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Transient ventilatory and heart rate responses to moderate nonabrupt pseudorandom exercise.

Dynamic responses of inspired minute ventilation, CO2 and O2 end-tidal gas fractions, and heart rate were obtained from six normal human volunteers in response to a complex dynamic exercise challenge. Subjects pedalled a chair ergometer at constant frequency. The retarding torque applied to the ergometer pedals was controlled by a low-pass-filtered pseudorandom binary sequence (fPRBS), which provided a complex, nonanticipatory exercise stimulus containing sufficient high- and low-frequency energy to excite the small signal, broadband ventilatory response. The exercise range was chosen to produce a mean level of O2 consumption at or below 50% maximum O2 consumption. Cross-covariant analysis of the fPRBS exercise with breath-by-breath ventilation provided an estimate of the dynamic (impulse) response to exercise, which contained both fast phase 1 and slow phase 2 components. The initial, phase one, hyperpnea occurred within the same breath as the exercise transition and preceded a hypocapnic response. The phase one hyperpnea represented 26% of the total ventilatory response. The secondary, phase 2, hyperpnea was delayed several breaths from the onset of phase 1. It contained slower dynamics and followed a hypercapnic response. Heart rate increased abruptly during phase 1, peaked near the phase 1-to-2 boundary, and then decreased rapidly. The experimental protocol was designed to minimize the subjective response and provide an adequate stimulus for the faster time constants. Results obtained from these experiments were consistent with a nonhumoral induced phase 1 exercise hyperpnea.

Adult↗

Acute effects of carbon monoxide exposure on individuals with coronary artery disease.

The purpose of this study was to determine, using more objective evidence than that reported in previous studies, whether or not exposures to carbon monoxide that produce approximately 2% or 4% blood carboxyhemoglobin levels cause an exacerbation of myocardial ischemia during a progressive exercise test. The objective measurements were based on the development of electrocardiographic evidence of ischemia. In addition, time to onset of angina pectoris was studied. Male subjects, ages 35 to 75, with stable exertional angina pectoris and positive exercise treadmill tests with reproducible ischemic ST-segment changes in their electrocardiograms, were studied. In addition, each subject fulfilled at least one of the following criteria of coronary artery disease: angiographic evidence of at least a 70% occlusion of one or more major coronary artery; prior documented myocardial infarction; or a positive exercise thallium test. Each subject was evaluated on four separate occasions, a qualifying visit and three blinded test visits, which involved exposure (in random order) to air without added carbon monoxide and to air that contained carbon monoxide concentrations calculated to produce approximately 2.2% or 4.4% carboxyhemoglobin, measured by gas chromatography, at the end of the exposure period. These immediate postexposure target levels were set 10% higher than the desired postexercise carboxyhemoglobin levels of 2.0% and 4.0% because exercise while breathing room air results in loss of carbon monoxide. The actual one-minute postexercise levels reached were 2.0% +/- 0.1% (mean +/- standard error of the mean) and 3.9% +/- 0.1%. On each test day, the subject performed a symptom-limited exercise test on a treadmill, was exposed for approximately one hour to air or to one of two levels of carbon monoxide in air, and then performed a second exercise test. Time to the onset of ischemic ST-segment changes and time to the onset of angina were determined for each exercise test. The percent difference for these endpoints on the pre- and postexposure exercise tests was determined, and then the results on the 2%-COHb-target day and the results on the 4%-COHb-target day were compared to those on the control day. Data from the 63 subjects who completed the three test visits and met all protocol criteria were analyzed. There were 5.1% (p = 0.01) and 12.1% (p less than or equal to 0.0001) (trimmed mean) decreases in the time to development of ischemic ST-segment changes after the 2%- and 4%-COHb-target exposures, respectively, compared to the control day.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Sensation of breathlessness and respiratory oxygen cost during cycle exercise with and without conscious entrainment of the breathing rhythm.

The conscious entrainment of respiratory rhythm to exercise rhythm (ENT) has been hypothesized to alleviate breathing discomfort and reduce the oxygen (O2) cost of ventilation with a resulting decrease in total O2 uptake (VO2) during rhythmic exercise. This hypothesis has been tested in the study reported here. Eight female subjects performed cycle exercise at 50 rpm under two work load conditions of 40% and 60% of maximal VO2. During a 30-min exercise period at each work load, each subject was asked to breathe under two conditions for 15 min each: (1) spontaneously (non-ENT run), and (2) deliberately entraining the breathing rhythm to the cycling rhythm at preferred coupling ratios of the two rhythms (ENT run). In the ENT run, most subjects chose a ratio of 1:2. In each run, pulmonary ventilation (VE), total VO2 and the breathlessness sensation (BS) were measured at 4-5 min. BS was assessed according to a Borg category scale. The remaining 10 min of each 15-min run were allotted for measurement of the O2 cost of ventilation (delta VO2/delta VE), assessed by a hypercapnia-induced hyperventilation method in which the VO2 of the respiratory muscles (VO2RM) was calculated by multiplying delta VO2/delta VE by the prevailing VE. On average, there were no significant differences in any of the variables, VO2, delta VO2/delta VE, VO2RM and BS, between the non-ENT and ENT runs performed at any work load. However, there were wide variations among the subjects in the differences (delta) between the two runs, and significant correlations were found between delta VO2 vs delta VE, delta VO2 vs delta VO2RM, and delta BS vs delta VO2RM of individual subjects. These results indicate that reductions of the total VO2 and BS with ENT could occur in subjects in whom the VO2RM decreased during ENT.

Adult↗

Inspiratory pressure threshold training for upper airway limitation: a case of bilateral abductor vocal fold paralysis.

A single subject design was used to determine if pressure threshold training strengthens the inspiratory muscles in a subject with a limited glottal airway as well as diminish dyspnea and improve parameters of speech. The subject was a 19-year-old woman whose glottal airway was limited due to bilateral abductor vocal fold paralysis following a thyroidectomy. A 5-week inspiratory muscle strength-training program was implemented using a pressure-threshold trainer to strengthen the inspiratory muscles with the intent of enabling the generation of higher inspiratory pressures. The pressure threshold on the trainer was set at 75% of the subject's maximum inspiratory pressure (MIP). The subject was required to generate sufficient inspiratory pressure to bring air through the trainer during an inspiratory maneuver. MIP was the dependent variable used as an indication of inspiratory muscle strength. MIP increased by 47% following the training program. Maximal minute ventilation and oxygen uptake increased posttraining. Dyspnea during exercise and speech decreased as reported by the subject. Total reading duration and pause duration demonstrated a declining trend during connected speech. The results indicated that inspiratory muscle training using a pressure threshold device improves functional tasks such as exercise and speech in a subject with upper airway limitation.

Adult↗

Endurance training of respiratory muscles improves cycling performance in fit young cyclists.

BACKGROUND: Whether or not isolated endurance training of the respiratory muscles improves whole-body endurance exercise performance is controversial, with some studies reporting enhancements of 50% or more, and others reporting no change. Twenty fit (VO2 max 56.0 ml/kg/min), experienced cyclists were randomly assigned to three groups. The experimental group (n = 10) trained their respiratory muscles via 20, 45 min sessions of hyperpnea. The placebo group (n = 4) underwent "sham" training (20, 5 min sessions), and the control group (n = 6) did no training. RESULTS: After training, the experimental group increased their respiratory muscle endurance capacity by 12%. Performance on a bicycle time trial test designed to last about 40 min improved by 4.7% (9 of 10 subjects showed improvement). There were no test-re-test improvements in either respiratory muscle or bicycle exercise endurance performance in the placebo group, nor in the control group. After training, the experimental group had significantly higher ventilatory output and VO2, and lower PCO2, during constant work-rate exercise; the placebo and control groups did not show these changes. The perceived respiratory effort was unchanged in spite of the higher ventilation rate after training. CONCLUSIONS: The results suggest that respiratory muscle endurance training improves cycling performance in fit, experienced cyclists. The relative hyperventilation with no change in respiratory effort sensations suggest that respiratory muscle training allows subjects to tolerate the higher exercise ventilatory response without more dyspnea. Whether or not this can explain the enhanced performance is unknown.

Adolescent↗

Acute effect of percutaneous transvenous mitral commissurotomy on ventilatory and hemodynamic responses to exercise. Pathophysiological basis for early symptomatic improvement.

BACKGROUND: Improvement of exertional dyspnea occurs immediately after percutaneous transvenous mitral commissurotomy (PTMC), but the pathophysiological basis for this early symptomatic improvement has not been elucidated. METHODS AND RESULTS: Exercise hemodynamic measurement and exercise ventilatory measurement with arterial blood gas analysis were performed in 21 patients aged 50.4 +/- 9.5 years (mean +/- SD) with symptomatic mitral stenosis before and a few days after PTMC. Exercise ventilatory measurement were also performed in 14 normal control subjects aged 48.9 +/- 4.9 years. After PTMC, mitral valve area increased (from 1.0 +/- 0.3 to 1.7 +/- 0.3 cm2, P < .001), mean mitral gradient (from 12.2 +/- 5.2 to 5.2 +/- 2.2 mm Hg, P < .001), and mean left atrial pressure (from 18.7 +/- 6.1 to 12.1 +/- 4.0 mm Hg, P < .001) decreased. All patients experienced significant symptomatic improvement soon after PTMC. Comparison of hemodynamic parameters at the same ergometer work rate showed a significant decrease in pulmonary artery systolic pressure (from 77 +/- 18 to 67 +/- 14 mm Hg, P < .001) and diastolic pressure (from 36 +/- 10 to 28 +/- 7 mm Hg, P < .001) and a significant increase in cardiac output (from 6.4 +/- 1.4 to 8.1 +/- 1.9 L/min, P < .001). Despite the improvement in exercise hemodynamics and symptoms, exercise capacity determined by peak oxygen uptake (from 18.0 +/- 2.9 to 18.6 +/- 3.1 mL.kg-1 x min-1) and anaerobic threshold (from 11.7 +/- 2.4 to 12.0 +/- 2.4 mL.kg-1 x min-1) remained unchanged. Excessive exercise ventilation, as assessed by the slope of the regression line between expired minute ventilation and carbon dioxide output, decreased significantly from 37.2 +/- 6.7 to 33.9 +/- 5.8 (P < .001), but remained significantly higher than that in the normal subjects (27.9 +/- 3.6, P < .01). The ratio of total dead space to tidal volume and total dead space per breath during exercise decreased significantly after PTMC (P < .05). The change in excessive exercise ventilation after PTMC was correlated with the change in dead space to tidal volume ratio (r = .59). CONCLUSIONS: Significant relief of exertional dyspnea immediately after PTMC is not accompanied by an improvement in exercise capacity. A decrease in excessive ventilation due to a decrease in physiological dead space resulting from hemodynamic improvement partly contributes to the early relief of symptoms after PTMC. However, lung compliance, which was not measured in the present study, may have changed after PTMC. This change may also contribute to the symptomatic improvement.

Anaerobic Threshold↗

Re-evaluation of exercise prescription for Japanese type 2 diabetic patients by ventilatory threshold.

Prescription of aerobic exercise for Type 2 diabetes mellitus (Type 2 DM) in clinical practice is frequently based on exercise intensity at maximum heart rate (60<HR(max)<79%), heart rate reserve (50<HR(reserve)<74%), and rating of perceived exertion (12<RPE<13). We examined these parameters in Japanese males with Type 2 DM at ventilatory threshold (VT) to investigate the exercise capacity of Type 2 DM patients and re-evaluate the exercise prescription. Fifty-six Japanese Type 2 DM males without autonomic neuropathy [age, 53.5+/-7.7 years; body mass index (BMI), 23.7+/-3.6 kg/m(2)] were enrolled and compared with 56 age- and BMI-matched healthy Japanese males. VT was determined breath by breath during exercise test using a ramp protocol and rates of oxygen consumption (VO(2)), work rate (WR), HR, DeltaHR, %HR(max), %HR(reserve), and RPE were measured at VT. Type 2 DM patients had significantly lower VO(2) (3.6+/-0.4 metabolic equivalents (METs)) and WR (62+/-14 W) than controls (VO(2), 3.9+/-0.6 METs; WR, 74+/-13 W). %HR(reserve), (32.6+/-7.7%) was also significantly lower compared with controls (37.6+/-8.3%), while %HR(max), was not different. RPE was also similar in diabetics (12.4+/-1.5) and controls (12.9+/-1.2), however, it was significantly lower in diabetic patients aged 60-69 years (11.8+/-2.0) and those with distal symmetric sensory neuropathy (12.2+/-1.0). Our results indicate reduced exercise capacity in Japanese Type 2 DM males and the exercise intensity of 60%HR(max), 30%HR(reserve), and RPE 12 is recommended in elderly diabetics and those with diabetic sensory neuropathy.

Blood Pressure↗

Inspiratory resistive loading improves cycling capacity: a placebo controlled trial.

BACKGROUND: Respiratory muscle training has been shown to improve both its strength and endurance. The effect of these improvements on whole-body exercise performance remains controversial. OBJECTIVE: To assess the effect of a 10 week inspiratory resistive loading (IRL) intervention on respiratory muscle performance and whole-body exercise endurance. METHODS: Fifteen apparently healthy subjects (10 men, 5 women) were randomly allocated to one of three groups. One group underwent IRL set at 80% of maximum inspiratory pressure with ever decreasing work/rest ratios until task failure, for three days a week for 10 weeks (IRL group). A second placebo group performed the same training procedure but with a minimal resistance (PLA group). IRL and placebo training were performed at rest. The remaining five control subjects performed no IRL during the 10 week study period (CON group). Cycling endurance capacity at 75% VO(2)peak was measured before and after the intervention. RESULTS: After the 10 week IRL intervention, respiratory muscle strength (maximum inspiratory pressure) and endurance (sum of sustained maximum inspiratory pressure) had significantly improved (by 34% and 38% respectively). An increase in diaphragm thickness was also observed. These improvements translated into a 36% increase in cycling time to exhaustion at 75% VO(2)peak. During cycling trials, heart rate, ventilation, and rating of perceived exertion were attenuated in the IRL group. No changes were observed for the PLA or CON group either in the time to exhaustion or cardiorespiratory response to the same intensity of exercise. CONCLUSION: Ten weeks of IRL attenuated the heart rate, ventilatory, and perceptual response to constant workload exercise, and improved the cycling time to exhaustion. Familiarisation was not a factor and the placebo effect was minimal.

Adult↗

Increased fatigue resistance of respiratory muscles during exercise after respiratory muscle endurance training.

Respiratory muscle fatigue develops during exhaustive exercise and can limit exercise performance. Respiratory muscle training, in turn, can increase exercise performance. We investigated whether respiratory muscle endurance training (RMT) reduces exercise-induced inspiratory and expiratory muscle fatigue. Twenty-one healthy, male volunteers performed twenty 30-min sessions of either normocapnic hyperpnoea (n = 13) or sham training (CON, n = 8) over 4-5 wk. Before and after training, subjects performed a constant-load cycling test at 85% maximal power output to exhaustion (PRE(EXH), POST(EXH)). A further posttraining test was stopped at the pretraining duration (POST(ISO)) i.e., isotime. Before and after cycling, transdiaphragmatic pressure was measured during cervical magnetic stimulation to assess diaphragm contractility, and gastric pressure was measured during thoracic magnetic stimulation to assess abdominal muscle contractility. Overall, RMT did not reduce respiratory muscle fatigue. However, in subjects who developed >10% of diaphragm or abdominal muscle fatigue in PRE(EXH), fatigue was significantly reduced after RMT in POST(ISO) (inspiratory: -17 +/- 6% vs. -9 +/- 10%, P = 0.038, n = 9; abdominal: -19 +/- 10% vs. -11 +/- 11%, P = 0.038, n = 9), while sham training had no significant effect. Similarly, cycling endurance in POST(EXH) did not improve after RMT (P = 0.071), while a significant improvement was seen in the subgroup with >10% of diaphragm fatigue after PRE(EXH) (P = 0.017), but not in the sham training group (P = 0.674). However, changes in cycling endurance did not correlate with changes in respiratory muscle fatigue. In conclusion, RMT decreased the development of respiratory muscle fatigue during intensive exercise, but this change did not seem to improve cycling endurance.

Abdominal Muscles↗

[Effect of oxygen inhalation on the respiration function during exercise under conditions of added resistance to respiration].

Experiments were performed to investigate the effect of added resistance to inspiratory, expiratory and inspiratory-expiratory respiration on lung ventilation and pACO2 during exercise when breathing air or oxygen. Increase of resistance to respiration, particularly inspiratory-expiratory; reduced the work-induced growth of ventilation which caused pACO2 to increase. Oxygen inhalation aggravated those shifts significantly. The adverse effect of hyperoxia on the respiration function when exercise was combined with added resistance to respiration seems to be associated with inhibition of the respiration center produced by the lack of hyperoxid stimulation.

Adult↗

The pattern of breathing and the ventilatory response to breathing through a tube and to physical exercise in sport divers.

Well-trained divers can be expected to differ from healthy controls in their ventilatory response to breathing through a tube and to physical exercise. Therefore, we measured their minute ventilation (VE) at rest and during breathing through a tube combined with two levels of physical exercise (1 or 2 W.kg body weight-1). For breathing through a tube an additional dead space of 600 ml was used. All divers were trained in the breath-hold technique and in the use of the breathing apparatus. Their mean period of training as divers was 9 +/- 6 years. The approximate age of the subjects was 25 years. The pattern of breathing and the oxygen uptake were measured by spirometer, the end-tidal concentration of CO2 was measured and all experiments were carried out above sea level. The ventilation of the divers at rest was comparable to that of the controls. During physical exercise it was smaller whether during breathing through a tube or not. The inadequate increase of VE during exercise in divers was associated with hypercapnia only at a higher physical work intensity (of 2 W.kg-1). This finding is interpreted as a lower chemoregulatory response to the combined stimuli of hypercapnia, hypoxia and physical exercise. In some situations significant bradypnoea and higher tidal volumes were found in the divers.

Adolescent↗

Evidence that maturation of the peripheral chemoreceptors is not complete in childhood.

We examined the hypothesis that the peripheral chemoreceptors contribute a different degree of tone to respiration during exercise in normal young children as compared to adults. To improve resolution of the peripheral chemoreceptor contribution, the studies were conducted during controlled levels of exercise. Peripheral chemoreceptor function was assessed by the hyperoxic (FIO2 = 0.80) switch technique during steady-state, sub-anaerobic threshold exercise during air (FIO2 = 0.21) and midly hypoxic gas (FIO2 = 0.15) breathing in 9 healthy children (mean +/- 1 SD age (years) = 8.2 +/- 1.4) and 10 healthy adults (28.2 +/- 6.5). Ventilation during exercise was significantly greater under hypoxic conditions in both children and adults. During air breathing exercise the mean ventilatory decrease in response to the hyperoxic switch was similar in the two groups (27.9 +/- 10.7% in children and 23.3 +/- 6.3% in adults). In contrast, during hypoxic gas breathing exercise the children demonstrated a much greater decrease in ventilation following the hyperoxic switch (57.9 +/- 3.6%) compared to adults (38.9 +/- 5.5%) (P less than 0.0001). Thus, the peripheral chemoreceptors have a greater role in the exercise hyperpnea during hypoxic exercise in young children as compared to adults, suggesting attenuation of peripheral chemoreceptor function during maturation.

Adult↗

Breathing pattern and lung volumes during exercise.

The interrelationships of ventilation (V), tidal volume (VT), inspiratory (T1), expiratory (TE) and total breath (Ttot) durations, mean inspiratory (VT/TI) and expiratory (VT/TE) flows, and lung volumes were studied in normal subjects at rest and during exercise on a cycle ergometer. The ergometric load was increased by 10 W every minute, from zero W to 200 W. The TI/Ttot ratio increased with V in the range 15 to 60 1 X min-1, indicating that with increasing V the rate of increase of VT/TI decreased whereas that of VT/TE increased. Possible mechanisms responsible for the difference in behaviour of VT/TI and VT/TE are discussed. The VT-TI and VT-TE relationships both displayed three ranges with breakpoints at tidal volumes of about 1.4 and 2.4 1. The relations of TI and TE to end-inspiratory volume were approximately linear over the entire VT range studied, whereas the relations of TI and TE to end-expiratory volume showed three ranges with different characteristics. We conclude that the termination of inspiration during cycle exercise is dependent on volume-related afferent feedback from the lungs and/or chest walls, not only in the high but also in the low volume range.

Adult↗

Nifedipine inhibits hypoxic pulmonary vasoconstriction during rest and exercise in patients with cystic fibrosis and cor pulmonale.

Nifedipine has recently been reported to reduce pulmonary artery pressure and pulmonary vascular resistance during rest and exercise in adult patients with hypoxic pulmonary hypertension from chronic obstructive pulmonary disease. To determine whether nifedipine reduces pulmonary vascular resistance in patients with cor pulmonale from cystic fibrosis (CF), we studied 2 patients with severe CF lung disease during rest and exercise while breathing room air or receiving low-flow oxygen therapy. Nifedipine markedly lowered pulmonary vascular resistance and improved cardiac index and pulmonary pressure-flow relationships during all treatment conditions. Nifedipine did not substantially change arterial PO2, except for a slight decrease during exercise while receiving low-flow oxygen. Nifedipine, however, markedly increased oxygen delivery during rest and exercise. Both patients noted improved exercise tolerance with chronic nifedipine therapy. Nifedipine may be a useful adjuvant to supplemental oxygen in the treatment of patients with CF and cor pulmonale.

Adult↗

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 (VO2max = 64 +/- 2 ml x kg(-1) x min(-1); mean +/- s(x)) 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 < or = 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 < or = 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.

Adult↗

Increased muscle efficiency and sustained benefits in an outpatient community hospital-based pulmonary rehabilitation program.

Previous reports of pulmonary rehabilitation programs have demonstrated improvement in exercise capacity in subjects with disabling pulmonary disease. However, the cost-effectiveness, benefits to outpatients in a community setting, durability of these improvements, and mechanism of improved exercise capacity remain unclear. Forty-four patients with an average FEV1 of 33 +/- 4 percent of predicted completed a six-week long period of supervised treadmill exercise, as well as a continuing home program. Twenty percent had previously unsuspected cardiac disease discovered through the program, while 36 percent had previously unsuspected exercise desaturation. Cardiopulmonary stress testing before and after the program revealed a 73 +/- 16 percent improvement in aerobic capacity (METs peak [power]) and a 250 +/- 78 percent improvement in endurance (MET-min [work]). No significant change was seen in VE max, HR max, FEV1, or the degree of exercise desaturation. Only a small improvement was noted in VO2 max (15 +/- 8 percent) and O2 pulse (16 +/- 8 percent), suggesting that most of the improvement was due to improved muscle efficiency. Follow-up testing at 12 +/- 3 months in 24 subjects revealed that 89 +/- 7 percent of the peak exercise performance was maintained. The cost of the basic program was +800. The results demonstrated that an outpatient community hospital pulmonary rehabilitation program can accomplish substantial exercise capacity improvement with sustained benefits in a cost-effective manner.

Arrhythmias, Cardiac↗

[Training of inspiratory muscles in chronic obstructive lung disease. Its impact on functional changes and exercise tolerance].

The aim of this study was to evaluate the impact of inspiratory muscle training on lung function and exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). Thirty-five patients with stable COPD were enrolled. We measured lung function variables and peak inspiratory and expiratory pressures (PImax and PEmax). Tests of progressive maximal exercise tolerance and stable submaximal exercise tolerance were administered. Two study groups were formed. Group A patients (n = 20) were enrolled in a respiratory muscle training program lasting four months. Group B (n = 15) was the control group. At the end of the study period the patients underwent testing similar to the first battery of tests. All showed moderate to severe obstruction with no significant differences between groups (FEV1: group A 37.6 +/- 13%, group B 36.6 +/- 12%; FVC: group A 80.4 +/- 15%, group B 80 +/- 12%). Nor were there any significant differences between the two groups in initial results of either maximal respiratory pressures or exercise tolerance. No lung function changes were observed in either group. PImax in group A increased significantly at the end of the study (from 54 +/- 9 to 78 +/- 16 cmH2O; p < 0.001); there were no changes in group B. No changes were seen in VO2max or ventilatory response and/or gasometry during exercise in any of the groups. The trained group, on the other hand, experienced a significant decrease in dyspnea evaluated on the Borg scale exercise in maximal (5.7 +/- 1.1 versus 4.7 +/- 1.2, p < 0.005) and submaximal (5.9 +/- 0.9 versus 4.9 +/- 1.3, p < 0.005) and an increase in time of submaximal exercise tolerance (5.5 +/- 2 versus 7 +/- 3 min, p < 0.05), changes that were not observed in the control group. Based on these results, and although specific training of inspiratory muscles does not appear to improve lung function in patients with COPD, it is accompanied by a decreased sense of dyspnea during exercise and greater tolerance.

Aged↗