Aspects Of Respiratory Muscle Fatigue In A Mountain Ultramarathon Race

“Ultramarathon running offers a unique possibility to investigate the mechanisms contributing to the limitation of endurance performance. Investigations of locomotor muscle fatigue show that central fatigue is a major contributor to the loss of strength in the lower limbs after an ultramarathon. In addition, respiratory muscle fatigue is known to limit exercise performance, but only limited data are available on changes in respiratory muscle function after ultramarathon running and it is not known whether the observed impairment is caused by peripheral and/or central fatigue.”

Conclusion:

“Ultraendurance running reduces respiratory muscle strength for inspiratory muscles shown to result from significant peripheral muscle fatigue with only little contribution of central fatigue. This is in contrast to findings in locomotor muscles. Whether this difference between muscle groups results from inherent neuromuscular differences, their specific pattern of loading or other reasons remain to be clarified.”

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Respiratory Muscle Work Compromises Leg Blood Flow During Maximal Exercise

“This study hypothesized that during exercise at maximal O2 consumption (VO2max), high demand for respiratory muscle blood flow would elicit locomotor muscle vasoconstriction and compromise limb blood flow.”

Conclusion:

“Work of breathing normally incurred during maximal exercise causes vasoconstriction in locomotor muscles and compromises locomotor muscle perfusion and VO2.”

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Effect Of Inspiratory Muscle Work On Peripheral Fatigue Of Locomotor Muscles In Healthy Humans

“The work of breathing required during maximal exercise compromises blood flow to limb locomotor muscles and reduces exercise performance. This study asked if force output of the inspiratory muscles affected exercise-induced peripheral fatigue of locomotor muscles.”

Conclusion:

“Peripheral fatigue of locomotor muscles resulting from high-intensity sustained exercise is, in part, due to the accompanying high levels of respiratory muscle work.”

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Resistive Respiratory Muscle Training Improves And Maintains Endurance Swimming Performance In Divers

“In comparison to exercise on land, respiratory work during underwater exercise is increased due to the hydrostatic pressure differences across the chest as well as increased flow resistive respiratory work.”

“It has recently been shown in healthy individuals that ventilatory limitations may cause a reduction of maximal exercise performance on land. The weakened exercise capacity has been attributed to a reduction in locomotor muscle oxygen transport secondary to diminished locomotor muscle blood flow. In several studies on land, respiratory muscle fatigue has been reported as a contributing factor to reduced maximal and endurance exercise performance. These same factors may also limit exercise performance in divers.

Conclusion:

“The major findings of the present study were that 30 minutes of resistance respiratory muscle training carried out three or five days per week for four weeks substantially improved fin swimming endurance (at 70-75%V. O ) and that similar improvements in respiratory muscle performance were obtained.”

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Respiratory Muscle Training in Healthy Humans: Resolving the Controversy

“An overview of the literature that rationalizes contradictory findings about respiratory muscle training in healthy people.”

Conclusion:

“It is likely that the ergogenic effect of respiratory muscle training (RMT) has a multifactorial etiology that may include:

  1. The direct effect of RMT upon respiratory muscle fatigue
  2. RMT’s indirect effects upon improving blood flow distribution to limb locomotor muscles in heavy exercise
  3. RMT’s direct and indirect effect upon the intensity with which both respiratory and peripheral efforts are perceived.”

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Respiratory Muscle Energetics During Exercise In Healthy Subjects And Patients With COPD

“This article intended to answer the following:

  1. Does respiratory muscle fatigue affect alveolar ventilation (VE)
  2. May work and cost of breathing of primary and accessory respiratory muscles compete with locomotor muscles to blood supply and oxygen uptake
  3. What is the role of abnormality of O2 transport and utilization on the limitation of exercise tolerance in patients with COPD?

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