This study focused on the steady-state phase of exercise to evaluate the relative contribution of metabolic instability (measured with NIRS and haematochemical markers) and muscle activation (measured with EMG) to the oxygen consumption ([Formula: see text]) slow component ([Formula: see text]) in different intensity domains. We hypothesized that (i) after the transient phase, [Formula: see text], metabolic instability and muscle activation tend to increase differently over time depending on the relative exercise intensity and (ii) the increase in [Formula: see text] is explained by a combination of metabolic instability and muscle activation. Eight active men performed a constant work rate trial of 9 min in the moderate, heavy and severe intensity domains. [Formula: see text], root mean square by EMG (RMS), deoxyhaemoglobin by NIRS ([HHb]) and haematic markers of metabolic stability (i.e. [La-], pH, HCO3-) were measured. The physiological responses in different intensity domains were compared by two-way RM-ANOVA. The relationships between the increases of [HHb] and RMS with [Formula: see text] after the third min were compared by simple and multiple linear regressions. We found domain-dependent dynamics over time of [Formula: see text], [HHb], RMS and the haematic markers of metabolic instability. After the transient phase, the rises in [HHb] and RMS showed medium-high correlations with the rise in [Formula: see text] ([HHb] r = 0.68, p < 0.001; RMS r = 0.59, p = 0.002). Moreover, the multiple linear regression showed that both metabolic instability and muscle activation concurred to the [Formula: see text] (r = 0.75, [HHb] p = 0.005, RMS p = 0.042) with metabolic instability possibly having about threefold the relative weight compared to recruitment. Seventy-five percent of the dynamics of the [Formula: see text] was explained by [HHb] and RMS.

Metabolic instability vs fibre recruitment contribution to the [Formula: see text] slow component in different exercise intensity domains

Colosio, Alessandro L;Pogliaghi, Silvia
2021-01-01

Abstract

This study focused on the steady-state phase of exercise to evaluate the relative contribution of metabolic instability (measured with NIRS and haematochemical markers) and muscle activation (measured with EMG) to the oxygen consumption ([Formula: see text]) slow component ([Formula: see text]) in different intensity domains. We hypothesized that (i) after the transient phase, [Formula: see text], metabolic instability and muscle activation tend to increase differently over time depending on the relative exercise intensity and (ii) the increase in [Formula: see text] is explained by a combination of metabolic instability and muscle activation. Eight active men performed a constant work rate trial of 9 min in the moderate, heavy and severe intensity domains. [Formula: see text], root mean square by EMG (RMS), deoxyhaemoglobin by NIRS ([HHb]) and haematic markers of metabolic stability (i.e. [La-], pH, HCO3-) were measured. The physiological responses in different intensity domains were compared by two-way RM-ANOVA. The relationships between the increases of [HHb] and RMS with [Formula: see text] after the third min were compared by simple and multiple linear regressions. We found domain-dependent dynamics over time of [Formula: see text], [HHb], RMS and the haematic markers of metabolic instability. After the transient phase, the rises in [HHb] and RMS showed medium-high correlations with the rise in [Formula: see text] ([HHb] r = 0.68, p < 0.001; RMS r = 0.59, p = 0.002). Moreover, the multiple linear regression showed that both metabolic instability and muscle activation concurred to the [Formula: see text] (r = 0.75, [HHb] p = 0.005, RMS p = 0.042) with metabolic instability possibly having about threefold the relative weight compared to recruitment. Seventy-five percent of the dynamics of the [Formula: see text] was explained by [HHb] and RMS.
2021
excess &nbsp;&nbsp;
loss of efficiency
oxidative metabolism
oxygen consumption
&nbsp;kinetics
File in questo prodotto:
File Dimensione Formato  
Colosio2021_Article_MetabolicInstabilityVsFibreRec.pdf

accesso aperto

Descrizione: CC BY 4.0 publisher version
Tipologia: Versione dell'editore
Licenza: Creative commons
Dimensione 1.54 MB
Formato Adobe PDF
1.54 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/1043582
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 6
  • ???jsp.display-item.citation.isi??? 6
social impact