Exercise as it relates to Disease/Plyometric training and Parkinson's disease

What is Parkinson's disease?
Parkinson's disease (PD) is a progressive degenerative neurological disorder which affects the control of body movements. Parkinson's occurs when dopamine producing nerve cells start to deteriorate, or become impaired. These cells produce the dopamine, that is utilised by the body to facilitate smooth, coordinated body movements and muscle contractions. When approximately 70% of these cells are impacted, the symptoms of Parkinson's disease appear. These symptoms usually appear in the middle to latter stages of life, 50 – 70 years old. However, 20% of people diagnosed fall between the 30 - 50 age bracket.

Causes
While the cause of the neuronal degeneration in PD is uncertain, it is unlikely that it is a genetically inherited disorder. However, research has identified certain cellular characteristics and mutations, that are present in a majority of cases that also lead to neuronal degeneration, some of which are shared in familial cases. Potential causes:
 * Lewy bodies in nerve cells - unusual clumps of the brain protein, alpha-synuclein, which may prevent normal function
 * Mitochondrial dysfunction - Free radicals causing oxidative stress and damage to cell membranes and DNA, inducing a genetic mutation.
 * Genetic mutations
 * Environmental factors

Signs and Symptoms
There is great variance between the symptoms that diagnosed individuals exhibit, and no two people will be affected in exactly the same way. The three main symptoms used for diagnosis of the condition are: Other symptoms include:
 * Tremors - Shaking or trembling of body parts.
 * Usually exhibited in the hands first, and progresses down to the legs
 * Typically most noticeable when stressed or tired
 * Not absent in a third of people when first diagnosed
 * Stiffness - in the muscles.
 * Common in the early stages of PD
 * Muscles are unable to relax, and feel tight
 * Rigidity of movement may be experienced through entire range of motion
 * Bradykinesia - Slowness of movements due to the decreased function of the brain.
 * Spontaneous activity decreases e.g arm swing when walking
 * Diminished fine motor control
 * periods of immobility in gait
 * Decreased cognitive function
 * Difficulty speaking and swallowing
 * Anxiety and Depression

Treatments
As the causes of PD are not fully understood, there is no outright cure. To give individuals with PD the best quality of life, a combination of pharmaceutical treatment, and physical therapy to manage symptoms are utilised, where both methods serve to delay the degeneration of the neural pathways, and preserve current physical state.

Plyometrics
Plyometrics are a type of exercise that increase muscular power and explosiveness through improved neural pathways. Benefits are derived from the stretch shortening cycle, where muscles undergo a period of lengthening and shortening in as small amount of time as possible. While the elastic qualities of the stretch shortening cycle are in action, there is an increased neural impulse to the contracting muscles that is controlled by a myotatic reflex, which is the monitoring of the changes in length undergone by the muscle spindle. As you train your muscles and nervous system simultaneously, contractions and movements become almost reflexive in nature, so with greater proficiency in plyometrics, neural pathways, balance, strength and power are all improved.

Recommendations
The main purpose of plyometric exercise in PD individuals is to improve the impulse strength of the remaining neural pathways, coordination of movement, strength, balance and proprioception.
 * Good base level of strength is required
 * Exercises should be basic and progress as the person gets more confident
 * Sessions should not be too long due to the high neural demand

Considerations
Because plyometrics are high intensity, they may not be for everyone, due to the majority of those with PD being over 50, there is a possibility they might have additional physical contraindications, that would be made worse by plyometrics.

Further information
Although plyometrics are thought to be only for elite athletes, there have been cases where people living with PD have seen great improvements in their physical competency and quality of life:Plyometric exercises to fight Parkinson's disease

For more information on plyometric exercises: exercise.about.com/od/cardioworkouts/tp/Plyometric-Exercises.htm

For more information on Parkinson's disease: www.parkinsons.org.au/about-ps/whatps.html#description