Effect of inspiratory muscle strength training on inspiratory motor drive and RREP early peak components

Huang, Ching Jer; Martin, A. Daniel; Davenport, Paul W.

doi:10.1152/japplphysiol.00364.2002

Cited by 62 publications

(49 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Thus, it seems that reduced respiratory muscle strength increases inspiratory motor drive, which in turn results in an increase in respiratory sensitivity. 22 Hence, the major factor determining inspiratory muscle weakness is the magnitude of the ratio between the inspiratory pressure demand (P 0.1 ) and the maximal inspiratory pressure (P Imax ). P 0.1 /P Imax ratio reflects a balance between the magnitude of the respiratory load and the muscle strength available to meet the load.…”

Section: Discussionmentioning

confidence: 99%

Inspiratory muscle activity during incremental exercise in obese men

Chlif¹,

Keochkerian²,

Feki

et al. 2007

Int J Obes

View full text Add to dashboard Cite

Objective: The aim of this study was to assess overall inspiratory muscle activity during incremental exercise in obese men and healthy controls using the non-invasive, inspiratory muscle tension-time index (T T0.1 ). We studied 17 obese subjects (mean age7s.d.; 49713 years) and 14 control subjects (42716) during an incremental, maximal exercise test. Methods: Measurements included anthropometric parameters, spirometry, breathing patterns and inspiratory muscle activity. T T0.1 was calculated using the equation T T0.1 ¼ P 0.1 /P Imax Â T I /T TOT (where P 0.1 is mouth occlusion pressure, P Imax is maximal inspiratory pressure and T I /T TOT is the duty cycle). Results: At same levels of maximal exercise (%W max ) (20, 40, 60, 80, 100% W max ), obese subjects showed higher P 0.1 (Po0.001) and P 0.1 /P Imax (Po0.001) values than controls. T T0.1 was thus higher in obese subjects for each workload increment and at maximal exercise (Po0.001). Conclusions: During exercise, patients with obesity show alterations in inspiratory muscle activity as a result of both reduced inspiratory strength (as measured by maximal inspiratory pressure) and increased ventilatory drive (as reflected by mouth occlusion pressure), which prone obese subject to respiratory muscle weakness. Our results suggest that impaired respiratory muscle activity could contribute to a decrease in exercise capacity. T T0.1 may be useful in our understanding concerning the benefits of endurance training.

show abstract

Section: Discussionmentioning

confidence: 99%

Inspiratory muscle activity during incremental exercise in obese men

Chlif¹,

Keochkerian²,

Feki

et al. 2007

Int J Obes

View full text Add to dashboard Cite

show abstract

“…Therefore, it seems that reduced respiratory muscle strength increases inspiratory motor drive, which in turn results in an increase in respiratory sensitivity. 29 Occlusion pressure is the pressure generated in the airway by contraction of inspiratory muscles when the airway has been occluded at end-expiration. P 0.1 was introduced so as to distinguish hypoventilation due to high pulmonary resistance or elastance from hypoventilation due to respiratory pump failure (as seen in obese subjects).…”

Section: Discussionmentioning

confidence: 99%

Noninvasive assessment of the tension–time index of inspiratory muscles at rest in obese male subjects

Chlif¹,

Keochkerian²,

Mourlhon³

et al. 2005

Int J Obes

View full text Add to dashboard Cite

OBJECTIVE:The aim of this study was to investigate the effect of excessive mechanical load caused by obesity on the inspiratory muscle performance in obese men at rest. METHODS:We therefore measure at rest spirometric flows and the noninvasive tension time index of inspiratory muscle (T Tmus ¼ P I /P Imax Â T I /T TOT ) in eight obese male subjects (body mass index (BMI)430) and 10 controls. RESULTS: Spirometric flow (FEV 1 % pred, FVC% pred) and maximal inspiratory pressure (P Imax ) were significantly lower in obese subjects compared to controls (Po0.001). The mean T Tmus was significantly higher in obese subjects than in controls (0.13670.003 vs 0.04570.01). The increase in T Tmus was primarily due to an increase in the ratio of mean inspiratory pressure to maximal inspiratory pressure (P I /P Imax ) and the duty cycle (T I /T TOT ). We found a significant negative relationship between P Imax and BMI (r ¼ À0.74, Po0.001), a positive correlation between T Tmus and BMI (r ¼ 0.80, Po0.001) and a negative correlation between T Tmus and forced expiratory volume in 1 s (r ¼ À0.85, Po 0.001). CONCLUSION: Excessive mechanical load caused by obesity imposes a great burden on the inspiratory muscle, which may predispose such subjects to respiratory muscle weakness at rest.

show abstract

“…However, measuring respiratory muscle pressure at the mouth, as was performed in our study, has been shown to elicit similar effects as BPNS and been used in many previous studies (Huang et al, 2003;Inbar et al, 2000;Romer, McConnell, & Jones, 2002a;Romer, McConnell, & Jones, 2002b;Sonetti et al, 2001). Since P Imax maneuvers are effort-dependent, subjects in our study were highly encouraged to perform maximal effort, tests were made in triplicate, and lung volume measures were made with each trial to ensure consistency.…”

Section: Limitationsmentioning

confidence: 81%

“…Maximal inspiratory pressure (P Imax ) was measured from RV and maximal expiratory pressure (P Emax ) was measured from TLC. P Imax and P Emax are measurements of respiratory muscle strength measured at the mouth and have been shown to be a good estimate of respiratory muscle strength (Huang, Martin, & Davenport, 2003;Inbar, Weiner, Azgad, Rotstein, & Weinstein, 2000; during the discontinuous bouts when P Imax and P Emax were measured in duplicate due to time constraints. The average values of acceptable trials were used in analysis.…”

Section: Pulmonary Function Testsmentioning

confidence: 99%

The Effects of N-Acetylcysteine on Respiratory Muscle Fatigue During Heavy Exercise

Kelly

Wicker

Barstow

et al. 2008

Medicine &Amp; Science in Sports &Amp; Exercise

View full text Add to dashboard Cite

Diaphragmatic fatigue is known to limit endurance performance during heavy exercise in humans. Previous reports have shown that diaphragmatic fatigue is reduced in rats with N-acetylcysteine (NAC; a nonspecific antioxidant) infusion, suggesting that oxidative stress contributes to this fatigue. However, it is not known if oral supplementation of NAC will reduce respiratory muscle fatigue during heavy exercise in humans. Therefore, the purpose of this study was to determine the effect of an acute oral dose of NAC on respiratory muscle fatigue during whole body heavy exercise. Eight healthy, non-smoking men (22+2 yrs), with no history of cardiovascular or lung disease, completed baseline pulmonary function tests followed by an incremental cycle VO 2peak test. A randomized, double blind crossover design was then used where subjects were given either placebo (PLA) or NAC (1800 mg) 45 min prior to a 30 minute constant load (85% VO 2peak ) discontinuous (six-five minute stages) or continuous (cycle until volitional exhaustion) exercise test. Tests were separated by approximately one week. Maximum pressures (inspiratory, P Imax ; expiratory, P Emax ) and venous blood samples (plasma lactate and total plasma glutathione) were made prior to-and following each 5-min of exercise in discontinuous tests and pre-and post-exercise in continuous tests. Subject's VO 2peak was 43+5 ml/kg/min. There was no difference (p>0.05) in P Imax between NAC (127.9+34.1 cmH 2 O) or PLA (134.1+28.1 cmH 2 O) at rest. During exercise, P Imax was significantly lower (~14%) in 6 of 8 subjects with PLA compared to NAC at minutes 25 and 30 of the discontinuous test indicating respiratory muscle fatigue. With NAC, P Imax did not change (p>0.05) from rest throughout exercise indicating no respiratory muscle fatigue. There was no difference (p>0.05) in P Emax , plasma glutathione, lactate, oxygen uptake (VO 2 ), ventilation (VE), heart rate (HR), or rating of perceived exertion between PLA and NAC at rest or during exercise. Time to exhaustion was not different (p>0.05) during the continuous tests (PLA: 1263 + 334 sec; NAC: 1047 + 136 sec). These results suggest that an acute dose of NAC reduces respiratory muscle fatigue during high intensity exercise but does not alter other ventilatory or metabolic indices. The significance of this reduced respiratory muscle fatigue with NAC on whole body exercise performance remains to be determined.

show abstract

Effect of inspiratory muscle strength training on inspiratory motor drive and RREP early peak components

Cited by 62 publications

References 38 publications

Inspiratory muscle activity during incremental exercise in obese men

Inspiratory muscle activity during incremental exercise in obese men

Noninvasive assessment of the tension–time index of inspiratory muscles at rest in obese male subjects

The Effects of N-Acetylcysteine on Respiratory Muscle Fatigue During Heavy Exercise

Contact Info

Product

Resources

About