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

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).

Background to the research

Mild asthma, or mild persistent asthma symptoms are identified as:

• Episodes of wheezing
• Coughing
• Shortness of breath

For mild asthma to be diagnosed, these symptoms need to occur more than twice a week but less than once a day. They usually occur twice a month at night and may affect normal physical activity. This is where the importance of this specific study comes into play and the real world implications of the research are recognised. While the study does not focus on children specifically, if adults can have the adaptations shown in this study, one would assume that children diagnosed with mild asthma could have the same, if not better adaptations due to their age, though genetics might skew the results in both adults and children unfortunately so this would have to be taken into account when conducting future research.

Where is the research from?

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.

What kind of research was this?

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?

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?

Spirometry and Respiratory Symptoms

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

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

Respiratory Physiology

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. Unfortunately, there is no mention of how these results can be used in a clinical setting but they are still statistically significant.

What conclusions can we take from this research?

Firstly, this study demonstrates that exercise rehabilitation improves aerobic fitness and decreases the hyperpnea of exercise in patients with mild asthma and 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 in which the participants achieved a higher level of work. Though the mechanisms of these improvements are unclear within the study, as well as no supporting evidence of a change in disease activity within the mild asthma patients, overall the fitness attributes in question have shown desirable improvements for future researchers to refer to.

Practical Advice

The author's have included their own advice 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 and exercise physiologists should be present at all times 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

3 studies, 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.