Acute effects of thixotropy conditioning of inspiratory muscles on end-expiratory chest wall and lung volumes in normal humans

Izumizaki, Masahiko; Iwase, Michiko; Ohshima, Yasuyoshi; Homma, Ikuo

doi:10.1152/japplphysiol.01598.2005

Cited by 14 publications

(36 citation statements)

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“…Significance was accepted at P < 0.05. Sample size calculations for the present study were based on changes in the IC reported in a previous study [7], in which we observed means ± SD for post IC at 1 min of -0.13 ± 0.12 liter (conditioning at FRC + 60% IC) and 0.12 ± 0.10 liter (conditioning at RV), though the primary outcome of the present study was the change in end-expiratory Vcw. We assumed an alpha level of 0.01 to account for multiple comparisons.…”

Section: Subjectsmentioning

confidence: 99%

“…We have reported that inspiratory muscle conditioning based on the principles of muscle thixotropy acutely changes end-expiratory chest wall volume (Vcw) and lung volume in healthy humans and patients with chronic obstructive pulmonary disease (COPD) [6][7][8][9][10]. Thixotropy conditioning of inspiratory muscles involves inspiratory muscle contraction at an inflated or deflated lung volume [6][7][8][9][10].…”

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confidence: 99%

“…Thixotropy conditioning of inspiratory muscles involves inspiratory muscle contraction at an inflated or deflated lung volume [6][7][8][9][10]. Inspiratory muscles include the diaphragm, the external intercostals, and the parasternal intercostals, and these muscles shorten and lengthen with lung inflation and deflation, respectively [11][12][13][14].…”

mentioning

confidence: 99%

“…Inspiratory muscles include the diaphragm, the external intercostals, and the parasternal intercostals, and these muscles shorten and lengthen with lung inflation and deflation, respectively [11][12][13][14]. Conditioning at an inflated lung volume, which corresponds to hold-short conditioning to increase muscle stiffness, is followed by an increase in end-expiratory Vcw, measured with respiratory induction plethysmography (RIP), and conditioning at a deflated lung volume, which corresponds to hold-long conditioning to decrease muscle stiffness, is followed by a reduction in end-expiratory Vcw [7].…”

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confidence: 99%

“…Our previous reports have highlighted the effects of muscle thixotropy on end-expiratory volumes during several breath cycles, although changes in spirometrically determined inspiratory capacity (IC) after thixotropy conditioning, which may mirror end-expiratory lung volume, extend over a period of 1 min [7]. The time course of muscle thixotropy has been shown in limb muscles.…”

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Chest Wall Motion after Thixotropy Conditioning of Inspiratory Muscles in Healthy Humans

et al. 2006

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Abstract:Inspiratory muscle conditioning at a lower or higher lung volume based on the principles of muscle thixotropy causes acute changes in end-expiratory chest wall and lung volumes. The present study aimed to demonstrate the time course of effects of this conditioning on both end-expiratory chest wall volume and thoracoabdominal synchrony. We measured chest wall motion with respiratory induction plethysmography at 0.5, 1, 2, 3, and 6 min after conditioning at three different lung volumes in 15 healthy men. After conditioning at total lung capacity -20% inspiratory capacity, increases in end-expiratory chest wall volume were significant at 0.5, 1, and 2 min (P < 0.05), being most obvious at 0.5 min (∆0.24 ± 0.20 liter). After conditioning at residual volume, reductions in end-expiratory chest wall volume were significant at any time point (P < 0.05), being most obvious at 0.5 min (∆0.16 ± 0.08 liter). Conditioning at functional residual capacity had little effect on the volume. Spirometric inspiratory capacity at 6 min after conditioning at residual volume (2.68 ± 0.35 liter) was higher than the baseline value (2.53 ± 0.31 liter, P < 0.05). Reductions in the phase angle, quantified by the KonnoMead diagram, occurred after conditioning at residual volume at any time point (P < 0.05), being most obvious at 2 min (∆3.47 ± 3.02 degrees). In conclusion, there is a 6-min time course of changes in end-expiratory chest wall volume after conditioning. More synchronous motion between the rib cage and abdomen occurs after conditioning at residual volume.

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Chest Wall Motion after Thixotropy Conditioning of Inspiratory Muscles in Healthy Humans

et al. 2006

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Mechanical Properties of Respiratory Muscles

Sieck

Ferreira

Reid

et al. 2013

Comprehensive Physiology

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Striated respiratory muscles are necessary for lung ventilation and to maintain the patency of the upper airway. The basic structural and functional properties of respiratory muscles are similar to those of other striated muscles (both skeletal and cardiac). The sarcomere is the fundamental organizational unit of striated muscles and sarcomeric proteins underlie the passive and active mechanical properties of muscle fibers. In this respect, the functional categorization of different fiber types provides a conceptual framework to understand the physiological properties of respiratory muscles. Within the sarcomere, the interaction between the thick and thin filaments at the level of cross-bridges provides the elementary unit of force generation and contraction. Key to an understanding of the unique functional differences across muscle fiber types are differences in cross-bridge recruitment and cycling that relate to the expression of different myosin heavy chain isoforms in the thick filament. The active mechanical properties of muscle fibers are characterized by the relationship between myoplasmic Ca2+ and cross-bridge recruitment, force generation and sarcomere length (also cross-bridge recruitment), external load and shortening velocity (cross-bridge cycling rate), and cross-bridge cycling rate and ATP consumption. Passive mechanical properties are also important reflecting viscoelastic elements within sarcomeres as well as the extracellular matrix. Conditions that affect respiratory muscle performance may have a range of underlying pathophysiological causes, but their manifestations will depend on their impact on these basic elemental structures.

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Direct Evidence for Structural Transition Promoting Shear Thinning in Cylindrical Colloid Assemblies

Shikinaka

Kaneda

Mori

et al. 2014

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In this paper, we describe stimuli-responsive hydrogels prepared from a rigid rod-like polyelectrolyte 'imogolite' and a dicarboxylic acid. The hydrogel exhibited thixotropy in response to mechanical shock within the order of seconds or sub-seconds. Here, using the latest structural/rheological characterisation techniques, the relationship between the structural transition processes and the shear thinning was estimated. The evidence obtained by the experiments revealed for the first time the direct relationship between the microscopic structural change and the macroscopic thixotropic behavior that have been extensively discussed. The thixotropic hydrogel has the hierarchical architecture in the combination of imogolite and dicarboxylic acid, i.e., sheathed nanotubes/hydroclusters of cross-bridged nanotubes/frameworks. The formation and disintegration of the network structure upon resting and agitating, respectively, were the origin of gel/sol transition (thixotropy), although the hydroclusters of cross-bridged nanotubes were maintained throughout the transition.

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Acute effects of thixotropy conditioning of inspiratory muscles on end-expiratory chest wall and lung volumes in normal humans

Cited by 14 publications

References 30 publications

Chest Wall Motion after Thixotropy Conditioning of Inspiratory Muscles in Healthy Humans

Chest Wall Motion after Thixotropy Conditioning of Inspiratory Muscles in Healthy Humans

Mechanical Properties of Respiratory Muscles

Direct Evidence for Structural Transition Promoting Shear Thinning in Cylindrical Colloid Assemblies

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