Aerobic exercise for a patient with chronic multisystem impairments.

Key Words: Exercise, Heterotopic ossification, Traumatic brain injury.

In many patients with chronic disorders, deconditioning in addition to an already increased energy cost of mobility further contributes to a decline in function.[1-3] Several researchers[4-6] have shown that the aerobic capacity, as reflected by maximal oxygen consumption (V[O.sub.2]) and workload, of persons with hemiparesis following stroke is lower than that observed for age-matched counterparts who do not have known impairments. Inactivity increases the risk of developing chronic diseases such as coronary artery disease, stroke, type II diabetes, osteoporosis, and some types of cancer.[7] Therefore, to prevent these diseases and maintain wellness, it is important to develop feasible aerobic programs for patients with chronic impairments.

When prescribing exercise for patients with chronic disorders, physical therapists often need to use ingenuity and a knowledge of pathophysiology and pathokinesiology to develop an exercise protocol with sufficient exercise intensity, duration, and frequency to cause a training effect. The exercise intensity must elicit an adequate physiologic demand to produce beneficial adaptations such as increased maximal cardiac output, stroke volume, and V[O.sub.2], decreased resting and submaximal heart rate (HR), and improved skeletal muscle oxidative capacity.[7-9] To produce these beneficial effects, the American College of Sports Medicine (ACSM) recommends an exercise intensity of 60% to 90% of maximum HR or 50% to 85% of maximum V[O.sub.2].[7] The ACSM suggests that lower exercise intensities, such as 50% to 60% of maximum HR, may be appropriate to produce training effects in deconditioned individuals.[7] The important point is for each patient's exercise intensity to match this range as closely as possible but to remain within the limits of patient safety and tolerance. The ACSM recommends a minimum exercise duration of 20 minutes and a minimum exercise frequency of three times a week.[7]

The physiologic demand produced by exercise is related to the amount of muscle mass recruited during an activity and the duration of use. Exercises to improve aerobic performance, therefore, should use large muscle groups. Traditionally, activities such as walking, running, biking, and swimming have been used. The mode of exercise selected must also be safe for the patient, specifically with regard to lower-extremity weight bearing and impact, risk of falling, and cardiac stress.

Due to decreased motor control or sensory loss, full-weight-bearing and high-impact activities may be inappropriate for some people with disabilities. In addition, many commonly used aerobic exercises are too challenging to the person's balance and coordination. Because many patients with neurologic impairment also have cardiac disease, the effect of the mode of exercise on myocardial oxygen demand is also an important safety consideration. Isometric stabilizing contractions and recruitment of a small muscle mass produce a relatively high myocardial oxygen demand.[10] Upper-extremity exercises elicit a greater HR, systolic blood pressure (BP), and total peripheral resistance for a given submaximal workload compared with lower-extremity exercises.[11-14] As straightforward as this seems, it is often difficult to identify a mode of exercise that a patient with chronic multisystem disorders can perform safely and successfully enough to increase HR appropriately. The purpose of this case report is to illustrate the process used to develop an exercise prescription to enhance aerobic capacity in a patient with chronic multisystem impairments.

Case Description

Subject

The patient was a 43-year-old man who was self-referred to an outpatient exercise program administered through a free medical clinic. The patient incurred multiple traumas in a motorcycle accident 15 years previously, including a traumatic brain injury (TBI), a pneumothorax, and fractures of the right hip, skull, and multiple ribs. He said that after the accident he underwent many surgical procedures, including open reduction internal fixation of the right hip. He also reported developing heterotopic ossification around the right hip, and he stated that he currently had constant right hip pain, dizziness and lightheadedness, frequent headaches, difficulty sleeping, and emotional stress. The patient described his right hip pain by giving it a score of 2 out of 10 on a verbal rating scale. He said that his left side had been uncoordinated since the accident. The patient was not taking any medications at the time of the initial examination. He described having a 12-year history of smoking one pack of cigarettes per day. He had recently separated from his wife and lived in a one-level first-floor apartment. He had not worked since the motorcycle accident, but he said that he planned to begin taking classes at a local university. He had not participated regularly in any exercise program since his initial rehabilitation, except for a self-initiated daily regimen of push-ups. The patient stated that his goals were to improve his "strength, endurance, and overall performance." During the initial visit, he read and signed an informed consent statement to participate in exercise therapy.

Examination

Motor and Sensory Function

During the examination, the patient displayed several motor and sensory abnormalities. He had diminished sensation to light touch in his right lower extremity in the L1-5 dermatomal distributions. Sensation to light touch in his other extremities was normal. Deep tendon reflexes were normal throughout both upper extremities (triceps, biceps, brachioradialis) and both lower extremities (patellar, Achilles, posterior tibia!). He did not have a Babinski's sign in either lower extremity. Ankle clonus was present bilaterally, but wrist clonus was not present. Passive range of motion (ROM) was limited in right shoulder abduction and adduction from 0 to 150 degrees and in right hip flexion and extension from 15 to 55 degrees. With passive right hip flexion, a bone-to-bone end-feel (an abrupt halt to movement, presumably when two hard surfaces meet) was noted.[15] Passive ROM in all other joints was Normal. Because the patient could perform isolated movements, manual muscle testing of both upper extremities and both lower extremities was performed and was Normal throughout his available ROM.

Functional Activities and Gait

The patient was independent for all bed mobility, transfer, and ambulation skills. He did not use an assistive device for ambulation, but did have what we considered an abnormal gait pattern. We observed a decreased stride length, with the right step length less than the left step length. We observed decreased hip flexion on the right side during swing and no hip hyperextension during single-leg stance. His pelvis appeared to be protracted on the right side throughout the gait cycle, with greater left hip lateral (external) rotation and right hip medial (internal) rotation than normal. Initial contact during the stance phase consisted bilaterally of the foot flat on the floor (de, there was no heel-strike and subsequent rolling over). We noted an increased base of support during double-leg stance. There was no arm swing on the left side. In addition, his preferred walking speed was very slow. Although we did not measure his walking speed, in our opinion, the patient walked at approximately 40% to 60% of the speed normally used by a 43-year-old without neurological or orthopedic impairments.

Balance and Coordination

The patient's balance and coordination were moderately impaired. In a sitting position, he demonstrated normal head righting, equilibrium, and protective extension in all directions. He could voluntarily reach without delay, and he could maintain a sitting posture in response to maximum perturbations to balance. In a standing position, he was able to maintain balance and to move from and return to midline, but with delayed responses. He was able to tolerate minimum to moderate perturbations to balance. Perturbations to balance were administered manually by the examiner. The patient could stand on his right lower extremity for 5 seconds, but could not do this test with his left lower extremity. There was a negative Romberg's sign.

To assess coordination, we asked the patient to oppose his thumb to each finger. He was able to do this task correctly with both hands. To further assess coordination, he was asked to perform rapid alternating movements. With forearm supination and proration, he performed one to three fewer repetitions with the left upper extremity than with the right upper extremity in the same time interval. Rapid alternating ankle dorsiflexion and planter flexion were equal on the left and right sides. The patient performed a finger-to-nose test slower and with greater difficulty with the left upper extremity compared with the right upper extremity, but he hit the target correctly on both sides. He was able to coordinate lower-extremity cycling, but he shifted his center of gravity from side to side excessively.

Cardiopulmonary Status

The patient became short of breath when ambulating from the waiting room to the treatment area (approximately 6 m [20 ft] and eight steps). He weighed 88.5 kg and was 180 cm tall. He did not exhibit accessory muscle activity with breathing, and his chest wall configuration and breathing pattern appeared normal. He reported having an infrequent cough that was nonproductive. His speech was somewhat incoordinated, but he was able to produce a coordinated, effective cough. Auscultation of the lungs and heart revealed normal breath sounds throughout the lung fields and normal [S.sub.1] and [S.sub.2] sounds, respectively. His radial, posterior tibial, and dorsal pedal pulses were strong bilaterally. His skin was warm to touch, and Homan's sign was negative bilaterally.

Baseline vital signs and electrocardiographic (ECG) data were obtained for screening purposes and to develop an exercise prescription. A modified five-electrode ECG configuration (right arm, left arm, right leg, left leg, and [V.sub.5]) was used to assess his response at rest and during exercise. His ECG tracing at rest was normal. His BP was 142/90 mm Hg (systolic/diastolic), and his HR was 76 beats per minute (bpm) at rest. Unfortunately, we were not able to have him perform a submaximal or maximal graded exercise test, because the clinic did not have a treadmill or a well-calibrated cycle ergometer. Based on our assessment of the patient's cardiopulmonary status, we determined that he did not have any contraindications to exercise and that he could proceed with exercise training.[7]

Exercise Evaluation and Prescription

We selected a "nontraditional" mode of exercise that we believed safely accommodated the patient's neurologic and orthopedic deficits. The mode of exercise that we chose allows the upper and lower extremities to flex and then to extend nonreciprocally, such that the elbows and wrists are flexed and the shoulders are extended while the hip, knees, and ankles extended, and vice versa. The Healthrider [R](*) was used by this patient, but several companies manufacture this type of equipment, which we call an "alternate flexion and extension of four extremities (AFE x 4) apparatus." The resistance with this type of exercise equipment is determined by the participant's body weight and therefore is not adjustable. The exercise intensity is regulated solely by the exercise speed (in cycles per minute). One cycle consists of the upper and lower extremities moving through complete flexion and extension or extension and flexion, respectively. The Figure shows the patient exercising on the AFE x 4 apparatus.

[Figure 1 ILLUSTRATION OMITTED]

We chose this mode of exercise for this patient for several reasons. First, we believe that exercise using this type of equipment may elicit greater physiological responses than other more "traditional" modes, especially in patients with neurological impairment, because this type of exercise potentially recruits a large muscle mass. Activities that involve all four extremities have the greatest ability to increase V[O.sub.2] with a relatively low cardiac workload and therefore have the greatest potential to produce safe adaptation; lower cardiac workloads occur with activities that produce a lower rate-pressure product for a given level of V[O.sub.2].[16-19]

Although walking involves a large muscle mass and is functional, we did not choose this mode of exercise for several reasons. The patient's voluntary walking speed was very slow and as a consequence increased his HR only about 10 bpm above resting values, which probably would not be an adequate exercise stimulus. Furthermore, because of his deficits in dynamic standing balance, we did not believe that he would be safe walking on a treadmill at a speed greater than his voluntary walking speed. Even though the patient was able to coordinate lower-extremity cycling, we believe that side-to-side shifting of his center of gravity during cycling and problems mounting and dismounting the ergometer made this activity unsafe for him.

We ruled out upper-extremity cycle ergometry for the patient because we believed that it would not have elicited an adequate physiological response. This mode of exercise also may have been hemodynamically dangerous by causing abnormal rises in diastolic or systolic BP, which would be further exacerbated by his moderately elevated resting BP. Upper-extremity exercise produces greater increases in BP relative to V[O.sub.2] than lower-extremity exercise produces because less muscle mass is recruited, resulting in less metabolically induced peripheral vasodilation.[11-14]

During the initial evaluation, the patient was able to perform 8 minutes of exercise on the AFE x 4 apparatus at an intensity of 30 cycles per minute. Exercise was terminated when the patient said he could no longer continue the exercise test. His ECG tracing was normal throughout the exercise and recovery period. Because both upper extremities are involved with this type of exercise, BP and HR were measured when the patient briefly stopped exercising. His BP and HR were 168/96 mm Hg and 100 bpm, respectively, after 4 minutes of exercise and 170/100 mm Hg and 100 bpm, respectively, after 8 minutes of exercise. Because the patient demonstrated normal physiologic responses (increased HR, increased systolic BP, stable diastolic BP, normal ECG recording) to the AFE x 4 exercise, we concluded that he could safely participate in an aerobic exercise program and that the AFE x 4 exercise was a viable mode of exercise for him. We believed that the exercise intensity selected (ie, 30 cycles per minute) was an adequate physiologic stimulus because the patient's HR was within the desirable range (92-166 bpm) based on his age-predicted maximum HR of 184 (205-1/2 age).[20]

Outcome

Subsequent to the initial evaluation, the patient attended 12 exercise sessions over a 1-month period. The progression of his exercise program, with regard to exercise duration and BP and HR responses, is outlined in Table 1. For each exercise session, the patient's BP and HR were recorded four times: before exercise (resting) following 5 minutes of quiet sitting, approximately midway through the exercise, toward the end of the exercise, and after exercise (recovery) following 5 minutes of quiet sitting. Peak vital signs were defined as the greater of the two values recorded during the exercise. Table 2 summarizes the patient's preexercise to postexercise training changes by presenting the mean of each variable for the first and last three exercise sessions.

Table 1.
Patient Response Over a 1-Month Period of Time

                              Intervention Session

               1         2         3        4         5        6

Duration
(min)         10        10        12       14        16       18

Resting
HR(a)
(bpm)         86        88        76       64        78       72

Resting
BP(b)
(mm Hg)      142/102   135/100   125/94   145/100   146/86   140/90

Peak HR
(bpm)        120       112       120      110       108      112

Peak BP
(mm Hg)      174/104   160/95     --      156/100   180/78    --

Recovery
HR (bpm)               100        90       68        76       88

Recovery
BP (mm Hg)     --      135/105   124/94   150/100   152/80   140/102

                             Intervention Session

               7        8         9       10        11        12

Duration
(min)         20       16        18       18        18        20

Resting
HR(a)
(bpm)         66       76        88       76        72        72

Resting
BP(b)
(mm Hg)      138/66   128/98    132/86   144/100   146/100   152/100

Peak HR
(bpm)        102       96       112      104       104       104

Peak BP
(mm Hg)      146/86   160/116   148/84   158/102   162/96    162/104

Recovery
HR (bpm)      90       88        84       80        80        80

Recovery
BP (mm Hg)   124/82   124/100   140/90   142/104   158/100   144/104

(a) HR= heart rate.

(b) BP= blood pressure.

(c) Data not available.

Table 2.
Patient's Preexercise to Postexercise Training Adaptations(a)

                         Preexercise    Postexercise

Duration (min)              10.70           18.70
Resting HR(b) (bpm)         83              73
Resting BP(c) (mm Hg)      134/99          147/100
Peak HR (bpm)              117             104
Peak BP (mm Hg)            163/100         161/101
Recovery HR (bpm)           86              80
Recovery BP (mm Hg)        136/100         148/103

(a) Values represent the means for each variable for the first and last three exercise sessions.

(b) HR=heart rate.

(c) BP=blood pressure.

Throughout the exercise program, the intensity of the AFE x 4 exercise remained constant at 30 cycles per minute and duration was progressively modified. We decided on this approach because during the initial evaluation we determined that this intensity was within the desirable HR range for this patient but his initial exercise duration (ie, 8 minutes) was less than the 20 minutes advocated by the ACSM for physiologic adaptation and disease prevention.[7]

Exercise duration was increased each treatment session, except during session 8, in which duration was reduced because the patient reported experiencing mild muscle soreness. Over the month-long program, the patient was able to increase his exercise time from 8 to 20 minutes. From beginning to end of the exercise program, he demonstrated a reduction in HR during submaximal exercise. The patient said that at the end of the exercise program he was able to "breathe easier during exercise" and that his "overall strength had increased." We were unsuccessful at persuading him to seek help for smoking cessation, and he continued to smoke a pack of cigarettes per day. After repeatedly noting that the patient had an elevated resting BP, we referred him to a physician for possible medical intervention to treat his essential hypertension. After 4 weeks, we believed that the patient could safely exercise independently in a maintenance exercise program. At the time of discharge, arrangements were made for him to continue a maintenance exercise program using the AFE x 4 apparatus at the free clinic.

Discussion

Prescribing an exercise program for this patient was challenging because of the long-term neurologic and orthopedic deficits resulting from a motorcycle accident 15 years earlier. Exercise prescription was also complicated by his deconditioned state, which was most likely the result of his motor and sensory impairments reinforcing a pattern of inactivity, compounded by a history of smoking. Information obtained during his initial examination was used to determine an individualized exercise prescription. Limitations in gait, hip ROM, balance, and coordination coupled with normal strength and planter sensation guided us in choosing the AFE x 4 mode of exercise for this patient.

Several studies[21-24] have examined the utility of "traditional" modes for exercise testing and training in patients with TBI. Jankowski and Sullivan[21] found improvements in oxidative capacity and fatigability in patients with TBI after a 6-week circuit training program. Some of the activities included in the circuit training program were cycling, rope skipping, jogging, and stair climbing.[21] Wolman et al[22] found improvements in exercise duration and maximum workload in subjects who had participated in a 6-week program of biking. Hunter et al[23] compared the effects of exercise testing and training among treadmill walking, leg cycle ergometry, and stair-stepping modes in patients with TBI. Additionally, a walk-run test has been shown to yield reliable estimates of aerobic capacity in patients with TBI.[24] Due to limitations in hip ROM, gait, balance, and coordination, the patient in our case report probably could not participate successfully in these more "traditional" exercise modes.

Based on our assessment of the patient's gait, balance, and coordination, the AFE x 4 exercise mode was chosen over more "traditional" exercise modes. The patient's deficits were not severe enough to prohibit reciprocal extremity activities, but they may have decreased safety during performance due to his exaggerated weight shifting. Based on our observations, we believed that use of an activity requiring the upper and lower extremities to flex and extend synchronously rather than reciprocally would require less balance. We also believed that the patient would be able to successfully use the AFE x 4 apparatus for aerobic conditioning, despite his coordination deficits, because it required a relatively simple movement pattern.

Due to his hip pathology, this patient appeared to need an exercise mode that minimized joint impact, reduced weight bearing, and limited hip movement within a pain-free ROM. His signs, symptoms, and history are consistent with the reported diagnosis of heterotopic ossification around the right hip. Chronic manifestations of heterotopic ossification include loss of ROM and potential nerve impingement. The patient demonstrated loss of ROM in flexion and extension of the right hip and possible femoral nerve impingement, as evidenced by sensory loss in the right lower extremity. Consistent with the history of this patient, heterotopic ossification has been associated with trauma, including surgical procedures and vigorous passive stretching, as well as being found in patients with TBI, total hip arthroplasties, and spinal cord injuries.[25-28] Long-term treatment should include active and resistive ROM exercises within a pain-free range, which was accomplished in this patient through AFE x 4 exercise.[29]

The patient demonstrated an appropriate acute HR and BP response to exercising on the AFE x 4 apparatus. The exercise stimulus elicited a peak HR of approximately 100 to 120 bpm in this patient. This HR response corresponds to 55% to 66% of the patient's age-predicted maximum HR, which, although somewhat low, is an appropriate exercise intensity for a considerably deconditioned individual.[7] This exercise intensity may actually have been relatively greater, because AFE x 4 exercise elicits a maximum HR approximately 20 bpm lower than that elicited by walking in persons without known impairments.[30] In addition, several studies[4,31,32] suggest that maximum HR may be blunted in patients with neurological impairment secondary to low oxidative capacity of paretic muscle, decreased number of recruitable motor units, or low overall endurance. Similar to the exercising HRs observed in this patient, a maximum HR of 121 to 126 bpm has been reported for patients with hemiparesis following a stroke during cycle ergometry exercise.[6,33,34] The patient's exercise intensity may have been relatively higher than that stated from the age-predicted maximum HR. The patient demonstrated a normal BP response during AFE x 4 exercise, his diastolic BP remained relatively constant, and his systolic BP increased in proportion to th exercise intensity.[7 to 9]

At the end of the exercise program, the patient exhibited several signs of improved exercise tolerance. His exercise duration increased by 12 minutes from beginning to end of the exercise program. Wolman et al[22] also found an increase in exercise duration following exercise training in patients with TBI. The patient's HR for a given submaximal workload (30 cycles per minute) was approximately 13 bpm lower following the 4 weeks of exercise training. These changes indicate potential central cardiac or peripheral skeletal muscle adaptations to the exercise training. The patient's resting HR was not lowered as much as would be expected with exercise training. Aerobic exercise training usually results in a lower resting HR,[8,9] which was not observed in this patient. Hunter et al[23] found a reduction in resting HR after exercise training in patients with TBI, but they used a 3-month training period. We did not note improvement in the patient's recovery HR 5 minutes after exercise. Some of the difficulty interpreting the patient's chronic adaptations to exercise training may be due to the daily variability in HR. Even though the exercise training took place at the same time of day and the vital signs were measured by the same physical therapist, often more than once during the exercise session, the variability in HR that was noted may have been due to the patient's inconsistent cigarette smoking and emotional stress. In addition, we speculate that more dramatic physiologic adaptations may have been seen with a longer training period (eg, 6-8 weeks).

In summary, the AFE x 4 mode of exercise was chosen as a component of this patient's exercise prescription, along with an appropriate frequency, duration, and intensity, because it had the potential to recruit a large muscle mass and it accommodated this patient's neurologic and orthopedic disorders. This mode of exercise produced an appropriate physiologic stimulus. Because it required a relatively simple movement pattern, the patient was able to successfully use the AFE x 4 apparatus for aerobic conditioning, despite his coordination deficits. He could safely mount and dismount and exercise on the AFE x 4 apparatus with little risk of falling. Furthermore, AFE x 4 exercise was an appealing mode to the patient, which may have increased his motivation. Lastly, AFE x 4 exercise provided the patient with a low-impact, reduced weight-bearing activity that he could perform with minimal right hip pain. Future studies are needed to evaluate the use of "nontraditional" modes of exercise for testing and training patients with chronic multisystem impairments.

(*) Exerhealth Inc, Salt Lake City, UT 84101. systolic BP increased in proportion to the exercise intensity.[7-9]

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TL Kinney LaPier, PT, is Assistant Professor, Department of Physical Therapy, Idaho State University, Campus Box 8002, Pocatello, ID 83209-8002 ([e-mail]). Address all correspondence to Ms Kinney LaPier.

N Sirotnak, PT, is Assistant Professor, Department of Physical Therapy, Idaho State University.

K Alexander, PT, OCS, is Assistant Professor, Department of Physical Therapy, Idaho State University.

This article was submitted January 14, 1997, and was accepted June 21, 1997