Respiratory muscle endurance training reduces the O2 cost of cycling and perceived exertion in obese adolescents

In obesity, the increased O 2 cost of breathing negatively affects the O 2 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 2 cost of exercise and perceived exertion. Nine male obese adolescents [16.0 ± 1.4 yr ( x ± 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 2 uptake (V̇o 2 ), heart rate (HR), and ratings of perceived exertion for dyspnea/respiratory discomfort (RPE R ) and leg effort (RPE L ) were determined. Body mass decreased (by ~3.0 kg) after both RMET ( P = 0.003) and CTRL ( P = 0.002). Peak V̇o 2 was not affected by both interventions. Peak work rate was slightly, but significantly ( P = 0.04), greater after RMET but not after CTRL. During CWR GET, the O 2 cost of cycling at the end of exercise ( P = 0.02), the slope of V̇o 2 vs. time (3–12 min) ( P = 0.01), RPE R ( P = 0.01), and RPE L ( P = 0.01) decreased following RMET, but not following CTRL. HR decreased after both RMET ( P = 0.02) and CTRL ( P = 0.03), whereas V̇e did not change. In obese adolescents RMET, superimposed on a standard body mass reduction program, lowered the O 2 cost of cycling and perceived exertion during constant heavy-intensity exercise.