BackgroundHigh intensity exercise is considered as an effective means for reducing body fat. The aims of the present study were to investigate (1) whether body mass would be lost and body composition would change and (2) whether variables of anaerobic fitness prior to the intervention period would be related to loss of body mass and changes in body composition in overweight and obese children and adolescents.MethodsA total of 28 children and adolescents (19 boys, 9 girls) attended an 8-week multicomponent inpatient program. Caloric intake was based on the subject’s weight and a daily energy deficit of ~500 kcal was targeted. At the beginning and at the end of the program, variables of anaerobic fitness were assessed using Wingate tests. Body composition was measured before and after the program using dual-energy X-ray absorptiometry.ResultsBody mass decreased by 11.4% ± 1.6% in boys and by 11.0% ± 2.8% in girls (P < 0.001). Fat mass decreased by 23.8% ± 6.1% in boys and by 21.5% ± 5.2% in girls (P < 0.001). The decrease in fat mass was associated with the decrease in body mass in boys (r = 0.54, P = 0.017) but not in girls (P > 0.05). The decrease in body mass and the decrease in fat mass were neither associated with overall energy expenditure nor with the energy deficit in both genders (P > 0.05). Mean power in W/kg increased in the Wingate tests by 95.4% ± 109.1% in boys and by 100.0% ± 119.9% in girls (P < 0.001).ConclusionsAdjustments of the chronically positive imbalance of energy intake and energy expenditure of obese children and adolescents living in obesogenic environments should be addressed in a multisectoral approach. Future research in multicomponent childhood and adolescent weight loss programs should be directed towards a better understanding of the underlying complex dynamics in energy homeostasis which promote weight loss and changes in body composition due to high intensity exercise interventions.

Exercise in water compared to land-based exercise (LE) results in a higher release of natriuretic peptides, which are involved in the regulation of exercise-induced adipose tissue lipolysis. The present study was performed to compare the release of atrial natriuretic peptide (ANP) and free fatty acids (FFA) during prolonged aerobic water-based exercise (WE) with the release after an identical LE. 14 untrained overweight subjects performed 2 steady state workload tests on the same ergometer in water and on land. Before and after exercise, venous blood samples were collected for measuring ANP, FFA, epinephrine, norepinephrine, insulin and glucose. The respiratory exchange ratio (RER) was determined for fat oxidation.The exercises resulted in a significant increase in ANP in LE (61%) and in WE (177%), and FFA increased about 3-fold in LE and WE with no significant difference between the groups. Epinephrine increased, while insulin decreased similarly in both groups. The RER values decreased during the exercises, but there was no significant difference between LE and WE. In conclusion, the higher ANP concentrations in WE had no additional effect on lipid mobilization, FFA release and fat oxidation. Moderate-intensity exercises in water offer no benefit regarding adipose tissue lipolysis in comparison to LE.

Background: It is generally assumed that the physical properties of water improve aerobic metabolism by O 2 utilization of the working muscle particular if a great muscle mass is recruited. This study investigated the changes in VO 2 (VO 2 -work rate relationship; ∆ VO 2 / ∆ WR) during increasing work rates in different exercise conditions in water immersed exercise and on land based exercise. Methods: In order to identify possible differences in VO 2 required for a given work rate twelve trained cyclists performed four incremental exercise tests. The tests comprised whole body work and leg work, both in water and on land and were conducted on the same, electromagnetically braked whole body ergometer. Results: The ∆ VO 2 / ∆ WR curves were found to be similar in the four exercise conditions reaching from 11.9 to 12.4 ml·W -1 during water immersed exercise and 12.6 to 12.7 ml·W -1 during land based exercise respectively. When coupling arms with leg exercise the ∆ VO 2 / ∆ WR curves shift upwards at similar work rates indicating a higher oxygen demand for an enlarged muscle mass. The extra O 2 cost ( ∆ VO 2 ) for recruited arms was lower in water immersed exercise compared to land based exercise (0.057±0.072 l ·min -1 and 0.367 1±0.057·min -1 , respectively; p=.000). Differences exist in the rate of performing physical work above ventilatory threshold two. Work load values attained on land based exercise surpass that of water immersed exercise (204.2 watts vs. 154.0 watts for whole body work and 227.1 watts vs. 150.0 watts for leg work, respectively). Conclusions: Differences in ∆ VO 2 at a given work rate are to be explained rather from a biomechanical point of view. More likely ∆ VO 2 in water seems to be influenced by both familiarity of the task and fitness level. Exercise intensity in water need to be selected at lower levels than on land.