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Low-frequency HIIT improves body composition and aerobic capacity in overweight men |
Chin EC, Yu AP, Lai CW, Fong DY, Chan DK, Wong SH, Sun F, Ngai HH, Yung PSH, Siu PM |
Medicine and Science in Sports and Exercise 2019;52(1):56-66 |
clinical trial |
4/10 [Eligibility criteria: No; Random allocation: Yes; Concealed allocation: No; Baseline comparability: Yes; Blind subjects: No; Blind therapists: No; Blind assessors: No; Adequate follow-up: No; Intention-to-treat analysis: No; Between-group comparisons: Yes; Point estimates and variability: Yes. Note: Eligibility criteria item does not contribute to total score] *This score has been confirmed* |
BACKGROUND: The relationship between the frequency of high-intensity interval training (HIIT) and the resultant adaptations is largely unclear. PURPOSE: This study compared the effects of different frequencies of HIIT with those of moderate-intensity continuous training (MICT) on body composition in overweight or obese adults. METHODS: Fifty-six overweight or obese (BMI 26.4 +/- 2.9) men aged between 18 and 30 years (age 22.8 +/- 3.1) were randomly assigned to the following groups: no-intervention control (CON n = 14), MICT performed thrice weekly (MICTx3/wk n = 9), HIIT performed thrice weekly (HIITx3/wk n = 14), HIIT performed twice weekly (HIITx2/wk n = 10), and HIIT performed once weekly (HIITx1/wk n = 9). Each HIIT session consisted of 12x1-min bouts at 90% heart rate reserve (HRR), interspersed with 11x1-min bouts at 70% HRR. Aerobic capacity, body composition, resting heart rate, vascular function, insulin resistance, and biomarkers of metabolic syndrome risk factor were examined at baseline, after 4 weeks and after 8 weeks of intervention. RESULTS: Aerobic capacity and percent fat-free mass significantly increased in all exercise groups compared with those in the CON group (CON versus all exercise groups p < 0.05), whereas body fat mass and systolic blood pressure significantly decreased after 8 weeks of intervention in all exercise groups compared with those in the CON group (CON versus all exercise groups p < 0.05). Body fat mass significantly decreased after 4 weeks in all HIIT groups compared with those in the CON group (CON versus all HIIT groups p < 0.05) but not in the MICTx3/wk group. CONCLUSION: These novel results demonstrated that performing HIIT once weekly, even with a lower weekly volume of exercise, improved cardiorespiratory fitness, body composition, and blood pressure in overweight/obese adults. Low-frequency HIIT might be a feasible and effective strategy for the prescription of an initial exercise program for inactive, overweight or obese young men.
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