Exercise as it relates to Disease/Weight Training vs Aerobic Training For Parkinson's Disease

=What is Parkinson’s disease?= Parkinson's Disease (PD) is a chronic neurodegenerative disease which affects the physical, psychological, social and functional status of patients lives. Parkinson’s is primarily caused from the progressive degeneration of neuronal cells located in the Substantia Nigra. This causes a deficiency in the availability of dopamine; a chemical neurotransmitter which is necessary for regulation of smooth movement and coordination. PD is the second most common neurological disease in the world, behind Alzheimer's disease affecting nearly 6.3 million people world wide. In Australia, it affects almost 1 in every 350 Australians. The average age of diagnosis is 55 and 65 years, but its not uncommon for younger people, aged as low as 21 to be diagnosed.

Parkinson’s patients have reduced levels of physical activity compared to healthy people their age. They also have lower levels of strength and functional ability, caused by an impairment of the basal ganglia effect on cortical motor centers, which results in decreased activation of motor neurons, and therefore muscle weakness. Furthermore, inactivity can accelerate the degenerative progress of PD. Exercise stimulates dopamine synthesis in the remaining dopaminegic cells which reduces the symptoms of PD. In addition, exercise appears to have a neuro-protective effect against developing PD.

=Symptoms= The symptoms of PD generally appear when around 70% of the dopamine producing cells stop functioning normally. These symptoms will gradually progress and develop as patients get older.

The diagnostic criteria is composed of 4 motor symptoms which are:
 * Tremor
 * Muscle Rigidity
 * Bradykinesia (Slowness of voluntary movement)
 * Postural Instability (including Gait disturbances)

Other non-motor symptoms can include: Anosmia (loss of smell), Sweating, Postural Hypotension (drop in blood pressure when rising from a sitting position), Festinating of speech and Muscle weakness

Research has shown that PD sufferers may also develop: Sleep Disturbances, Anxiety, Depression and Fatigue

=Resistance Training= Parkinson's Disease can have a huge effect on the physical and neural components of muscular strength in sufferers. One of the main problems caused is decreased isokinetic muscle strength which affects the flexors and extensors of the hip, knee and wrist. This is what can affect the walking gait of sufferers. Other problems can include longer times to reach peak torque and contraction and lower force development rates. The motor neurons of the muscles are also affected, as their activation is decreased due to inadequate basal ganglia stimulation of cortical motor centers as well as incomplete contractions caused by action tremors.

=Aerobic Training= Unlike the specific negative effects PD has on the strength of patients, before resistance training improves those areas affected, the effects PD has on the aerobic exercise of patients is more generalized. One of the main problems that will cause general exercise decrease in patients is the affect that PD has on the gait. Although this is also strength related, a problem with the walking gate will any type of exercise, including aerobic. Despite this, numerous studies have shown that Aerobic exercise has a huge effect on improving certain symptoms, factors and problems caused by Parkinson's. The 3 main types of aerobic exercise in the numerous studies are either treadmill, cycling, elliptical trainer or a combination with the benefits of aerobic exercise becoming evident almost immediately.

=Recommendations= Numerous studies have concluded that with any resistance exercise program for PD patients, the goal should be to maximize intensity while minimizing fatigue. This is due to the amount of problems that can be caused by long duration exercise and become more hazardous then helpful for patients. The general resistance recommendations for PD consists of 3 sets of high load resistance 2 to 3 times per week, focusing on eccentric movements to minimize metabolic demand. Kelly et al’s 16 week program suggests that a variety of high intensity resistance exercises including leg, overhead and body weight should be done to help activate muscles, generate power and produce energy. Meanwhile, a 24 month study by Corcos et al, showed that one hour of resistance training twice a week resulted in improvements in motor symptoms as well as tremors.

The varying aerobic exercise studies that included using a treadmill, cycling or elliptical trainer all produced different positive results for PD patients depending on the duration of the study. What was uniform across the studies was the need for the training to be moderate to high in intensity and short duration up to 30 minutes per session, wether the studies lasted a few weeks, a few months or even 2 years.

=Conclusions= It seems that any exercise is good exercise for PD patients, whether its in the form of resistance or aerobic exercise. Despite the fact that both have many positive effects on the symptoms that PD causes, it is worth noting that neither one will have a bigger impact by itself compared to when both are used in conjunction in a program. Even though aerobic exercise interventions seems to have more benefits, there are some benefits that only resistance exercise will bring which means that worth it to include both. Its also worth acknowledging that there is no “one size fits all” exercise prescription for such a variable and progressive disease. Every case of PD, the effects it has on patients will be different which means the exercise program will have to be individualized. But as a foundation for prescription, exercise interventions should be a moderate to high intensity, long term program that combines the benefits from both aerobic and resistance training, 2 -3 times a week lasting between 30 and 60 minutes.

=Further Reading=
 * http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Parkinson's_disease_explained
 * http://www.parkinson.org/Parkinson-s-Disease/Treatment/Exercise/Neuroprotective-Benefits-of-Exercise
 * http://www.parkinson.org/Parkinson-s-Disease/Treatment/Exercise/Neuroprotective-Benefits-of-Exercise

=References=