Short term effects of aerobic training in the clinical management of moderate to severe asthma in children

BACKGROUND: Aerobic training has a number of well known beneficial effects in both normal and asthmatic children. However, the impact of training on the clinical management of the underlying bronchial asthma remains controversial, particularly in the most severe patients. METHODS: Clinical evaluation, spirometric tests, symptom limited maximum exercise testing, and exercise challenge tests were performed in a group of children with stable moderate to severe asthma. Forty two patients (24 boys) aged 8-16 were evaluated twice: before and after supervised aerobic training (group 1, n = 26) and two months apart (untrained group 2, n = 16). RESULTS: Spirometric and maximal exercise variables in the initial evaluation were significantly reduced in group 1 (p < 0.05) but medication and clinical scores and the occurrence of exercise induced bronchospasm (EIB) did not differ between the two groups. Aerobic improvement with training (maximal oxygen uptake and/or anaerobic threshold increment > 10% and 100 ml) was inversely related to the baseline level of fitness and was independent of disease severity. Although the clinical score and the occurrence of EIB did not change after training, aerobic improvement was associated with a significant reduction in the medication score and the daily use of both inhaled and oral steroids (p < 0.05). CONCLUSIONS: Aerobic improvement with training in less fit asthmatic children is related to a short term decrease in the daily use of inhaled and oral steroids, independent of the severity of the disease.     

Prevalence of exercise induced bronchospasm in Kenyan school children: an urban-rural comparison

BACKGROUND: Higher rates of exercise induced bronchospasm (EIB) have been reported for urban than for rural African schoolchildren. The change from a traditional to a westernized lifestyle has been implicated. This study was undertaken to examine the impact of various features of urban living on the prevalence of EIB in Kenyan school children. METHODS: A total of 1226 children aged 8-17 years attending grade 4 at five randomly selected schools in Nairobi (urban) and five in Muranga district (rural) underwent an exercise challenge test. A respiratory health and home environment questionnaire was also administered to parents/guardians. This report is limited to 1071 children aged < or = 12 years. Prevalence rates of EIB for the two areas were compared and the differences analysed to model the respective contributions of personal characteristics, host and environmental factors implicated in childhood asthma. RESULTS: A fall in forced expiratory volume in one second (FEV1) after exercise of > or = 10% occurred in 22.9% of urban children and 13.2% of rural children (OR 1.96, 95% CI 1.41 to 2.71). The OR decreased to 1.65 (95% CI 1.10 to 2.47) after accounting for age, sex, and host factors (a family history of asthma and breast feeding for less than six months), and to 1.21 (95% CI 0.69 to 2.11) after further adjustment for environmental factors (parental education, use of biomass fuel and kerosene for cooking, and exposure to motor vehicle fumes). CONCLUSIONS: The EIB rates in this study are higher than any other reported for African children, even using more rigorous criteria for EIB. The study findings support a view which is gaining increasing credence that the increase in prevalence of childhood asthma associated with urbanisation is the consequence of various harmful environmental exposures acting on increasingly susceptible populations.     

Relationship between the acid-induced cough response and airway responsiveness and obstruction in children with asthma.

BACKGROUND: In children with asthma little is known about the direct effect of the bronchoconstrictor and bronchodilator response on the cough threshold, or the relationship between bronchial responsiveness and the cough threshold. A study was undertaken to determine the effect of histamine-induced bronchoconstriction and salbutamol-induced bronchodilatation on the cough threshold in response to inhaled acetic acid, and to examine the relationship between the acetic acid cough threshold and bronchial hyperresponsiveness to histamine in children with asthma. METHODS: Nineteen children with asthma (16 boys) of mean (SE) age 10.6 (0.6) years were enrolled in the study. On day 1 each underwent a histamine inhalation challenge to determine the provocative concentration causing a fall in forced expiratory volume in one second (FEV1) of more than 20% (PC20) as an index of individual bronchial hyperresponsiveness. On day 2 the acetic acid cough threshold was determined before and just after the inhalation of the PC20 concentration of histamine, and then salbutamol (1 mg/m2) was inhaled to relieve the bronchoconstriction. Ten of the 19 patients (eight boys) of mean age 12.2 (0.7) years also tried acetic acid inhalation challenge just after salbutamol inhalation. RESULTS: There was no relationship between the bronchial responsiveness to histamine and acetic acid cough threshold in these patients. The acetic acid cough threshold after histamine inhalation was similar to that before histamine, although FEV1 decreased after histamine. In the 10 patients who also tried acetic acid inhalation challenge after salbutamol the cough threshold did not change. CONCLUSIONS: These findings suggest that acid-induced cough sensitivity and bronchomotor tone are independently regulated in children with asthma.     

Recombinant erythropoietin improves exercise capacity in anemic hemodialysis patients

The objective of this study was to quantitate the improvement in exercise capacity produced in anemic chronic hemodialysis (HD) patients after correction of their anemia with recombinant human erythropoietin (rHuEPO). The maximal exercise capacity and quadriceps strength of 19 anemic HD patients was tested before and after correction of the anemia with rHuEPO. A progressive work exercise protocol (PWET) on a cycle ergometer was used to compare measurements of maximal oxygen uptake (VO2max), maximal heart rate, and subjective assessment of fatigue during the test. Measurements of quadriceps strength were performed before the cycle ergometer studies. At baseline, all patients had reduced VO2max (15.3 +/- 5.4 mL/kg/min) and maximal exercise heart rates (138.5 +/- 23.9 beats/min). rHuEPO increased the mean hematocrit from 21.2% to 35%, and this was associated with a 17% increase (P less than 0.0005) in the VO2max. At any specified work load, rHuEPO treatment decreased heart rate, minute ventilation, and the subjective perception of fatigue. Both isometric and isokinetic measurements of quadriceps strength were improved following administration of rHuEPO. The maximal exercise heart rate was decreased in comparison to the baseline measurements (P less than 0.04), suggesting that in contrast to normal subjects, HD patients stop exercise before oxygen transport limitations are reached. In this unselected group of chronic HD patients, rHuEPO produced clinically significant improvements in both aerobic exercise capacity and isometric and isokinetic quadriceps strength. The improvement in aerobic capacity was substantially less than would have been expected from the correction of a comparable degree of anemia in non-HD patients. None of the 19 treated patients attained the exercise performance level predicted for a sedentary normal subject.     

Exercise-induced bronchoconstriction by ethnicity and presence of asthma in British nine year olds.

BACKGROUND: The prevalence of exercise-induced bronchoconstriction among British children by ethnicity has not been studied. METHODS: Peak expiratory flow rate (PEFR) was measured before and after an exercise challenge test using a cycle ergometer in 593 nine year olds from Scottish and inner city English schools. Logistic regression analysis was carried out to assess the association between changes in PEFR with exercise by reported asthma, ethnicity, and sex. RESULTS: The probability of exercise-induced bronchoconstriction was greater among the asthmatics than in either the children without asthma attacks or wheeze, or in the children with only wheeze (p < 0.01). Asian children were 3.6 times more likely to have exercise-induced bronchoconstriction than white inner city children, and also were more likely to have exercise-induced bronchoconstriction than those from the other ethnic groups (p < 0.01). CONCLUSION: Exercise challenge can assess the prevalence of asthma in the community and detect under-reporting of asthma in ethnic minorities.     

Effects of 3 months of non-weight-bearing cycle ergometric exercise on bone metabolism

We evaluated the effect of non-weight-bearing exercise on bone metabolism by measuring serum levels of biochemical markers, N-terminal osteocalcin (OC), and intact OC. N-terminal assay using the radioimmunoassay (RIA) method is considered to be a marker of bone turnover. Intact OC was measured as a marker of bone formation by the sandwich enzyme-linked immunosorbent assay (ELISA) method. As is commonly known, the cycle ergometer is a very popular and useful tool for aerobic exercise used world wide to improve health. In this study, we evaluated the effect of such common exercise on N-terminal OC and intact OC using a cycle ergometer. N-terminal OC was not significantly changed after 30min of aerobic training with a cycle ergometer three times a week for 3 months, whereas intact OC decreased significantly. No changes in bone mineral density of weight-bearing or non-weight-bearing bones were found. These results suggest that the type and duration of exercise using the current training method were insufficient to produce a favorable effect on bone. The current training method consisted of aerobic, non-weight-bearing exercise alone using a cycle ergometer. It is unknown whether the non-weight-bearing form of exercise was responsible for our results, or whether the aerobic exercise itself was insufficient. The 3-month period may have been insufficient to stimulate osteogenesis, and it is possible that an exercise period of this duration may instead result in a tendency to suppress bone formation. At any rate, we believe it is significant that we were able to demonstrate, on the basis of changes in bone metabolism markers and bone mineral density, that the nature of this exercise was insufficient to stimulate osteogenesis.     

Physical Condition,Glycemia, Liver Function,and Quality of Life in Liver Transplant Recipients After a 12-Month Supervised Exercise Program

Background and aimsDespite the excellent long-term outcomes in liver transplant (LT) recipients, several medical complications related to lifestyle still represent an issue. This study examined the effects of a 12-month supervised aerobic and strength training program on the aerobic capacity, muscle strength, metabolic profile, liver function, and quality of life of a cohort of LT recipients.MethodsLT recipients with stable liver function were assigned to interventional exercise (group A) or usual care (group B). Aerobic capacity, muscle strength, metabolic profile, liver and kidney function, and health-related quality of life were assessed at baseline and after 6 and 12 months. Group A attended supervised training sessions 3 times per week for 12 months. Group B received general recommendations about home-based exercise.ResultsForty patients from 6 Italian LT centers were randomized. Twenty-nine (72.5%, men-to-women ratio 23:6, mean age, 52 ± 8 years) LT recipients completed the study. Baseline characteristics were similar between groups except for body mass index and time from LT. No episode of acute rejection nor increase of transaminases occurred. Maximum workload and body mass index increased in both groups over time, but fasting glucose significantly decreased in group A (94.0 ± 15.0 mg/dL vs 90.0 ± 17.0 mg/dL; P = .037) and increased in controls (95.0 ± 24.0 mg/dL vs 102.0 ± 34.0 mg/dL, P = .04). Upper limb muscle strength increased only in supervised LT recipients. Vitality and general and mental health domains significantly improved after physical exercise.ConclusionsSupervised combined training was safe and effective in increasing aerobic capacity, muscle strength, and quality of life and in improving glucose metabolism in stable LT recipients.     

Sample size estimation in studies monitoring exercise-induced bronchoconstriction in asthmatic children

BACKGROUND: The repeatability of the response to standardised treadmill exercise testing using dry air and monitoring of heart rate in asthmatic children suffering from exercise-induced bronchoconstriction (EIB) has not been well established. METHODS: Twenty seven asthmatic children with known EIB performed standardised exercise testing twice within a period of three weeks. The tests were performed on a treadmill while breathing dry air. During both tests heart rate had to reach 90% of the predicted maximum. Response to exercise was expressed as % fall in forced expiratory volume in one second (FEV1) from baseline and as area under the curve (AUC) of the time-response curve. RESULTS: The intra-class correlation coefficients for % fall and AUC (log- transformed) were 0.57 and 0.67, respectively. From these data, power curves were constructed that allowed estimations to be made of sample sizes required for studies of EIB in children. These indicated that, if a drug is expected to reduce EIB by 50%, as few as 12 patients would be sufficient to demonstrate this effect (90% power) using a parallel design study. CONCLUSIONS: Standardised exercise testing for EIB using dry air and monitoring of heart rate is adequately repeatable for use in research and clinical practice in children with asthma.     

The effects of aerobic training on the emotional response in patients who underwent cardiac surgery

It has been reported that cardiac surgery and aerobic training influence the patient's emotional response. We investigated the changes in emotional response before and after cardiac surgery and during aerobic exercise training as a cardiac rehabilitation using profile of mood states (POMS). Subjects were thirty-five patients (25 men and 10 women, average 57 years) who underwent cardiac surgery. All patients participated in the rehabilitation program which included aerobic exercise training after cardiac surgery. Aerobic training consisted of cycle ergometer or treadmill. Emotional states were evaluated by POMS score at the preoperative phase, early postoperative phase (about 10 days after surgery) and aerobic training (about 20 days after surgery). Most of the emotional state (tension, anxiety, anger and hostility) significantly improved after cardiac surgery. In particular, aerobic training has an additional effect for improving one of the emotional state which is tension and anxiety. However, several factors such as deconditioning, postoperative complications and high age delayed the improving of emotional response.     

Relation of the hypertonic saline responsiveness of the airways to exercise induced asthma symptom severity and to histamine or methacholine reactivity.

BACKGROUND: Conflicting views exist over whether responsiveness of the airways to hypertonic saline relates to non-specific bronchial hyperresponsiveness measured by histamine or methacholine challenge. The bronchoconstrictor responses to exercise and hypertonic saline are reported to be closely related, but the relationship between the symptoms of exercise induced asthma and airway responsiveness to hypertonic saline is not known. METHODS: In 29 asthmatic patients with a history of exercise induced asthma, the response to an ultrasonically nebulised hypertonic saline (3.6% sodium chloride) aerosol, measured as the volume of hypertonic saline laden air required to produce a fall in forced expiratory volume in one second (FEV1) of > or = 20% (PD20), was compared with the concentration of histamine (PC20; group 1) and methacholine (PC20; group 2) producing a 20% fall in baseline FEV1 and exercise induced asthma symptom severity score (groups 1 and 2). The hypertonic responsiveness was determined in a dose-response manner to a maximum dose of 310 1 and the exercise induced asthma symptom severity was scored on a scale of 0-5. RESULTS: Of the 29 patients, 23 (79%) were responsive to the hypertonic saline, with PD20 values ranging from 9 to 310 1. A significant correlation was found between the PD20 hypertonic saline and the exercise induced asthma symptom score. There was no significant correlation between the PD20 response to hypertonic saline and the histamine PC20 or methacholine PC20. The exclusion of those subjects who failed to respond to hypertonic saline improved the relationship between hypertonic saline and methacholine PC20. No significant correlation was found between the exercise induced asthma symptom score and histamine PC20 or methacholine PC20. CONCLUSION: These findings suggest that hypertonic saline responsiveness bears a closer relationship to the severity of exercise induced asthma symptoms than to the non-specific bronchial hyperresponsiveness measured by histamine or methacholine reactivity.     

Exercise induced bronchospasm in Ghana: differences in prevalence between urban and rural schoolchildren

BACKGROUND: As more developing countries adopt a westernised style of living, an increase in the prevalence of asthma can be expected to occur in these areas. A study was undertaken to establish the normal response to exercise in Ghanaian children and to use these normal values to determine the prevalence of exercise induced bronchospasm (EIB) in urban rich (UR), urban poor (UP), and rural (R) school children. Skin test reactivity to common inhalant allergens in UR, UP, and R children with and without EIB was also investigated. METHODS: Two hundred children aged 9-16 years without a previous history of respiratory symptoms were randomly selected and underwent free running exercise testing. A normal response to exercise was defined as the group mean change in peak expiratory flow rate (PEFR) +/- 2 standard deviations. This value was used to identify the prevalence of EIB in UR, UP, and R schoolchildren. A total of 1095 children from three different schools underwent exercise testing (220 UP, 599 UR, 276 R), after which 916 children underwent skin prick testing to six common inhalant allergens (D farinae, D pteronyssinus, cat, dog, Aspergillus flavus and Candida albicans). RESULTS: From the results of exercise testing in asymptomatic children the normal range was defined as a fall in PEFR of < 12.5% after exercise. Thirty four children were classified as having EIB on the basis of the above definition, giving an overall prevalence of 3.1%. The prevalence of EIB was significantly higher in UR children (4.7%) than in both UP (2.2%; p < 0.05) and R children (1.4%; p < 0.01). However, the prevalence rates in the UP and R children were similar. The prevalence of atopy in the whole population was 4.4%. Of the children with EIB, 10% were skin test positive to at least one of the allergens tested. The prevalence of atopy was significantly higher in UR children (6.55%, 95% confidence interval (CI) 4.5% to 9.2%) than in UP (2.9%, 95% CI 0.9% to 6.7%) and R children (1.5%, 95% CI 0.4% to 3.7%), respectively (p < 0.005). CONCLUSIONS: The prevalence of EIB and atopy is higher in urban rich than in urban poor or rural children suggesting that, in addition to genetic predisposition, social and environmental factors such as wealth, life style, and housing are important determinants of these phenotypes.


     

Aerobic training exercises for individuals who had amputation of the lower limb

The findings in ten subjects who had an amputation of the lower limb or limbs were studied before and after a fifteen-week aerobic conditioning program to determine if it improved cardiovascular fitness and reduced the effort of walking. Each subject exercised on an Air-Dyne ergometer (Schwinn, Chicago, Illinois) regularly during each week of the study period at 60 to 80 per cent of their estimated maximum heart rate. A test of maximum exercise on the ergometer and a test of walking on a treadmill were administered before and after training. After training, there was an increase of 25 per cent in the maximum capacity for exercise on the ergometer as well as significantly lower values for heart rate and consumption of oxygen during submaximum walking on the treadmill at various inclined grades. Aerobic conditioning was shown not only to improve cardiovascular fitness but also to increase the economy of walking in the subject who had an amputation of the lower limb or limbs.     

Angiotensin I Converting Enzyme Gene Polymorphism and Exercise Trainability in Elderly Women: An Electrocardiological Approach

Angiotensin I converting enzyme (ACE) gene Insertion / Deletion (I/D) polymorphism is associated with exercise trainability and exercise induced left ventricular hypertrophy. However, it is unclear whether this polymorphism influences exercise trainability in the elderly, and the electrocardiological alterations by exercise training is unknown among the genotypes. We herein investigated the association between ACE gene insertion/deletion (I/D) polymorphism, exercise trainability and the electrocardiological alternations by exercise in elderly women. Eighty four elderly women participated in this study. In all subjects the leg extension power (LEP) and lactate threshold (LT) were determined in order to evaluate the muscle strength, aerobic capacity and to also select the appropriate training intensity for each individual. They performed bench step exercise training for 12 weeks. A resting electrocardiogram was recorded for the obtained QTc interval in before and after the program. The baseline of aerobic capacity was higher in I/I than that in I/D, and the QTc interval was shorter in I/I than that in I/D. All other characteristics were similar among the genotypes. The QTc interval tended to be shorten only in the D/D. Furthermore, the value of the QTc interval change showed a significant difference between the I/I and D/D genotype after the program. The LT and LEP demonstrated a similar response among the genotypes. The D allele of ACE gene I/D polymorphism may therefore play a role in the electrocardiological aspect during exercise training, however, it was not found to influence the aerobic capacity.

Key points

• The D allele of ACE gene I/D polymorphism may play a role in the electrocardiological aspects during exercise training
• ACE gene I/D polymorphism was not determined the aerobic capacity and leg strength in elderly people.
• The ACE gene I/D polymorphism did not influence aerobic and strength trainability in elderly people.

Key Words: Electrophysiology, exercise, genes     

No effect of group-based aerobic interval training on N-terminal pro- B-type natriuretic peptide levels in patients with chronic heart failure

Abstract

Objectives. Exercise training might improve cardiac function as well as functional capacity in patients with chronic heart failure (CHF). N-terminal pro-B-type natriuretic peptide (NT pro-BNP), is associated with the severity of the disease, and has been reported to be an independent predictor of outcome in CHF. We evaluated the effect of a four months group-based aerobic interval training program on circulating levels of NT pro-BNP in patients with CHF. We have previously reported improved functional capacity in 80 patients after exercise in this exercise program. Methods. Seventy-eight patients with stable CHF (21% women; 70±8 years; left ventricular ejection fraction 30±8.6%) on optimal medical treatment were randomized either to interval training (n=39), or to a control group (n=39). Circulating levels of NT pro-BNP, a six minute walk test (6MWT) and cycle ergometer test were evaluated at baseline, post exercise, and further after 12 months. Results. There were no significant differences in NT pro-BNP levels from baseline to either post exercise or long-term follow-up between or within the groups. Inverse correlations were observed between NT pro-BNP and 6MWT (r=?0.24, p=0.035) and cycle exercise time (r=?0.48, p<0.001) at baseline. But no significant correlations were observed between change in NT pro-BNP and change in functional capacity (6MWT; r=0.12, p=0.33, cycle exercise time; r=0.04, p=0.72). Conclusion. No significant changes in NT pro-BNP levels were observed after interval training, despite significant improvement of functional capacity.     

Effect of dietary supplementation with fish oil lipids on mild asthma.

Recruitment of inflammatory leucocytes to the airways may play a part in the pathogenesis of asthma. As dietary enrichment with fish oil lipids can suppress leucocyte function, the effect of these lipids on asthma control and neutrophil function was studied in 20 subjects with mild asthma. Twelve subjects received capsules containing 3.2 g of eicosapentaenoic acid and 2.2 g of docosahexaenoic acid daily and eight subjects received placebo capsules containing olive oil for 10 weeks in a double blind fashion. Baseline specific airways conductance, airways responsiveness to histamine and exercise, diurnal peak expiratory flow, symptom scores, and bronchodilator use were measured. Neutrophil fatty acid composition was evaluated by gas chromatography, calcium ionophore induced neutrophil leukotriene (LT)B4 and LTB5 generation were measured by reverse phase high performance liquid chromatography and radioimmunoassay, and neutrophil chemotactic responses to formyl-methionyl-leucyl-phenylalanine (FMLP) and LTB4 were assessed by a microchemotaxis technique. Although the fish oil supplemented diet produced a greater than 10 fold increase in the eicosapentaenoic acid content of neutrophil phospholipids, there was no significant change in airways responsiveness to histamine or any change in any of the clinical measurements. After dietary supplementation with fish oil there was a 50% inhibition of total LTB (LTB4 + LTB5) generation by ionophore stimulated neutrophils and neutrophil chemotaxis was substantially suppressed. Neutrophil function remained unchanged in the placebo group. It is concluded that in subjects with mild asthma a fish oil enriched diet attenuates neutrophil function without changing the severity of asthma.     

Prevalence of exercise-induced bronchospasm in Thokoza schoolchildren.

BACKGROUND: Asthma is a common childhood illness, with a prevalence of 1 in 10 children. Exercise-induced bronchospasm (EIB) is a common feature of asthma and is found more often in children than in adults. OBJECTIVE: To determine the prevalence and potential impact of various factors on the prevalence of EIB in Thokoza schoolchildren. METHODS: Data were collected on respiratory health and the home environment of children living in Thokoza, Gauteng. A total of 475 9- and 10-year-old children performed the free-running asthma screening test (FRAST). An abnormal response to FRAST was defined as a reduction in the post-exercise peak flow of more than 15% of the pre-exercise value, at 3- and 10- minute intervals. All children who had a fall in post-exercise flow rate (PEFR) of more than 15% on 2 occasions after FRAST were classified as having EIB. RESULTS: Using the above criteria to diagnose EIB, an overall prevalence rate of 7.26% (95% confidence interval (CI): 4.5 - 10.3%) was recorded. A less rigorous definition of EIB is a fall in PEFR of more than 10% on 2 occasions after FRAST, and if this was used then the prevalence of EIB was 15.69% (95% CI: 10.6 - 20.8%). Difficulty breathing and a tight chest were the most prevalent respiratory symptoms in children with EIB (odds ratio (OR): 1.79, 95% CI: 0.49 - 6.49 and OR 1.69, 95% CI: 0.72 - 3.99, respectively). The use of gas and electricity as domestic fuels was the strongest risk factor associated with EIB, as shown by logistical regression analysis using an adjusted OR in a reduced model (OR 2.44, 95% CI: 0.71 - 8.44 and OR 2.33, 95% CI: 0.59 - 9.24, respectively). CONCLUSION: The prevalence of EIB reported in this study is higher than that reported in studies from other African countries, with the exception of a study from Kenya. Findings of the present study suggest that there may be a trend towards increasing prevalence of EIB in South African urban areas.     

Randomised controlled trial of weightlifting exercise in patients with chronic airflow limitation.

BACKGROUND PATIENTS: with chronic airflow obstruction are often limited by muscle fatigue and weakness. As exercise rehabilitation programmes have produced modest improvements at best a study was designed to determine whether specific muscle training techniques are helpful. METHODS: Thirty four patients with chronic airflow limitation (forced expiratory volume in one second (FEV1) 38% of predicted values) were stratified for FEV1 to vital capacity (VC) ratio less than 40% and arterial oxygen desaturation during exercise and randomised to a control or weightlifting training group. In the experimental group training was prescribed for upper and lower limb muscles as a percentage of the maximum weight that could be lifted once only. It was carried out three times a week for eight weeks. RESULTS: Three subjects dropped out of each group; results in the remaining 14 patients in each group were analysed. Adherence in the training group was 90%. In the trained subjects muscle strength and endurance time during cycling at 80% of maximum power output increased by 73% from 518 (SE69) to 898 (95) s, with control subjects showing no change (506 (86) s before training and 479 (89) s after training). No significant changes in maximum cycle ergometer exercise capacity or distance walked in six minutes were found in either group. Responses to a chronic respiratory questionnaire showed significant improvements in dyspnoea and mastery of daily living activities in the trained group. CONCLUSIONS: Weightlifting training may be successfully used in patients with chronic airflow limitation, with benefits in muscle strength, exercise endurance, and subjective responses to some of the demands of daily living.     

Perception of breathlessness during bronchoconstriction induced by antigen, exercise, and histamine challenges.

Perception of breathlessness was studied in eight patients with mild, stable asthma after a histamine and exercise challenge performed before and 24 and 48 hours respectively after an antigen challenge. FEV1 and perception of breathlessness, evaluated by Borg's 10 point category scale, were measured after each administration of doubling antigen or histamine concentrations to achieve a greater than 20% fall in FEV1, and after six minutes of steady state exercise at 80% of maximal oxygen consumption (VO2max). The geometric mean provocative concentration of histamine causing a 20% fall in FEV1 (PC20) fell from 1.67 mg/ml before antigen challenge to 0.52 mg/ml 24 hours after the challenge. The median maximal % fall in FEV1 with exercise was 24.9% (range 10.5-40.5%) before and 30.6% (range 13.8-52.3%) 48 hours after antigen challenge. The median maximum % fall in FEV1 after antigen inhalation was 20.1% (range 13.3-35.2%) within the first hour; only two subjects had a late fall in FEV1 (23% and 58%). The median (range) of Borg scores obtained when FEV1 was reduced by 20% did not differ significantly for the three types of acute challenges: 1.25 (0.5-2.5) and 1.0 (0.5-3.0) after histamine tests, 1.0 (0.5-4.1) and 1.55 (0.5-2.0) after exercise, and 1.5 (0-3.0) after antigen challenge. In the two subjects who had a late response to antigen the Borg score was reduced for the same % fall in FEV1 as with the early response. It is concluded that the perception of breathlessness does not differ appreciably during the early response to histamine, antigen exposure, or exercise, but that it is reduced during the late asthmatic response. It was not influenced by previous antigen exposure, despite an increase in airway responsiveness.     

Effect of an oral potassium channel activator, BRL 38227, on airway function and responsiveness in asthmatic patients: comparison with oral salbutamol.

BACKGROUND: Potassium (K+) channel activators, such as cromakalim, open ATP sensitive K+ channels and relax airway smooth muscle in vitro and inhibit induced bronchoconstriction in vivo in animals. The prolonged half life of cromakalim gives it potential as an oral bronchodilator. The effect of orally administered BRL 38227 (the active enantiomer of cromakalim), at doses of 0.125, 0.25, and 0.5 mg, on airway function and airway responsiveness to histamine and methacholine has been investigated in asthmatic patients. METHODS: Seventeen patients with asthma were studied in three separate randomised double blind, placebo controlled studies. In the first study eight patients with moderately severe asthma were given 0.125, 0.25, and 0.5 mg of BRL 38227 or placebo, and responses to histamine were assessed before and five hours after treatment. In the second study responses to methacholine were measured before and five hours after 0.125 and 0.5 mg of BRL 38227 or placebo were given to nine patients with mild asthma. In the third study the effect of 0.5 mg of BRL 38227 or placebo was assessed in eight patients with mild asthma. Responses to histamine were measured before treatment and two and five hours after treatment. To provide a positive control study eight subjects who had taken part in studies 1 and 3 were also given oral salbutamol (8 mg) in a placebo controlled, double blind study. Responses to histamine were assessed before and two hours after treatment. RESULTS: BRL 38227 did not cause significant bronchodilatation or changes in airway responsiveness in any of the studies. Headache was reported in 19 of 25 of patients receiving (in some cases twice) 0.5 mg of BRL 38227. By contrast, oral salbutamol gave significant protection against histamine challenge (geometric mean 2.23 doubling dilutions). CONCLUSIONS: After a single oral dose of BRL 38227 no beneficial effect on airway function was detected, despite a high incidence of side effects, which indicates that the orally administered K+ channel activator BRL 38227 may not be useful in the management of asthma.     

Assessment of bronchodilatation after spontaneous recovery from a histamine challenge in asthmatic children.

BACKGROUND: It would be convenient to be able to measure airway responsiveness to histamine and to bronchodilator drugs on the same day, but whether this can be done reliably is unknown. METHODS: The effect of a prior histamine challenge on the bronchodilator response to salbutamol after spontaneous recovery of FEV1 to 95% of the prechallenge level was studied in two groups of asthmatic children. Fourteen children inhaled 400 micrograms salbutamol after spontaneous recovery from a histamine challenge, followed by a further 100 micrograms salbutamol 20 minutes later. In a second group of eight asthmatic children the study was repeated with 800 micrograms salbutamol, followed by a further 200 micrograms 20 minutes later. RESULTS: After histamine challenge FEV1 returned to baseline in 70 minutes or less on all occasions. The FEV1 20 minutes after 400 micrograms salbutamol was significantly lower after the histamine challenge than on the control day. After the further 100 micrograms salbutamol FEV1 values were similar after the histamine challenge and on the control day. FEV1 values after 800 micrograms salbutamol and the further 200 micrograms dose were not influenced by a prior histamine challenge. CONCLUSIONS: In children with stable asthma in whom FEV1 has returned to baseline after a histamine challenge the FEV1 achieved after 800 micrograms salbutamol is not affected by the histamine challenge. Histamine and bronchodilator responsiveness can thus be assessed reliably on the same day in patients with stable asthma. This has clear advantages for patient care.