Article

A plateau in oxygen consumption ((V) over dot O-2) is the primary means of confirming that maximal oxygen uptake ((V) over dot O(2)MAX) is attained during incremental exercise to fatigue. However, it is still unresolved what causes expression of a plateau in (V) over dot O-2 at the end of incremental exercise. Objectives: To elucidate incidence and identify determinants of the (V) over dot O-2 plateau in subjects of varying fitness. Methods: Thirty subjects ( mean (SD) age and (V) over dot O(2)MAX 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: (V) over dot O(2)MAX was significantly higher ( p< 0.05) in the ET group vs STR and Rec. The change in (V) over dot O-2 ( DV. O2) at V. 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 Delta(V) over dot O-2 at (V) over dot O(2)MAX and (V) over dot O(2)MAX (r = 0.05), fat-free mass ( r = 0.12), and muscular strength ( r = -0.12). Conclusions: The incidence of a plateau in (V) over dot O-2 at (V) over dot O(2)MAX ( 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.

Langue : ANGLAIS

Tiré à part : OUI