Exercise as it relates to Disease/Effects of physical activity on asthma

This is an analysis of the journal article, "Benefits and Problems of a Physical Training Programme For Asthmatic Patients", by L.M Cochrane, C.J Clark (1990).

What is the background to this research?

Scadding, as quoted in Godfrey defines asthma as "... a disease characterised by wide variations over short periods of time in resistance to flow in intrapulmonary airways". Another source defines asthma as a chronic lung disease that narrows the airways and causes them to become inflamed. It is well known and accepted that physical activity supports health, although individuals who suffer from asthma experience many difficulties when participating in sport, and as a result, may refrain from taking part in physical activities. Almost all asthmatic sufferers show decreased ventilatory capacity after physical exercise and it has been found that there is a negative correlation between the severity of asthma and the capacity to perform and participate in exercise safely and effectively. Although asthma cannot be cured, the study by Cochrane and Clark attempts to determine if physical activity may reduce the symptoms of asthma.

Where is the research from?

This study was conducted at the Hairmyres Hospital, in East Kilbride, Glasgow, under the Department of Respiratory Medicine. Cochrane resides as a doctor at this hospital.

What kind of research was this?

This was a clinical study that was medically supervised. It used an indoor physical activity programme over a period of three months to assess the physiological and clinical effects of this programme on asthmatic patients.

What did the research involve?

The study looked at 36 young adults aged 16–40 years of age. The subjects all suffered from chronic asthma of mild to moderate severity, and 30 out of the 36 participants identified as suffering from exercise induced asthma. Cochrane and Clark tested the subjects prior to training by having them undertake progressive incremental exercise on an electronically braked bicycle ergometer. Measurements such as heart rate, respiratory frequency, minute ventilation and mixed concentrations of carbon dioxide and oxygen were taken continuously in order to calculate VO₂ and VCO₂. Subjects also used the Borg index to estimate their sense of breathlessness. A clinical history and examination occurred before subjects were randomly split into either the training or the control group. The control group attended educational sessions which were designed to increase understanding of asthma and improve their self-management of asthma. The training group also attended similar sessions, although were also required to complete a three month indoor training programme. This involved exercising for 30 minutes, three times a week, at a target heart rate of 75% of their predicted maximum heart rate. Medical supervision was provided during all training sessions.

What were the basic results?

The changes in maximal exercise performance differed greatly between the training and control groups. The training group showed increases in VO₂max and anaerobic threshold. Heart rate was seen to decrease in relation to VO₂ in the training group, and showed no change in the control group. The study showed physiological improvements in oxygen delivery throughout submaximal exercise, which was shown by decreases in blood lactate, carbon dioxide output and minute ventilation.

How did the researchers interpret the results?

The researchers looked at the results of the study in terms of maximal exercise performance, submaximal exercise performance and factors influencing training improvements. Cochrane and Clark evaluated the benefits that their training programme had on:

• cardiorespiratory fitness
• ventilatory and metabolic adaptations during submaximal exercise
• effects on breathlessness during exercise
• changes in disease severity.

The researchers conclude that there is no significant change on the severity of asthma after exercise. They believe that the improvements in exercise induced asthma that occur with training may be due to a reduction in minute ventilation.

What conclusions should be taken away from this research?

The conclusions that should be taken away from this study is that exercise rehabilitation can bring about many cardiorespiratory improvements in individuals suffering from asthma, including reduced breathlessness. The decreases that were seen in ventilation most likely contributed to the decreases in Borg scale ratings for breathlessness during exercise. The authors conclude that continuous medical supervision of exercise is essential for monitoring asthma and adjusting treatment as necessary.

What are the implications of this research?

There is a lot of conflicting research on the relationship of physical activity and asthma, although this study shows that exercise can have positive effects in reducing the symptoms of asthma, particularly breathlessness. It has been found that adults with mild to moderate asthma have very low levels of fitness compared with healthy individuals. Participating in a training program that is medically supervised and is designed to produce desirable performance results can help to increase the fitness of the people suffering the disease by helping to reduce the symptoms mentioned previously.