Elucidating determinants of the plateau in oxygen consumption at V̇O2MAX

Abstract

Background: A plateau in oxygen consumption (V̇O2) is the primary means of confirming that maximal oxygen uptake (V̇O2MAX) is attained during incremental exercise to fatigue. However, it is still unresolved what causes expression of a plateau in V̇O2 at the end of incremental exercise. Objectives: To elucidate incidence and identify determinants of the V̇O2 plateau in subjects of varying fitness. Methods: Thirty subjects (mean (SD) age and V̇O2MAX 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: V̇O2MAX was significantly higher (p<0.05) in the ET group vs STR and Rec. The change in V̇O 2 (ΔV̇O2) at V̇O2MAX 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 ΔV̇O2 at V̇O2MAX and V̇O2MAX (r = 0.05), fat-free mass (r = 0.12), and muscular strength (r = -0.12). Conclusions: The incidence of a plateau in V̇O2 at V̇O2MAX (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.