This column continues a series of articles addressing exercise testing and programming considerations for special populations. The current column presents considerations regarding exercise that are unique and specific for the individual with a spinal cord injury (SCI). Also discussed is current innovative and exciting research regarding an exercise training modality called “locomotor training” that has the potential to change the quality of life of individuals with SCI.
SCI affects millions of individuals worldwide (18) and results in devastating economic, functional, and psychological consequences (6,14). According to the National Spinal Cord Injury Statistics Center, traumatic SCI affects approximately 262,000 individuals in the United States (14), and each year, there are approximately 12,000 new cases. The average age for individuals affected by SCI is 28.7 years, and approximately 81% of SCI cases occur in men. About 98% of spinal cord lesions are at the level of the cervical or thoracic vertebrae (57% of the cases are cervical; 41% thoracic). Because both the level and severity of lesion (complete/incomplete) determine the degree of impairment, a large number of SCI cases have severe and devastating consequences. Most SCIs are caused by motor vehicle accidents (41%), followed by falls (27%), gunshots (15%), and sports accidents (in particular, diving) (8%).
The high incidence of SCI cases and the secondary complications, such as cardiovascular and pulmonary disease and obesity and obesity-related diseases, result in enormous financial costs. Although many of these comorbidities, including obesity and obesity-related diseases, could be preventable with exercise training (10,17), they still are among the leading causes of death secondary to SCI. Physical capacity is significantly decreased in individuals with cervical or thoracic SCI because of paralysis and atrophy of the muscles below the level of the injury, altered nervous system control, and inactivity (8). These three characteristics in individuals with SCI are the overarching characteristics that define the exercise response. The unique and specific factors for individuals with SCI that are related to exercise testing and programming stem from these three characteristics, and a brief discussion is presented later.
SPECIAL CONSIDERATIONS FOR EXERCISE TESTING FOR INDIVIDUALS WITH SCI
The mode of exercise testing for SCI will depend in part on the muscle mass available but is typically arm or wheelchair ergometry, wheelchair propulsion, or treadmill testing with a wheelchair. Recommended measures obtained during testing include a peak heart rate, blood pressure, oxygen uptake (V˙O2), and rating of perceived exertion (RPE). Sympathetic nervous system function can be affected to a varying degree depending on the level and severity of the lesion (12), possibly disturbing heart rate and blood redistribution capacity during exercise (11,15,16). For this reason, heart rate may not be an accurate measure to predict V˙O2max in the SCI population during exercise testing. In fact, individuals with high lesions of the spinal cord may only reach a maximal heart rate of 120 to 130 per minute. The 6 to 20 RPE scale developed by Borg and routinely used in clinical and rehabilitation settings has shown a strong positive correlation with heart rate and V˙O2max in healthy populations (1,4) and in individuals with SCI (2), and thus, RPE can be used as a marker of exercise intensity in this population.
The maximal and submaximal testing protocols currently in use for this population that have been validated have used arm crank ergometry (1,2). However, the small and easily exhaustible muscles of the upper body often do not adequately stress the cardiovascular system, perhaps resulting in lower oxygen consumption values. In addition, these arm crank ergometer tests may place individuals with SCI at a higher risk of overuse of the upper limbs, thus increasing the risk of musculoskeletal injuries. Because of expanded training modalities available now for individuals with SCI, such as functional electrical stimulation and locomotor training (to be discussed later), there is a critical need to have validated testing methods that include a larger muscle mass to track the effectiveness of training (e.g., changes in maximal oxygen consumption) for individuals with SCI.
SPECIAL CONSIDERATIONS FOR EXERCISE PROGRAMMING FOR INDIVIDUALS WITH SCI
Similar to exercise testing, the modes of exercise training for individuals with SCI are dependent, for the most part, on available muscle mass. These modes are diverse and include wheelchair ergometry, wheelchair propulsion on a treadmill, swimming, and other sports such as basketball and rugby. The ACSM recommendations for exercise programming for individuals with SCI include both aerobic (40% to 90% V˙O2 reserve; 3 to 5 days per week, 20 to 60 minutes per day) and strength training (8 to 12 exercises, 2 to 3 days per week). Because of the reduced sympathetic nervous system response, exercise training should occur in a thermo-neutral environment.
Individuals with a cervical or upper thoracic SCI show abnormal blood pressure control in that the response to exercise can be hypotensive or hypertensive. Generally, resting blood pressure is lower than that in able-bodied individuals, and it is common to observe orthostatic hypotension. Therefore, some individuals with SCI may show significant increases or decreases in blood pressure by solely changing positions (sitting to supine and vice versa) or exercising at high intensities.
In addition, individuals with SCI may experience transient episodes of life-threatening hypertension, known as autonomic dysreflexia (7). Autonomic dysreflexia occurs in up to 90% of individuals with a cervical or high-thoracic SCI and requires prompt intervention. These episodes often are elicited by some type of noxious (harmful or painful) stimulus such as an ingrown nail, bladder distension, or skin blister. For this reason, it is important to check the skin regularly and ask the participant to empty his or her bladder before exercise. Autonomic dysreflexia also can be voluntarily induced, and it has been used as a “boosting” to improve performance among athletes (3). Although boosting has been banned by the International Paralympic Committee, it is important for trainers and clinicians to understand that autonomic dysreflexia can be spontaneous or intentionally induced, and it is an important aspect to consider when training individuals with SCI.
INNOVATIVE PROGRAMMING FOR INDIVIDUALS WITH SCI
Activity-based therapy is a rehabilitation strategy in which muscles below the level of the lesion are activated and strengthened (9). Locomotor training is an example of activity-based therapy used for individuals with SCI. During locomotor training, the individuals are placed on a treadmill, with body weight partially supported by a harness and repetitively practicing standing and stepping, with manual facilitation from therapists. The goal is to retrain individuals with SCI to walk again. Eric Legrand talks about locomotor training at the following Web site: http://www.youtube.com/watch?v=wtxHCnFD6UY.
The effect of activity-based therapy has been studied (5,13), demonstrating the efficacy of this modality in maintaining muscle mass, decrease osteoporosis, diminishing the number and severity of infections, and improving cardiorespiratory function for individuals with SCI. The Neurorecovery Network (NRN) is a cooperative network of cutting-edge rehabilitation centers designed to provide and develop therapies to promote functional recovery and improve the health and quality of life of people living with paralysis, including locomotor training. To learn more about the NRN, go to the following Web site: http://www.christopherreeve.org/site/c.ddJFKRNoFiG/b.5399929/k.6F37/NeuroRecovery_Network.htm.
In addition, there are NRN community fitness and wellness facilities that host activity-based exercise programs designed specifically for individuals with physical disabilities. These NRN community fitness and wellness facilities have a need for appropriately trained clinical exercise physiologists to perform their mission. To learn more about the NRN community fitness and wellness facilities, click here:
CONSIDERATIONS FOR EXERCISE TESTING AND PROGRAMMING WITH INDIVIDUALS WITH SCI
- Endurance training should be performed at intensities between 40% and 90% V˙O2 reserve; 3 to 5 days per week, 20 to 60 minutes per day
- Strength training (8 to 12 exercises, 2 to 3 days per week)
- Include flexibility exercises and avoid overuse of shoulder and elbow joins
- Always exercise in thermo-neutral environments
- Heart rate is not an accurate measurement of intensity in quadriplegics and in most paraplegic individuals; RPE is preferred.
- Oscillations in blood pressure may impair performance and can be life threatening. Check blood pressure and symptoms of autonomic dysreflexia.
- It is very important to empty the bladder before exercising and stay well hydrated before, during, and after exercise.
Exercise testing and programming for individuals with SCI present some unique challenges for the trainer and clinician, and current research is changing the landscape for this population. The next column will discuss exercise testing and programming for individuals with chronic heart failure and associated comorbidities.
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© 2014 American College of Sports Medicine.
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