High-intensity Training And A Low-caloric-diet Improves Maximal Oxygen Consumption And Body Composition In Overweight Adults

Abstract

Obesity and low cardiorespiratory fitness are global challenges causing a massive burden on the health care system worldwide. Thus, efficient exercise and nutritional interventions are warranted. PURPOSE: We investigate the effect of high-intensity training executed as full body circuit training and a calorie-restricted diet plan on cardiorespiratory fitness and body composition in overweight sedentary adults. METHODS: Sedentary overweight men (n = 34) and women (n = 46) were recruited. The selection criteria were a sedentary lifestyle for the last five years, an age range of 25-55 yrs and a body mass index >25. The study was a randomized controlled trial, where participants were randomized gender-specifically into a high-intensity training group (HIT; age 38 ± 9 (25-54) yrs; height 174 ± 10 cm; weight 96.1 ± 19.3 kg; n = 40) and control group (CON; age 39 ± 7 (27-52) yrs, height 168 ± 8 cm, weight 89.9 ± 17.2 kg; n = 40). HIT completed full-body high-intensity circuit training with 2-4 weekly sessions combined with a calorie-restricted dietary plan for 8 wks. CON had no training or lifestyle changes in the same interval. VO2max-tests and body composition assessments were performed at baseline and post-intervention. RESULTS: VO2max was 2.3 ± 0.6 and 2.1 ± 0.5 L⸱min-1 at baseline in HIT and CON respectively and did not change during the intervention period. However, VO2max adjusted for body weight improved (P < 0.05) by ~7% in HIT (24.5 ± 5.1 vs 25.7 ± 5.5 ml⸱min-1⸱kg-1) during the intervention period with greater (P < 0.05) change score than CON where a reduction (P < 0.05) of ~5% (24.1 ± 5.1 vs 22.6 ± 4.6 ml⸱min-1⸱kg-1) was observed. Body weight decreased (P < 0.05) by 5.9 ± 3.2 kg post-intervention in HIT with higher (P < 0.05) change score than CON (+0.3 ± 1.6 kg). Also, BMI declined (P < 0.05) from 31.8 ± 5.5 to 29.9 ± 4.4 kg/m2 in HIT only. Body fat content was also lowered (P < 0.05) from 32.0 ± 9.5% at baseline to 30.9 ± 9.3% post-intervention in HIT with a greater change score compared to CON. No change was observed in skeletal muscle mass in neither HIT nor CON. CONCLUSION: High-intensity training performed as full body circuit training combined with a caloric-restricted diet over an eight-week period moderately improved body weight adjusted VO2max, but induced a marked weight loss and reduction in body fat content in overweight sedentary adults.