Exercise as it relates to Disease/The impact of progressive resistance exercise on symptoms of Parkinson’s disease

This Wikibooks page is a critical appraisal of the journal article "A two‐year randomized controlled trial of progressive resistance exercise for Parkinson's disease" by Corcos et al. (2013).

= What is the background to this research? =

Parkinson's Disease
Parkinson’s disease (PD) is a degenerative neurological disease which affects an extensive population worldwide. Individuals with PD have been known to display the characteristics of rigidity, tremor and bradykinesia. PD tends to progress over time with the development of numerous cognitive issues including poor memory, problems of viso-spatial functioning and slowness in motor tasks and psychological responses.

Progressive Resistance Exercise
Progressive resistance Exercise (PRE) is a popular intervention in various forms of studies due to the mental and physical improvements which it can have on individuals. In a general population, PRE has been seen to decrease symptoms of depression, whilst also improving bone mineral density and reversing aging factors in skeletal muscle along with various other physical improvements.

Unified Parkinson's Disease Rating Scale, motor subscale (UPDRS‐III)
One of the scales used in this study is the Unified Parkinson’s Disease Rating Scale, motor subscale (UPDRS-III). The UPDRS-III is one of the four sections comprising the Unified Parkinson’s Disease Rating Scale, and focuses on the motor aspects related to individuals with PD. The UPDRS-III is the most frequently used outcome measure throughout clinical trials working with PD.

modified Physical Performance Test (mPPT)
The modified Physical Performance Test (mPPT) is a mobility function examination which includes various whole-body skills, with integrated tasks of gross and fine motor skills, whilst also including activities targeting the upper extremities.

Parkinson's Disease Questionnaire (PDQ‐39)
The Parkinson’s Disease Questionnaire (PDQ-39) is the most common patient reported rating scale regarding PD. The PDQ-39 is comprised of 39 items which cover 8 different dimensions and is developed to systematically evaluate the effect which PD has upon an individual and their quality of life.

= Where is the research from? = This study was conducted in America, primarily throughout Chicago. The study was published in volume 28, issue 9 of Movement Disorders: Official Journal of the International Parkinson and Movement Disorder Society.

Authors
Daniel M. Corcos PhD [] Julie A. Robichaud PT, PhD Fabian J. David PhD [] Sue E. Leurgans PhD [] David E. Vaillancourt PhD [] Cynthia Poon PhD [] Miriam R. Rafferty DPT [] Wendy M. Kohrt PhD [] Cynthia L. Comella MD []
 * Kinesiology and Nutrition: University of Illinois
 * Bioengineering and Psychology, University of Illinois
 * Neurological Sciences, Rush University Medical centre
 * Kinesiology and Nutrition: University of Illinois
 * Kinesiology and Nutrition: University of Illinois
 * Neurological Sciences, Rush University Medical centre
 * Preventative Medicine, Rush University Medical centre
 * Applied Physiology and Kinesiology, Biomedical Engineering, and Neurology: University of Florida
 * Kinesiology and Nutrition: University of Illinois
 * Neuroscience: University of Illinois
 * Geriatric Medicine: University of Colorado School of Medicine
 * Neurological Sciences, Rush University Medical centre

= What kind of research was this? = This study is a randomized controlled trial where the participants are randomly allocated into one of the intervention groups.

= What did the research involve? =

Population
The criteria for the population for this study is as follows: Individuals were ineligible if they had: The population was then followed for 24 months with measures being taken at baseline, 6, 12, 18 and 24 months.
 * Idiopathic PD
 * Moderate severity
 * Aged 50-67
 * On stable dopaminergic therapy
 * Able to walk for 6 minutes
 * A neurological history other than PD
 * Significant arthritis
 * Were already exercising
 * Had undergone surgery for PD

Interventions
The two interventions were completed with programs identical in all aspects, twice a week and with no additional exercise.

Modified Fitness Counts (mFC)

 * Stretches
 * Balance exercises
 * Breathing
 * Nonprogressive strengthening

Progressive Resistance Exercise (PRE)

 * Chest press
 * Latissimus pull downs
 * Reverse flys
 * Double leg press
 * Hip extension
 * Shoulder press
 * Biceps curl
 * Rotary calf
 * Triceps extension
 * Seated quadriceps extension
 * Back extension

Strengths

 * The duration of the study allows for numerous measures to be taken.
 * Use of numerous well recognised tests and scales.
 * Variety of measures taken that relate to both physical and mental health

Limitations

 * The study didn't have a control group which made it difficult to understand the overall improvement which both interventions can provide to the population.
 * Patients who had previous surgical procedures related to PD were excluded from the trial. Inclusion of this population would provide an understanding of the greatest extent of improvement possible for these patients.

= What were the basic results? =

Motor signs and medication status
The mean off-medication UPDRS-III score had decreased for both interventions between baseline and 6 months. At 24 months, the mFC group had returned to a similar score to their baseline measure, whilst the PRE group’s score had continued to decrease. The final difference between groups was a mean score difference of 7.3 at 24 months.

Torque
Mean off-medication elbow flexion torque increased in both intervention groups from baseline to 6 months. At 24 months elbow flexion torque had improved by 9.0±6.9 Nm in the PRE group whilst it had decreased 5.3±9.5 Nm in the mFC group.

Speed
Mean off-medication elbow flexion speed increased in both intervention groups from baseline to 6 months. At 24 months, the PRE group was faster than the mFC group (43.5 degrees per second), although both intervention groups had shown improvement. The mFC group made a 74.8±53.5 degrees/second improvement from baseline to 24 months, while the PRE group made a 118.3±60.7 degrees per second improvement over the same time period.

Physical function
The mean off-medication mPPT scores for both intervention groups showed a significant increase between baseline and 6 months. The mean score for the mFC group remained quite steady between 6-24 months, whilst the PRE group’s mean score continually increased. At 24 months there was no significant difference between the two interventions.

Quality of life
The mean PDQ-39 score in the PRE group decreased significantly at 6 months, whilst the mFC group’s mean score remained relatively stable. At 24 months there was no significant difference between the two intervention groups.

= What conclusions can we take from this research? = Results of this study have shown that PRE in PD patients can lead to significant improvements to UPDRS-III scores and both elbow flexion torque and velocity. The short-term quality of life of patients is also benefited significantly by participation in PRE. This improvement, in comparison to mFC participation, also leads to a minimal long-term benefit. In evaluating these results, PRE is a more appropriate intervention for PD patients, when seeking improvement to motor signs, quality of life and strength and movement speed.

= Practical advice = Individuals with PD should initially consult their medical experts to understand their limitations when exercising. With medical clearance, Individuals with PD should try to participate in PRE at least twice a week, which corresponds with the frequency of this study. Participation in such exercise can lead to improvements to motor control, strength and movement speed. Not only have physical benefits been identified, the mental health and quality of life of an individual can also be benefited.

= Further reading =
 * Unified Parkinson’s Disease Rating Scale (UPDRS):[]
 * modified Physical Performance Test (mPPT):[]
 * Parkinson’s Disease Questionnaire (PDQ-39):[]

= References =