Abstract
Among various strategies of exercise intensification proposed for the management of obesity and type 2 diabetes, endurance training remains a well recognized procedure. When targeted with exercise calorimetry at levels where lipid oxidation is maximal (LIPOXmax), it has been shown to improve mitochondrial respiration, blood glucose control and blood lipids, low grade inflammation and body composition, even at low weekly volume. We investigated in this study its long term effects over 3 years (3x45 min/week) compared to low fat diet without exercise (LFD) and a control group without any exercise or diet (C). 88 subjects that continued LIPOXmax training more than 1 year (23 men, 65 women, age=20-85 years, body mass index =23-48 kg/m2) were compared to two matched groups (C and LFD). While C gained weight over this period, LFD and LIPOXmax group lose weight. Weight loss at 1 year was the same in exercise and diet group, but at 2 years and even more at 3 years there was a gradual weight regain in LFD so that results were better (p<0.01) in the exercise group who maintained weight loss in 80% of subjects. Average weight loss was -2,95 ± 0,37 kg after 3 months, -4,56 ± 0,68 kg after 1 year, -5,31 ± 1,26 kg at 2 years and -8,49 ± 2,39 kg at 3 years. The level at which LIPOXmax occurs is a predictor of weight loss at 1 year (r=-0,346 p<0,001) but not at 2 and 3 years. Weight loss at 3 months is a predictor of weight loss at 1 year (r=0,523 p<0,001) but not at 2 and 3 years. At 1 year subjects with LIPOX max in the lower quartile (<35% VO2max n=23) lose less weight than the others (-2.3 ± 0.98 vs -5.4 ± 0.83 p=0,05) but this difference vanishes over time. This study shows that this low intensity exercise training maintains its weight-reducing effect 3 years while diet is no longer efficient, and that this effect is initially related to muscular ability to oxidize lipids but that metabolic and behavioral adaptations have been further developed and contribute to a long lasting effect.