Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC322
Comparison of haemodynamics and metaboreflex sensitivity between high intensity interval and constant aerobic exercise in prehypertensive individuals
J. Chang1, Y. Sim1, J. Lee1, I. Kong1
1. Physiology, Yonsei Univ. Wonju College of Medicine, Wonju, Gangwon-do, Korea, Republic of.
Hypertension is one of the most serious clinical risk factors of the cardiometabolic syndrome. Exercise has been shown to reduce arterial blood pressure in normotensive and hypertensive individuals. Although high intensity interval exercise (HIE) has similar or greater benefits to the cardiovascular system compared to constant aerobic exercise (CE), the acute effects of HIE on haemodynamics and metaboreflex sensitivity are less known, particularly in individuals with prehypertension or hypertension. Therefore, we evaluated haemodynamic responses and metaboreflex sensitivity in pre-hypertensive individuals following acute HIE and CE on the treadmill. A total of 13 pre-hypertensive males (systolic arterial pressure; SAP 130±6 mmHg, diastolic arterial pressure; DAP 76±3 mmHg, 43±4 years, height 170±4 cm, body weight 72.8±7.0 kg, body mass index 25.1±2.1 kg/m2) performed a bout of HIE and CE on a treadmill. CE was performed at 60% of target heart rate (THR) and IE was alternated between 80% THR and 50% THR in the ratio of 1:2 for 30 min, including 3 min warm-up and cool-down for each period. Total exercise calorie expenditures (calculated by respiratory gas analysis) were determined during both exercises (203.8±19.7 kcal for HIE and 205.7±19.3 kcal for CE). Beat to beat SAP, DAP, heart rate and metaboreflex sensitivity were measured noninvasively (Finometer) during 30 min pre and post exercise. Subsequently, dynamic handgrip exercise was performed to measure the metaboreflex sensitivity for 3 min followed by 2 min of postexercise ischemia. Values represent means ± S.D., which were compared by Wilcoxon-signed rank test. R-R interval and stroke volume were decreased by a similar magnitude following both exercises. However, after 30 min recovery period, values of SAP (HIE vs. CE; 114±7 vs. 118±4 mmHg, p<0.05), DBP (72±4 vs. 76±3 mmHg, p<0.05), MAP (89±5 vs. 93±3 mmHg, p<0.05) and total peripheral resistance (TPR: 0.826±0.117 vs. 0.949±0.129 mmHg*s/ml, p<0.05) were significantly lower following HIE than CE . In addition, aortic impedance after HIE was lower (49.1±2.4 vs. 50.1±2.0 milli-mmHg*s/ml, p<0.05), whereas arterial compliance was greater (2.25±0.23 vs. 2.11±0.18 ml/mmHg, p<0.05) compared to those after CE. As compared to resting values, the change (Δ mmHg) in MAP during post exercise ischemia was significantly lower in magnitude following HIE than that following CE (HIE: Δ = 14±6 mmHg, CE: Δ = 20±6 mmHg, p<0.05). Taken together, HIE results in lower arterial stiffness and reduced metaboreflex sensitivity than CE, which suggests that HIE would be more effective in reducing high blood pressure than CE.
Where applicable, experiments conform with Society ethical requirements