The effect body composition has on adaptions to high-intensity interval exercise
Obesity rates have increased worldwide and recently a sedentary lifestyle have been associated with obesity incidence. Being obese and/or overweight is associated with adverse effects on health. Given that time is consistently reported as the biggest barrier to exercise, particularly amongst young adults females, traditional training methods are deemed time consuming methods of training. High-intensity interval exercise (HIIE) is a time-efficient method of training that induces positive health effects despite having a substantially lower training volume and time commitment. The current study investigated the effects 6 weeks of HIIE has on specific health markers in the normal weighted and overweight female populations.Methods:Nineteen females were recruited and split into 3 training groups; Normal (n=7, 21 ± 0.5years; BMI, 20 ± 0.7 kg.m-2), Overweight (n=6, 23 ± 3.7years; BMI, 30 ± 6kg.m-2) and Control (n=6, 22 ± 1years; BMI, 22 ± 1kg.m-2). The normal and overweight group performed three weekly HIIE sessions for 6 weeks with the control group serving as a non-training group. HIIE involved 4x15 second (s) sprints for week 1 & 2, 5x15 s sprints for week 3 & 4 and 6x15 s sprints for week 5 & 6, all alternated with a 2 minute recovery against a resistance of 7% body weight. Health markers measured before and after training were; immediate word recall, verbal fluency, segmental analysis and body composition, perception of happiness, subjective happiness, waist to hip ratio blood pressure, triglycerides, delayed memory recall and V̇O2 peak. Heart rate recovery between sprints was also measured during the first and last sprinting session.Results:In response to 6 weeks of HIIE, V̇O2 peak significantly increased by 25% in the normal weighted group (N: 33.7±6.3 to 41.8±8.8 ml.kg.-1.min-1; p = 0.008), but no change in the overweight group. Time to exhaustion significantly increased by 18% in the normal weighted group (N: 424 ± 69 to 498 ± 84s; p = 0.005) and 12% in the overweight group (O: 497 ± 140 to 561 ± 177s; p = 0.051). Significant reductions of 3.6% were found in the normal weighted group (N; 116.7±8 to 112.4±7 mm Hg; p = 0.037) and 4.5% reduction in the overweight group (O; 125.4 ± 8.2 to 119.3 ± 7.4 mm Hg; p = 0.001) in left arm systolic pressure. A 21% enhancement in memory recall was observed in the overweight group (O; 7.8 ± 1.2 to 9.5 ± 1.8words; p = 0.019) and a 44% increase in verbal fluency letter 1 score was found in the overweight group (O; 9.8 ± 2.2 to 16 ± 4.7words; p = 0.071). A significant reduction in waist to hip ratio was found in the normal weighted group (N; 0.82 ± 0.03 to 0.81 ± 0.03; p = 0.033). Results suggest adaptations to HIIE are partially regulated by body composition in females.
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