The Effect of a Four Week High Intensity Interval Training Programme on Physiological Health Measures – A Pilot Study

Introduction: High intensity interval training (HIIT) has repeatedly been shown to represent a time-efficient exercise strategy that induces many physiological, performance and health-related adaptations. A number of these positive adaptations have been demonstrated to occur within a 6-12 week period. However, it is unclear if a shorter intervention elicits similar effects. Aim: To determine the effects of a short term (4 week) HIIT intervention on health measures in recreationally active individuals. Methods: Sixteen healthy participants (12 females, 4 males, 47 ± 10 years; BMI 26.6 ± 3.6; <4 hours physical activity p/w) were randomly assigned to a control or HIIT group. All subjects underwent physiological health tests: blood pressure, fasting glucose, glucose tolerance, total cholesterol, HDL-C, and body fat before and after the intervention. The HIIT group performed x2 HIIT sessions p/w for four weeks (10 x 60s intervals performed at 95% maximal aerobic capacity, interspersed with 120s of active recovery). The control group performed no physical training. Results: There was a significant decrease in systolic and diastolic blood pressure post intervention in the HIIT group (130.8 to 126.4 mmHg for systolic, p<0.05, d=0.92 and 81.1 to 76.4 mmHg for diastolic, p<0.05, d=0.58). There was no significant change in the other health measures in either group. Conclusion: A four week HIIT programme has a positive effect on blood pressure, but does not influence other physiological health markers in recreationally active individuals.