The oxygen uptake kinetic response to moderate intensity exercise in overweight and non-overweight children

C.R. Potter, J.K. Zakrzewski, S.B. Draper, V.B. Unnithan

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Objective:To compare the phase II oxygen uptake time constant (τV′O2) and V′O2 mean response time (V′O2MRT) in overweight (OW) and non-OW (NO) children during moderate intensity exercise.
Design:Between subjects where participants completed a maximal ramp exercise test on an electromagnetically braked cycle ergometer to determine peak V′O2 (V′O2peak) and gas exchange threshold (GET). Gas exchange was measured breath-by-breath using a mass spectrometer. On subsequent visits, 6 square-wave transitions (less than or equal to2 per day) from 0 W to 90% GET were completed. Individual phase II τV′O2 and V′O2MRTs were estimated from time aligned average V′O2 traces.
Subjects:Eleven OW (11.8±0.4 years) and 12 NO (11.9±0.4 years) children were recruited to the study. The OW group was significantly heavier (62.9±9.7 vs 39.4±5.8 kg, P<0.001), taller (1.58±0.05 vs 1.47±0.07 m, P<0.001) and had a higher body mass index (25.8±3.4 vs 18.3±1.8 kg m−2, P<0.001).
Results:Both τV′O2 (30.2±9.6 vs 22.8±7.1 s, P<0.05) and V′O2MRT (43.5±10.7 vs 36.3±5.3 s, P<0.05) were significantly slower in OW compared with NO children; absolute V′O2peak was higher in the OW compared with NO group (2.23±0.04 vs 1.74±0.04 l min−1, P<0.05); mass relative V′O2peak was lower in OW compared with NO children (35.9±8.3 vs 43.8±6.2 ml kg−1 min−1, P<0.05); allometrically scaled V′O2peak was similar between OW and NO groups whether relative to body mass0.67 (139.8±29.1 vs 147.2±23.9 ml kg−67 min−1) or stature3 (576.0±87.2 vs 544.9±84.9 ml m−3 min−1) (P>0.05); absolute V′O2 at GET was similar between OW and NO groups (0.94±0.24 vs 0.78±0.27 l min−1, P>0.05); GET expressed as percentage of V′O2peak was similar between the groups (42.0±0.1 vs 44.8±0.1%, P>0.05).
Conclusion:These findings demonstrate impairment in the factors determining V′O2 kinetics in OW children at a relatively young age. Furthermore, assessment of cardiorespiratory fitness using peak exercise values is likely to be misleading and not useful when designing exercise programmes for OW children.
Original languageEnglish
Pages (from-to)101-106
Number of pages6
JournalInternational Journal of Obesity
Publication statusPublished - Jan 2013


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