Alveolar CO2 during breath holding and exercise.
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Breath Holding↗
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The effects of beta-adrenoceptor blockade on breathing during progressive exercise in normal man.
1 We have studied the effects of single oral doses of 80 mg propranolol and 100 mg atenolol on breathing during progressive exercise in nine healthy men in a double-blind, placebo-controlled experiment. As judged by their effects on exercise heart rate significant levels of beta-adrenoceptor blockade were achieved. 2 At the two lower levels of work rate (50 watts and 100 watts) minute ventilation on atenolol was lower than on placebo while at the highest level of work (200 watts) minute ventilation was higher on atenolol than on placebo. The regression of VE atenolol on VE placebo was 1.28 which is significantly different from unity (P less than 0.001). The results with propranolol were more scattered and failed to reach the 5% level of significance. 3 Effects on the pattern of breathing are small but when minute ventilation is matched with placebo, atenolol results in larger tidal volumes and prolonged inspiratory and expiratory time. 4 These observations are discussed in relation to other work in the literature.
Adrenergic beta-Antagonists↗
Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers.
This study addressed the effects of apnea in air and apnea with face immersion in cold water (10 degrees C) on the diving response and arterial oxygen saturation during dynamic exercise. Eight trained breath-hold divers performed steady-state exercise on a cycle ergometer at 100 W. During exercise, each subject performed 30-s apneas in air and 30-s apneas with face immersion. The heart rate and arterial oxygen saturation decreased and blood pressure increased during the apneas. Compared with apneas in air, apneas with face immersion augmented the heart rate reduction from 21 to 33% (P < 0.001) and the blood pressure increase from 34 to 42% (P < 0.05). The reduction in arterial oxygen saturation from eupneic control was 6.8% during apneas in air and 5.2% during apneas with face immersion (P < 0.05). The results indicate that augmentation of the diving response slows down the depletion of the lung oxygen store, possibly associated with a larger reduction in peripheral venous oxygen stores and increased anaerobiosis. This mechanism delays the fall in alveolar and arterial PO(2) and, thereby, the development of hypoxia in vital organs. Accordingly, we conclude that the human diving response has an oxygen-conserving effect during exercise.
Adult↗
Exercise performance and breathing patterns in cystic fibrosis: male-female differences and influence of resting pulmonary function.
Despite improved prognosis for patients with cystic fibrosis (CF), they continue to suffer from progressive decline in pulmonary function and exercise tolerance. Beyond puberty, female patients have greater loss of pulmonary function and higher mortality than males, yet no one has studied male-female differences in exercise tolerance among patients. We therefore compared the responses to progressive exercise in 58 male and 52 female patients with CF and analyzed the influence of resting pulmonary function and gender on these responses and on breathing patterns during exercise. Within each of three pulmonary function groups (group 1: FEV1 greater than or equal to 65% predicted; group 2: FEV1 = 50-64% predicted; and group 3: FEV1 less than 50% predicted), female patients had lower exercise tolerance than males. This was reflected in the overall group for each gender: males' peak work load was 130 +/- 64 W, females' 111 +/- 32 W (P = 0.04); males' peak oxygen consumption, 36.9 +/- 11.4 mL/kg/min and females', 31.0 +/- 7.4 mL/kg/min (P = 0.0006). There was no interactive effect between gender and pulmonary function. Neither respiratory rate nor tidal volume differed between sexes. Male and female patients, irrespective of disease severity, employed similar proportions of their ventilatory capacity at exhaustion; group mean minute ventilation to maximum voluntary ventilation ratio ranged from 62.9 to 78.3%, with no apparent relationship to disease severity.
Adolescent↗
Physical exercise and resistive breathing training in severe chronic airways obstruction--are they effective?
Twenty-one patients with severe chronic irreversible airflow obstruction (FEV1 consistently less than 1.2 l) were allocated randomly to one of two training programmes designed to reduce respiratory disability or a placebo training control group. Daily structured physical exercise, twice daily inspiratory muscle training by resistive breathing, or daily placebo training were undertaken for 10 weeks, and the effects on lung function, exercise capacity, respiratory symptoms and psychological state compared. Maximal work achieved on a progressive bicycle exercise test was significantly increased in all groups (36%, 23% and 34% respectively) and global improvement in mood also occurred. There was no significant change in respiratory symptom score, static lung function tests or 12 min walking distance. Neither form of active treatment showed superiority over placebo training.
Airway Obstruction↗
Voluntary decrease in breathing frequency in exercising asthmatic subjects.
Exercise rehabilitation programmes are increasingly recommended in young asthmatics, but it is unclear whether or not training should incorporate instructions on breathing pattern. In this study, we examined the effects of voluntarily decreasing breathing frequency on their ventilatory equivalents for oxygen and carbon dioxide (minute ventilation (V'E)/oxygen consumption (V'O2) and V'E/CO2 production (V'CO2), respectively), noninvasively determined physiological dead space/tidal volume (VD/VT) and dyspnoea. Fifteen young asthmatic subjects were assigned to two groups: low frequency breathing (LFB) and controls. They first underwent an exercise test at a cardiac frequency of 150 beats x min(-1). They were trained at this level for nine sessions. LFB subjects were instructed to decrease respiratory frequency by 40% during exercise. Control subjects received no instructions. A second test was then performed in the same conditions. LFB subjects decreased V'E/V'O2, V'E/V'CO2 and VD/VT by 22, 19 and 12%, respectively. Arterial oxygen saturation (Sa,O2) fell to 89+/-4% and end-tidal carbon dioxide tension (PET,CO2) rose to 6.5+/-0.7 kPa (49+/-5 mmHg). In controls, these variables were identical in the two tests. Dyspnoea was lower in the second test in all subjects. In conclusion, breathing pattern may be profoundly altered during exercise without concomitant increase in dyspnoea. However, directing breathing patterns for exercise rehabilitation requires an individual assessment of the desired pattern in order to prevent hypercapnia or hypoxia.
Adaptation, Physiological↗
Breathing retraining and exercise conditioning in patients with chronic obstructive pulmonary disease (COPD): a physiological approach.
In this review we shall consider the commonest techniques to reduce dyspnea that are being applied to patients with chronic obstructive pulmonary disease (COPD) subjected to a pulmonary rehabilitation program (PRP). Pursed lip breathing (PLB) and diaphragmatic breathing (DB) are breathing retraining strategies employed by COPD patients in order to relieve and control dyspnea. However, the effectiveness of PLB in reducing dyspnoea is controversial. Moreover, DB may be associated with asynchronous and paradoxical breathing movements, reflecting a decrease in the efficiency ofthe diaphragm. Exercise training (EXT) is a mandatory component of PRP.EXT has been shown to improve exercise performances and peripheral muscle strength. Recent studies have focused on the effect of EXT on breathlessness. However, concerns persist as to whether the decreased sensation of dyspnea for a given exercise stimulus is principally due to psychological benefits of rehabilitation or to improved physiological ability to perform exercise. The effect of EXT on breathlessness may be reinforced by inhaling oxygen. However, two studies have recently shown that breathing supplemental oxygen during training has either a marginal effect or no advantage over training. In a comprehensive PRP, strength training (ST) and arm endurance training (AET) could have a role in decreasing peripheral muscle weakness and metabolic and ventilatory requirements for AET. The role of unloading the respiratory muscles during EXT has to be
Breathing Exercises↗
Effects of ankle exercise combined with deep breathing on blood flow velocity in the femoral vein.
Ankle exercises are commonly used to facilitate venous return in the lower extremity and to prevent deep vein thrombosis. Moreover, the respiratory cycle affects venous return. This study examined the effects of ankle exercise combined with deep breathing on the blood flow velocity in the femoral vein. Twenty healthy males (mean age 21.3 years), who had no medical history of lower extremity disease, were recruited for this study. The blood flow velocity in the femoral vein was measured while performing four exercise protocols: quiet breathing while resting (QR), deep breathing (DB), ankle exercise with quiet breathing (AQB), and ankle exercising combined with deep breathing (ADB). Using a Doppler ultrasound with an 8 MHz probe, peak blood flow velocities were collected for a 20 second period at the start of the inspiration phase in each protocol, three times. There were statistically significant differences in the peak blood flow velocity in the femoral vein with the four protocols (p lt 0.001). The mean (SD) peak blood flow velocity in the femoral vein was as follows: QR 10.1 (4.2) cm/sec, DB 15.5 (3.9) cm/sec, AQB 20.7 (6.6) cm/sec, and ADB 26.5 (9.4) cm/sec. Post hoc analyses revealed significant differences between each of the four protocols (p(adj) lt 0.01). The mean peak blood flow velocity in the femoral vein was greatest with the ADB protocol, which implies that the ADB protocol may be useful to prevent the blood stasis in patients at risk of deep vein thrombosis.
Adult↗
A nomogram for assessment of breathing patterns during treadmill exercise.
OBJECTIVE: To assess the breathing patterns of trained athletes under different conditions. The hypothesis is that the breathing pattern during a progressive treadmill exercise is independent of the protocol, at least in healthy people, and can be assessed using a nomogram. METHODS: A total of 43 male and 21 female athletes from different sports were studied. They performed one of two different protocols (steps or ramp) on a treadmill. The two protocols started at the same speed and had the same rate of increase in work. During the test, the expired air was analysed for CO2 and O2. Ventilation (VE) was continuously recorded, and tidal volume (Vt) and breathing frequency (BF) at the same intensity were analysed for both protocols, as well as Vt/T(i) and T(i)/T(tot). RESULTS: No significant differences were observed in Vt and BF between the two protocols in either the men or women at any level (confidence intervals up to 0.958 in all the groups). T(i)/T(tot) remained constant, and all increases in VE were strongly related to the respective increases in Vt/T(i). Plots of data for men and women showed a curvilinear relation between Vt and BF which could be fitted with an exponential function with a strong correlation (R2 = 0.98 for men and 0.97 for women). CONCLUSIONS: Graphic expression of Vt v BF is a useful nomogram for the routine assessment of ventilatory response during exercise in healthy trained subjects.
Adolescent↗
Respiratory drive and breathing pattern during exercise in man.
Changes in respiratory drive, as assessed by mouth occlusion pressure (P0.1), and in breathing pattern were studied in 19 healthy subjects who exercised on a cycle ergometer with work loads ranging from loadless pedalling up to the highest load that could be sustained for 4 min. In the P0.1 studies, experiments were carried out both at normal atmospheric pressure and during hyperbaric conditions in which the density (D) of the respired gas was increased. Analyses of observed changes in P0.1 and in the interrelations of minute ventilation (V), tidal volume (VT), inspiratory (TI), expiratory (TE) and total breath (Ttot) durations, and lung volumes yielded the following results and conclusions: Analyses of inspiratory and expiratory volume threshold curves in terms of the relations between end-inspiratory volume and TI on one hand, and end-expiratory volume and TE on the other, suggest that the termination of inspiration during cycle exercise is dependent on volume-related afferent feedback from the lungs and/or chest wall, not only in the high but also in the low volume range, and expiratory muscle activity occurs already at low exercise intensities, combined with active control of expiratory flow, end-expiratory volume and TE as exercise hyperpnea intensifies. TI/Ttot increased with V and work intensity through a number of mechanisms which accelerate the increase in mean expiratory flow compared with that in mean inspiratory flow (VT/TI), the change in timing presumably reducing the oxygen cost of respiration at any given exercise-induced ventilatory demand. With increments in work load, P0.1 increased at higher rates than V and VT/TI, both in the normo- and hyperbaric conditions. Respiratory impedance, P0.1/(VT/TI), increased with both D and VT/TI. The relationship of P0.1, D and VT/TI approximated the equation P0.1 = K X D0.5(VT/TI)b, where K varies among subjects due to differences in i.a. vital capacity, and b has a value close to 1.5. The observed changes in P0.1 suggest that the respiratory drive was reflexly enhanced in response to loading as airway resistance increased with D and/or VT/TI, whereby any depression of V or VT/TI attributable to the increased respiratory impedance was counteracted.
Adult↗
Breathing pattern during exercise in young black and Caucasian subjects.
Lung volumes in sex-, age-, height-, and weight-matched Black subjects are 10-15% lower than those in Caucasians. To determine whether this decreased lung volume affected the ventilatory adaptation to exercise, minute ventilation (VE), its components, frequency (f) and tidal volume (VT), and breathing pattern were observed during incremental cycle-ergometer exercise. Eighteen Caucasian (age 8-30 yr) and 14 Black (age 8-25 yr) subjects were studied. Vital capacity (VC) was lower (P less than 0.001) in the Black subjects [90.6 +/- 8.6 (SD) vs. 112.9 +/- 9.9% predicted], whereas functional residual capacity/total lung capacity was higher (P less than 0.05). VE, mixed expired O2 and CO2, VT, f, and inspiratory (TI), expiratory (TE), and total respiratory cycle (TT) duration were measured during the last 30 s of each 2-min load. Statistical comparisons with increasing power output were made at rest and from 0.6 to 2.4 W/kg in 0.3-W/kg increments. VE was higher in Blacks at all work loads and reached significance (P less than 0.05) at 0.6 and 1.5 W/kg. VE/VO2 was also higher throughout exercise, reaching significance (P less than 0.01) at 1.2, 1.5, and 1.8 W/kg. The Black subjects attained any given level of VE with a higher f (P less than 0.001) and lower VT. TI and TE were shortened proportionately so that TI/TT was not different. Differences in lung volume and the ventilatory response to exercise in these Black and Caucasian subjects suggest differences in the respiratory pressure-volume relationships or that the Black subjects may breathe higher on their pressure-volume curve.
Adolescent↗
Lack of protective effect of high-dose ipratropium on bronchoconstriction following exercise with cold air breathing in patients with mild asthma.
To evaluate the preventive effect of inhaled ipratropium powder on low-grade bronchoconstriction elicited by breathing cold air during exercise, we subjected 10 adult patients with mild asthma to four identical treadmill exercise tests. The temperature of inhaled air during exercise was -9 +/- 1 degree C. Sixty minutes before exercise, the patients inhaled either placebo or 0.2, 1, or 2 mg of ipratropium powder according to a cross-over, double-blind arrangement. The mean post-exercise fall from the post-treatment pre-exercise values in the four treatment groups was 14, 14, 16 and 16% for FEV1, and 59, 52, 52 and 55% for SGaw, respectively. We concluded that doses of ipratropium up to 20-50 times higher than those known to have a marked effect on resting bronchomotor tone in clinically stable asthma did not blunt the bronchoconstriction response following exercise with cold air breathing in our patients with mild asthma.
Adolescent↗
Comparison of indirect calorimetry and a new breath 13C/12C ratio method during strenuous exercise.
A new stable isotope method for the determination of substrate oxidation rates in vivo is described and compared with indirect calorimetry at rest and during high-intensity exercise (30 min at 80-85% maximal O2 uptake capacity) in six well-trained cyclists. This method uses the absolute ratios of 13C/12C in expired air, endogenous glucose, fat, and protein in addition to O2 consumption and is independent of CO2 production (VCO2). Carbohydrate and fat oxidation rates at rest, calculated by both methods, were not significantly different. During exercise the breath 13C/12C ratio increased and reached a steady state after 15-20 min. Carbohydrate oxidation rates during exercise were 39.4 +/- 5.2 and 41.7 +/- 5.7 mg.kg-1.min-1 [not significant (NS)], and fat oxidation rates were 7.3 +/- 1.3 and 6.9 +/- 1.2 mg.kg-1.min-1 (NS), using indirect calorimetry, and the breath ratio method, respectively. We conclude that the breath 13C/12C ratio method can be used to calculate substrate oxidation under different conditions, such as the basal state and exercise. In addition, the results obtained by this new method support the validity of the underlying assumption that indirect calorimetry regards VCO2 as a reflection of tissue CO2 production, during exercise in trained subjects, even up to 80-85% maximal O2 uptake.
Adult↗
Residence at 3,800-m altitude for 5 mo in growing dogs enhances lung diffusing capacity for oxygen that persists at least 2.5 years.
Mammals native to high altitude (HA) exhibit larger lung volumes than their lowland counterparts. To test the hypothesis that adaptation induced by HA residence during somatic maturation improves pulmonary gas exchange in adulthood, male foxhounds born at sea level (SL) were raised at HA (3,800 m) from 2.5 to 7.5 mo of age and then returned to SL prior to somatic maturity while their littermates were simultaneously raised at SL. Following return to SL, all animals were trained to run on a treadmill; gas exchange and hemodynamics were measured 2.5 years later at rest and during exercise while breathing 21% and 13% O(2). The multiple inert gas elimination technique was employed to estimate ventilation-perfusion (Va/Q) distributions and lung diffusing capacity for O(2) (Dl(O(2))). There were no significant intergroup differences during exercise breathing 21% O(2). During exercise breathing 13% O(2), peak O(2) uptake and Va/Q distributions were similar between groups but arterial pH, base excess, and O(2) saturation were higher while peak lactate concentration was lower in animals raised at HA than at SL. At a given exercise intensity, alveolar-arterial O(2) tension gradient (A-aDo(2)) attributable to diffusion limitation was lower while Dlo(2) was 12-25% higher in HA-raised animals. Mean systemic arterial blood pressure was also lower in HA-raised animals; mean pulmonary arterial pressures were similar. We conclude that 5 mo of HA residence during maturation enhances long-term gas exchange efficiency and Dl(O(2)) without impacting Va/Q inequality during hypoxic exercise at SL.
Acclimatization↗
Respiratory muscle oxygenation kinetics: relationships with breathing pattern during exercise.
This work aimed to investigate accessory respiratory muscle oxygenation (RMO(2)) during exercise, using near-infrared spectroscopy, and to study relationships between RMO(2) kinetics and breathing parameters. Nineteen young males (19.3 +/- 1.5 years) performed a maximal incremental test on a cycle ergometer. Changes in breathing pattern were characterized by accelerated rise in the breathing frequency (f (Racc)), plateau of tidal volume (V (Tplateau)) and inflection point in the V. (E)/V (T) relationship (V. (E)/V (T inflection)). First and second ventilatory thresholds (VT1 and VT2) were also determined. RMO (2) kinetics were monitored by NIRS on the serratus anterior. During exercise, all subjects showed reduced RMO (2) (deoxygenation) with a breakdown (B-RMO(2)) at submaximal workload (86 % .VO(2max)). .VO(2) corresponding to B-RMO (2) and to f (Racc), V (Tplateau), .V(E)/V(T inflection), or VT2 were not different. Relationships were found between the .VO(2) at B-RMO(2) and the .VO(2) at f (Racc) (r = 0.88, p < 0.001), V (Tplateau) (r = 0.84, p < 0.001), V. (E)/V (T inflection) (r = 0.58, p < 0.05) or VT2 (r = 0.79, p < 0.001). The amplitude of RMO(2) at maximal workload was weakly related to .VO(2max) (r = 0.58, p < 0.05). B-RMO (2) seems to be due to the change in breathing pattern and especially to the important rise in breathing frequency at the VT2 exercise level. Moreover, subjects who exhibit higher .VO(2max) also exhibit a higher decrease in respiratory muscle oxygenation during exercise.
Adult↗
Breathing pattern retraining and exercise in persons with chronic obstructive pulmonary disease.
Breathing pattern retaining, in the form of pursed-lip breathing, has been used as one method in pulmonary rehabilitation to help alleviate the symptoms of dyspnea endured by people who suffer from airflow obstruction secondary to chronic obstructive pulmonary disease (COPD). Other techniques such as biofeedback also have been successfully used. This article describes the altered breathing patterns used by patients with COPD at rest and during physical activity. The literature is reviewed regarding techniques of breathing pattern retraining that have been developed to improve the capacity of persons with COPD to perform activities of daily living, a primarily rehabilitative outcome.
Breathing Exercises↗
Bicycle exercises and deep breathing in the prevention of thrombosis.
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Bicycling↗
Breathing patterns during submaximal and maximal exercise in elite oarsmen.
Continuous breath-by-breath measurements of ventilatory parameters were performed during submaximal and maximal treadmill exercise in 21 highly conditioned oarsmen. Average maximum values of O2 uptake, minute ventilation (VI), tidal volume (VT), and respiratory frequency (f) were 6.60 l/min (73.5 ml X kg-1 X min-1), 200 l/min, 3.29 l, and 62 breaths/min, respectively. During the transition from moderate to heavy submaximal exercise, VT and f increased progressively. At near-maximal to maximal work loads, VT plateaued and then decreased slightly, while f continued to increase. Increase in f at the start of exercise was achieved predominantly by an abrupt decrease in expiratory duration (TE) with an equally abrupt, but much smaller, decrease in inspiratory duration (TI). During the transition from submaximal to maximal exercise, both TE and TI decreased progressively. Although f appeared to be entrained by stepping rate in a few subjects, the dominant trend during submaximal to maximal exercise was characterized by a relatively small increase in stepping rate with a much larger increment in f. Our data are consistent with the conclusion that exercise breathing patterns are determined by many interacting factors that vary at different work loads, in different individuals, and are probably also influenced by physical conditioning and previous experience.
Adult↗