Effects of high-intensity interval training on cardiometabolic risk in overweight and obese African-American women: a pilot study

Objective: Little is known about high-intensity interval training (HIIT) in African-American (AA) women. The purpose of this pilot study was to evaluate the effects of HIIT and steady-state (SS) exercise on cardiometabolic risk factors in young AA women. Design: A 16-week exercise intervention was conducted 3x/week. Twenty-seven AA women were randomized to SS (n=11; 32 continuous minutes of treadmill walking at 60-70% of maximum heart rate (HRmax)), or HIIT (n=16; 32 min of treadmill HIIT alternating 3 min at 60-70% of HRmax with 1 min at 80-90% of HRmax). Two-way repeated measures ANOVA with intention-to-treat analysis was used to identify changes between groups. Significance was accepted at P <= 0.05. Results: Of the 27 women who entered the study (age: 30.5 +/- 6.8 years; BMI: 35.1 +/- 5.1 kg/m(2); 5274 +/- 1646 baseline steps/day), 14 completed the intervention. HIIT significantly decreased waist circumference (107.0 +/- 11.3 to 105.1 +/- 11.9 cm) compared to SS, which showed no change. There was a significant time effect for steps where HIIT increased steps/day (5334 +/- 1586 to 7604 +/- 1817 steps/day), and SS had no change. There were no significant changes in either group for any other measurements. Conclusion: HIIT was more effective at reducing waist circumference and increasing daily steps/day than SS treadmill exercise over 16 weeks. Further research in a larger sample is indicated to evaluate the effects of each protocol on cardiometabolic risk factors.