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2013, Number 1

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Rev Hosp Jua Mex 2013; 80 (1)

The on- and off-transient phase two VO2 kinetics during submaximal exercise in young men

Padilla-Pérez J

Language: Spanish
References: 20
Page: 6-13
PDF size: 202.80 Kb.


ABSTRACT

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 (τ, time constant two) on-off symmetry (Φ2 VO2: τon similar τoff) 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., τ2) were determined for each component. Results. Our best statistically and/ or physiologically fitting models showed symmetry τ2 values for Mod with 2C7PEntire 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,7POmitting phase 1VO2 off-transient response, and for HvyRel (25.30 ± 7.0 s) with 3C10PEntire VO2 on-transient response (great mean τ2: on = 25.36 ± 9.5 s, off = 23.44 ± 6.2 s). Conclusion. The symmetry between the on- and off-transient Φ2 VO2 kinetics is strikingly influenced by the dynamics of the VO2 during muscular submaximal exercise in young adult men.


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