Evidence-based Exercise Prescription for Individuals with Spinal Cord Injury

Abstract

Purpose 

Individuals with spinal cord injury can benefit from regular exercise. Exercise prescription for these individuals is based on the same 4 principles of exercise used for nondisabled individuals. The purpose of this paper is to describe a process by which physical therapists may generate an exercise prescription for individuals with SCI.

Description 

Examination of the individual with SCI to identify occult disease and/or impairments that can cause adverse events or limit participation in the exercise session is outlined. The 4 principles of exercise: overload, specificity, individuality, and reversibility are defined. Guidelines for achieving overload, which include both aerobic and anaerobic training, are outlined in detail. The literature on specificity of training for individuals with SCI is highlighted.

INTRODUCTION

The benefits of exercise for those without a disability or for those with chronic diseases are well documented in the literature.¹⁴ Further, the recommendations for exercise dose are known for nondisabled adults. For individuals with disabilities or chronic disease, however, this is not the case.⁵ As Nash points out in the accompanying article persons with spinal cord injury (SCI) have even greater risk for the diseases associated with a sedentary lifestyle than do persons without a disability. Therefore exercise can have a protective or positive role for individuals with SCI. The question is not whether to exercise a person with a SCI but how to effectively and safely administer exercise. There are no evidence-based guidelines for promoting and prescribing exercise in this population.⁶ Therefore, the purpose of this article is to present an approach to the development of exercise and prescription for individuals with a SCI that is based on best evidence.

Basic principles of exercise training developed for nondisabled individuals are used to formulate exercise prescriptions for persons with SCI. The principles of overload, specificity, individuality, and reversibility are applied to achieve the desired training outcomes.¹ Overload refers to the application of a load that enhances physiologic function to bring about a training response. Manipulation of frequency, intensity, and duration will achieve the appropriate training overload. Overload focuses on the specifics of the prescription. Specificity refers to the adaptations in metabolic and physiologic functions that depend upon the overload imposed. Exercise outcomes are specific to the muscles and energy systems trained as well as the type of training mode. Specificity focuses on the ‘how to’ of goal achievement. Individuality refers to the individual variation in the training response. This principle takes into account the person's level of fitness and other specific factors to gear the prescription to the person's needs and capacities. For those with SCI, it would take into account their level of lesion as well. Individuality focuses on the skilled interventions required for these individuals to exercise safely and preventing any adverse effects of exercise. Reversibility relates to the detraining response that occurs rapidly when the overload is removed. This principle emphasizes the importance of exercise compliance. These basic principles of exercise serve as an outline for exercise prescription for those with SCI or for anyone in the population. The principles of overload and specificity will be discussed further.

EXAMINATION

Prior to formulating the plan of care that includes the exercise prescription, persons with SCI should undergo an examination by their physician and physical therapist to screen for occult disease and impairments that may con-traindicate or limit participation in exercise or cause adverse events. The examination should also include tests and measures that will develop the exercise prescription based on the person's capacities, goals, and limitations. Based on the review article by Jacobs and Nash⁷ and the research by DeVivo et al,⁸ the following diagnostic tests are recommended:

1. Exercise Stress Test
1. Rule out occult cardiovascular disease.
2. Provides an objective peak heart rate for the exercise prescription since those with tetraplegia have peak heart rates that do not usually exceed 120B/ min due to autonomic dysregulation and those who have paraplegia generally have a high resting and exercise heart rate due to decrease stroke volume.
3. Provides information on the exercise tolerance of the individual.
4. Ideally, a metabolic test should be done on these individuals to obtain an objective VO2peak since the predication equations used for individuals without a disability have not been validated in those with a SCI.
2. Bone Mineral Density (BMD) Scan
1. As osteoporosis is prevalent in this population, this test will allow determination of fracture risk.
3. Blood Work
1. Lipid Panel – due to the commonly reported athero-genic lipid profile.
2. Glucose test – due to the high prevalence of type 2 diabetes.
4. Pulmonary Function Test (PFT)
1. Provides objective measurement of the restricted ventilatory impairment, which correlates, inversely with the level of spinal lesion.

EXERCISE PRESCRIPTION

The prescription will be based on the principles of exercise training already discussed. The precautions, adverse effects, risks, and expected responses for those with tetraplegia and paraplegia have already been discussed in the companion article by Nash. The following are specific details on how to achieve training overload.

Overload

1. Aerobic Training
1. Intensity – refers to the target heart rate (THR). Generally, 40% to 80% of heart rate reserve (HRR) or the Karvonen Formula^9–11 which is given as:

Where MHR = max heart rate from the stress test, RHR = resting heart rate, % = the higher percentages will yield better training results but increases should be gradual.
If a stress test was not performed, the THR is 20 – 30 beats above resting.¹

2. Duration – 30 minutes of continuous aerobic exer-cise.^9–16
3. Frequency – either 2 or 3 times per week.^9–16
4. Mode–arm ergometer, wheelchair ergometer, wheelchair treadmill, free wheeling, seated aerobics, swimming, electrical stimulation leg cycle ergometry, circuit resistance training (CRT).^7,9–16
2. Anaerobic Training
1. Intensity – generally, 50% to 80% of 1RPM.^{7,10–11,14,17}
2. Duration – 2–3 sets of 10 reps.^{7,10–11,14,17}
3. Frequency – 2 times per week.^{7,10–11,14,17}
4. Mode – weight stations, free weights, T-bands.^{7,10–11,14,17}

Specificity

For individuals with SCI who are deconditioned, a transfer of training will occur.¹⁸ This means that one can train an individual who is deconditioned and see a generalized positive response to all muscles and all energy systems even though they were not directly trained. This will not occur in those individuals who are not deconditioned. This principle has positive clinical implications for the patient. If strength is the focus of the physical therapy intervention, increases in aerobic capacity may also be noted. This can allow for greater flexibility in the program and also increase the efficiency of the treatment. Jacobs et al¹⁹ found an increase in VO_2peak, power output, and time to fatigue in arm ergometry after FNS ambulation training in persons with paraplegia. Conversely, Silva et al²⁰ found an increase in ventilatory muscle endurance with aerobic training and Uijl et al²¹ found an increase in aerobic exercise performance with respiratory muscle training. This also has clinical implications. If the person with SCI cannot participate in a program 2 to 3 times per week they can at least perform respiratory muscle training at home and increase their aerobic endurance.

In keeping with the principle of specificity, it has been found that arm cranking has no benefit in increasing function of the upper extremities or for improving wheelchair propulsion.^7,17 To improve wheelchair performance, it is important to increase the strength of the posterior shoulder muscles and upper back and to use wheelchair ergometry. An added benefit of the strengthening of the posterior shoulder muscles and upper back is decrease in pain, which also can increase function.

CONCLUSION

Exercise prescription for individuals with spinal cord injury is necessary to ensure the safety, efficiency, and efficacy of the exercise program. Exercises should be prescribed based on the physiologic principles of exercise training with the goals of the individual in mind. When this does not occur, the person's safety is at risk and the desired outcomes may not be achieved. Until further research is provided, it is prudent to follow established guidelines based on the evidence and not to use data from individuals who do not have a SCI as the basis of exercise prescription for individuals with SCI.