Severe endurance training fails to change myosin heavy-chain distribution of diaphragm

Okumoto, Tadashi; Imoto, Takayuki; Katsuta, Shigeru; Wada, Masanobu

doi:10.1016/0034-5687(96)00008-4

Cited by 11 publications

(13 citation statements)

References 17 publications

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“…This increased endurance is consistent with results from animal experiments that demonstrate increased activity of oxidative metabolism in the diaphragm following various types of endurance training 12–16 . However, it should be noted that other studies have been unable to detect such changes in diaphragmatic oxidative capacity after endurance training 17–21 . These conflicting findings may be attributable to differences in the site of sampling (costal or crural diaphragm), 12–14,39 the intensity of the endurance exercise and therefore the load placed on the respiratory muscles, 12–14,40 the age of the experimental animal, 41 or possibly to species differences.…”

Section: Discussionsupporting

confidence: 78%

“…Metabolic changes consistent with improved respiratory muscle endurance have been reported in animal studies following various types of endurance training 12–16 although this does not seem to apply to the diaphragm's oxidative capacity 17–21 . In humans, improved ventilatory muscle endurance is reported after swimming, 22 running 10 or cycling training 11 .…”

Section: Introductionmentioning

confidence: 99%

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Inspiratory muscle performance in endurance athletes and sedentary subjects

2001

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Objective: The aim of this study was to determine whether whole‐body endurance training is associated with increased respiratory muscle strength and endurance. Methodology: Respiratory muscle strength (maximum inspiratory pressure (PImax)) and endurance (progressive threshold loading of the inspiratory muscles) were measured in six marathon runners and six sedentary subjects. Results: PImax was similar between the two groups of subjects but the maximum threshold pressure achieved was greater in marathon runners (90 ± 8 vs 78 ± 10% of PImax, respectively, mean ± SD, P < 0.05). During progressive threshold loading, marathon runners breathed with lower frequency, higher tidal volume, and longer inspiratory and expiratory time. At maximum threshold pressure, marathon runners had lower arterial O2 saturation, but perceived effort (Borg scale) was maximal in both groups. Efficiency of the respiratory muscles was similar in both groups being 2.0 ± 1.7% and 2.3 ± 1.8% for marathon runners and sedentary subjects, respectively. Conclusions: The apparent increase in respiratory muscle endurance of athletes was a consequence of a difference in the breathing pattern adopted during loaded breathing rather than respiratory muscle strength or efficiency. This implies that sensory rather than respiratory muscle conditioning may be an important mechanism by which whole‐body endurance is increased.

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Section: Discussionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Inspiratory muscle performance in endurance athletes and sedentary subjects

2001

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“…By electrophoretic separation, Sugiura et al [28] found IIb MHC to represent 6.1% of all MHC protein in young rat diaphragm, and their IId/IIx result of 44.9% is also quite different from our PCR result, while their I and IIa findings are very similar to our PCR results, and their IId/IIx result closely parallels our IIx area percentage immunocytochemistry result. Okumoto et al reported even less IIb and more IId protein by electrophoresis in 5-month-old rats [29]. …”

Section: Discussionmentioning

confidence: 99%

“…Although various treadmill-running protocols have shown increases in the aerobic capacity of the rat diaphragm [32,34-37], running has generally not been demonstrated to cause consistent changes in the relative expression of MHC isoforms [29,38]. Although one paper has shown a decrease in type IIb fibers and an increase in type I fibers [38], and another has shown only a significant decrease in type IIb fibers [39], a third paper reported a surprising increase in type IIb fibers [40].…”

Section: Discussionmentioning

confidence: 99%

Myosin heavy chain and physiological adaptation of the rat diaphragm in elastase-induced emphysema

et al. 2003

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Background: Several physiological adaptations occur in the respiratory muscles in rodent models of elastase-induced emphysema. Although the contractile properties of the diaphragm are altered in a way that suggests expression of slower isoforms of myosin heavy chain (MHC), it has been difficult to demonstrate a shift in MHCs in an animal model that corresponds to the shift toward slower MHCs seen in human emphysema.

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“…Voluntary wheel running has shown that a volitional training stimulus can induce significantly greater adaptations in the oxidative capacity of inspiratory and expiratory rat muscle than the aforementioned fixed-load treadmill training protocols [25], possibly because the animals can either: (1) perform intermittent high intensity bouts of exercise for many weeks, and/or (2) reach daily running distances that are more than those of treadmill exercise models. It appears that the more intense the training regime the greater the adaptations, although there appears to be a threshold beyond which adaptation fails to occur as demonstrated by severe endurance training [56].…”

Section: Effects Of Endurance Training On the Respiratory Systemmentioning

confidence: 98%

Cardiovascular and Respiratory System Responses and Limitations to Exercise

Rodman¹,

Haverkamp²,

Gordon³

et al. 2002

Clinical Exercise Testing

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The design and dimensions of the healthy pulmonary system are nearly perfect to meet the considerable demands on O 2 transport and CO 2 elimination imposed by physical exercise. In our chapter, we briefly describe the features of the nervous system pathways and the structure of the airways, lung surface area and respiratory muscles which ensure both the completeness of gas exchange at the level of alveolar gas, pulmonary capillaries and arterial blood and the high level of mechanical efficiency with which the respiratory muscle pump operates. We also discuss the absence of a physical training effect on pulmonary vs. systemic structures which determine O 2 delivery and the implications of a relatively underbuilt lung and chest wall to exercise-induced arterial hypoxemia, diaphragm fatigue and the distribution of systemic vascular conductance and blood flow.

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Severe endurance training fails to change myosin heavy-chain distribution of diaphragm

Cited by 11 publications

References 17 publications

Inspiratory muscle performance in endurance athletes and sedentary subjects

Inspiratory muscle performance in endurance athletes and sedentary subjects

Myosin heavy chain and physiological adaptation of the rat diaphragm in elastase-induced emphysema

Cardiovascular and Respiratory System Responses and Limitations to Exercise

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