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 (SciVal)


Objective: To compare the phase II oxygen uptake time constant (τV′O 2) and V′O 2 mean response time (V′O 2 MRT) 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′O 2 (V′O 2peak) and gas exchange threshold (GET). Gas exchange was measured breath-by-breath using a mass spectrometer. On subsequent visits, 6 square-wave transitions (≤2 per day) from 0 W to 90% GET were completed. Individual phase II τV′O 2 and V′O 2 MRTs were estimated from time aligned average V′O 2 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′O 2 (30.2±9.6 vs 22.8±7.1 s, P<0.05) and V′O 2 MRT (43.5±10.7 vs 36.3±5.3 s, P<0.05) were significantly slower in OW compared with NO children; absolute V′O 2peak 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′O 2peak 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′O 2peak was similar between OW and NO groups whether relative to body mass 0.67 (139.8±29.1 vs 147.2±23.9 ml kg -67 min -1) or stature 3 (576.0±87.2 vs 544.9±84.9 ml m -3 min -1) (P>0.05); absolute V′O 2 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′O 2peak 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′O 2 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
JournalInternational Journal of Obesity
Issue number1
Early online date20 Aug 2012
Publication statusPublished - Jan 2013


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