The influence of inspiratory muscle work history and specific inspiratory muscle training upon human limb muscle fatigue.

McConnell, A. K. and Lomax, M., 2006. The influence of inspiratory muscle work history and specific inspiratory muscle training upon human limb muscle fatigue. Journal of Physiology, 577 (Pt 1), 445 - 457 .

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DOI: 10.1113/jphysiol.2006.117614

Abstract

The purpose of this study was to assess the influence of the work history of the inspiratory muscles upon the fatigue characteristics of the plantar flexors (PF). We hypothesized that under conditions where the inspiratory muscle metaboreflex has been elicited, PF fatigue would be hastened due to peripheral vasoconstriction. Eight volunteers undertook seven test conditions, two of which followed 4 week of inspiratory muscle training (IMT). The inspiratory metaboreflex was induced by inspiring against a calibrated flow resistor. We measured torque and EMG during isometric PF exercise at 85% of maximal voluntary contraction (MVC) torque. Supramaximal twitches were superimposed upon MVC efforts at 1 min intervals (MVC(TI)); twitch interpolation assessed the level of central activation. PF was terminated (T(lim)) when MVC(TI) was <50% of baseline MVC. PF T(lim) was significantly shorter than control (9.93 +/- 1.95 min) in the presence of a leg cuff inflated to 140 mmHg (4.89 +/- 1.78 min; P = 0.006), as well as when PF was preceded immediately by fatiguing inspiratory muscle work (6.28 +/- 2.24 min; P = 0.009). Resting the inspiratory muscles for 30 min restored the PF T(lim) to control. After 4 weeks, IMT, inspiratory muscle work at the same absolute intensity did not influence PF T(lim), but T(lim) was significantly shorter at the same relative intensity. The data are the first to provide evidence that the inspiratory muscle metaboreflex accelerates the rate of calf fatigue during PF, and that IMT attenuates this effect.

Item Type:Article
ISSN:0022-3751
Uncontrolled Keywords:Adaptation, Physiological ; Adult ; Ankle Joint ; Exercise ; Female ; Humans ; Inhalation ; Intercostal Muscles ; Male ; Muscle Contraction ; Muscle Fatigue ; Physical Endurance ; Physical Exertion ; Respiratory Muscles
Subjects:UNSPECIFIED
Group:School of Health and Social Care
ID Code:22180
Deposited By: Unnamed user with email symplectic@symplectic
Deposited On:06 Jul 2015 15:23
Last Modified:06 Jul 2015 15:23

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