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Exercise Your Power Over Parkinson’s Disease

The Gist:

The National Parkinson’s Disease Foundation recently revealed exciting findings from their Parkinson’s Outcomes Project: regular exercise may slow the decline in health-related quality of life in individuals with Parkinson’s Disease. Of note, those who start exercising earlier demonstrated a slower decline than those who start exercising later. These findings not only challenge the notion that individuals with PD are sedentary, but also support the idea that exercise may slow disease progression.

Exercise may reduce the impact of PD through a process called neuroplasticity, which refers to the brain’s ability to change in response to various experiences. By reorganizing neural pathways, the brain learns to adjust to new situations and compensate for injury and disease.

Neuroplasticity is capable of contributing to behavioral recovery in PD through both protective and restorative mechanisms in the brain ; which process governs depends on when exercise is adopted. Studies suggest that beginning exercise early may protect the brain against damage and perhaps even restore impaired neurological processes. Later in the disease, exercise may enhance the efficiency of impaired processes. Conversely, inactivity may even contribute to the exacerbation of PD symptoms. These findings, coupled with the recent data from the Parkinson’s Outcomes Project, underscore the importance of adopting exercise habits early on and continuing to stay active throughout the disease.

So what is the best exercise to drive neuroplasticity in the brain? While a conclusive answer is yet to come about, some researchers believe that certain key principles maximize exercise’s impact on neuroplasticity in individuals with mild-to-moderate PD. Specifically,

• Exercise should be aerobic in nature to optimize brain health and prime neurons to “learn”
• Exercise should be goal-oriented, which means targeted to improve a specific dysfunction in PD (e.g., balance), to optimize brain repair and adaptation
• Exercise should be performed in a cognitively engaging context; this means, that the exercise should demand increased attention, planning, processing of information and/or multitasking
• Exercise should integrate parameters with established roles in driving neuroplasticity, including intensity, repetition, specificity, complexity and difficulty.

Research shows that exercise programs that unite these principles can result in measurable chemical, functional and even structural changes in the brain, which may be associated with improvements in PD patients’ both motor (e.g., balance, mobility) and non-motor (e.g., cognition, depression) function. Examples of exercises that are based in neuroplasticity principles include: progressive treadmill training, forced cycling, Tai Chi, dance, boxing, amplitude training, among others.

Studies confirming the short-term benefit of exercise have informed the development of the American College of Sports Medicine’s Exercise Management for Persons with Chronic Diseases and Disabilities to provide patients with evidence-based exercise recommendations. While rigorous large-scale randomized control trials with sufficient follow-up are still needed to determine which regimens confer the greatest benefit and whether the short-term effects of exercise translate into long-term benefits, the bottom line remains: exercise should be a cornerstone in every PD patient’s disease management approach.

Safety should always be a priority, so it is important to speak with a doctor or physical therapist prior to starting a new exercise program.

The Score

Progressive treadmill and forced cycling programs are goal-based aerobic exercises in which feedback from the instructor increases patients’ attentional demand and challenges patients to simultaneously process information while executing movement beyond voluntary limits. Several studies have shown that intense treadmill training and forced cycling (where PD patients were required to pedal 30% faster than the rate they would have chosen themselves) have led to the retention of benefit and even its transfer to untrained body parts ; for example, forced cycling may improve manual dexterity, handwriting and possibly even sense of smell. These changes may be explained by neuroprotective and/or neurorestorative exercise-induced changes in the brain.

In fact, studies of the brain have shown that these exercises may alter excitability and activation of brain regions that are typically affected in PD, recruit other brain regions with established roles in motor learning and increase levels of important neuroplastic mediators such as brain-derived neurotrophic factor (BDNF), which are typically low in PD patients.

Tai Chi and dance challenge individuals with PD to increase their sensory attention and body awareness, while executing the appropriate sequence of movements. By incorporating muscle strength, flexibility, balance and aerobic conditioning, they simultaneously target many PD disabilities. Several studies have documented the retention of motor benefit over time. and its transfer to upper limbs, suggesting that central changes may lead to global motor benefit. One study showed that PD patients who danced remained stable in freezing of gait throughout the twelve month intervention, while those who did not dance worsened over this period, suggesting a potential slowing effect of dance on disease progression. It is possible that dancing and Tai Chi, which target balance and focus the mind on movement, elicit similar volumetric changes in the brain during the learning process that have been documented following balance training and mindfulness meditation-based interventions. Boxing, a lesser-studied alternative based on similar principles, may also improve balance, gait and quality of life in the long-term.

Amplitude training is an exercise in which individuals with PD are asked to focus their attention on generating high effort, large amplitude, whole body movements during the practice of a skill such as stepping and reaching. Tasks progress in difficulty and intensity over the course of the training, and participants are challenged to translate their skills into everyday functional activities. One study demonstrated that the whole body movements elicited during training translate to improvements in speed and amplitude of upper and lower limb movement, and clinically relevant improvements in motor performance are retained several weeks after program completion. This effect may be greater in patients with mild PD than those with more severe PD. Large amplitude movements may also be incorporated into aerobic exercise to potentially amplify the mechanisms that drive neuroplasticity in the brain.

Virtual reality (VR) is a motor-cognitive intervention in which individuals are directed by visual and auditory stimuli in a real-time simulated environment. VR requires complex thinking, attention and planning, while simultaneously necessitating the execution movement. Programs that integrate VR with aerobic training, referred to as exergaming, include virtual dancing and bicycling, among others. Custom VR rehabilitation programs also exist. For example, a recent study of patients at high risk for falls showed that a six-week treadmill training combined with a VR program that included obstacles, distractors, and multiple pathways, led to a significant reduction in falls in PD patients during the six months after the training ended.A study is currently underway to examine the effect on PD symptomatic relief of an at-home bicycling/exergaming program that is monitored virtually by a physiotherapist.

Importantly, recent studies show that the effect of exercise may extend beyond motor improvement. Several studies have shown that aerobic exercise that includes a strength training component improves executive functions important in daily living such as the capacity for abstraction, mental flexibility and verbal fluency. Even short bouts of passive cycling (where a motorized bicycle performs the pedaling) can produce improvements in executive function. A recent study suggests that both progressive and non-progressive resistance training may improve working memory and inhibition with the progressive training also improving attention. Evidence is growing that different types of exercises – Tango, Tai Chi, Virtual Reality", amplitude training — can improve some aspect of cognitive function. Multimodal training may also have positive effects on depression, fatigue and sleep, while Tango and Tai Chi may improve depression, apathy, fatigue, quality of life and activities of daily living. A study is currently underway to determine which exercise (spinning, dance or yoga) confers the greatest benefit on fatigue, anxiety and depression.

So What Does This Mean for Patients?

NPF data shows that those who report exercising ≥ 2.5 hours weekly demonstrated better quality of life, mobility, physical function, less disease progression and cognitive decline when assessed one year later than those who exercised less. Researchers agree that exercise should begin as early as possible. However, animal studies show that behavioral recovery occurs even in more advanced stages of the disease with longer training periods. These data underscore the importance of integrating exercise as a cornerstone of the disease management approach. To accomplish this, it is important to choose an exercise plan to which patients can commit to long-term.

Remember, safety should always be a priority, so it is important to speak with a doctor or physical therapist prior to starting a new exercise program. It is important to be safe, start off easy and gradually work up towards goals. When possible, intensity should be stressed, particularly in those with early stage disease and/or younger PD patients who are able to handle more rigorous exercise. Others should try to integrate bouts of vigorous aerobic exercise into their existing exercise routine.

One way to do so is through High Intensity Interval Training, which cycles between short bursts of exercise near one’s capacity and more leisurely exercise for the same time frame. For instance, a small study showed that interval training on a bicycle increased BDNF levels in PD patients, which was associated with improved rigidity and global effect on both lower and upper body function. However, it is important to note another study’s findings: while interval and continuous improved fitness and gait speed to the same degree, interval training was associated with higher exercise-related adverse events, such as knee pain.

Intensive inpatient rehabilitation treatment is also being studied as an alternate, but costly approach to integrating intensity. For instance, in one study patients with moderate PD underwent an intensive, four-week inpatient rehabilitation program. These patients demonstrated no decline in PD symptoms one year following the program completion, while those who did not undergo the program showed clinically significant deterioration in PD symptoms. Of note, daily medication dosage was reduced in the rehabilitated patients, while it was significantly increased in controls. A second rehabilitation cycle administered after one year was as effective as the first treatment in improving PD symptoms.

In a follow up study, newly diagnosed patients treated with rasagiline that participated in the rehabilitation program once every year improved their motor scores and remained on stable treatment dose, while those in the control group remained clinically stable but needed to increase their treatment and required polytherapy more often than rehabilitated patients. It is important to note that the patients were encouraged to continue exercising during the interim periods of both studies. These studies highlight the potential of annual intense rehabilitation as an adjunct treatment for PD patients in offsetting the worsening of symptoms associated with PD.

Although studies indicate that intense aerobic exercise provides the most benefit to PD patients, achieving high intensity is not always feasible for PD patients. To learn whether moderate exercise produces similar benefit, a study is currently underway to compare two levels of exercise, moderate and vigorous. Since intensity of the exercise depends on several factors, including frequency and duration, number of repetitions and its difficulty/complexity, these parameters might also be important in promoting benefit. For instance, one study showed that a lower intensity treadmill training program completed over a longer duration improved gait speed more consistently than did a shorter, higher intensity treadmill program. Another recent study found that when the exercise duration is short, frequency becomes the critical factor. More studies are needed to determine the optimal parameters.

Exercise should be progressive and challenge PD patients beyond their self-determined limits. Trying a brand-new exercise forces the brain to figure out how to do something for the first time. Some researchers have suggested that there is ““no one superior exercise, but that benefit may be achieved as long as a critical threshold of high effort (difficulty and complexity) exists over an adequate period time (repetition).” The more complex and difficult a task, the more cortical motor areas are recruited, likely potentiating more durable connections in the brain. Since PD presents with a gamma of motor and non-motor symptoms, it is important to tailor the exercise approach to each individual’s clinical status and needs. A French study is currently recruiting to evaluate the benefits of a personalized physical activity coaching program specific for each patient’s needs.

There is mounting evidence that traditional exercise approaches such as aerobic and strength training provide short-term motor benefits for PD patients, which has informed the development of the American College of Sports Medicine evidence-based guidelines (2007) for older adults and patients ≥50 years living with chronic disorders. Patients should work with their physical therapists to identify a task-specific exercise program that teaches them strategies that they can translate into daily living to improve specific activities that are impaired by the disease. For instance:

According to the ACSM, aerobic training should be performed at ≥5 days/week for 30 minutes of moderate intensity or ≥3 days per week for 20 minutes at vigorous intensity. If possible, heart rate should be monitored to achieve these goals (50-70% maximum heart rate for moderate intensity or 70-85% for vigorous, according to Mayo Clinic). Treadmill training most consistently improves gait, specifically walking speed and stride length. Some studies have reported improvements in motor symptoms, balance and decreased risk of falls. PD patients who have balance difficulties or freezing episodes should not use treadmills without safety support harnessing or supervision. If harness is unavailable, a stationary bicycle may be more appropriate. Patients should exercise at their optimally medicated state, as dopaminergic medication allows safer and longer performance of aerobic exercise.

• The ACSM recommends that resistance training be performed ≥2 nonconsecutive days per week (8-10 exercises involving all major muscle groups of 10-15 repetitions). While beginners should start at light intensity and higher repetitions, the program should be progressive, following the results of a randomized controlled trial showing the superiority of progressive training (increase of at least 5% increase as participants were able) in comparison to non-progressive programs for improving motor symptoms. In addition to the ACSM recommendations, one group recommends focusing on strengthening the extensor muscles to counteract flexion of the hips and trunk. Furthermore, including eccentric (i.e., lengthening) resistive training may reduce fatigue and allow individuals to withstand greater imposed loads. Resistance training generally improves muscle strength, but results concerning balance, gait and motor symptoms are mixed with some noting positive effects and others noting none.

• Flexibility exercises should be performed ≥2 days per week for at least 10 minutes each day and should focus on static stretching, holding each stretch at a level of mild discomfort for about 30 seconds. Dynamic and proprioceptive neuromuscular facilitation stretching (advanced form of flexibility involving stretching and contraction of the targeted muscle group) may also be of benefit. It is recommended to perform flexibility exercises for each of the major muscle-tendon units with a focus on the spine, trunk, hips and shoulders. In addition to the ACSM recommendation, one group suggests focusing flexibility on the frequently shortened flexor, axial, and cervical muscles.

• Although the ACSM recommends balance training only in those at-risk for falls, some suggest to begin balance training early, as many of the risk factors predisposing one to falls already exist in the early stages of the disease. Balance training should focus on challenging dynamic stability tasks, involving moving the center of mass, narrowing the base of support and minimizing upper limb support.

Although no study evaluates the benefit of a combined intervention over strength or aerobic training alone, it is likely that the most beneficial exercise regimen combines different modalities of exercise, including endurance, strength and balance training. Similarly, multifaceted exercise programs may simultaneously target multiple aspects of PD disability:

Several different types of dance genres show benefit for body function with Tango being the most studied. Studies have demonstrated improvement in motor signs/symptoms, gait parameters, balance and upper extremity function. Most studies support the implementation of two dance classes per week of one hour each, in order to achieve improvements in balance, motor impairment, endurance and quality of life. Longer duration interventions may be more beneficial with greater improvements evident in balance and motor impairment.

• Studies have shown that Tai Chi may improve motor function, balance capacity and number of falls. Importantly, these benefits may be retained for months after completion of the program. Performing Tai Chi while using medication results in significantly greater benefit in terms of general motor symptoms, balance, mobility and stride length, with few adverse events. The reduction in falls is greater after a long-term (e.g. 6 months) Tai Chi program than in other exercise. Most of the studies were conducted for 60-minute sessions 2-3 times per week.

A recent Cochrane Systematic review comparing a variety of exercise interventions found that exercise in the short-term has positive benefits on mobility, balance, strength and physical functioning for PD patients; however, it was unable to identify the most optimal intervention. An extensive overview of literature between 1981-2015 echoed these findings, confirming the positive effect of physical activity on physical capacities, physical and cognitive functional capacities and motor symptoms (UPDRS III) of PD.

As we await answers from new randomized controlled trials, the implication of existing studies remains strong: PD is a progressive disease, but exercise may slow its effects, reduce disability and improve quality of life for PD patients.

Complete list of references: Exercise_References.docx