In obesity, the increased O cost of breathing negatively affects the O cost of exercise and exercise tolerance. The purpose of the study was to determine whether, in obese adolescents, the addition of respiratory muscle endurance training (RMET) (isocapnic hyperpnea) to a standard body mass reduction program decreases the O cost of exercise and perceived exertion. Nine male obese adolescents [16.0 ± 1.4 yr ( ± SD), body mass 114.4 ± 22.3 kg] underwent 3 wk of RMET (5 days/week) in addition to a standard body mass reduction program. Eight age- and sex-matched obese adolescents underwent only the standard program (CTRL). Before and after interventions, patients performed on a cycle ergometer: incremental exercise; 12-min exercises at a constant work rate (CWR) of 65% and 120% at the gas exchange threshold (GET) determined before the intervention. Breath-by-breath pulmonary ventilation (V̇e) and O uptake (V̇o), heart rate (HR), and ratings of perceived exertion for dyspnea/respiratory discomfort (RPE) and leg effort (RPE) were determined. Body mass decreased (by ~3.0 kg) after both RMET ( = 0.003) and CTRL ( = 0.002). Peak V̇o was not affected by both interventions. Peak work rate was slightly, but significantly ( = 0.04), greater after RMET but not after CTRL. During CWR < GET, no changes were observed after both interventions. During CWR > GET, the O cost of cycling at the end of exercise ( = 0.02), the slope of V̇o vs. time (3-12 min) ( = 0.01), RPE ( = 0.01), and RPE ( = 0.01) decreased following RMET, but not following CTRL. HR decreased after both RMET ( = 0.02) and CTRL ( = 0.03), whereas V̇e did not change. In obese adolescents RMET, superimposed on a standard body mass reduction program, lowered the O cost of cycling and perceived exertion during constant heavy-intensity exercise.

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Background: Whole body vibration (WBV) has been reported to exert growth hormone(GH)-releasing effects in healthy subjects. Despite the potential of WBV to positively affect body composition changes via lipolytic effects, few studies have been performed in obese subjects to date. Methods: This studyevaluated the acute effects of WBV alone or in combination with squatting plus external load (WBV+S) on serum GH levels and blood lactate concentrations in 7 severely obese women (age 22 ± 5 years; BMI 39.9 ± 2.9 kg/m²). Results: WBV and WBV+S determined a significant GH increase (mean GH peaks 5.1 ± 1.9 ng/ml, p < 0.001 vs. basal, and 6.5 ± 3.7 ng/ml, p < 0.001 vs. basal, respectively), GH peaks occurring immediately after both exercise sessions. No significant differences were observed between GH peaks and GH net incremental area under the curve (nAUC) after both conditions (p = 0.39 and p = 0.53, respectively), the whole pattern of GH responsiveness being comparable among all the subjects. Lactate concentrations increased after both conditions (mean lactate peaks 2.0 ± 0.5 mmol/l, p < 0.05 vs. basal, and 4.5 ± 2.0 mmol/l, p < 0.001 vs. basal, respectively). The lactate response was significantly higher after WBV+S than after WBV (p < 0.05). Baseline GH and GH peak values positively correlated to baseline lactate and lactate peak concentrations in both conditions (R² = 0.64, p < 0.001, and R² = 0.52, p < 0.05, respectively). Conclusions: WBV alone stimulates GH release and lactate production in severely obese female subjects, with no additive effect when combined with squatting plus external load. Further additional studies are required to verify the chronic effects of WBV exercise on the GH/IGF-1 system, which could represent a potentially effective approach for weight management in obese subjects.