Silvia Pogliaghi1, Enrico Tam2,3, Carlo Capelli1. 1. Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy. 2. Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy. enrico.tam@univr.it. 3. Section of Movement Science, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Via Casorati, 43, 37132, Verona, Italy. enrico.tam@univr.it.
Abstract
PURPOSE: τ of the primary phase of [Formula: see text] kinetics during square-wave, moderate-intensity exercise mirrors that of PCr splitting (τPCr). Pre-exercise [PCr] and the absolute variations of PCr (∆[PCr]) occurring during transient have been suggested to control τPCr and, in turn, to modulate [Formula: see text] kinetics. In addition, [Formula: see text] kinetics may be slower when exercise initiates from a raised metabolic level, i.e., from a less-favorable energetic state. We verified the hypothesis that: (i) pre-exercise [PCr], (ii) pre-exercise metabolic rate, or (iii) ∆[PCr] may affect the kinetics of muscular oxidative metabolism and, therefore, τ. METHODS: To this aim, seven active males (23.0 yy ± 2.3; 1.76 m ± 0.06, [Formula: see text]: 3.32 L min-1 ± 0.67) performed three repetitions of series consisting of six 6-min step exercise transitions of identical workload interspersed with different times of recovery: 30, 60, 90, 120, 300 s. RESULTS: Mono-exponential fitting was applied to breath-by-breath [Formula: see text], so that τ was determined. τ decays as a first-order exponential function of the time of recovery (τ = 109.5 × e(-t/14.0) + 18.9 r2 = 0.32) and linearly decreased as a function of the estimated pre-exercise [PCr] (τ = - 1.07 [PCr] + 44.9, r2 = 0.513, P < 0.01); it was unaffected by the estimated ∆[PCr]. CONCLUSIONS: Our results in vivo do not confirm the positive linear relationship between τ and pre-exercise [PCr] and ∆[PCr]. Instead, [Formula: see text] kinetics seems to be influenced by the pre-exercise metabolic rate and the altered intramuscular energetic state.
PURPOSE: τ of the primary phase of [Formula: see text] kinetics during square-wave, moderate-intensity exercise mirrors that of PCr splitting (τPCr). Pre-exercise [PCr] and the absolute variations of PCr (∆[PCr]) occurring during transient have been suggested to control τPCr and, in turn, to modulate [Formula: see text] kinetics. In addition, [Formula: see text] kinetics may be slower when exercise initiates from a raised metabolic level, i.e., from a less-favorable energetic state. We verified the hypothesis that: (i) pre-exercise [PCr], (ii) pre-exercise metabolic rate, or (iii) ∆[PCr] may affect the kinetics of muscular oxidative metabolism and, therefore, τ. METHODS: To this aim, seven active males (23.0 yy ± 2.3; 1.76 m ± 0.06, [Formula: see text]: 3.32 L min-1 ± 0.67) performed three repetitions of series consisting of six 6-min step exercise transitions of identical workload interspersed with different times of recovery: 30, 60, 90, 120, 300 s. RESULTS: Mono-exponential fitting was applied to breath-by-breath [Formula: see text], so that τ was determined. τ decays as a first-order exponential function of the time of recovery (τ = 109.5 × e(-t/14.0) + 18.9 r2 = 0.32) and linearly decreased as a function of the estimated pre-exercise [PCr] (τ = - 1.07 [PCr] + 44.9, r2 = 0.513, P < 0.01); it was unaffected by the estimated ∆[PCr]. CONCLUSIONS: Our results in vivo do not confirm the positive linear relationship between τ and pre-exercise [PCr] and ∆[PCr]. Instead, [Formula: see text] kinetics seems to be influenced by the pre-exercise metabolic rate and the altered intramuscular energetic state.
Authors: T Scott Bowen; Scott R Murgatroyd; Daniel T Cannon; Thomas J Cuff; Allison F Lainey; Andrea D Marjerrison; Matthew D Spencer; Alan P Benson; Donald H Paterson; John M Kowalchuk; Harry B Rossiter Journal: Exp Physiol Date: 2011-06-24 Impact factor: 2.969