Inspiratory Muscle Fatigue In Trained Cyclists: Effects Of Inspiratory Muscle Training

“This study evaluated the influence of simulated 20- and 40-km time trials upon postexercise inspiratory muscle function of trained competitive cyclists. In addition, it examined the influence of specific inspiratory muscle training (IMT) upon the responses observed.”

Conclusion:

“Data support existing evidence that there is significant global inspiratory muscle fatigue after sustained heavy endurance exercise. Furthermore, the present study provides new evidence that performance enhancements observed after IMT are accompanied by a decrease in inspiratory muscle fatigue.”

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Oxygen Uptake Kinetics And Maximal Aerobic Power Are Unaffected By IMT In Healthy Subjects Where Time To Exhaustion Is Extended

“The aim of this study was to determine whether 4 weeks of inspiratory muscle training (IMT) would be accompanied by alteration in cardiopulmonary fitness as assessed through moderate intensity oxygen uptake (V_O2) kinetics and maximal aerobic power (V_ O2max).”

Conclusion:

“The improvement of maximal static inspiratory mouth pressure (Pi,max) in training group shows that IMT training enhances inspiratory muscle strength; however, this is not supported by improvement in either VO2 kinetics or VO2max. It is therefore likely that IMT training alone is not of direct benefit to the cardiopulmonary fitness of healthy subjects. However, diaphragmatic fatigue may have a limiting role in maximal constant-load exercise and consequently, IMT might be a useful stratagem of extracting greater volumes of endurance work at high ventilatory loads, which in turn could improve cardio-pulmonary fitness.”

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Effect of Inspiratory Muscle Training on Exercise Tolerance in Asthmatic Individuals

“The aim of this study was to determine the effects of inspiratory muscle training (IMT) on exercise tolerance, inspiratory muscle fatigue, and the perception of dyspnea in asthmatic individuals.”

Conclusion:

“This study has shown that 6 wk of IMT in individuals with mild to moderate asthma significantly increased inspiratory muscle strength, reduced inspiratory muscle fatigue, improved exercise tolerance, and reduced the perception of dyspnea during cycling exercise at È70% V ̇O2max to the limit of tolerance. These data suggest that IMT may be a helpful adjunct to asthma management and has the potential to improve participation and adherence to exercise training in this group. However, it should also be noted that the perception of breathlessness is also an important signal of bronchoconstriction, and thus, caution should be exercised if this symptom is abnormally low.”

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Effects of High-Intensity Inspiratory Muscle Training Following a Near-Fatal Gunshot Wound

“Severe injuries sustained during combat may classify individuals as undeployable for active service. It is imperative that every effort is made to optimize physical function following such injuries.”

“In this case, a 38-year-old man sustained a gunshot wound during armed combat. The bullet entered via the left axilla and exited from the right side of the abdomen, resulting in severe thoracic and abdominal injuries. The main goals of therapy were to reduce dyspnea on exertion and to enable return to full work duties. A program of high-intensity, interval-based threshold inspiratory muscle training (IMT) was undertaken.”

Conclusion:

“Given that IMT was introduced 12 months following the injury, at which point progress had reached a plateau with other rehabilitation strategies, it seems reasonable to attribute the increased maximum forced inspiratory flow recorded at rest and change in the locus of symptom limitation during exercise from the dyspnea to leg fatigue to the introduction of IMT. These data should be seen as hypothesis-generating.”

Clinical Implications and Future Research:

“The flow-volume loops recorded during the CPET allowed us to identify inefficiencies in breathing strategy and respiratory mechanics that were responsible for this patient’s intolerable dyspnea during exercise. Notably, the measurement of Pimax was of no diagnostic value and was used only to prescribe the initial load for IMT. These findings suggest that static measures of the pressure-generating capacity of the inspiratory pump muscles convey little information about how they operate under dynamic conditions such as exercise. In this patient, chest fluoroscopy and the CPET with flow-volume loops provided the most useful diagnostic information. A program of high-intensity IMT should be considered for individuals who demonstrate inspiratory flows during exercise that approximate the maximum inspiratory flow recorded at rest. Further study is needed to confirm the role of IMT in people with diaphragm injury.”

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Effects of IMT on Resistance to Fatigue of Respiratory Muscles During Exhaustive Exercise

“The aim of this study was to assess the effect of inspiratory muscle training (IMT) on resistance to fatigue of the diaphragm, parasternal, sternocleidomastoid and scalene muscles in healthy humans during exhaustive exercise.”

Conclusion:

“The study found that in healthy subjects, IMT results in significant increase in maximal inspiratory pressure, a delay of inspiratory muscle fatigue during exhaustive exercise, and a significant improvement in maximal work performance. We conclude that the IMT elicits resistance to the development of inspiratory muscles fatigue during high-intensity exercise.”

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Inspiratory Muscle Fatigue In Swimmers After A Single 200m Swim

“Inspiratory muscle fatigue may occur in as little as 6 min during high-intensity spontaneously breathing exercise. The aims of this study were to determine whether inspiratory muscle fatigue occurs during swimming exercise and whether inspiratory muscle strength differs between the supine and standing body positions.”

Conclusion:

“Results indicate that a single 200m front-crawl swim corresponding to 90-95% of race pace was sufficient to induce inspiratory muscle fatigue in less than 2.7 min. Furthermore, although diaphragm muscle length is optimized when supine, our results indicate that the force output of the diaphragm and inspiratory accessory muscles is greater when upright than when supine.”

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Influence Of Different Breathing Frequencies On Severity Of Inspiratory Muscle Fatigue Induced By High-Intensity Front Crawl Swimming

“The aim of this study was to assess the influence of two different breathing frequencies on the magnitude of inspiratory muscle fatigue after high-intensity front crawl swimming.”

Conclusion:

“Data suggested that there is significant global inspiratory muscle fatigue after high-intensity swimming. Inspiratory muscle fatigue is, however, greater when breathing frequency is reduced during high-intensity front crawl swimming. Respiratory muscle training should be used to improve respiratory muscle strength and endurance in swimmers.”

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The Impact Of Swimming Speed On Respiratory Muscle Fatigue During Front Crawl Swimming

“The Critical velocity (Vcrit) represents a holistic swimming fatigue threshold and critical stroke rate is thought to coincide with Vcrit. Whether Vcrit, and in-turn critical stroke rate, also represent an inspiratory muscle fatigue threshold is not known.”

Conclusion:

“The study provided data demonstrating that inspiratory muscle fatigue is correlated with relative but not absolute front crawl swimming velocity, and stroke rate. Whilst this finding is obvious and to be expected, the novel aspect is that the study was able to determine the relative velocity associated with the development of inspiratory muscle fatigue. Specifically, inspiratory muscle fatigue occurred when swimming at (in some) and above (in all) Vcrit and when stroke rate was at (in some) or above (in all) 92% of critical stroke rate in both male and female adolescent swimmers.”

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400-Meter and 800-Meter Track Running Induces Inspiratory Muscle Fatigue In Trained Female Middle-Distance Runners

“Inspiratory muscle fatigue (IMF) may limit exercise performance. A few studies have reported that IMF occurs after short-duration swimming exercise, but whether short-duration running can induce IMF remains unclear.”

Conclusion:

“IMF occurs after short-duration running exercise. Coaches could consider prescribing inspiratory muscle training or warm-up in an effort to reduce the inevitable IMF associated with maximal effort running.”

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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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