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Oxygen uptake kinetics of older humans are slowed with age but are unaffected by hyperoxia.
Exp Physiol 1999; 84(4):747-59EP

Abstract

Cross-sectional studies have compared the oxygen uptake (VO2) kinetics during the on-transient of moderate intensity exercise in older and younger adults. The slower values in the older adults may have been due to an age-related reduction in the capacity for O2 transport or alternatively a reduced intramuscular oxidative capacity. We studied: (1) the effects of ageing on VO2 kinetics in older adults on two occasions 9 years apart, and (2) the effect of hyperoxia on VO2 kinetics at the second test time. After a 9 year period, follow-up testing was undertaken on seven older adults (78 +/- 5 years, mean +/- S.D.). They each performed six repeats of 6 min bouts of constant-load cycle exercise from loadless cycling to 80% of their ventilatory threshold. They breathed one of two gas mixtures (euoxia: inspired O2 fraction, FI,O2, 0.21; hyperoxia: FI,O2, 0.70) on different trials determined on a random basis. Breath-by-breath VO2 data were time aligned and ensemble averaged. VO2 kinetics, modelled with a single exponential from phase 2 onset (+20 s) to steady state and described by the exponential time constant (tau) were compared with data collected from the same adults 9 years earlier. One-way repeated measures analysis of variance revealed that tau was slowed significantly with age (from 30 +/- 8 to 46 +/- 10 s), but was unaffected by hyperoxia (43 +/- 15 s). We concluded that: (1) in older adults studied longitudinally over a 9 year period, the on-transient VO2 kinetics are slowed, in agreement with, but to a greater extent, than from cross-sectional data; and (2) the phase 2 time constant (tau) for these older adults was not accelerated by hyperoxic breathing. Thus the expected hyperoxia-induced increase in the capacity for O2 transport was not associated with faster on-transient VO2 kinetics suggesting either that O2 transport may not limit VO2 kinetics during the 8th decade, or that O2 transport was not improved with hyperoxia.

Authors+Show Affiliations

Centre for Activity and Ageing, School of Kinesiology, University of Western Ontario, London, Canada.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10481231

Citation

Bell, C, et al. "Oxygen Uptake Kinetics of Older Humans Are Slowed With Age but Are Unaffected By Hyperoxia." Experimental Physiology, vol. 84, no. 4, 1999, pp. 747-59.
Bell C, Paterson DH, Kowalchuk JM, et al. Oxygen uptake kinetics of older humans are slowed with age but are unaffected by hyperoxia. Exp Physiol. 1999;84(4):747-59.
Bell, C., Paterson, D. H., Kowalchuk, J. M., & Cunningham, D. A. (1999). Oxygen uptake kinetics of older humans are slowed with age but are unaffected by hyperoxia. Experimental Physiology, 84(4), pp. 747-59.
Bell C, et al. Oxygen Uptake Kinetics of Older Humans Are Slowed With Age but Are Unaffected By Hyperoxia. Exp Physiol. 1999;84(4):747-59. PubMed PMID: 10481231.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oxygen uptake kinetics of older humans are slowed with age but are unaffected by hyperoxia. AU - Bell,C, AU - Paterson,D H, AU - Kowalchuk,J M, AU - Cunningham,D A, PY - 1999/9/11/pubmed PY - 1999/9/11/medline PY - 1999/9/11/entrez SP - 747 EP - 59 JF - Experimental physiology JO - Exp. Physiol. VL - 84 IS - 4 N2 - Cross-sectional studies have compared the oxygen uptake (VO2) kinetics during the on-transient of moderate intensity exercise in older and younger adults. The slower values in the older adults may have been due to an age-related reduction in the capacity for O2 transport or alternatively a reduced intramuscular oxidative capacity. We studied: (1) the effects of ageing on VO2 kinetics in older adults on two occasions 9 years apart, and (2) the effect of hyperoxia on VO2 kinetics at the second test time. After a 9 year period, follow-up testing was undertaken on seven older adults (78 +/- 5 years, mean +/- S.D.). They each performed six repeats of 6 min bouts of constant-load cycle exercise from loadless cycling to 80% of their ventilatory threshold. They breathed one of two gas mixtures (euoxia: inspired O2 fraction, FI,O2, 0.21; hyperoxia: FI,O2, 0.70) on different trials determined on a random basis. Breath-by-breath VO2 data were time aligned and ensemble averaged. VO2 kinetics, modelled with a single exponential from phase 2 onset (+20 s) to steady state and described by the exponential time constant (tau) were compared with data collected from the same adults 9 years earlier. One-way repeated measures analysis of variance revealed that tau was slowed significantly with age (from 30 +/- 8 to 46 +/- 10 s), but was unaffected by hyperoxia (43 +/- 15 s). We concluded that: (1) in older adults studied longitudinally over a 9 year period, the on-transient VO2 kinetics are slowed, in agreement with, but to a greater extent, than from cross-sectional data; and (2) the phase 2 time constant (tau) for these older adults was not accelerated by hyperoxic breathing. Thus the expected hyperoxia-induced increase in the capacity for O2 transport was not associated with faster on-transient VO2 kinetics suggesting either that O2 transport may not limit VO2 kinetics during the 8th decade, or that O2 transport was not improved with hyperoxia. SN - 0958-0670 UR - https://www.unboundmedicine.com/medline/citation/10481231/Oxygen_uptake_kinetics_of_older_humans_are_slowed_with_age_but_are_unaffected_by_hyperoxia_ L2 - https://medlineplus.gov/seniorshealth.html DB - PRIME DP - Unbound Medicine ER -