Exercise as it relates to Disease/The effect of an aerobic conditioning program on fitness attributes in patients with mild asthma

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The Article "Aerobic Conditioning in Mild Asthma Decreases the Hyperpnea of Exercise and Improves Exercise and Ventilatory Capacity", is a study conducted and written by Teal S. Hallstrand, MD; Robert B. Schoene, MD (Division of Pulmonary and Critical Care Medicine, University of Washington) and Peter W. Bates, MD, FCCP (Department of Medicine, Maine Medical Center, Portland).

Where is the research from?[edit]

The University of Washington's Pulmonary and Critical Care and Sleep Medicine division is one of the largest and strongest in the country, founded in 1965, it now has 58 full time faculty members. The findings of this study were and still are relevant in Australia. At the time of the publication of this article (2000), both Australia and America's health statistics were slowly looking the same. In the modern era the health statistics of both countries are even closer now and therefore this study is still relevant despite it's age. The title of the article essentially states that an exercise program given to patients suffering from mild asthma will help to decrease the depth and rate of breathing of these patients during and after exercise and for an interested party, this will entice further reading.

The abstract contains brief statements firstly regarding the objective (or purpose) of the study to ask a question of the title of the article, the methods used in the study are also covered in this section with mention of both asthma and control subjects and also the tests that were performed before and after the conditioning program. The results section is large and to the untrained eye in exercise science would be difficult to understand so the authors have also included a key of abbreviations at the bottom of the abstract to guide readers and the conclusion has effectively summarised all aspects of the results section without getting into too much detail and has proven the title of the article itself to be accurate. Unfortunately there was no mention of any clinical relevance in the abstract or what exactly this means for athletes and non-athletes suffering from mild asthma patients.

What kind of research was this?[edit]

The authors made reference to which type of research the study was following and this was of a prospective cohort study - a longitudinal study that follows over time a group of similar individuals who differ (mild asthma and control) with certain factors to determine how these factors affect rates of a certain outcome. Cohort studies have a few advantages including; clarity of temporal sequence, allowing the calculation of incidence, they facilitate the study of rare exposures, allow examination of multiple effects of a single exposure and they avoid selection bias at enrollment. Unfortunately, like many other types of research, it has disadvantages, which include:

  • Following a large number of subjects for for a long time.
  • They can be very expensive and time consuming.
  • They are not good for rare diseases.
  • They are not good for diseases with a long latency.
  • Differential loss to follow up can introduce bias.

What did the research involve?[edit]

The mild asthma group consisted of 9 adult patients (where informed consent and exercise pre-screening would have been undertaken) with mild intermittent asthma as defined by the National Asthma Education and Prevention Program, Expert Panel Report 2 and 7 sedentary individuals without a history of asthma were the control group. Of these 16 individuals initially screened, only 5 of these individuals in each group entered the 10 week conditioning program. Lung function and Exercise tests were conducted both at baseline level and after the initial exercise bouts, the conditioning program itself was also detailed and a physical therapist or exercise physiologist professional was present, all exercises and skills needed were explained to the participants (monitoring their own heart rates). Something that might call into question some of the data collected is that while an exercise professional was present, all monitoring was self-reported and self monitored rather than recorded by the professional present. It is assumed that all participants would follow the guidelines and directions given to them, some might not and this might challenge the validity of the research. Another is that there was a physical therapist OR an exercise physiologist present, not specifying which sessions or how often each was present. Was one only present for one session or for all of them? This would call into question how the data gathered during exercise was interpreted due to these exercise professionals having different perspectives on exercise.

What were the basic results?[edit]

Spirometry and Respiratory Symptoms[edit]

Spirometry and Respiratory Symptoms were recorded and stated that the asthma group demonstrated a post-exercise reduction in FEV1 (Forced Expiratory Volume) though after the 10 week program, there was no change in overall FEV1. Unfortunately there was no significant change in bronchodilator use, daytime or nocturnal asthma symptom scores, or cough after the conditioning program which could present trouble for the validity of the research - this being said it does not necessarily rule out that there was change in these symptoms, just no significant change.

Fitness[edit]

Fitness was also tested and gains in both VO2max and anaerobic threshold were found in both asthma and control groups.

Respiratory Physiology[edit]

Respiratory Physiology is discussed to further length within the results with the dyspnea index being significantly reduced at 75% of maximum exercise in the asthma group, while the dyspnea index in the control group rose after the 10 weeks of conditioning. After the conditioning program, the ventilatory equivalent at 75% of maximum and maximum exercise decreased significantly in the asthma group. The respiratory rate at each level of oxygen consumption was reduced in both groups, but the asthma group saw the greater differences, this was also the case for the measured carbon dioxide production for each level of oxygen consumption while there was also an increase for the asthma group in the partial pressure of end-tidal carbon dioxide pressure. These results were also included in the discussion section of the article where more of the changes which were observed during the study and results have been elaborated on further and with less of a scientific approach. To the untrained eye, this would be more beneficial as opposed to reading straight from the results section itself.

What conclusions can we take from this research?[edit]

Firstly, this study demonstrates that exercise rehabilitation improves aerobic fitness and decreases the hyperpnea of exercise in patients with mild asthma. Secondly, aerobic conditioning is well tolerated and leads to fitness gains similar to those in non-asthmatic individuals. The data contained in this study are consistent with results of other conditioning programs that show no change in the severity of exercise-induced bronchospasm after a post-conditioning maximal exercise test i which the participants achieved a higher level of work. Third, aerobic conditioning improves the MVV in patients with asthma, although the mechanism of this improvement is unclear within the study, as well as no evidence of a change in disease activity within mild asthma patients. The author's concluded that, 'physical training results in beneficial adaptations that allow individuals with mild asthma to participate comfortably in aerobic activities.'

Practical Advice[edit]

The author's have included their own advice, or for want of a better word; notes, about the adaptations recorded throughout the study. Further study is necessary to determine if a change in central respiratory drive occurs in response to conditioning and to determine the underlying basis of these adaptations recorded throughout the study. To better record results during the conditioning program itself, exercise professionals such as sports scientists, sports trainers or even team doctors should be present throughout the monitoring of the target heart rate and B2-agonist therapy (a professional trained in asthma treatment and identification should be present for this).

Further Information/Resources[edit]

3 recent studies, Effects of Aerobic Training on Airway Inflammation in Asthmatic Patients, Aerobic Exercise Attenuates Airway Inflammatory Responses in a Mouse Model of Atopic Asthma and Effect of Aerobic Exercise Training on Pulmonary Function and Tolerance of Activity in Asthmatic Patients, carried out in 2004, 2005 and more recently in 2011 respectively essentially, while they may differ in design and other attributes, support the conclusion drawn from the current study under critique. Again, respectively, the conclusions from the 3 above studies were; results suggest that aerobic exercise reduces airway inflammation in a mouse-model via modulation NF-kB activation. There is also the potential for the use of aerobic exercise training as a non-drug therapeutic modality. Aerobic exercises in asthmatic patients lead to an improvement in pulmonary functions and aerobic exercise rehabilitation can be a complement to medical treatment of asthma. Aerobic training reduces sputum eosinophil and FeNO (fractional exhaled nitric oxide) in patients with moderate or severe asthma. This suggests that aerobic training might be useful as an adjuvant therapy in asthmatic patients under optimized medical treatment.

References[edit]