Inspiratory Muscles Experience Fatigue Faster Than Calf Muscles During Treadmill Marching

“The aim of this study was to determine whether treadmill marching exercise induces respiratory muscle fatigue, and to compare the extent and rate of respiratory muscle fatigue to those of the calf musculature.


“Results indicated that:

  1. the inspiratory and calf muscles are the ones experiencing the most dominant fatigue during treadmill marching
  2. the rate of fatigue of each muscle group was monotonic between the initial and terminal phases of exercise
  3. the inspiratory muscles fatigue significantly faster than the calf at the terminal phase of exercise, and are likely to fatigue faster during the initial exercise as well.

Accordingly, this study supports the hypothesis that fatigue of the inspiratory muscles may be a limiting factor during exercise.”

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A Comparison Of Inspiratory Muscle Fatigue Following Maximal Exercise In Moderately Trained Males And Females

“Exercise-induced inspiratory muscle fatigue (IMF) has been reported in males but there are few reports of IMF in females. It is not known if a gender difference exists for inspiratory muscle strength following heavy exercise, as is reported in locomotor muscles.”


“Inspiratory Muscle Fatigue observed immediately following maximal exercise, demonstrated the same pattern of recovery for both genders.”

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Exercise-Induced Diaphragmatic Fatigue In Healthy Humans

“In part of this study, twelve healthy subjects (33 +/- 3 years) with a variety of fitness levels exercised at 95 and 85% VO2, max to exhaustion.


“Significant diaphragmatic fatigue is caused by the ventilatory requirements imposed by heavy endurance exercise in healthy persons with a variety of fitness levels. The magnitude of the fatigue and the likelihood of its occurrence increases as the relative intensity of the exercise exceeds 85% of VO2, max.”

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Influence Of Environmental Temperature On Exercise-Induced Inspiratory Muscle Fatigue

“If blood is diverted away from the inspiratory muscles to the skin during exercise in the heat, exercise-induced inspiratory muscle fatigue might be exacerbated. This study hypothesised that prolonged heavy endurance exercise in the heat would impair exercise performance and exacerbate inspiratory muscle fatigue compared to exercise in a thermo-neutral environment.


“This study concluded that heavy sustained exercise in the heat impaired subsequent time-trial performance but did not exacerbate inspiratory muscle fatigue in endurance-trained subjects.”

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Contribution Of Respiratory Muscle Blood Flow To Exercise-Induced Diaphragmatic Fatigue In Trained Cyclists

“This study investigated whether the greater degree of exercise-induced diaphragmatic fatigue previously reported in highly trained athletes in hypoxia (compared with normoxia) could have a contribution from limited respiratory muscle blood flow.”


“When respiratory muscle energy requirement is not different between normoxia and hypoxia, diaphragmatic fatigue is greater in hypoxia as intercostal muscle blood flow is not increased (compared with normoxia) to compensate for the reduction in PaO2 , thus further compromising O2 supply to the respiratory muscles.”

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