Resumen

We kinetically assessed pulmonary oxygen uptake (O₂) off-transient (P_ost-E_xercise R_ecovery) response during moderate (M)- and heavy (H)-intensity (Sub = M + H) exercise comparing among several common modelling strategies to assess the best fitting exponential model. The parameter estimated for phase 2 VO₂ was the time constant (off-τΦ₂VO₂) in older male adults [n = 9; 72 (±4) yrs; mean (±sd)]. Subjects performed an incremental ramp test (12 W•min^-1) to the limit of tolerance to determine O_2peak and the estimated lactate threshold (V_ET). Constant-load cycle exercise was performed at 50 W (M) and work rates corresponding to 80% (M) and 120% V_ET (H). Each transition in work rate lasted 6 min and was preceded by 6 min cycling at a baseline of 20 W; transitions at each intensity were repeated 4-6 times. O₂ was measured breath-by-breath. Each subject pedalled at 60 rpm and protocol began with a base line off 1 min end exercise load-cycling, followed by a step decrease in power output (without warning the subject) back to loadless cycling lasting 6 min in duration (PER). Data from each transition were filtered, interpolated to 1 s intervals and ensemble-averaged to yield a single response profile for each subject and intensity. Responses were modelled by means of nonlinear regression techniques with one-(1C), two-(2C) and three-component (time delay) (3C) exponential models using different fitting windows. The off-Φ₂VO₂ for Sub was both physiologically and stastistically well described and kinetically characterized (off-τ₂VO₂) by a two component doble exponential function (2C) for M (^aτ₂ = 56 ± 14 s)-, and by a threecomponent triple exponential function (3C) (^bτ₂ = 39 ± 7, ^a≠bP < 0.05) for H in old men.

Palabras clave: Old men post-exercise recovery off-O₂ uptake kinetics phase two O₂ exponential modelling time constant.

2014-09-09   |   629 visitas   |   Evalua este artículo 0 valoraciones

Vol. 81 Núm.2. Abril-Junio 2014 Pags. 92-103 Rev Hosp Jua Mex 2014; 81(2)