Pressure Threshold Inspiratory Muscle Training Research Articles

EFFECTS OF INSPIRATORY MUSCLE TRAINING ON FUNCTIONAL CAPACITY AND QUALITY OF LIFE IN PULMONARY HYPERTENSIVE PATIENT

Background: Exercise intolerance is present even in the early stages of pulmonary arterial hypertension (PAH) and is associated with poor prognosis. Respiratory muscle dysfunction is common and may contribute to exercise limitation. Objective: To determine the effects of inspiratory muscle training (IMT) in pulmonary hypertensive patient. Methodology: A randomized control trial was conducted at Services Hospital Lahore after approval from Medical Superintendent. A total of n=18 subjects were randomly allocated into two groups, both group received deep breathing exercise (DBE) and 2nd group received additionally Inspiratory muscle training (IMT) with pressure threshold Inspiratory muscle training device. All participants received 12 sessions in two weeks; the duration of each session was of 20 minutes. The outcome variables were functional capacity and quality of life (SF-36). In functional capacity, of the blood pressure (BP), heart rate (HR), partial pressure of oxygen (SpO2), distance walk (6min walk test) and level of dyspnea were recorded The data was evaluated at baseline and after 12th session. Results: The mean age of patients was 58.11±7.11 years, with 9 male and 9 female. After 2 weeks, the general health, social activities and energy were significantly (p<0.05) improved in experimental group. But no significant difference (p≥0.05) was observed between the group regarding activity limitation, physical and emotional health items of quality of life (SF-36). When comparing the Blood pressure and heart rate, no significant difference was observed between the groups, after 2 weeks of intervention (p≥0.05). While SpO2,6 MWT and dyspnea score was significantly (p<0.05) improved in experimental group as compare to control group. Conclusion: The Deep breathing and inspiratory muscle training both are equally effective with respect to improving the quality of life but IMT is more efficient as compared to Deep breathing for improving dyspnea and it also improves the pulmonary functional and exercise capacity. Key words: breathing exercises, dyspnea, inspiratory muscle training, pulmonary hypertension, quality of life.

The functional capacity of the patients after open heart surgery following physiotherapy utilizing inspiratory muscle training

Background: Post-operative pulmonary dysfunction is common after open heart surgery. This causes impairment in the routine activities of an individual. Exercise rehabilitation may benefit in open heart surgery patients, improving their exercise capacity. Objective: The objective of the study was to assess and compare functional capacity in open heart surgery patients following conventional physiotherapy (CP), and CP plus inspiratory muscle training (IMT). Materials and Methods: In this prospective randomized control study, participants were taken from cardiac hospital using balance block computer generated randomization method. There were 102 participants, 52 in Group-A and 50 in Group-B. Group-A has been given CP and the Group-B has been given conventional plus IMT exercise by Pressure Threshold IMT instrument. For the functional capacity measurement, 6 minute walk test (MWT) and incentive spirometry (IS) was used at pre-operative, “at discharge” and at “1st follow-up” of patients. Results: Addition of IMT exercises to the conventional physiotherapy did not show statistically significant difference in functional capacity after open heart surgery. Though the component of functional capacity- 6MWT showed an incremental change which was statistically significant within the groups (P < 0.05). Conclusion: No any significant difference was found in functional capacity in CP and conventional plus inspiratory muscle trainer group in “pre-operative,” “at discharge” and “1st follow-up,” in open heart surgery patient.

Elastic Taping’s Effect on Exercise Capacity in Recreational Runner with Inspiratory Muscle Training

Background: Running is a new trend of recreational sports in Indonesia. About 70% of recreational runners have difficulty in improving exercise capacity due to exercise-related transient abdominal pain (ETAP), caused by fatigue of the diaphragmatic muscles. Previous studies have shown that various training methods may increase diaphragmatic muscle strength and endurance, for example, inspiratory muscle training (IMT). Unfortunately, improvement of inspiratory muscle strength and endurance after exercise and IMT are still varies. Therefore, other methods are needed to optimize the effect of IMT. Application of the elastic taping on thoracic wall during exercise allows the inspiratory muscles to contract optimally which might improve functional capacity.Aim: To assess the effect of elastic taping on inspiratory muscle training using the pressure threshold IMT, in increasing the functional exercise capacity of recreational runners. Functional capacity was measured based on VO2max value, rating of perceived breathlessness (RPB) and rating of perceived exertion (RPE).Methods: an experimental study involved 14 nonsmoker recreational runners, ages 20-40 years, at Outpatient Clinic of Physical Medicine and Rehabilitation Department of Dr. Soetomo Hospital Surabaya. Subjects were divided into two groups (pressure threshold IMT with and without elastic taping groups), which were observed for four weeks. IMT was done five times a week, twice a day, with 30 repetitions, and 60% resistance 30 RM using Respironics®. Elastic taping Leukotape® was applied on the first until fifth day in each IMT sessions. The running exercises were done three times a week with EnMill® Treadmill ETB-03195 with a speed of 4.5 mph and 0% inclination. RBP, RPE and VO2max were measured using Borg Dyspneu scale, Borg Scale, and Bruce Treadmill Protocol test, respectively, before the first exercise and after 4 weeks of exercise.Results: There were an improvement of functional exercise capacity in both groups which were marked with a decline of RPB and RPE and increase of VO2max (p values &lt; 0.05). However, there were no significant differences in the decrease of RPB and RPE and an increase of VO2max between groups (p values of were 0.31, 0.83, and 0.13, respectively). The effect of the elastic taping (r2 = 0.99) was not reflected in the differences of RPB, RPE and increasing VO2max.Conclusion: Inspiratory muscle training using pressure threshold IMT with or without the elastic taping for four weeks can improve exercise capacity of recreational runners.

Elastic Taping’s Effect on Exercise Capacity in Recreational Runner with Inspiratory Muscle Training

Background: Running is a new trend of recreational sports in Indonesia. About 70% of recreational runners have difficulty in improving exercise capacity due to exercise-related transient abdominal pain (ETAP), caused by fatigue of the diaphragmatic muscles. Previous studies have shown that various training methods may increase diaphragmatic muscle strength and endurance, for example, inspiratory muscle training (IMT). Unfortunately, improvement of inspiratory muscle strength and endurance after exercise and IMT are still varies. Therefore, other methods are needed to optimize the effect of IMT. Application of the elastic taping on thoracic wall during exercise allows the inspiratory muscles to contract optimally which might improve functional capacity.Aim: To assess the effect of elastic taping on inspiratory muscle training using the pressure threshold IMT, in increasing the functional exercise capacity of recreational runners. Functional capacity was measured based on VO2max value, rating of perceived breathlessness (RPB) and rating of perceived exertion (RPE).Methods: an experimental study involved 14 nonsmoker recreational runners, ages 20-40 years, at Outpatient Clinic of Physical Medicine and Rehabilitation Department of Dr. Soetomo Hospital Surabaya. Subjects were divided into two groups (pressure threshold IMT with and without elastic taping groups), which were observed for four weeks. IMT was done five times a week, twice a day, with 30 repetitions, and 60% resistance 30 RM using Respironics®. Elastic taping Leukotape® was applied on the first until fifth day in each IMT sessions. The running exercises were done three times a week with EnMill® Treadmill ETB-03195 with a speed of 4.5 mph and 0% inclination. RBP, RPE and VO2max were measured using Borg Dyspneu scale, Borg Scale, and Bruce Treadmill Protocol test, respectively, before the first exercise and after 4 weeks of exercise.Results: There were an improvement of functional exercise capacity in both groups which were marked with a decline of RPB and RPE and increase of VO2max (p values &lt; 0.05). However, there were no significant differences in the decrease of RPB and RPE and an increase of VO2max between groups (p values of were 0.31, 0.83, and 0.13, respectively). The effect of the elastic taping (r2 = 0.99) was not reflected in the differences of RPB, RPE and increasing VO2max.Conclusion: Inspiratory muscle training using pressure threshold IMT with or without the elastic taping for four weeks can improve exercise capacity of recreational runners.

Maximum inspiratory pressure of the patients after open-heart surgery following physiotherapy

Background: After open-heart surgery, various complications require specific care, especially in the respiratory system. To reestablish it, several strategies should be used, such as respiratory muscle training, which aims to improve respiratory muscle strength, leading to a reduction in post-operative pulmonary complications in patients undergoing cardiac surgery. Aims and Objectives: The objective of the study was to measure and compare maximum inspiratory pressure (MIP) in open-heart surgery patients following conventional physiotherapy group and conventional physiotherapy plus inspiratory muscle training (IMT) group. Materials and Methods: The study was an experimental design and it was a prospective randomized control study where participants were taken from cardiac hospital using balance block computer-generated randomization method. Fifty participants were divided into two groups of 25 each. Group A received conventional physiotherapy and Group B received conventional plus inspiratory muscle exercise (B) by pressure threshold IMT instrument. Physiotherapy treatment was delivered by qualified physiotherapy, twice a day preoperatively and after extubation, 4–5 sessions per day were given until they discharged. The pre-operative, at discharge, and at the 1st follow-up, patient MIP was measured. Results: There was no statistically significant change in inspiratory muscle strength in patients exposed to an IMT program compared to the control group (P > 0.05). Conclusion: There was no difference in MIP in conventional physiotherapy and conventional plus inspiratory muscle trainer group in “pre-operative,” “discharged,” and “1st follow-up” in open-heart surgery patient.

Effects Of Inspiratory Muscle Training On Inspiratory And Locomotor Muscle Hemodynamics During Exercise In Men

High levels of respiratory muscle work may elicit a redistribution of blood flow from the locomotor to the respiratory muscles during exercise. It is unknown if specific inspiratory muscle training (IMT) can attenuate this response during high-intensity, whole-body exercise. PURPOSE: To examine the hemodynamic responses of multiple inspiratory muscles and the vastus lateralis (VL) during incremental cycling before and after 5 weeks of IMT. METHODS: After a comprehensive familiarization visit, 25 recreationally active healthy men (mean±SD; age=24±4; maximal aerobic power (V[Combining Dot Above]O2max)=52±10 ml·kg-1·min-1) completed two maximal incremental cycle exercise tests (25W/2min steps) separated by 5 weeks of pressure threshold IMT or sham-control training (SC). The IMT group (n=12) performed 30 inspiratory efforts twice daily against a minimum resistance of 50% of maximum inspiratory pressure (MIP), adjusted weekly. The SC (n=13) group performed a daily bout of 60 inspiratory efforts against 10% MIP using the same device with no weekly adjustments. During the incremental cycle tests, participants were instrumented with NIRS optodes on the sternocleidomastoid (SCM), parasternal intercostals (PIC), 7th intercostal space (7IC), and VL to measure changes in oxygenated, deoxygenated, and total hemoglobin (tHb) concentrations. RESULTS: The IMT and SC groups were well matched for age, height, mass, and V[Combining Dot Above]O2max. There was a significant increase in MIP in the IMT group (mean±SD, 135±44 vs. 159±35 cmH2O, p<0.05) but not in the SC group (134±39 vs. 134±44 cmH2O, p>0.05). No differences were detected when comparing pre vs. post-IMT for any NIRS derived variables at relative percentages of maximal work rate (20, 40, 60, 80,100%) for any muscle in both the IMT and SC groups. The tHb (muscle blood volume) at the highest equivalent absolute work rate achieved by an individual on each test in the IMT group (pre vs. post-IMT) was 3±15 vs. 1±25, 1±9 vs. 2±11, -6±12 vs. -6±12, and 12±10 vs. 11±9[INCREMENT]μM whereas the SC group was 2±11 vs. 3±6, 1±9 vs. 4±8, -6±6 vs. -6±8, and 12±8 vs. 9±10[INCREMENT]μM in the SCM, PIC, 7IC, and VL, respectively (all p>0.05). CONCLUSION: Five weeks of pressure-threshold IMT had no effect on respiratory or locomotor muscle hemodynamics during incremental cycle exercise in healthy recreationally active men. Supported NSERC

The effects of inspiratory muscle training in older adults.

Declining inspiratory muscle function and structure and systemic low-level inflammation and oxidative stress may contribute to morbidity and mortality during normal ageing. Therefore, we examined the effects of inspiratory muscle training (IMT) in older adults on inspiratory muscle function and structure and systemic inflammation and oxidative stress, and reexamined the reported positive effects of IMT on respiratory muscle strength, inspiratory muscle endurance, spirometry, exercise performance, physical activity levels (PAL), and quality of life (QoL). Thirty-four healthy older adults (68 ± 3 yr) with normal spirometry, respiratory muscle strength, and physical fitness were divided equally into a pressure-threshold IMT or sham-hypoxic placebo group. Before and after an 8-wk intervention, measurements were taken for dynamic inspiratory muscle function and inspiratory muscle endurance using a weighted plunger pressure-threshold loading device; diaphragm thickness by using B-mode ultrasonography; plasma cytokine concentrations by using immunoassays; DNA damage levels in peripheral blood mononuclear cells by using comet assays; spirometry, maximal mouth pressures, and exercise performance by using a 6-min walk test; PAL by using a questionnaire and accelerometry; and QoL using a questionnaire. Compared with placebo, IMT increased maximal inspiratory pressure (+34% ± 43%, P = 0.008), diaphragm thickness at residual volume (+38% ± 39%, P = 0.03), and peak inspiratory flow (+35% ± 42%, P = 0.049) but did not change other spirometry measures, plasma cytokine concentrations, DNA damage levels in peripheral blood mononuclear cells, dynamic inspiratory muscle function, inspiratory muscle endurance, exercise performance, PAL, or QoL. These novel data indicate that in healthy older adults, IMT elicits some positive changes in inspiratory muscle function and structure but neither attenuates systemic inflammation and oxidative stress nor improves exercise performance, PAL, or QoL.

Effects of inspiratory muscle training on exercise responses in Paralympic athletes with cervical spinal cord injury

We asked whether specific inspiratory muscle training (IMT) improves respiratory structure and function and peak exercise responses in highly trained athletes with cervical spinal cord injury (SCI). Ten Paralympic wheelchair rugby players with motor-complete SCI (C5-C7) were paired by functional classification then randomly assigned to an IMT or placebo group. Diaphragm thickness (B-mode ultrasonography), respiratory function [spirometry and maximum static inspiratory (PI ,max ) and expiratory (PE ,max ) pressures], chronic activity-related dyspnea (Baseline and Transition Dyspnea Indices), and physiological responses to incremental arm-crank exercise were assessed before and after 6 weeks of pressure threshold IMT or sham bronchodilator treatment. Compared to placebo, the IMT group showed significant increases in diaphragm thickness (P = 0.001) and PI ,max (P = 0.016). There was a significant increase in tidal volume at peak exercise in IMT vs placebo (P = 0.048) and a strong trend toward an increase in peak work rate (P = 0.081, partial eta-squared = 0.33) and peak oxygen uptake (P = 0.077, partial eta-squared = 0.34). No other indices changed post-intervention. In conclusion, IMT resulted in significant diaphragmatic hypertrophy and increased inspiratory muscle strength in highly trained athletes with cervical SCI. The strong trend, with large observed effect, toward an increase in peak aerobic performance suggests IMT may provide a useful adjunct to training in this population.

Loading of Trained Inspiratory Muscles Speeds Lactate Recovery Kinetics

The purpose of this study was to investigate the effects of inspiratory threshold loading (ITL) and inspiratory muscle training (IMT) on blood lactate concentration ([lac(-)]B) and acid-base balance after maximal incremental cycling. Eighteen subjects were divided into a control (n = 9) or an IMT group (n = 9). Before and after a 6-wk intervention, subjects completed two maximal incremental cycling tests followed by 20 min of recovery with (ITL) or without (passive recovery (PR)) a constant inspiratory resistance (15 cm H2O). The IMT group performed 6 wk of pressure threshold IMT at 50% maximal inspiratory mouth pressure. Throughout recovery, acid-base balance was quantified using the physicochemical approach by measuring the strong ion difference ([SID] = [Na+] + [K+] - [Cl-] + [lac-]), the total concentration of weak acids ([Atot-]), and the partial pressure of carbon dioxide (PCO2). After the intervention, maximal inspiratory mouth pressure increased in the IMT group only (+34%). No differences in lactate clearance were observed between PR and ITL before the intervention in both groups and after the intervention in the control group. After IMT, relative to PR, [lac-]B was reduced throughout ITL (minutes 2-20) by 0.66 +/- 1.28 mmol x L(-1) (P < 0.05), and both the fast (lactate exchange) and the slow (lactate clearance) velocity constants of the lactate recovery kinetics were increased (P < 0.05). Relative to pre-IMT, ITL reduced plasma [H], which was accounted for by an IMT-mediated increase in [SID] due almost exclusively to a 1.7-mmol x L(-1) reduction in [lac-]B. After maximal exercise, ITL affected lactate recovery kinetics only after IMT. Our data support the notion that the inspiratory muscles are capable of lactate clearance that increases [SID] and reduces [H+]. These effects may facilitate subsequent bouts of high-intensity exercise.

Inspiratory muscle training enhances pulmonary O2 uptake kinetics and high-intensity exercise tolerance in humans

Fatigue of the respiratory muscles during intense exercise might compromise leg blood flow, thereby constraining oxygen uptake (Vo(2)) and limiting exercise tolerance. We tested the hypothesis that inspiratory muscle training (IMT) would reduce inspiratory muscle fatigue, speed Vo(2) kinetics and enhance exercise tolerance. Sixteen recreationally active subjects (mean + or - SD, age 22 + or - 4 yr) were randomly assigned to receive 4 wk of either pressure threshold IMT [30 breaths twice daily at approximately 50% of maximum inspiratory pressure (MIP)] or sham treatment (60 breaths once daily at approximately 15% of MIP). The subjects completed moderate-, severe- and maximal-intensity "step" exercise transitions on a cycle ergometer before (Pre) and after (Post) the 4-wk intervention period for determination of Vo(2) kinetics and exercise tolerance. There were no significant changes in the physiological variables of interest after Sham. After IMT, baseline MIP was significantly increased (Pre vs. Post: 155 + or - 22 vs. 181 + or - 21 cmH(2)O; P < 0.001), and the degree of inspiratory muscle fatigue was reduced after severe- and maximal-intensity exercise. During severe exercise, the Vo(2) slow component was reduced (Pre vs. Post: 0.60 + or - 0.20 vs. 0.53 + or - 0.24 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 765 + or - 249 vs. 1,061 + or - 304 s; P < 0.01). Similarly, during maximal exercise, the Vo(2) slow component was reduced (Pre vs. Post: 0.28 + or - 0.14 vs. 0.18 + or - 0.07 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 177 + or - 24 vs. 208 + or - 37 s; P < 0.01). Four weeks of IMT, which reduced inspiratory muscle fatigue, resulted in a reduced Vo(2) slow-component amplitude and an improved exercise tolerance during severe- and maximal-intensity exercise. The results indicate that the enhanced exercise tolerance observed after IMT might be related, at least in part, to improved Vo(2) dynamics, presumably as a consequence of increased blood flow to the exercising limbs.

Inspiratory muscle training improves 100 and 200 m swimming performance

Inspiratory muscle training (IMT) has been shown to improve time trial performance in competitive athletes across a range of sports. Surprisingly, however, the effect of specific IMT on surface swimming performance remains un-investigated. Similarly, it is not known whether any ergogenic influence of IMT upon swimming performance is confined to specific race distances. To determine the influence of IMT upon swimming performance over 3 competitive distances, 16 competitive club-level swimmers were assigned at random to either an experimental (pressure threshold IMT) or sham IMT placebo control group. Participants performed a series of physiological and performance tests, before and following 6 weeks of IMT, including (1) an incremental swim test to the limit of tolerance to determine lactate, heart rate and perceived exertion responses; (2) standard measures of lung function (forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow) and maximal inspiratory pressure (MIP); and (3) 100, 200 and 400 m swim time trials. Training utilised a hand-held pressure threshold device and consisted of 30 repetitions, twice per day. Relative to control, the IMT group showed the following percentage changes in swim times: 100 m, -1.70% (90% confidence limits, +/-1.4%), 200 m, -1.5% (+/-1.0), and 400 m, 0.6% (+/-1.2). Large effects were observed for MIP and rates of perceived exertion. In conclusion, 6 weeks of IMT has a small positive effect on swimming performance in club-level trained swimmers in events shorter than 400 m.

Inspiratory muscle training improves cycling time-trial performance and anaerobic work capacity but not critical power

We examined whether inspiratory muscle training (IMT) improved cycling time-trial performance and changed the relationship between limit work (W (lim)) and limit time (T (lim)), which is described by the parameters critical power (CP) and anaerobic work capacity (AWC). Eighteen male cyclists were assigned to either a pressure-threshold IMT or sham hypoxic-training placebo (PLC) group. Prior to and following a 6 week intervention subjects completed a 25-km cycling time-trial and three constant-power tests to establish the W (lim)-T (lim) relationship. Constant-power tests were prescribed to elicit exercise intolerance within 3-10 (Ex1), 10-20 (Ex2), and 20-30 (Ex3) min. Maximal inspiratory mouth pressure increased by (mean +/- SD) 17.1 +/- 12.2% following IMT (P < 0.01) and was accompanied by a 2.66 +/- 2.51% improvement in 25-km time-trial performance (P < 0.05); there were no changes following PLC. Constant-power cycling endurance was unchanged following PLC, as was CP (pre vs. post: 249 +/- 32 vs. 250 +/- 32 W) and AWC (30.7 +/- 12.7 vs. 30.1 +/- 12.5 kJ). Following IMT Ex1 and Ex3 cycling endurance improved by 18.3 +/- 15.1 and 15.3 +/- 19.1% (P < 0.05), respectively, CP was unchanged (264 +/- 62 vs. 263 +/- 61 W), but AWC increased from 24.8 +/- 5.6 to 29.0 +/- 8.4 kJ (P < 0.05). In conclusion, these data provide novel evidence that improvements in constant-power and cycling time-trial performance following IMT in cyclists may be explained, in part, by an increase in AWC.

Acute and chronic responses of the upper airway to inspiratory loading in healthy awake humans: An MRI study

We assessed upper airway responses to acute and chronic inspiratory loading. In Experiment I, 11 healthy subjects underwent T(2)-weighted magnetic resonance imaging (MRI) of upper airway dilator muscles (genioglossus and geniohyoid) before and up to 10 min after a single bout of pressure threshold inspiratory muscle training (IMT) at 60% maximal inspiratory mouth pressure (MIP). T(2) values for genioglossus and geniohyoid were increased versus control (p<0.001), suggesting that these airway dilator muscles are activated in response to acute IMT. In Experiment II, nine subjects underwent 2D-Flash sequence MRI of the upper airway during quiet breathing and while performing single inspirations against resistive loads (10%, 30% and 50% MIP); this procedure was repeated after 6 weeks of IMT. Lateral narrowing of the upper airway occurred at all loads, whilst anteroposterior narrowing occurred at the level of the laryngopharynx at loads > or =30% MIP. Changes in upper airway morphology and narrowing after IMT were undetectable using MRI.

Differentiating the Influence of Inspiratory and Expiratory Muscle Training upon Rowing Performance in Club-Level Oarsmen

Respiratory muscle training (RMT) has been shown to yield improvements in exercise performance in healthy young people. In these studies, two different forms of respiratory training have been employed, with similar outcomes; 1) voluntary isocapnic hyperpnoea (VIH); 2) pressure threshold inspiratory muscle training (IMT). The former is an endurance training approach that involves both the inspiratory and expiratory muscles, the latter employs resistance training principles and is confined to the inspiratory muscles. It remains unclear whether the addition of expiratory muscle training (EMT), as occurs during VIH, provides any additional benefit to IMT alone. PURPOSE: To investigate the effects of 4-wk of inspiratory muscle training (IMT) or expiratory muscle training (EMT), as well as the effect of a subsequent 6-wk period of concurrent IMT/EMT upon rowing performance in club-level oarsmen. METHODS: Informed, written consent was obtained from 17 male rowers who were allocated randomly to either an IMT (n=10) or EMT (n=7) group for the first 4-wks of training. Performance and physiological responses were measured during an incremental rowing ergometer 'step-test' and a 6-min all-out (6MAO) effort. Respiratory muscle training was undertaken at the 30 repetition maximum load (∼50% of the peak respiratory mouth pressure, PImax or PEmax) using one of two pressure threshold devices. RESULTS: Table 1. Changes in respiratory muscle function and performance in the 6MAO (mean±SD). *=different from baseline, p <0.05; V=different from preceding time point, p <0.05). Table 1 Image ToolsThere was no change in minute ventilation (VE) or maximal oxygen uptake (VO2max) in either group at any time point. The IMT group showed a decrease in heart rate (∼3-6 bpm) at all 'step-test' stages, and a decreased sensation of breathlessness (Borg CR10) following the 6MAO effort (11.1%, P = 0.05). There were no significant physiological changes in the EMT group. CONCLUSIONS: IMT improved rowing performance, but EMT and concurrent IMT/EMT did not.

Inspiratory muscle training in obstructive lung disease

<h3>Key points</h3> Dyspnoea is influenced by inspiratory muscle strength and the load placed upon the inspiratory muscles. Dynamic hyperinflation is a major cause of dyspnoea and exercise intolerance in patients with expiratory flow limitation due to its detrimental effect upon inspiratory muscle loading. Specific IMT improves inspiratory muscle strength, reduces dyspnoea and improves exercise tolerance, even in individuals without inspiratory muscle weakness or hyperinflation. Pressure threshold IMT is the most reliable, convenient and commonly used method of IMT, eliciting improvements in a wide range of muscle functional characteristics, including strength, shortening velocity, power and endurance. Inspiratory muscles adhere to the same training principles as other skeletal muscles, with respect to overload, specificity and reversibility. Training loads must exceed 30% of inspiratory muscle strength, with at least once daily training and weekly increases in training load. Programmes should be least 6 weeks in duration, after which frequency can be reduced to two sessions, three times per week. IMT can be implemented as a stand-alone intervention or as part of a comprehensive programme of rehabilitation. Monitored outcomes should include inspiratory muscle strength, an index of dyspnoea (e.g. BDI/TDI and/or Borg CR-10) and exercise tolerance (<i>e.g</i>. 6MWD). <h3>Educational aims</h3> To provide an overview of the role of respiratory muscle function in the genesis of dyspnoea. To describe the response of inspiratory muscles to different types of training stimuli. To offer guidance on the implementation and monitoring of IMT. <h3>Summary</h3> Dyspnoea is strongly influenced by respiratory muscle function. Patients with obstructive lung disease become hyperinflated and experience an associated functional deficit in inspiratory muscle function, as well as a concomitant increase in the work of breathing. These changes result in a heightened sense of respiratory effort and a propensity for inspiratory muscle fatigue. There is now convincing evidence that specific inspiratory muscle training (IMT) improves respiratory muscle function, reduces dyspnoea and improves exercise tolerance. This review will describe the two most commonly implemented methods of IMT, and the specific functional adaptations that are elicited by each. It will also describe successful, evidence-based implementation and monitoring of the most commonly used method of IMT.

The effect of inspiratory muscle training upon maximum lactate steady-state and blood lactate concentration

Several studies have reported that improvements in endurance performance following respiratory muscle training (RMT) are associated with a decrease in blood lactate concentration ([Lac](B)). The present study examined whether pressure threshold inspiratory muscle training (IMT) elicits an increase in the cycling power output corresponding to the maximum lactate steady state (MLSS). Using a double-blind, placebo-controlled design, 12 healthy, non-endurance-trained male participants were assigned in equal numbers to an experimental (IMT) or sham training control (placebo) group. Cycling power output at MLSS was initially identified using a lactate minimum protocol followed by a series of constant power output rides (2.5% increments) of 29.5 min duration; MLSS was reassessed following six weeks of IMT or sham IMT. Maximum inspiratory mouth pressure increased significantly (26%) in the IMT group, but remained unchanged in the placebo group. The cycling power output corresponding to MLSS remained unchanged in both groups after the intervention. After IMT, [Lac](B) decreased significantly at MLSS power in the IMT group [-1.17 (1.01) mmol l(-1) after 29.5 min of cycling; mean (SD)], but remained unchanged in the placebo group [+0.37 (1.66) mmol l(-1)]. These data support previous observations that IMT results in a decrease in [Lac](B )at a given intensity of exercise. That such a decrease in [Lac](B) was not associated with a substantial (>2.5%) increase in MLSS power is a new finding suggesting that RMT-induced increases in exercise tolerance and reductions in [Lac](B) are not ascribable to a substantial increase in the 'lactate threshold'.

Effects of inspiratory muscle training on time-trial performance in trained cyclists

We evaluated the effects of specific inspiratory muscle training on simulated time-trial performance in trained cyclists. Using a double-blind, placebo-controlled design, 16 male cyclists (VO 2max = 64 - 2 ml·kg -1 ·min -1 ; mean - sx ¥ ) were assigned at random to either an experimental (pressure-threshold inspiratory muscle training) or sham-training control (placebo) group. Pulmonary function, maximum dynamic inspiratory muscle function and the physiological and perceptual responses to maximal incremental cycling were assessed. Simulated time-trial performance (20 and 40 km) was quantified as the time to complete pre-set amounts of work. Pulmonary function was unchanged after the intervention, but dynamic inspiratory muscle function improved in the inspiratory muscle training group ( P h 0.05). After the intervention, the inspiratory muscle training group experienced a reduction in the perception of respiratory and peripheral effort (Borg CR10: 16 - 4% and 18 - 4% respectively; compared with placebo, P h 0.01) and completed the simulated 20 and 40 km time-trials faster than the placebo group [66 - 30 and 115 - 38 s (3.8 - 1.7% and 4.6 - 1.9%) faster respectively; P = 0.025 and 0.009]. These results support evidence that specific inspiratory muscle training attenuates the perceptual response to maximal incremental exercise. Furthermore, they provide evidence of performance enhancements in competitive cyclists after inspiratory muscle training.