Resumen

Material and methods: We assessed in young healthy male volunteers if the fundamental VO₂ response (Φ₂ VO₂) to submaximal exercise (on-transient response) and its recovery (off-transient response) show in the Φ₂ VO₂ kinetics (Φ, time constant two) on-off symmetry (Φ₂ VO₂: τ_on similar τ_off) characterised from best exponential fitting models. Subjects (n = 8; mean ± SD: 25.2 ± 3.0 yrs) completed an initial incremental ramp test (25 W•min_-1) to volitional fatigue from which the ventilatory threshold (θ) and work rates corresponding to 80% θ(ModRel) and 120% q (HvyRel) were identified, plus a selected “absolute” work rate of 50 W (ModAbs) (submaximal exercise). On and off step-transitions in work rate were initiated from a baseline without warning to the subject. Each transition (on, off) lasted 6 min and 4-6 transitions were performed at each intensity. The VO₂ response was measured breath-by-breath at baseline and throughout each transition. Data were filtered, interpolated to 1-s intervals and ensemble-averaged to yield a single response profile for each subject and intensity. The averaged response for each subject was fit with a two- (2C), and three-component (3C) exponential model by using different fitting windows, and parameter (P) estimates (i.e., θ₂) were determined for each component. Results: Our best statistically and/or physiologically fitting models showed symmetry τ2 values for Mod with 2C7P_{Entire VO2} on (Abs = 23.21 ± 12.1 s, Rel = 28.30 ± 9.1 s)-, and off (Abs = 25.08±8.4 s)-transient responses; for Rel (Mod = 22.50 ± 4.2 s, Hvy = 22.8 ± 6.0 s) with 2C,7P_{Omitting phase 1VO2off-transient response}, and for HvyRel (25.30±7.0 s) with 3C10P_{Entire VO2 on-transient response} (great mean θ2: on = 25.36 ± 9.5 s, off = 23.44 ± 6.2 s). Conclusion: The symmetry between the on- and off-transient θ₂VO₂ kinetics is strikingly influenced by the dynamics of the VO₂ during muscular submaximal exercise in young adult men.

Palabras clave: O₂ uptake kinetics on- and off-phase two O₂ time constant young adults.

2014-01-29   |   427 visitas   |   Evalua este artículo 0 valoraciones

Vol. 80 Núm.1. Enero-Marzo 2013 Pags. 6-13 Rev Hosp Jua Mex 2013; 80(1)