ORIGINAL ARTICLE

Elucidating determinants of the plateau in oxygen consumption at O₂MAX

T A Astorino¹, J Willey², J Kinnahan², S M Larsson², H Welch² and L C Dalleck³

¹ CSU, San Marcos, CA, USA
² Salisbury University, Salisbury, MD, USA
³ University of New Mexico, Albuquerque, NM, USA

Correspondence to:
Correspondence to:
T A Astorino
CSU, San Marcos, CA 92096, USA; astorino{at}csusm.edu

Background: A plateau in oxygen consumption (O₂) is the primary means of confirming that maximal oxygen uptake (O₂MAX) is attained during incremental exercise to fatigue. However, it is still unresolved what causes expression of a plateau in O₂ at the end of incremental exercise.

Objectives: To elucidate incidence and identify determinants of the O₂ plateau in subjects of varying fitness.

Methods: Thirty subjects (mean (SD) age and O₂MAX 26.9 (9.8) years and 3.4 (0.8) litre/min respectively) were separated into three groups: endurance trained (ET; n = 9), recreationally active (Rec; n = 11), and strength/sprint trained (STR; n = 10). During three separate visits, subjects completed incremental treadmill exercise during which breath by breath gas exchange data were obtained. Body composition was measured using a three site skinfolds model. Force production of the knee extensors and flexors was assessed using isokinetic dynamometry.

Results: O₂MAX was significantly higher (p<0.05) in the ET group vs STR and Rec. The change in O₂ (O₂) at O₂MAX was not different (p>0.05) in the ET group (33.0 (27.3) ml/min) compared with the Rec group (30.3 (24.1) ml/min) and the STR group (44.4 (23.8) ml/min). No correlations (p>0.05) were evident between O₂ at O₂MAX and O₂MAX (r = 0.05), fat-free mass (r = 0.12), and muscular strength (r = –0.12).

Conclusions: The incidence of a plateau in O₂ at O₂MAX (from correlation data) is not due to factors related to training status or physical fitness of subjects, but is altered by analysis and interpretation of gas exchange data.

Abbreviations: FFM, fat-free mass; O₂MAX, maximal oxygen consumption

Keywords: maximal oxygen uptake; incremental exercise; sampling interval; treadmill running

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Commentary

R J Shephard⁴

⁴ PO Box 521, Brackendale, Canada VON 1HO; royjshep{at}shaw.ca

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