Effect of interval training intensity on fat oxidation, blood lactate and the rate of perceived exertion in obese men
Shaea A Alkahtani1, Neil A King, Andrew P Hills
1School of Exercise and Nutrition Sciences, Queensland University of Technology, Australia & University of Dammam, P.O. Box 2375, Dammam, 31451 Saudi Arabia.
Purpose:
The objectives of this study were to examine the effect of 4-week moderate- and high-intensity interval training (MIIT and HIIT) on fat oxidation and the responses of blood lactate (BLa) and rating of perceived exertion (RPE).
Methods:
Ten overweight/obese men (age = 29 ±3.7 years, BMI = 30.7 ±3.4 kg/m(2)) participated in a cross-over study of 4-week MIIT and HIIT training. The MIIT training sessions consisted of 5-min cycling stages at mechanical workloads 20% above and 20% below 45%VO2peak. The HIIT sessions consisted of intervals of 30-s work at 90%VO2peak and 30-s rest. Pre- and post-training assessments included VO2max using a graded exercise test (GXT) and fat oxidation using a 45-min constant-load test at 45%VO2max. BLa and RPE were also measured during the constant-load exercise test.
Results:
There were no significant changes in body composition with either intervention. There were significant increases in fat oxidation after MIIT and HIIT (p ≤ 0.01), with no effect of intensity. BLa during the constant-load exercise test significantly decreased after MIIT and HIIT (p ≤ 0.01), and the difference between MIIT and HIIT was not significant (p = 0.09). RPE significantly decreased after HIIT greater than MIIT (p ≤ 0.05).
Conclusion:
Interval training can increase fat oxidation with no effect of exercise intensity, but BLa and RPE decreased after HIIT to greater extent than MIIT.
