Exercise as it relates to Disease/The effect of Tai Chi on postural stability in patients with Parkinson's Disease

This Wikibooks page is a critical appraisal of the journal article "Tai Chi and Postural Stability in Patients with Parkinson's Disease" from Li et al. (2012). From The New England Journal of Medicine.

What is the background to this research?
Parkinson's disease (PD) is a neurodegenerative disorder characterised by the slowing of movements (bradykinesia) and generally rigidity or resting tremor. Parkinson's disease presents onset in life and is progressive. Movement impairments adversely affect function and quality of life in patients with Parkinson's Disease and with progressive stages, loss of postural stability and gait control contribute to difficulty with daily living. These impairments can increase a decline in physical activity and fear of falling. Although some symptoms of motor dysfunction (e.g. tremor) can be alleviated with drug therapy, there is controversy over the effectiveness of the method towards postural stability.

Exercise has been an integral part of managing PD as research has shown to slow motor deterioration and prolong function independence in patients. Research towards resistance-based exercises have shown positive effects in balance and strength, however are equipment dependent and require safety measures.

Tai chi is a balanced based exercise which integrates flexibility, balance, neuromuscular coordination and cognitive components. Cognitive components include body awareness, imagery, multitasking, goal-oriented training and focused mental attention. Which in contrast to other meditative practices, Tai Chi focuses on standing and dynamic movements which have potential to enhance muscle strength, gait and balance. Hence likelihood preventing falls and improving functional independence.

Where is this research from?
The article was published in The New England Journal of Medicine one of the oldest and most reputable medical journals worldwide.

This paper was completed at the Oregon Research Institute (ORI) by the Oregon Medical Group with lead researcher Fuzhong Li. This research was funded by a grant from the National Institute of Neurological Disorders and Stroke,. Principle author of this paper Fuzhong Li Ph.D is a senior scientist at ORI and is a widely published author specifically regarding exercise based interventions for neurological disorders and epidemiological analyses. He has published 135 articles predominately concerning exercise intervention with patients with various chronic disease regarding fall prevention, implying strong reputation within this field.

Furthermore, his co authors and researchers have developed other research associated with improving movement impairments with similar exercise interventions and other pharmaceutical therapies in patients with PD. Deep knowledge across Parkinson's disease with the co-authors is advantageous considering the unknowns of finding a cure for the disease.

What kind of research was this?
This study was a Randomised Control Trial (RCT), where groups were assigned to interventions in the form of exercise. RCT is regarded as the gold standard for evaluating the effectiveness of an intervention and eliminates potential selection bias decreasing the impact of compounding factors. However, given the behaviour based treatments participants were aware of their interventions.

Two other pilot research studies suggest there may be an improvement of axial symptoms of Parkinson's disease such as gait and posture. However, there are few data results from a large-scale RCT that have addressed the effectiveness of Tai Chi as an intervention in this context. Which is advantageous in this area of research to weed out abnormalities and exigent circumstances.

No conflict of interest was declared.

What did the research involve?
The study involved 195 patients with stages 1-4 of the disease using the Hoehn and Yahr scale. The participants were divided into groups: Tai Chi, resistance training and stretching. The patients participated in 60 minute exercise sessions, twice a week for 24 weeks.

The interventions protocol consisted of: The interventions were measured using the following outcomes.

Primary Outcomes: Postural stability

Scores on both measures range from 0-100%, with higher percentages indicating better control and balance, and measured by computerised dynamic posturography.
 * 1) Maximum excursion - Assessments of limits of self-initiated movements as patients shift without falling in each of eight target directions.
 * 2) Directional control - Measure of movement accuracy comparing the amount of movement towards a target with the amount of extraneous movement.

Secondary Outcomes: Gait (stride length and walking velocity)

Participants walked normal pace for 4 trials; results averaged to derive score for each measure and higher score indicating better gait.

Outcome measures were assessed at baseline, three and six months and three months post intervention. To which participants were instructed to resume their normal physical activity and medication.

This study has some limitations. Given the participants awareness of their intervention, bias may have been introduced; interest and positive motivation. Although there was strong methodologies regarding testing and measuring the outcomes, there was no control group reported. This is a major disadvantage in reading results as it doesn't ensure internal validity of the research, so net gain of the intervention cannot be gauged. Assessments were also conducted when patients were in "on" periods (i.e. when symptoms were controlled and medication was working) , to which may have masked underlying changes induced by the training interventions.

What were the basic results?
The Tai Chi group performed consistently better across both the resistance training and stretching groups in maximum excursion and directional control. The Tai Chi groups also reported greater secondary outcomes in comparison to the stretching group and resistance training group in stride length and functional reach.


 * From baseline to 24 weeks, the Tai Chi group had a mean increase of 9.56 percentage points in maximum excursion and 8.02 percentage points in directional control.
 * Improvements in maximal excursion with reduced deviation in movement, showed ᛏ ability to adopt effective strategies in gait (ankle or hip), controlled movements and balance control.
 * Tai Chi protocol stresses weight shifting and ankle sway increasing limits in moving centre of gravity.
 * Tai Chi decreased fall incidence compared to stretching but not as much compared with resistance training.
 * The effects of the Tai Chi training were maintained post intervention at 3 months.
 * No serious adverse events observed.

What conclusions can we take from these results?
The exercise program for Tai Chi as compared to resistance training and a stretching program was found to be effective in improving postural stability and functional outcomes for patients with stages 1-4 of Parkinson's disease. Tai Chi improved both the primary outcomes of maximum excursion and directional control and secondary outcome of gait. These improvements significantly reduced fall incidences in comparison to the stretching group and maintained 3 months post the intervention. As no adverse events were observed during the Tai Chi training, this intervention indicates practicality and safety of the exercise.

There is strong statistical evidence from this paper to conclude Tai Chi is a positive intervention for patients with mild to moderate patients with Parkinson's disease. However, there was no research regarding the effects of using the "on" periods for measuring the outcomes and also the exclusion of the control group. Further research should be completed on the cognitive functional improvements from Tai Chi to further extend knowledge of this disease.

Practical advice?
Although the improvements shown in the study indicate positively in neuromuscular applications, mechanisms behind the therapeutic change in participants motor control and mobility warrant further research. As too the effectiveness of exercise reducing falls within the population. Physical activity has shown to improve motor and non-motor symptoms. It is highly advised that patients with PD should participate in as much physical activity as they can, modifying and progressing as needed. Safety is high priority, and supervision will reduce likelihood of adverse events occurring and increasing motivation.

Based on peer reviewed research and the presented study, physical activity for this population should incorporate:

These factors contribute to the overall postural stability and gait function of patients and hence increase in daily functionality.
 * Balance and agility
 * Multitasking cognitive activity
 * Stretching
 * Strength resistance training
 * Aerobic activity

Further information/resources
Below there is further information regarding Parkinson's disease and appropriate management for the disease and physical activity:


 * Parkinson's Exercise Recommendations
 * Physiotherapy exercises for Parkinson's
 * Treating Parkinson's Disease With Tai Chi

Below is an example of Tai Chi used in a class and how it can be adapted for all levels


 * Tai Chi for Parkinson's Disease