Gait impairment and loss of mobility is the single greatest cause of disability in Parkinson's disease. Although it makes sense to look at exercise as being efficacious for these problems, there really has been relatively little focus over the years in non-pharmacological interventions due to inadequate funding.
Recently, there's been a lot more interest around this area and certainly more work done. The study by Dr. Lisa Shulman is one of the larger studies that's ever been done in this area in Parkinson's disease. It's a randomized, single-blinded clinical trial of the efficacy of three different models of exercise to improve gait mobility and Parkinson's disease. The researchers compared three different interventions. The first is a high-intensity treadmill training intervention. The second is a low-intensity treadmill training intervention. The third was stretching and resistance training. All three patients in each of these groups were training for three times a week for three months.
Patients randomised to the high-intensity treadmill training started at 15 minutes and they were encouraged to increase their duration, velocity and incline until they reached 30 minutes for each training period at 70 to 80% of their heartbeat reserve, which is based on their age and their resting heart rate.
For the low intensity walking on the treadmill, the patients also started at 15 minutes but they walked at their comfortable pace that they would walk ordinarily. They were encouraged week by week to reach a target of 50 minutes versus the 30 minutes of the higher intensity work. They went to 50 minutes but at 40 to 50% of their heart rate reserve. It was less intense in terms of the aerobics stimulus, there wasn't incline of velocity but it was longer in duration.
Stretching and Resistance Exercises
Finally, in the third group, the stretching and resistance group, the patients had resistance exercises of the lower body, followed by stretching of the upper and lower body. This entailed two sets of ten repetitions of three different exercises on machines. These were: a leg press, leg extension, and leg curl. These patients were encouraged to increase their resistance that they could manage their muscle strengthening over time.
All three groups were able to increase over time. The velocity group, the group that was going at a higher velocity, got to 30 minutes at an increased incline and velocity. The duration group, the lower intensity treadmill group, got to 50 minutes. The stretching and resistance group increased their muscle strengthening by 50 percent.
In terms of the population that was recruited, there were 67 patients in total. Therefore, there were 22 to 23 people in each of the study groups. The gender breakdown was 75% male and 25% female. The mean age was 66 years but the patients varied from 42 years to 86 years. The mean duration of disease was about six years although the range was from 1 to 18 years.
There were a number of areas of interest in terms of objectives. The first objective was to assess the efficacy of exercise to improve gait and mobility. The researchers looked at a number of gait speed tests. The primary outcome measure was the six-minute walk. That involves how many feet somebody walks over a period of six minutes. The low-intensity treadmill group and the stretching and resistance group had significant improvements in their distance. Whereas the high-intensity treadmill group had a trend of improvement but it did not reach statistical significance. There are a number of other gait speed tests that were also applied. Overall, the low-intensity treadmill group had the most consistent improvements in all of the gait speed measures.
Another objective was to look at the efficacy of exercise to improve cardiovascular fitness. In this regard, the researchers saw significant improvements in terms of the peak V02 which is considered the gold standard measure of fitness as well as Max VO2. The researchers saw significant improvements in both the low intensity and high-intensity treadmill groups, with no significant improvement in the stretching resistance group.
Another objective was to look at the efficacy of exercise to improve disease severity in Parkinson's disease and disability. This applied the gold standard measure for Parkinson's disease known as the UPDRS or Unified Parkinson's Disease Rating Scale. In this case, the researchers saw only a significant change on the motor subscale of the UPDRS. The only group that showed significant improvement was the stretching and resistance group.
There was also an interest in getting a secondary outcome measure, whether exercise improved non-motor symptoms of Parkinson's disease. These include things like depression, apathy, fatigue, quality of life and false self-efficacy or somebody’s confidence in that they can prevent or manage falls. There were no significant changes in any of the non-motor outcomes following training with any of the three exercise models.
Conclusions from the Study
There are a number of conclusions to derive from the study. Training effects were seen across all three exercise models. The exercise was shown to improve both gait speed and cardiovascular fitness. Both the high and low-intensity treadmill training resulted in improvements in gait speed, mobility, and fitness. Importantly, it wasn’t necessary to greatly increase the intensity of walking to achieve these benefits. Overall, the low-intensity treadmill training, walking at a comfortable pace for a longer duration, resulted in the most significant improvements in gait speed and mobility. The stretching and resistance group improved gait and mobility more than frankly was anticipated. This non-treadmill arm of the study resulted in improvements in the six-minute walk that exceeded the results of high-intensity gait training.
Somewhat surprisingly, there were no improvements on a range of non-motor outcomes following the three months of training. This may be because people who are interested in participating in this kind of study tend to be somewhat above normal in terms of their depression levels and other factors. The researchers were not able to show translation of the improvements in gait and fitness to daily function. In other words, the measures of disability did not show significant changes. And it's possible that that's the case but it is also possible that the researchers don't have adequately sensitive measures of daily function and disability. Finally, the stretching and resistance group was the only type of training that improved the motor examination of Parkinson's and symptoms.
Overall, many patients wonder all the time… What should they do for themselves? What kind of exercise might help their symptoms of Parkinson's disease? These results suggest a combination of low-intensity treadmill training plus stretching and resistance training is likely to provide the greatest range of improvements for gait mobility and cardiovascular fitness in Parkinson's disease.