The effect of intensity of interval training on fat oxidation, blood lactate and rating of perceived exertion in obese men (#69)
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, insulin sensitivity 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.m2) 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 insulin sensitivity using the homeostasis model assessment of insulin resistance (HOMA-IR), 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 or HOMA-IR with either intervention. There was a significant increase 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). It decreased after HIIT greater than MIIT, but 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 during HIIT greater than MIIT.