiovascular disease 6 Increases in C-reactive protein have been positively correlated with increases in pulse wave velocity, indicating decreased vascular health 3 E XERCISE, H IGH B LOOD P RESSURE, AND I NFLAMMATION ACSM recommends continuous aerobic exercise to prevent and decrease high blood pressure Meta-analyses have shown at least four weeks of aerobic exercise can decrease mean arterial blood pressure (MAP) approximately 5% 1 Exercise has been shown to have an anti-inflammatory response in various tissues due to a TNF-α independent release of IL-6 from contracting muscle 5 This effect has shown to decrease levels of CRP in the blood Lack of time is a primary barrier to meeting daily exercise recommendations H IGH I NTENSITY I NTERVAL T RAINING (HIIT) HIIT is considered multiple bout of high intensity exercise interspersed with bouts of low intensity exercise or rest; bouts can vary in duration or frequency HIIT has been shown to produce similar adaptations as more traditional, continuous aerobic exercise training Hood et al. (2011) have shown a low-volume, time-efficient HIIT protocol to increase insulin sensitivity and muscle oxidative capacity in sedentary adults 2. Notably, the time commitment was less than half of the ACSM recommendations 1.High intensity interval training (HIIT) reduced mean arterial, systolic and diastolic blood pressures equally effective as endurance training (ET) in prehypertensive subjects. 2.HIIT reduced systemic inflammation (CRP), while there was no decrease with ET in prehypertensive subjects. 3.HIIT showed similar exercise training adaptations as ET after 8 weeks of exercise 4.HIIT may be a time efficient alternative to ET in reducing high blood pressure and systemic inflammation in individuals with hypertension. ET (n=5)HIIT (n=7) Age (yrs)33.8 ± ± 7.4 Height (cm)164.4 ± ± 8.1 Weight (kg)75.8 ± ± 13.7 BMI (kg/m 2 )28.3 ± ± 3.8 MAP (mmHg)98.4 ± ± 5.4 SBP (mmHg)124.2 ± ± 8.2 DBP (mmHg)85.5 ± ± 4.3 hs-CRP (mg/dL)2.0 ± ± 2.6 VO 2max (mL/kg/min)22.9 ± ± 3.5 HR rest (bpm)79.2 ± ± 8.5 P URPOSE & H YPOTHESES P URPOSE To examine the benefits of a time-efficient high intensity interval training protocol in regulation of mean arterial blood pressure and low-grade systemic inflammation (via CRP) in prehypertensive subjects. H YPOTHESES High intensity interval training (HIIT) will reduce resting mean arterial pressure in prehypertensive subjects greater than endurance training (ET). HIIT will reduce resting levels of C-reactive protein in prehypertensive subjects greater than ET Table 1: Subject Characteristics No differences (p>0.05) between groups Figure 1: Mean Arterial Pressure Individual Responses HIIT elicited a similar (p>0.05) decrease as ET in MAP over 8 weeks of exercise training. Significant reductions were also observed in SBP and DBP in both groups. Figure 2: C-reactive Protein Individual Responses HIIT elicited a significant decrease in CRP over 8 weeks of exercise training with no change (p>0.05) in ET. ET (n=5)HIIT (n=7) TimePrePostPrePost VO 2 (mL/kg/min)22.9 ± ± 2.8*23.7 ± ± 1.8* Power peak (Watts)170 ± ± 12*182 ± ± 14* Table 2: VO2max and Power HIIT elicited a similar (p>0.05) training effect (~25%) as ET over 8 weeks of exercise training.