title: The effect of baseline metabolic rate on pulmonary O₂ uptake kinetics during very heavy intensity exercise in boys and men.
abstract: This study tested the hypothesis that pulmonary VO₂ kinetics would be slowed during 'work-to-work' exercise in adults but not in children. Eight boys (mean age=12.5 ± 0.5 years) and nine men completed very heavy step transitions initiated from either 'unloaded' pedalling (U→VH) or unloaded-to-moderate cycling (i.e. U→M to M→VH). The phase II τ was significantly (p<0.05) lengthened in M→VH compared to U→M and U→VH in boys (30 ± 5 vs. 19 ± 5 vs. 21 ± 5 s) and men (49 ± 14 vs. 30 ± 5 vs. 34 ± 8 s). In U→VH, a greater relative VO₂ slow component temporally coincided with an increased linear iEMG slope in men compared boys (VO₂ slow component: 16 ± 3 vs. 11 ± 4%; iEMG slope: 0.19 ± 0.24 vs. -0.06 ± 0.14%, p<0.05). These results suggest that an age-linked modulation of VO₂ kinetics might be influenced by alterations in muscle fibre recruitment following the onset of exercise.
authors.affiliation: Children's Health and Exercise Research Centre, College of Life and Environmental Sciences, University of Exeter, UK.
authors.forename: Brynmor C
authors.initials: BC
authors.lastname: Breese
authors.forename: Alan R
authors.initials: AR
authors.lastname: Barker
authors.forename: Neil
authors.initials: N
authors.lastname: Armstrong
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Jones
authors.forename: Craig A
authors.initials: CA
authors.lastname: Williams
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D000465:Algorithms; D002648:Child; D003627:Data Interpretation, Statistical; D004576:Electromyography; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007700:Kinetics; D007866:Leg / Q000294:innervation / Q000502:physiology; D008168:Lung / Q000378:metabolism*; D008297:Male; D008660:Metabolism / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011999:Recruitment, Neurophysiological / Q000502:physiology; D012132:Respiratory Muscles / Q000502:physiology