Abstract
A functional evaluation of skeletal muscle oxidative metabolism was performed in a group of obese adolescents (OB). The various components of pulmonary O2 uptake (V̇O2) kinetics were evaluated during 10-min constant-load exercises (CLE) on a cycloergometer at different percentages of V̇O2max. The relationships of these components with the gas exchange threshold (GET) were determined. Fourteen male OB [age 16.5 ± 1.0 (SD) yr, body mass index 34.5 ± 3.1 kg·m -2] and 13 normal-weight, age-matched nonathletic male volunteers (control group) were studied. The time-constant (τf) of the fundamental component and the presence, pattern, and relative amplitude of the slow component of V̇O2 kinetics were determined at 40, 60, and 80% of V̇O2max, previously estimated during an incremental test. V̇O2max (l/min) was similar in the two groups. GET was lower in OB (55.7 ± 6.7% of V̇O2max) than in control (65.1 ± 5.2%) groups. The τf was higher in OB subjects, indicating a slower fundamental component. At CLE 60% (above GET in OB subjects, below GET in control subjects) a slow component was observed in nine out of fourteen OB subjects, but none in the control group. All subjects developed a slow component at CLE 80% (above GET in both OB and control). Twelve OB subjects did not complete the 10-min CLE 80% due to voluntary exhaustion. In nine OB subjects, the slow component was characterized by a linear increase in V̇O2 as a function of time. The slope of this increase was inversely related to the time to exhaustion. The above findings should negatively affect exercise tolerance in obese adolescents and suggest an impairment of skeletal muscle oxidative metabolism. Also in obese adolescents, exercise evaluation and prescription at submaximal loads should be done with respect to GET and not at a given percentage of V̇O2max.
| Original language | English |
|---|---|
| Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
| Volume | 299 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - Nov 2010 |
Fingerprint
Keywords
- O uptake kinetics
- Obesity
- Oxidative metabolism
- Slow component
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
Cite this
Gas exchange kinetics in obese adolescents. Inferences on exercise tolerance and prescription. / Salvadego, Desy; Lazzer, Stefano; Busti, Carlo; Galli, Raffaela; Agosti, Fiorenza; Lafortuna, Claudio; Sartorio, Alessandro; Grassi, Bruno.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 299, No. 5, 11.2010.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Gas exchange kinetics in obese adolescents. Inferences on exercise tolerance and prescription
AU - Salvadego, Desy
AU - Lazzer, Stefano
AU - Busti, Carlo
AU - Galli, Raffaela
AU - Agosti, Fiorenza
AU - Lafortuna, Claudio
AU - Sartorio, Alessandro
AU - Grassi, Bruno
PY - 2010/11
Y1 - 2010/11
N2 - A functional evaluation of skeletal muscle oxidative metabolism was performed in a group of obese adolescents (OB). The various components of pulmonary O2 uptake (V̇O2) kinetics were evaluated during 10-min constant-load exercises (CLE) on a cycloergometer at different percentages of V̇O2max. The relationships of these components with the gas exchange threshold (GET) were determined. Fourteen male OB [age 16.5 ± 1.0 (SD) yr, body mass index 34.5 ± 3.1 kg·m -2] and 13 normal-weight, age-matched nonathletic male volunteers (control group) were studied. The time-constant (τf) of the fundamental component and the presence, pattern, and relative amplitude of the slow component of V̇O2 kinetics were determined at 40, 60, and 80% of V̇O2max, previously estimated during an incremental test. V̇O2max (l/min) was similar in the two groups. GET was lower in OB (55.7 ± 6.7% of V̇O2max) than in control (65.1 ± 5.2%) groups. The τf was higher in OB subjects, indicating a slower fundamental component. At CLE 60% (above GET in OB subjects, below GET in control subjects) a slow component was observed in nine out of fourteen OB subjects, but none in the control group. All subjects developed a slow component at CLE 80% (above GET in both OB and control). Twelve OB subjects did not complete the 10-min CLE 80% due to voluntary exhaustion. In nine OB subjects, the slow component was characterized by a linear increase in V̇O2 as a function of time. The slope of this increase was inversely related to the time to exhaustion. The above findings should negatively affect exercise tolerance in obese adolescents and suggest an impairment of skeletal muscle oxidative metabolism. Also in obese adolescents, exercise evaluation and prescription at submaximal loads should be done with respect to GET and not at a given percentage of V̇O2max.
AB - A functional evaluation of skeletal muscle oxidative metabolism was performed in a group of obese adolescents (OB). The various components of pulmonary O2 uptake (V̇O2) kinetics were evaluated during 10-min constant-load exercises (CLE) on a cycloergometer at different percentages of V̇O2max. The relationships of these components with the gas exchange threshold (GET) were determined. Fourteen male OB [age 16.5 ± 1.0 (SD) yr, body mass index 34.5 ± 3.1 kg·m -2] and 13 normal-weight, age-matched nonathletic male volunteers (control group) were studied. The time-constant (τf) of the fundamental component and the presence, pattern, and relative amplitude of the slow component of V̇O2 kinetics were determined at 40, 60, and 80% of V̇O2max, previously estimated during an incremental test. V̇O2max (l/min) was similar in the two groups. GET was lower in OB (55.7 ± 6.7% of V̇O2max) than in control (65.1 ± 5.2%) groups. The τf was higher in OB subjects, indicating a slower fundamental component. At CLE 60% (above GET in OB subjects, below GET in control subjects) a slow component was observed in nine out of fourteen OB subjects, but none in the control group. All subjects developed a slow component at CLE 80% (above GET in both OB and control). Twelve OB subjects did not complete the 10-min CLE 80% due to voluntary exhaustion. In nine OB subjects, the slow component was characterized by a linear increase in V̇O2 as a function of time. The slope of this increase was inversely related to the time to exhaustion. The above findings should negatively affect exercise tolerance in obese adolescents and suggest an impairment of skeletal muscle oxidative metabolism. Also in obese adolescents, exercise evaluation and prescription at submaximal loads should be done with respect to GET and not at a given percentage of V̇O2max.
KW - O uptake kinetics
KW - Obesity
KW - Oxidative metabolism
KW - Slow component
UR - http://www.scopus.com/inward/record.url?scp=78149487248&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78149487248&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.00038.2010
DO - 10.1152/ajpregu.00038.2010
M3 - Article
VL - 299
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6119
IS - 5
ER -