A functional evaluation of skeletal muscle oxidative metabolism in a group of obese adolescents (OB) was performed. The various components of pulmonary V'O(2) kinetics were evaluated during constant-load exercises (CLE) on a cycloergometer at different percentages of V'O(2)max, and the relationships of these components with the gas exchange threshold (GET) were determined. Fourteen male OB (age 16.5+/-1.0 [SD] years, body mass index 34.5+/-3.1 kgm(-2)) and 13 normal-weight, age-matched non-athletic male volunteers (CTRL) were studied. The time-constant (tauf) of the "fundamental component" and the presence, the pattern and the relative amplitude of the "slow component" of V'O(2) kinetics were determined at 40%, 60%, and 80% of V'O(2)max, previously estimated during an incremental test. V'O(2)max (L/min) was similar in the two groups. GET was lower in OB (54.4+/-7.1% of V'O(2)max) than in CTRL (65.1+/-5.2%). tauf was significantly higher in OB at the lowest and highest workloads. At CLE 60% (above GET in OB, below GET in CTRL) a slow component was observed in 9 out of 14 OB, but in no CTRL. All subjects developed a slow component at CLE 80% (above GET in both OB and CTRL). In OB the slow component was characterized by a different dynamic feature (linear increase in V'O(2)). The above findings negatively affect exercise tolerance in OB, and suggest an impairment of skeletal muscle oxidative metabolism. Also in OB exercise evaluation and prescription at submaximal loads should be done with respect of GET, and not at a given percentage of V'O(2)max.
Gas exchange kinetics in obese adolescents. Inferences on exercise tolerance and prescription
Lafortuna C;
2010
Abstract
A functional evaluation of skeletal muscle oxidative metabolism in a group of obese adolescents (OB) was performed. The various components of pulmonary V'O(2) kinetics were evaluated during constant-load exercises (CLE) on a cycloergometer at different percentages of V'O(2)max, and the relationships of these components with the gas exchange threshold (GET) were determined. Fourteen male OB (age 16.5+/-1.0 [SD] years, body mass index 34.5+/-3.1 kgm(-2)) and 13 normal-weight, age-matched non-athletic male volunteers (CTRL) were studied. The time-constant (tauf) of the "fundamental component" and the presence, the pattern and the relative amplitude of the "slow component" of V'O(2) kinetics were determined at 40%, 60%, and 80% of V'O(2)max, previously estimated during an incremental test. V'O(2)max (L/min) was similar in the two groups. GET was lower in OB (54.4+/-7.1% of V'O(2)max) than in CTRL (65.1+/-5.2%). tauf was significantly higher in OB at the lowest and highest workloads. At CLE 60% (above GET in OB, below GET in CTRL) a slow component was observed in 9 out of 14 OB, but in no CTRL. All subjects developed a slow component at CLE 80% (above GET in both OB and CTRL). In OB the slow component was characterized by a different dynamic feature (linear increase in V'O(2)). The above findings negatively affect exercise tolerance in OB, and suggest an impairment of skeletal muscle oxidative metabolism. Also in OB exercise evaluation and prescription at submaximal loads should be done with respect of GET, and not at a given percentage of V'O(2)max.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
