PHYS THER
Vol. 87, No. 5, May 2007, pp. 555-558
DOI: 10.2522/ptj.20060085.ic
Invited Commentary
Carol Leiper
CI Leiper, PT, PhD, is Adjunct Professor of Physical Therapy and Director, Dan Aaron Stay Fit Exercise Program for Individuals With Parkinson Disease or Multiple Sclerosis, Arcadia University, 450 S Easton Rd, Glenside, PA 19038 (USA)
Address all correspondence to Dr Leiper at: leiper{at}arcadia.edu
The authors should be congratulated for proposing this study to investigate the relationship between an aerobic cycling program and a functional activity outcome such as the cost of walking. As they point out, it is possible that the physical impairments that occur with the disease also may lead to a more sedentary lifestyle and deconditioning, resulting in further limitations in functional ability. For many years, limited knowledge of the pathophysiology of multiple sclerosis restricted our efforts to select the appropriate intensity of intervention and the prevention of accumulation of functional disability. Studies such as this help us to formulate better hypotheses for future interventions.
In summary, the authors found that an 8-week program of cycling on a lower-extremity ergometer with progressive resistance resulted in an increase in walking distance and speed for individuals with mild to moderate impairment related to multiple sclerosis. Improvements also were seen in measures of aerobic capacity. Similar changes did not occur when the subjects performed a "neurological rehabilitation" exercise program described as emphasizing active movements and gait exercises.
I would like to address 2 very different topics related to the study: (1) whether reported improvements represent real change and (2) the importance of continued physical activity for people with physical disability.
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Measurement of Change
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The measure of walking distance during the 6-minute walk tests will be used as the example to discuss the first question. The authors report a statistically significant improvement in walking distance of approximately 24 m following the aerobic training but not after the neurological training. However, the comparison between the 2 groups did not indicate the superiority of the aerobic training. How do we explain this discrepancy? One solution is to look at the size of the standard deviations of the measurements. The larger the standard deviation, the less likely the results will be significant unless the mean values are greatly different. The authors have used these variables to calculate the effect size and show us that for these 2 measures it is indeed small.
Another way to translate the results into meaningful values for the clinician would be to ask the question, "What is the minimal detectable change (MDC) of the measurements that would indicate a real change, indicating either improvement related to the intervention or, perhaps in a chronic disease, deterioration over time?" Because all measurements have some error associated with them, we would like to know that a reported change exceeded the likelihood of that due to errors of measurement. The MDC is frequently reported as the value of the standard error of measurement (SEM) multiplied by ±1.96 (±2 standard deviations) and therefore should be outside the range of measurement error. For example, Kennedy and colleagues1 determined the stability of both the speed of fast self-paced walking and the distance of the 6-minute walk in a sample of individuals with osteoarthritis who were waiting for hip or knee arthroplasty. They reported the SEMs for the tests and then determined the MDC for a 90% confidence interval (MDC90). For their group with osteoarthritis, a change of 4.04 seconds for the fast self-paced walk and a change of 61.34 m for the 6-minute walk would be needed to represent real changes.
Flansbjer and colleagues2 used a similar calculation referred to as the "smallest real difference" (SRD) when assessing the reliability of several gait performance measures in people with hemiparesis following stroke. The mean time since stroke in their sample was 16 months, but the range was 6 to 46 months. The authors reported the SEM for the 6-minute walk to be 18.6 m and the SRD to be 51.56 m. In both the study by Kennedy and colleagues1 and the study by Flansbjer and colleagues,2 the range of walking distances of the subjects was large (approximately 500 m in each case), and the means and standard deviations were similar to those of the study by Rampello et al. The authors may consider determining the SEM to further evaluate their results for this group of people with multiple sclerosis.
A potential cause of the wide standard deviations of the measures reported by Rampello et al might be the wide range of Expanded Disability Status Scale (EDSS) scores permitted for inclusion in the study, particularly because they cite another study showing an inverse relationship between distance walked and EDSS score. It may be necessary to limit the inclusion criteria to a smaller range on the EDSS scale or to use a different descriptor of disease severity. A similar comment could be made for the inclusion criteria in the studies of Kennedy et al1 and Flansbjer et al.2 Kennedy et al included subjects who were waiting for either knee or hip arthroplasty, and Flansbjer et al included individuals who had a stroke between 6 and 46 months prior to testing. As we attempt to be more specific in the nature and intensity of prescription of intervention for individuals with neurologic diseases, we find the need for better classification of individuals with the same general disease diagnosis. More specific classification of functional activity may provide the opportunity to set better definitions for goals either for improvement or to show maintenance of status rather than decline. Delitto et al3 have attempted to do this for individuals with low back syndrome, as has VanSwearingen and Brach4 for those with facial neuromotor disorders.
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Physical Activity and Fitness for Individuals With Disability
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As Rampello et al point out, there is only a small body of literature at present that attempts to look at the need for and effects of specified forms of exercise for those with multiple sclerosis to maintain function and possibly retard accumulation of impairments. Since the preparation of their manuscript, another study5 has been published in which aerobic treadmill training was the intervention of choice. Both treadmill and cycle ergometry are forms of exercise that can be carried out independently by the individuals described in the samples.
Physical therapists see only a small proportion of the individuals diagnosed with multiple sclerosis. In most instances, it is not until the person is in overt functional crisis that a referral is made. Some individuals have been advised to restrict exercise, others have tried to exercise and become fatigued, and still others have never thought about the need to work at maintaining flexibility, strength, and endurance.
In 1998, the US Department of Health and Human Services published a document titled Healthy People 20106 in which goals for increasing the health of US citizens are given. There is a chapter devoted to physical activity and fitness in which the current percentages of participation are given for several types of activity. One of the comparisons is between people with and without disabilities. The Table specifies the goals for 2010 and shows the current percentages of people engaged in physical activity.
In 1999, Physical Therapy published a professional perspective article by Rimmer in which he discussed the need to develop programs of health promotion that would be designed to reduce secondary conditions, maintain functional independence, provide opportunity for leisure and enjoyment, and enhance the overall quality of life for individuals with disability.7 Rimmer proposed a need for rehabilitation professionals to connect or partner with community-based fitness programs to create an environment that welcomes the inclusion of people with disabilities. Other authors8,9 have written about the benefits of physical activity, and in particular, in group settings, on the quality of life. In recent years, the American Physical therapy Association has offered programming at national meetings to assist physical therapists who desire to make the community connection or to develop community fitness centers within their own practices. It seems to me that one of the needs in such programs are simple functional tests that would allow the client to document real change or the maintenance of current status in a standard way. Each client seems to have a different personal measure of status quo, improvement or decline. We need to select tests that are meaningful to the clients and determine the measurement properties for well-defined groups (classification).
Rampello et al focus our attention on a specific form of exercise that is prevalent in fitness centers, physical therapist practices, and at home—leg cycle ergometry. Their functional measures were distance walked and speed of walking, which could be predicted to change based on exercise for the cardiopulmonary system and the musculoskeletal components of the legs. Their comparison intervention appears to be a more traditional program that encompasses a wide variety of exercise crossing the dimensions of motor control, flexibility, balance, and possibly strength. What are the functional measures or tests that will be useful to record health status for these dimensions? How specific are the guidelines to document a change in status? Could a change in health status actually have been achieved with the comparison intervention, but was unrecognized because the chosen tests did not measure the function represented by these characteristics? In formulating and reporting their research, the authors have afforded us the opportunity to propose new hypotheses and advance the knowledge of the specificity of exercise testing and prescription for individuals with physical disability.
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References
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- Kennedy DM, Stratford PW, Wessel J, et al. Assessing stability and change of four performance measures: a longitudinal study evaluating outcome following total hip and knee arthroplasty.
BMC Musculoskelet Disord. 2005;6:3.[CrossRef][Medline]
- Flansbjer UB, Holmback AM, Downham D, et al. Reliability of gait performance tests in men and women with hemiparesis after stroke.
J Rehabil Med. 2005;37:75–82.[CrossRef][ISI][Medline]
- Delitto A, Erhard RE, Bowling RW. A treatment-based classification approach to low back syndrome: identifying and staging patients for conservative treatment.
Phys Ther. 1995;75:470–489.[Abstract/Free Full Text]
- VanSwearingen JM, Brach JS. Validation of a treatment-based classification system for individuals with facial neuromotor disorders.
Phys Ther. 1998;78:678–689.[Abstract/Free Full Text]
- Newman MA, Dawes H, van den Berg M, et al. Can aerobic treadmill training reduce the effort of walking and fatigue in people with multiple sclerosis: a pilot study.
Mult Scler. 2007;13:113–119[Abstract/Free Full Text]
- Objectives for Improving Health, Part B: Focus Area 22: Physical Activity and Fitness. Healthy People 2010. Available at: www.health.gov/healthypeople.
- Rimmer JH. Health promotion for people with disabilities: the emerging paradigm shift from disability prevention to prevention of secondary conditions.
Phys Ther. 1999;79:495–502.[Abstract/Free Full Text]
- Stuifbergen AK. Physical activity and perceived health status in persons with multiple sclerosis.
J Neurosci Nurs. 1997;29:238–243.[Medline]
- Di Fabio RP, Choi T, Soderberg J, Hansen CR. Health-related quality of life for patients with progressive multiple sclerosis: influence of rehabilitation.
Phys Ther. 1997;77:1704–1716.[Abstract/Free Full Text]
Copyright © 2007 by the American Physical Therapy Association.
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