Maximal Inspiratory Mouth Pressure Research Articles

Sex differences in diaphragmatic fatigue and the metaboreflex following inspiratory pressure-threshold loading.

Sex differences in diaphragmatic fatigue and the metaboreflex following inspiratory pressure-threshold loading.

Sex differences in diaphragmatic fatigue: the cardiovascular response to inspiratory resistance.

Diaphragmatic fatigue (DF) elicits a sympathetically mediated metaboreflex resulting in increased heart rate, blood pressure and limb vascular resistance. Women may be more resistant to DF compared to men, and therefore it was hypothesised that women would experience an attenuated inspiratory muscle metaboreflex during inspiratory pressure-threshold loading (PTL) performed to task failure. At the time of PTL task failure, the severity of DF was not different between sexes; however, inspiratory muscle endurance time was significantly longer in women than in men. For a given cumulative diaphragmatic force output, the severity of DF was less in women than in men. Women exhibited a blunted cardiovascular response to inspiratory resistance (i.e. metaboreflex) that may have implications for exercise tolerance. Diaphragmatic fatigue (DF) elicits reflexive increases in sympathetic vasomotor outflow (i.e. metaboreflex). There is some evidence suggesting women may be more resistant to DF compared to men, and therefore may experience an attenuated inspiratory muscle metaboreflex. To this end, we sought to examine the cardiovascular response to inspiratory resistance in healthy young men (n=9, age=24±3years) and women (n=9, age=24±3years). Subjects performed isocapnic inspiratory pressure-threshold loading (PTL, 60% maximal inspiratory mouth pressure) to task failure. Diaphragmatic fatigue was assessed by measuring transdiaphragmatic twitch pressure (Pdi,tw ) using cervical magnetic stimulation. Heart rate (HR) and mean arterial pressure (MAP) were measured beat-by-beat throughout PTL via photoplethysmography, and low-frequency systolic pressure (LFSBP ; a surrogate for sympathetic vasomotor tone) calculated from arterial waveforms using power spectrum analysis. At PTL task failure, the degree of DF was similar between sexes (∼23% reduction in Pdi,tw ; P=0.33). However, time to task failure was significantly longer in women than in men (27±11vs. 16±11min, respectively; P=0.02). Women exhibited less of an increase in HR (13±8vs. 19±12bpm; P=0.02) and MAP (10±8vs. 14±9mmHg; P=0.01), and significantly lower LFSBP (23±11vs. 34±8mmHg2 ; P=0.04) during PTL compared to men. An attenuation of the inspiratory muscle metaboreflex may influence limb and respiratory muscle haemodynamics with implications for exercise performance.

Individual Variability in the Leg Blood Flow Response to Expiratory and Inspiratory Resistive Loading

BACKGROUND: Fatiguing inspiratory muscle work initiates the inspiratory muscle metaboreflex causing a time-dependent increase in muscle sympathetic nerve activity (MSNA) and a decrease in leg blood flow (Q[Combining Dot Above]L). Fatiguing contractions of the expiratory muscles also facilitates an increase in MSNA. However, the effect of fatiguing expiratory muscle work on Q[Combining Dot Above]L is somewhat unknown. PURPOSE: To determine the effect of expiratory resistive loading (ERL) compared to inspiratory resistive loading (IRL) on Q[Combining Dot Above]L in healthy humans. METHODS: Five healthy men (n = 2, 30 ± 6 y) and women (n = 3, 29 ± 5 y) performed ERL and IRL at 65% of maximal expiratory and maximal inspiratory mouth pressure (MEP; MIP) to task failure. Respiratory frequency was maintained at 15 breaths/min with an inspiratory duty cycle of 0.5. Q[Combining Dot Above]L (via Doppler ultrasound) and mean arterial pressure (MAP) (via finger photoplethysmography) were measured before, during and up to 3 min after ERL and IRL. Expiratory and inspiratory muscle fatigue was assessed by measuring the reduction in MEP and MIP from pre- to post-ERL and IRL. EMG was measured in each leg to ensure no muscular contraction occurred. RESULTS: Task failure occurred at 10.6 ± 2.4 min for ERL and at 20.6 ± 8.8 min for IRL; each subject performed ≥ 7 min of ERL and IRL. There was a 21 ± 4% reduction in MEP and a 7 ± 5% reduction in MIP from before to after ERL and IRL, respectively (P < 0.05). Despite an increase in group mean MAP from rest to during ERL (14 ± 14 mmHg, P = 0.035) and IRL (12 ± 6 mmHg, P = 0.021), there was no change in group mean Q[Combining Dot Above]L across time during either ERL or IRL (P > 0.05). There was, however, substantial individual subject variability in the Q[Combining Dot Above]L response to loaded breathing. During ERL, Q[Combining Dot Above]L decreased relative to baseline values at min 3 (−29 ± 20%) and min 7 (−17 ± 6%) in 2 of the 5 subjects; Q[Combining Dot Above]L increased by 15 ± 7% from rest to min 7 in the remaining 3 subjects. Similarly, there was a reduction in Q[Combining Dot Above]L from rest to min 3 (−23 ± 9%) and min 7 (−16 ± 3%) in 2 of the 5 subjects during IRL; Q[Combining Dot Above]L increased by 60 ± 26% from baseline to min 7 in the remaining 3 subjects. There was no significant change in MAP or Q[Combining Dot Above]L during ERL and IRL trials at 2% of MEP and MIP. CONCLUSION: Leg blood flow appears to decrease in some but not all healthy humans in response to ERL. Indeed, we report substantial individual variability in the leg blood flow response to both ERL and IRL.

Respiratory Muscle Training Positively Affects Vasomotor Response in Young Healthy Women

Vasomotor response is related to the capacity of the vessel to maintain the homeostasis of the vascular tone. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (local control). The aim of the study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow‐mediated dilation and heart rate variability, in young healthy females. The hypothesis was that RMT may enhance the balance between sympathetic and parasympathetic neural drive and reduce vessels shear stress. To this purpose, twenty‐four women were assigned randomly to RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation per week, eight weeks, for a total of twenty‐four training sessions. Heart rate variability was utilized to evaluate the autonomic balance, a global factor regulating vasomotor response. Endothelial function was determined by measuring brachial artery vasodilation normalized by the shear rate (%FMD/SR). After RMT, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively) only in RMT. Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in endothelial function (%FMD/SR +45%; p&lt;0.05). These data indicate a positive effect of RMT on vasomotor response likely via a reduction in shear stress in the vessels, and not through a modulation of sympatho‐vagal balance.Support or Funding InformationGrant from the Department of Biomedical Sciences for Health, Università degli Studi di Milano.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Diaphragmatic shear modulus at various submaximal inspiratory mouth pressure levels

This study assessed the shear modulus of the diaphragm at various submaximal inspiratory mouth pressure levels by ultrasound shear wave elastography. In 14 healthy male subjects, diaphragmatic shear moduli were assessed at end expiration during resting breathing and at submaximal inspiratory tasks at 15, 30, 45, 60, and 75% of the maximal inspiratory mouth pressure. The shear modulus increased along with mouth pressure, and the mouth-pressure–shear-modulus relationship fit the second-order polynomial regression equation (r2 = 0.99 ± 0.01; all subjects, r2 ≥ 0.95) better than it did the simple linear regression equation (r2 = 0.94 ± 0.05; 8/14 subjects, r2 ≥ 0.95). The second regression coefficient in the second-order polynomial equation was a negative value in 10 of 14 subjects, which indicates that the second-order polynomial regression equation opened downwards. These findings suggest that the diaphragmatic shear modulus increases along with inspiratory mouth pressure, but the rate of increase slows when the pressure reaches higher levels.

Early occurrence of inspiratory muscle weakness in Parkinson's disease.

IntroductionIn Parkinson’s disease (PD), respiratory insufficiency (including functional and muscle disorders) can impact dysarthria and swallowing. Most studies of this topic have been performed retrospectively in populations of patients with advanced PD. The objective of the present study was to characterize lung function (under off-drug conditions) in early-stage PD patients at baseline and then again two years later.MethodsForty-one early-stage PD patients (mean ± SD age: 61.7 ± 7.7; mean ± SD disease duration: 1.9 ± 1.7 years) were prospectively enrolled and compared with 36 age-matched healthy controls. Neurological evaluations and pulmonary function testing were performed in the off-drug condition at the inclusion visit and then two years later.ResultsPulmonary function testing did not reveal any restrictive or obstructive disorders; at baseline, inspiratory muscle weakness was the only abnormality observed in the PD group (in 53.7% of the patients, vs. 25% in controls; p = 0.0105). The PD patients had a lower mean maximal inspiratory mouth pressure than controls and a lower sniff nasal inspiratory pressure. Two years after the initiation of chronic treatment with antiparkinsonian medications, the maximal inspiratory mouth pressure and the sniff nasal inspiratory pressure tended to be higher. Lastly, overall motor outcomes were not significantly worse in patients with inspiratory muscle weakness than in patients without inspiratory muscle weakness.ConclusionInspiratory muscle weakness seems to be common in patients with early-stage PD, and was seen to be stable over a two-year period. Additional long-term follow-up studies are required to specify the impact of this new feature of PD.

Respiratory muscle strength in children with mild bronchial asthma disease

Background: Respiratory muscle strength can be decreased in patients with asthma; however, it is not well-documented whether a mild bronchial asthma disease can affect respiratory muscle strength in children and can be associated with higher presence of breathing difficulties. Objective: The main aim of the present study was to compare respiratory muscle strength between children with asthma and age-matched healthy children. The next aim of this study was to assess the incidence of decreased respiratory muscle strength in children with asthma and healthy children and assess the effect of decreased respiratory muscle strength on the incidence of breathing difficulties. Methods: Children with mild bronchial asthma (n = 167) and age-matched, healthy children (n = 100) were recruited into this study. Pulmonary function tests, maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures and the incidence of breathing difficulty were evaluated in children with asthma and healthy controls. Results: The inspiratory muscle strength was similar between children with asthma and healthy children. Conversely, the expiratory muscle strength was lower in asthmatic children. There was a statistically significant difference between girls with asthma and healthy girls (PEmax = 81.7 ± 29.8% vs. 100.1 ± 23.7% of predicted, p < .001). PEmax was significantly higher in boys with asthma than in girls with asthma (PEmax = 92.9 ± 26.4 % vs. 81.7 ± 29.8% of predicted, p = .03). A higher incidence of breathing difficulties during physical activity (uphill walking, running, swimming) was confirmed in children with asthma with lower respiratory muscle strength. Conclusions: There was a higher prevalence of decreased expiratory muscle strength in children with asthma; therefore, respiratory muscle strength should be tested in these children, especially in those who are symptomatic.

Impact of Weekly Swimming Training Distance on the Ergogenicity of Inspiratory Muscle Training in Well-Trained Youth Swimmers

Lomax, M, Kapus, J, Brown, PI, and Faghy, M. Impact of weekly swimming training distance on the ergogenicity of inspiratory muscle training in well-trained youth swimmers. J Strength Cond Res 33(8): 2185-2193, 2019-The aim of this study was to examine the impact of weekly swimming training distance on the ergogenicity of inspiratory muscle training (IMT). Thirty-three youth swimmers were recruited and separated into a LOW and HIGH group based on weekly training distance (≤31 km·wk and >41 km·wk, respectively). The LOW and HIGH groups were further subdivided into control and IMT groups for a 6-week IMT intervention giving a total of 4 groups: LOWcon, LOWIMT, HIGHcon, and HIGHIMT. Before and after the intervention period, swimmers completed maximal effort 100- and 200-m front crawl swims, with maximal inspiratory and expiratory mouth pressures (PImax and PEmax, respectively) assessed before and after each swim. Inspiratory muscle training increased PImax (but not PEmax) by 36% in LOWIMT and HIGHIMT groups (p ≤ 0.05), but 100- and 200-m swims were faster only in the LOWIMT group (3 and 7% respectively, p ≤ 0.05). Performance benefits only occurred in those training up to 31 km·wk and indicate that the ergogenicity of IMT is affected by weekly training distance. Consequently, training distances are important considerations, among others, when deciding whether or not to supplement swimming training with IMT.

Association of physical activity with lung function in lung-healthy German adults: results from the KORA FF4 study

BackgroundIn lung disease, physical activity (PA) yields beneficial health effects, but its association with the function of healthy lungs has rarely been studied. We investigated the association of accelerometer-based PA with spirometric indices, maximal inspiratory mouth pressure (PImax) and lung diffusion capacity in lung-healthy adults.MethodsIn total, 341 apparently lung-healthy participants from the population-based KORA (Cooperative Health Research in the Region of Augsburg) FF4 cohort study (45% male, aged 48-68 years, 47% never smokers) completed lung function testing and wore ActiGraph accelerometers over a one week period at the hip. In adjusted regression analyses, moderate to vigorous PA (MVPA) was characterized as: sex-specific activity quartiles, achieving ≥ 10 consecutive minutes (yes vs. no), and meeting the WHO PA recommendations (yes vs. no).ResultsPositive associations of MVPA-quartiles with forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and corresponding Global Lung Function Initiative z-scores were found. Subjects in the most active quartile (> 47 or > 50 min/day for females and males, respectively) had 142 ml [95% CI: 23, 260] higher FEV1 and 155 ml [95% CI: 10, 301] higher FVC than those in the least active quartile (< 17 or < 21 min/day for females and males, respectively); however these associations were stronger among ex−/current smokers. Achieving at least once 10 consecutive minutes of MVPA was only associated with higher PImax [β-estimate: 0.57 kPa; 95% CI: 0.04, 1.10], remaining significant among never smokers. No associations were found with diffusion capacity or for reaching the WHO-recommended 150 min of MVPA/week in 10-min bouts.ConclusionsAlthough the effects were small, active subjects showed higher spirometric results. The observed associations were more pronounced among ever smokers suggesting a higher benefit of PA for subjects being at a higher risk for chronic lung diseases.

Inspiratory Muscle Training Effects on Cycling During Acute Hypoxic Exposure.

Hypoxic environments increase the physiological demands of exercise. Inspiratory muscle training can reduce the demands of exhaustive exercise in this environment. This study examined the impact of inspiratory muscle training on moderate intensity hypoxic cycling exercise. There were 17 healthy adult men who undertook 4 wk of inspiratory muscle training (N = 8) or 4 wk of sham inspiratory muscle training (N = 9). Subjects completed four fixed intensity (100 W) and duration (10 min) cycle ergometry tests. Two were undertaken breathing normoxic ambient air and two breathing a hypoxic gas mixture (14.6% oxygen, balance nitrogen). One normoxic and hypoxic test occurred before, and one after, inspiratory muscle training. Inspiratory muscle training increased maximal inspiratory mouth pressure by 21 ± 16 cmH2O. Arterial oxygen saturation and its ratio to minute ventilation also increased after inspiratory muscle training during hypoxic exercise from 83 ± 4% to 86 ± 3% (approximately 3%) and 2.95 ± 0.48 to 3.52 ± 0.54% · L · min-1(approximately 21%), respectively. In addition, minute ventilation and carbon dioxide output fell by 12-13% after inspiratory muscle training during hypoxic exercise. Inspiratory muscle training reduced the physiological demand of moderate intensity exercise during acute hypoxic, but not normoxic, exercise. It may therefore be of benefit in adults exercising in a hypoxic environment.Lomax M, Massey HC, House JR. Inspiratory muscle training effects on cycling during acute hypoxic exposure. Aerosp Med Hum Perform. 2017; 88(6):544-549.

Relation Between Inspiratory Muscle Strength and Recruitment Onset of Neck Inspiratory Muscles

The diaphragm contributes approximately 70–90% to whole inspiratory muscle pressure generation. In contrast, the neck inspiratory muscles are not always active during quiet breathing in healthy people but frequently active in patients with respiratory disease who has lower inspiratory muscle strength, probably due to help performing inspiration for a certain lung volume. Taken together, the recruitment onset for the neck inspiratory muscles during an inspiration may depend on the inspiratory muscle strength. PURPOSE: To test whether inspiratory muscle strength is associated with the recruitment onset for the neck inspiratory muscles during an inspiration. METHODS: First, eight healthy young subjects measured maximal inspiratory mouth pressure (MIP) as inspiratory muscle strength, and peak inspiratory flow rate (PIFR). Then, subjects matched their flow rate to 20, 40, 60, 80, and 100% PIFR during volitional inspiration from residual volume (Flow rate-control task) to determine the index of recruitment onset for the neck inspiratory muscles. Flow rate-control task was performed with (W; 23cmH2O) and without (WO) inspiratory load. Mean %PIFR and EMG amplitude (aEMG) of the sternocleidomastoid (SCM) and scalene (SC) were calculated over the duration of every 10% of maximal lung volume (MLV) ranging from 20% to 60% of MLV. The index of recruitment onset for each muscle was determined by the processed %PIFR-aEMG curves at each %MLV. Finally, a linear regression analysis was performed between MIP normalized to body weight (MIP/BW) and index of recruitment onset for each muscle across subjects, for which the Pearson product-moment correlation coefficient (r) was calculated at each %MLV. RESULTS: MIP was ranged from 124 to 205 cmH2O across subjects. When collapsed across %MLV, there were highly negative correlations between MIP/BW and index of recruitment onset for both muscles under W (SCM: r = −0.866; SC: r = −0.877, P < 0.01) and WO (SCM: r = −0.789; SC: r = −0.735, P < 0.05). CONCLUSION: The current results indicate that the neck inspiratory muscles of a subject who has lower inspiratory muscle strength are recruited at lower flow rate with a certain lung volume, suggesting that MIP/BW becomes useful outcome for assessing not only inspiratory muscle strength but also recruitment onset of the neck inspiratory muscles.

Maximal inspiratory mouth pressure in Japanese elite female athletes

Maximal inspiratory mouth pressure (MIP) is a common measurement of inspiratory muscle strength, which is often used in a variety of exercises to evaluate the effects of inspiratory muscle training. The characteristics of MIP in elite female athletes remain unclear. This study aimed to determine the characteristics of MIP at rest in a variety of sport-specific elite female athletes. We also aimed to clarify if there is a sex difference of MIP in elite athletes. We studied 169 Japanese elite female athletes and 301 Japanese elite male athletes. MIP was assessed using a portable autospirometer with a handheld mouth pressure meter. Female athletes who regularly experienced exercise-induced inspiratory muscle fatigue tended to have higher MIP values. The mean absolute MIP value in females was significantly lower than that in males. However, when this value was expressed relative to body mass, this difference disappeared. Our findings provide essential information for prescribed, sport-specific, inspiratory muscle training in elite female athletes.

Contractile capability of the diaphragm assessed by ultrasonography predicts nocturnal oxygen saturation in COPD.

Diaphragm function might be useful to predict nocturnal oxygen desaturation in COPD. Ultrasonography has been widely used for the assessment of the diaphragm. We aimed to investigate the relationship between the contractile capability of the diaphragm assessed by ultrasonography and the nocturnal percutaneous arterial oxygen saturation (NSpO2 ) in COPD. Twenty-eight male patients with COPD (age, 73 ± 7 years; forced expiratory volume in 1 s (FEV1 ), 54.2 ± 17.0% predicted) were included. The thickness of the diaphragm (Tdi) was assessed by ultrasonography. We calculated the change ratio of Tdi at the end of maximal inspiration and expiration (%ΔTdi). The mean value of NSpO2 (NSpO2mean ), the percentage of total sleep time (TST) with desaturation above 4% (DA4%) and the percentage of TST with saturation below 90% (SB90%) were measured by overnight oximetry. Daytime arterial oxygen pressure (PaO2 ) and maximal inspiratory mouth pressure (PImax ) were also measured. All participants had mild or no daytime hypoxaemia (PaO2 , 77.3 ± 8.6 mm Hg). The NSpO2mean , DA4% and SB90% were significantly correlated with %ΔTdi, PaO2 , %PImax of the predicted value and the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage. The %ΔTdi and PaO2 were predictors of NSpO2 mean by multiple regression analysis. This study suggested a close relationship between the NSpO2 and the contractile capability of the diaphragm assessed by ultrasonography in COPD. The %ΔTdi combined with PaO2 might predict NSpO2 in COPD patients with mild or no daytime hypoxaemia.

Electrically induced mechanomyograms reflect inspiratory muscle strength in young or elderly subjects.

Respiratory muscle strength has been used as a tool for evaluating respiratory rehabilitation in chronic obstructive pulmonary disease. However, mouth pressure measurement evaluated by maximum expiratory mouth pressure (PEmax) or inspiratory mouth pressure (PImax) offers an indirect method for measuring respiratory muscle strength. We demonstrated the evaluation of diaphragm contractility using a mechanomyogram (MMG), which is the mechanical signal generated by the motion of the diaphragm induced by the electric stimulation of the phrenic nerve. Study participants were 21 young and 20 elderly subjects with no symptoms of respiratory disease. The elderly subjects were divided into non-smoker or smoker groups. The smoker group was defined as subjects having a Brinkman Index of greater than 300. We measured basic spirometric parameters, mouth pressure (PEmax, PImax), and diaphragmatic MMG. Diaphragmatic MMG showed more clear contrast between young subjects and elderly non-smoker or smoker subjects than the conventional method for respiratory muscle contraction (PEmax, PImax). In addition, the diaphragmatic MMG strongly correlated with inspiratory muscle strength. Diaphragmatic MMG may reflect diaphragmatic contractility more directly and sensitively than the conventional method.

Sex differences in the cardiovascular consequences of the inspiratory muscle metaboreflex.

It is currently unknown whether sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. We hypothesized that the activation of the inspiratory muscle metaboreflex will lead to less of an increase in mean arterial pressure (MAP) and limb vascular resistance (LVR) and less of a decrease in limb blood flow (Q̇L) in women compared with men. Twenty healthy men (n = 10, 23 ± 2 yr) and women (n = 10, 22 ± 3 yr) were recruited for this study. Subjects performed inspiratory resistive breathing tasks (IRBTs) at 2% or 65% of their maximal inspiratory mouth pressure (PIMAX). During the IRBTs, the breathing frequency was 20 breaths/min with a 50% duty cycle. At rest and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was measured via Doppler ultrasound, and LVR was calculated. EMG was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to attenuated increases (P < 0.01) from baseline in women compared with men for MAP (W: 7.3 ± 2.0 mmHg; M: 11.1 ± 5.0 mmHg) and LVR (W: 17.7% ± 14.0%; M: 47.9 ± 21.0%), as well as less of a decrease (P < 0.01) in Q̇L (W: -7.5 ± 9.9%; M: -23.3 ± 10.2%). These sex differences in MAP, Q̇L, and LVR were still present in a subset of subjects matched for PIMAX The 2% IRBT resulted in no significant changes in MAP, Q̇L, or LVR across time or between men and women. These data indicate premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with age-matched men.

Diaphragm Recruitment Increases during a Bout of Targeted Inspiratory Muscle Training

The extent to which the diaphragm is targeted during a bout of inspiratory muscle training (IMT) is unknown. The purpose of this study was to characterize the relative activation patterns of the diaphragm and extradiaphragmatic inspiratory muscles during a bout of IMT and to determine whether diaphragmatic recruitment can be increased by giving subjects specific diaphragmatic breathing instructions (IMTdi). Ten healthy men were instrumented with surface EMG electrodes on the sternocleidomastoid (EMGscm), scalenes (EMGsca), parasternal intercostals (EMGpic), and seventh intercostal space (EMG7ic). A multipair esophageal electrode catheter measured crural diaphragmatic EMG (EMGdi) and transdiaphragmatic pressure (Pdi). Trial 1 of IMT involved 25 dynamic inspiratory maneuvers at 40% of maximal inspiratory mouth pressure using a variable flow resistive loading device where subjects were free to choose their own inspiratory muscle recruitment strategy. Trial 2 involved the same procedures, but subjects were given specific instructions to actively recruit their diaphragm. Cervical magnetic stimulation of the phrenic nerves verified the absence of diaphragmatic fatigue before commencing the second trial. Compared with IMT, IMTdi resulted in a significant increase in EMGdi (56 ± 12 vs 73 ± 10%max, P = 0.002) and Pdi swings (39 ± 14 vs 64 ± 17 cm H2O, P < 0.0001) and a decrease in EMGsca (52 ± 21 vs 36 ± 22%max, P = 0.04). There was no difference in EMG7ic (26 ± 19 vs 33 ± 21%max, P = 0.36), EMGpic (31 ± 24 vs 25 ± 15%max, P = 0.22), and EMGscm (58 ± 21 vs 45 ± 24%max, P = 0.08) when comparing IMT versus IMTdi, respectively. Simple diaphragmatic breathing instructions can significantly increase the recruitment of the diaphragm during IMT compared with a bout of IMT where individuals are free to choose their own inspiratory muscle recruitment strategy.

Maximal inspiratory mouth pressure in Japanese elite male athletes

Maximal inspiratory mouth pressure (MIP) is a common measurement of inspiratory muscle strength, which is often used in a variety of exercises to evaluate the effects of inspiratory muscle training. An understanding of elite athletes’ MIP characteristics is needed to guide sport-specific inspiratory muscle training programs. The purpose of this study was to investigate and better understand the MIP characteristics of elite athletes from a variety of sports. A total of 301 Japanese elite male athletes participated in this study. MIP was assessed using a portable autospirometer with a handheld mouth pressure meter. Athletes with higher body mass tended to have stronger MIP values, in absolute terms. In relative terms, however, athletes who regularly experienced exercise-induced inspiratory muscle fatigue tended to have stronger MIP values. Our findings suggest that athletes could benefit from prescribed, sport-specific, inspiratory muscle training or warm-ups.

Marine Lipid Fraction Pcso-524™ (lyprinol®/omega-xl®) Of The New Zealand Green-lipped Mussel Does Not Improve Pulmonary And Respiratory Muscle Function In Non-asthmatic Elite Runners

Habitual endurance training may be associated with mild airway inflammation and subsequent deterioration in lung function. It has been shown that PCSO-524™ (Lyprinol®/Omega-XL®), a supplement extracted from the New Zealand green-lipped mussel (Perna canaliculus) comprising of up to 90 essential fatty acids, can moderate airway inflammation in humans with asthma, and in a murine-model of allergic airway disease. PURPOSE: To determine whether supplementation with PCSO-524™ (Lyprinol®/Omega-XL®) can improve pulmonary and respiratory muscle function in non-asthmatic elite runners. METHODS: 16 male, non-asthmatic elite runners participated in the study. Participants completed baseline resting pulmonary and respiratory muscle function testing, then were randomly assigned to either a treatment (PCSO-524™; 1 capsule contains 50 mg n-3 polyunsaturated fatty acids and 100 mg olive oil, n = 8) or placebo (1 capsule contains 100 mg olive oil; n = 8) group. During the supplementation period, subjects ingested 8 capsules of either treatment or placebo per day for 12 weeks. Following baseline testing, pulmonary and respiratory muscle function was assessed every two weeks throughout the 12 week supplementation period. RESULTS: Significant between-subjects main effects were not observed in forced vital capacity (FVC), forced expiratory volume in 1-second (FEV1.0), forced expiratory flow from 25-75% of lung volume (FEF25-75), peak expiratory flow (PEF), maximal voluntary ventilation (MVV), maximal inspiratory mouth pressure (PImax), maximal expiratory mouth pressure (PEmax), lung diffusion capacity (DLCO), and closing volume (CV) (all p > 0.05). A significant within-subjects main effect was observed in PEmax (p = 0.0242) and DLCO (p < 0.0001). No significant within-subject main effects were observed in FVC, FEV1.0, FEF25-75, PEF, MVV, PImax, and CV (all p > 0.05). A significant treatment by time interaction was observed in FEF25-75 (p = 0.0264) and DLCO (p = 0.0247), but no other significant interactions were observed (all p > 0.05). CONCLUSION: Supplementation with PCSO-524™ (Lyprinol®/Omega-XL®) does not improve pulmonary or respiratory muscle function in non-asthmatic elite runners.

Effect of respiratory muscle training on pulmonary function and aerobic endurance in soccer players.

Few studies investigated the effects of the respiratory muscle training (RMT) in soccer although exhaustive high intensity exercise is known to lead to muscle fatigue in respiratory muscles. The purpose of this study was to investigate the effect of RMT on pulmonary function and aerobic endurance in soccer players. Eighteen male soccer players (mean age 22.2±1.4 years) participated in this study. Participants were assigned randomly to either an RMT or a control (CON) group. The RMT group performed a 15-minute endurance training of respiratory muscles twice a week for 5 weeks. The CON group did not receive RMT during this period. All participants were evaluated for aerobic endurance using 20-meter shuttle run test (20-MST), pulmonary function, maximal inspiratory mouth pressure (MIP), and maximal expiratory mouth pressure (MEP) using spirometry. There was a significant improvement in RMT group (14%) as compared to CON group (4%) in MIP measurement (P=0.04). No significant differences were observed in forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), maximum voluntary ventilation (MVV), and MEP after a five week of RMT (P>0.05). Similarly, there was no difference in 20-MST in the RMT group compared to CON group (P>0.05). We concluded that a five week of RMT increased MIP, but FVC, FEV1, MVV, MEP and aerobic endurance did not improve in soccer players. The RMT in addition to soccer training may improve MIP but not the tolerance to high intensity exercise.

EFFECTS OF WEIGHT LOSS AFTER BARIATRIC SURGERY ON PULMONARY FUNCTION TESTS AND OBSTRUCTIVE SLEEP APNEA IN MORBIDLY OBESE WOMEN

obesity impacts on respiratory function and also it acts as a risk factor for obstructive sleep apnea (OSA). to study the effects of bariatric surgery on pulmonary function tests and on OSA in morbidly obese women over 4 years. fifteen morbidly obese women (mean body mass index [BMI] 50.52 ± 12.71 kg.m-2, mean age 40.13 ± 10.06 years) underwent pulmonary function tests (PFT) in two opportunities (before and after weight loss surgery). PFT included spirometry, body plethysmography and measure of maximal inspiratory mouth pressure (PImax) and of tension-time index for inspiratory muscles. Also, in both opportunities, resting arterial blood gas tensions were evaluated and a full night sleep register was performed. BMI significantly decreased after bariatric surgery (-44.07 kg.m-2 [CI 95% -38.32 - -49.81]). Also, there was a significantly increase in forced expiratory volume in 1 second (FEV1) (p < 0.01), forced vital capacity (FVC) (p < 0.01), expiratory reserve volume (ERV) (p = 0.040), functional residual capacity (FRC) (p = 0.009) and a decline in airways resistance (Raw) (p = 0.018). Concerning sleep registers, apnea hypopnea index (p = 0.001) and desaturation index (p = 0.001) were also reduced after weight loss. Improve in ERV had a significant correlation with weight loss (r = 0.774, p = 0.024). Conclussions: pulmonary function tests and apnea hypopnea index improve after bariatric surgery in mor bidly obese women. Improvement of ERV is well correlated with weight loss.