Exercise as it relates to Disease/Ground-based walking training to improve quality of life and exercise capacity in COPD

This is a critique looking at the effect of short-term, supervised ground-based walking training and its impact on health-related quality of life (HRQoL) and exercise capacity in people with COPD.

Critique article: Wootton S, Ng L, McKeough Z, Jenkins S, Hill K, Eastwood P et al. Ground-based walking training improves quality of life and exercise capacity in COPD. European Respiratory Journal. 2014;44(4):885-894.



What is the background to this research?
Chronic Obstructive Pulmonary Disease (COPD) is an umbrella term used to describe progressive lung disease and includes conditions such as emphysema, chronic bronchitis, refractory (non-reversible) asthma and some forms of bronchiectasis.

Pulmonary rehab has been shown to improve quality of life and exercise capacity in people with COPD, and it is widely considered that the most important aspect of pulmonary rehabilitation is exercise. These programs are however expensive to run, places are limited and access is often difficult for those people living rurally. This puts emphasis on finding effective exercise treatments for COPD sufferers which cater to patients with limited access and resources. Research has looked at ground-based walking training as part of pulmonary rehabilitation and found positive effects. There is however limited evidence assessing the effectiveness of ground-based walking as a sole exercise modality. This study was designed to determine the effect of short-term, supervised ground-based walking training and its impact on health-related quality of life and exercise capacity in people with COPD when compared to standard medical treatment.

Where is the research from?
Participants were recruited from referrals to outpatient Pulmonary Rehabilitation programs in Sydney and Perth. The article was made in collaboration with a number of researchers from Sydney University and the University of Western Australia. The authors include well established names such as Dr Zoe McKeough (Senior Researcher at The University of Sydney) and Dr Sue Jenkins (Head of the Physiotherapy Unit at the University of Western Australia). Funding was provided by the Australian National Health and Medical Research Council and there appeared to be no conflict of interest or bias in the findings or sponsors.

What kind of research was this?
Prospective, single blinded (assessor and statistician), multicenter randomized controlled trial with concealed allocation.

What did the research involve?
This study involved an intervention group, which participated in ground-based walking training, and a control group which received medical intervention.

Inclusion Criteria:
 * Medical diagnosis of moderate, severe or very severe COPD
 * Stable clinical state
 * Smoking history of greater than 10 pack-years.

Exclusion Criteria:
 * Had been prescribed long-term oxygen therapy
 * Were morbidly obese
 * Used a walking aid
 * Had comorbidities likely to adversely affect exercise performance
 * Or had participated in supervised exercise training in the past 12 months.

Method:

Walking Group:
 * 95 participants
 * Aged 69 ± 8
 * Walking training sessions 3 times a week for 8 weeks.
 * Performed on a flat indoor track and supervised by Physiotherapists.

Control Group:
 * 48 participants
 * 69 ± 9
 * Letter sent to general practitioner that included:
 * Encouragement for optimal medical management
 * Best practice management guidelines for COPD
 * COPD action plan that recommended individualized medication

Outcome measures: (completed at baseline and study completion)

HRQol:
 * St George Respiratory Questionnaire (SGRQ)
 * Chronic Respiratory Disease Questionnaire (CRQ)

Endurance exercise capacity:
 * Endurance Shuttle Walk Test (ESWT)

Functional exercise capacity:
 * 6 Minute Walk Test (6MWT)

Peak exercise capacity:
 * Incremental Shuttle Walk Test (ISWT)

Limitations of the Method:

One of the inclusion criteria is a pack year history of greater than 10 years. COPD is a blanket term, with 20% of COPD cases occurring in people who have never smoked. By making this distinction in the selection criteria, the researches have targeting a specific group of COPD sufferers, raising the question of whether this should be specified throughout.

The method used for the intervention group was clear and standardized, allowing for easy replication between studies and in clinical practice. The medical management for the control group varied considerably, this leaves room for error and allows for skewing of results.

It has been found however that COPD patients often lose functional exercise capacity 1 year post pulmonary rehabilitation. Raising the question of whether follow up at 6 months or 1 year would provide valuable information about the sustained effectiveness of the intervention.

What were the basic results?
Improvements were found in HRQoL, endurance exercise capacity, functional exercise capacity and peak exercise capacity between the intervention and control groups. However, minimal important difference was only met for HRQoL in one of two outcome measures, and in endurance exercise capacity.

The authors concluded that ground-based walking training improved HRQoL and endurance exercise capacity when compared to usual medical care in people with COPD. Although positive outcomes were found, this statement is too broad for the results demonstrated.

Only one of the two HRQoL outcome measures (SGRQ) found minimally significant difference, the authors acknowledged this explaining that many of the questions within the SGRQ are focused on activities involving walking whereas those the CRQ often do not and therefore may not have been altered by the effect of the intervention. This raises the question of whether the statement ‘ground based walking training improves HRQoL’ is too broad, and should be more elicit in stating it improves walking ability.

In addition, this statement can only be applied to a distinct group of COPD suffers. That is, COPD sufferers of age range 60-70 who do not use walking aids, have a 10 pack year history, are not morbidly obese, or on home o2. Many of these criteria are common in COPD suffers, therefore we can’t apply the findings of this research to a blanket population of COPD suffers.

What conclusions can we take from this research?
We can conclude that in a specific group of COPD patients, ground-based walking training improves performance in walking based activities and endurance exercise capacity as shown via improvements in St George Respiratory Questionnaire and Endurance Shuttle Walk Test results.

This statement aligns with the current research available, that ground-based walking training is effective in COPD patients  and it adds to the current research available in that it proved the hypothesis that when performed as a sole intervention ground-based walking training is still effective.

Practical advice
When looking to improve walking based activity performance and exercise capacity in COPD suffers, the findings from this study can be applied. However, it’s important that in practical application, this intervention is applied to an appropriate patient group.

This research suggests ground-based walking programs are beneficial as a sole intervention, but the intervention still must be applied in a supervised setting.

Further information/resources
Additional Resources:
 * Lung Foundation Fact Sheet