PHYSICAL CONDITIONING IN ASTHMA. II. CHANGES IN VEBTPS, VO2, AND EXTERNAL WORK

Effects of exercise training on airway hyperreactivity in asthma: a systematic review and meta-analysis

BACKGROUND

Although physical exercise is recommended for asthmatics, evidence on the effects of exercise on clinical key factors is still missing.

OBJECTIVES

We performed a systematic review and meta-analysis to determine the effect of exercise training (EXT) on quality of life (QoL), bronchial hyperresponsiveness (BHR), exercise-induced bronchoconstriction (EIB), lung function and exercise capacity, plus the factors affecting changes in QoL and exercise capacity in asthmatics after a period of EXT.

DATA SOURCES

A computerized search was conducted in MEDLINE, EMBASE, and CINAHL (last search on 15 November 2012), without language restriction, and references of original studies and reviews were searched for further relevant studies.

STUDY SELECTION

Two independent investigators screened full-text studies with asthmatic subjects undertaking EXT (defined as training for ≥7 days, ≥2 times per week, ≥5 training sessions in total) that assessed at least one of the following outcomes: QoL, airway hyperreactivity, forced expiratory volume in one second (FEV₁), peak expiratory flow (PEF), inflammatory parameters, exercise capacity, or exercise endurance. Potentially relevant studies were excluded if only respiratory muscle training, breathing exercises or yoga was performed, if asthmatic subjects with co-morbidities were investigated, if only data of mixed patient groups without separate results for asthmatics were presented, if training regimens were not sufficiently specified, if no numerical outcome data were presented, and if new long-term medication was introduced in addition to physical training. Of 500 potentially relevant articles, 13.4 % (67 studies including 2,059 subjects) met the eligibility criteria and were included for further analyses.

STUDY APPRAISAL AND SYNTHESIS METHODS

Data extraction and risk of bias assessment was performed according to the Cochrane Handbook for Systematic Reviews of Interventions. A meta-analysis of all randomized controlled trials (RCTs) was performed to determine the effect of EXT on asthma symptoms, BHR, EIB, FEV₁, exercise capacity and exercise endurance compared with control training. In addition, relative pre/post changes were analysed in all RCTs and controlled trials. Finally, multiple linear regression models were used to identify effects of relative changes in airway hyperreactivity (BHR or EIB), lung function (FEV₁ or PEF) and training hours on QoL and exercise performance.

RESULTS

In a total of 17 studies including 599 subjects, meta-analyses showed a significant improvement in days without asthma symptoms, FEV1 and exercise capacity while BHR only tended to improve. The analysis of relative within-group changes after EXT showed, however, significant improvements in QoL (17 %), BHR (53 %), EIB (9 %), and FEV1 (3 %) compared with control conditions. Multiple linear regression models revealed that changes in airway hyperreactivity and lung function significantly contributed to the change in QoL, while mainly the changes in airway hyperreactivity contributed to the change in exercise capacity.

CONCLUSION

EXT was shown to improve asthma symptoms, QoL, exercise capacity, BHR, EIB, and FEV1 in asthmatics and improvements in BHR explained part of the improvement in QoL and exercise capacity. Thus, physical activity should be recommended as a supplementary therapy to medication. However, more well controlled studies should be performed assessing the relationship of physical activity, QoL, airway hyperreactivity, lung function and especially airway inflammation as well as medication intake.

Respiratory function, cardiovascular dimensions and work capacity in boys with bronchial asthma

Twenty boys with bronchial asthma, aged 8-13 years, were studied with regard to the size of their respiratory and circulatory organs and to their excercise tolerance. The boys were divided into two groups (A and B) depending on the severity of their subjective symptoms. Normal values were found for TLC, VC, and FRC in both groups, whereas the group with the most severe asthma had a slightly increased RV. In both groups THb, blood and heart volumes were normal. A quite normal relationship between these variables was observed as well as with work capacity (W170 and VO2 max) with no intergroup differences. Respiratory rate was lower and ventilation was increased in group B, both in submaximal and maximal exercise. Thus, tidal volume in maximal exercise exceeded 50 per cent of vital capacity in this group. These boys also had the highest blood lactate concentration at submaximal and maximal exercise. In half of the boys asthma-like attacks were elicited by the excercise. The symptoms subsided without treatment shortly after work. The frequency and intensity of attacks were similar in the two groups.