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RIGINAL ARTICLE

ugmented Exercise in the Treatment of Deconditioning Fromajor Burn Injury

arbara J. de Lateur, MD, Gina Magyar-Russell, PhD, Melissa G. Bresnick, BS, Faedra A. Bernier, MS,ichelle S. Ober, OTR, Brian J. Krabak, MD, Linda Ware, OTR, CHT, Michael P. Hayes, PhD,

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ABSTRACT. de Lateur BJ, Magyar-Russell G, BresnickG, Bernier FA, Ober MS, Krabak BJ, Ware L, Hayes MP,

auerbach JA. Augmented exercise in the treatment of de-onditioning from major burn injury. Arch Phys Med Re-abil 2007;88(12 Suppl 2):S18-23.

Objective: To investigate the efficacy of a 12-week exerciserogram in producing greater improvement in aerobic capacityn adult burn survivors, relative to usual care.

Design: Randomized, controlled, double-blinded trial.Setting: Burn center.Participants: A population-based sample of 35 adult pa-

ients admitted to a burn center for treatment of a serious burnnjury.

Intervention: A 12-week, 36-session, aerobic treadmillxercise program where work to quota (WTQ) participantsntensified their exercise according to preset quotas and work toolerance (WTT) participants continued to their tolerance. Par-icipants completed a maximal stress test at baseline and 12eeks to measure physical fitness.Main Outcome Measure: Maximal aerobic capacity.Results: The WTT and the WTQ exercise groups both made

ignificant improvements in aerobic capacity from baseline to2 weeks (t��3.60, P�.01; t��3.17, P�.01, respectively).he control group did not (t��1.39, P�.19). WTT and WTQarticipants demonstrated significantly greater improvementsn aerobic capacity in comparison to the control group mem-ers (F�4.6, P�.05). The WTT and WTQ groups did notiffer significantly from each other with regard to their respec-ive improvements in aerobic capacity (F�.014, P�.907).

Conclusions: The aerobic capacity of adult burn survivorsan be improved with participation in a structured, 12-weekxercise program after injury.

Key Words: Aerobic exercise; Burns; Cardiovascular de-onditioning; Exercise; Rehabilitation.

© 2007 by the American Congress of Rehabilitation Medicine

From the Departments of Physical Medicine and Rehabilitation (de Lateur, Ober,rabak, Ware), Psychiatry and Behavioral Sciences (Magyar-Russell, Bresnick,auerbach), and Orthopedic Surgery (Krabak), Johns Hopkins University School ofedicine, Baltimore, MD; General Clinical Research Center, Johns Hopkins Univer-

ity School of Medicine, Baltimore, MD (Bernier); and the Johns Hopkins Burnenter, Johns Hopkins Bayview Medical Center, Baltimore, MD (de Lateur, Magyar-ussell, Bresnick, Ober, Krabak, Ware, Hayes, Fauerbach).Supported by the National Institute on Disability and Rehabilitation Research,

ffice of Special Education and Rehabilitative Services, U.S. Department of Educa-ion (grant no. H133A020101) and the Community Fund, Johns Hopkins Burn Center.

No commercial party having a direct financial interest in the results of the researchupporting this article has or will confer a benefit upon the author(s) or upon anyrganization with which the author(s) is/are associated.Reprint requests to James A. Fauerbach, PhD, Johns Hopkins Bayview Medical

enter / Burn Center, 4940 Eastern Ave, Baltimore, MD 21224, e-mail:fauerba@jhmi.edu.

r0003-9993/07/8812S-11401$32.00/0doi:10.1016/j.apmr.2007.09.003

rch Phys Med Rehabil Vol 88, Suppl 2, December 2007

URVIVAL RATES AFTER severe burn injury have sig-nificantly improved in the past 2 decades.1,2 This progres-

ive decline in mortality has highlighted the importance ofhysical rehabilitation after burn injury to maximize the recov-ry of physical function. Typically, standard physical and oc-upational rehabilitation therapy targets the improvement ofvert physical changes associated with burn injury, such asncomfortable scarring, range of motion (ROM) limitations,nd contractures.3 A recent study4 found, however, that inde-endence in locomotion was the single variable that discrimi-ated between patients who went home after discharge fromhose who were discharged to another institution. Thus, factorsffecting locomotion, such as fatigue and muscle decondition-ng, are also important during the rehabilitation phase of burnecovery.

There are at least 2 major factors that contribute to muscleeconditioning after major burn injury: bedrest and catabolicrocesses that lead to muscle atrophy. A serious burn injuryesults in the greatest hypermetabolic response in comparisonith other physical traumas.5 This increased metabolic rate canersist until wound closure is achieved6 and perhaps for 6 to 9onths after wound closure.7 Prolonged states of hypermetab-

lism result in catabolic consequences that may not be recog-ized in the acute phase of the injury but can later causeignificant muscle wasting and deconditioning.

With the overall increase in survival rates from seriousurns, loss of lean body mass (LBM) and decreased aerobicapacity are being recognized as common sequelae of seriousurn injury that can impair wound healing, raise the risk ofnfection, and ultimately increase the likelihood of burn-asso-iated morbidity or mortality.8 In a recent investigation,9 peo-le with smaller burns did not differ with respect to muscletrength from a nonburned control group matched for age, sex,ody mass index, and physical activity level. People with burnsf 30% total-body surface area (TBSA) or larger producedignificantly less torque, work, and power in the quadricepshan control subjects. The ability to develop muscle power athe elbow was also compromised in subjects with severe burnnjuries.

Prevention and treatment of deconditioning and muscleasting are emerging as important areas for research in burn

ehabilitation. Exercise has been shown to counteract the mus-le-wasting effects of age and inactivity.10-12 A recent review13

f the evidence in burn rehabilitation did not find any publishedontrolled investigations of the effectiveness of aerobic exer-ise intervention in adult burn survivors. However, Celis14 anduman15 and colleagues have examined the effects of exercise

n children with thermal injury. Celis found that exercise andhysiotherapy programs significantly decreased the likelihoodf having to have surgery to release burn scar contractures, anduman reported a significant improvement in muscle strength,ower, and LBM relative to a standard rehabilitation programithout exercise. Hart et al8 further emphasized the need for

ehabilitation efforts to combat catabolism and concluded that

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S19AUGMENTED EXERCISE IN BURN INJURY, de Lateur

epsis and excessive hypermetabolism are associated with mus-le catabolism.

Fordyce et al16-21 observed that patients with chronic pain ofarious etiologies were often deconditioned and experienced pac-ng challenges during rehabilitation as they attempted to increasectivity levels. During periods of reduced pain, patients tended toverexert themselves physically and would then experience aubsequent increase in pain and an inability or unwillingness tongage in their usual levels of activity. In an effort to better helphronic pain patients through physical recovery, Fordyce and hiseam advise physical therapists to have patients perform a quan-ifiable activity (eg, walking laps) to their tolerance (work-to-olerance [WTT]) and then determine an individualized, gradual,uota increase based on their baseline performance (work-to-uota [WTQ]). Patients should then be instructed to perform onlyt quota. According to Fordyce, after the WTQ system is initiated,atients are more likely to progress without major setbacks fromncreased pain and to obtain positive reinforcement through theirradual increase in activity levels.16 Ehde et al22 adapted the quotaystem in a patient with severe burns who displayed signs ofassivity, learned helplessness, and depressive symptomatology,hich the authors proposed contributed to decreased participation

n physical therapies (ie, walking, ROM exercises, pressure gar-ent use, splint use). Their results suggest that quota-guided

xercise was successful in mitigating a sense of learned helpless-ess and in increasing that patient’s participation in rehabilitativeherapies. Similar to chronic pain patients, survivors of seriousurn injury often display symptoms of learned helplessness, de-onditioning, and rehabilitation challenges, yet the literature hasot compared the efficacy of WTT and WTQ exercise programsn improving adherence to therapies and, consequently, aerobicapacity in burn patients.

Our objective in this double-blinded, randomized, controlledrial was to test whether an early exercise intervention, com-ined with the usual and customary care, hastens aerobicapacity recovery in adults with major burn injuries. Thexercise intervention was a structured, 12-week program oferobic training designed to promote return to fitness, preventrolonged aerobic deconditioning, and compare the efficacy ofWTQ with a WTT program (both compared with a control

roup). The training was performed 3 times a week. Based onlinical research with chronic pain patients, we hypothesizedhat burn-injured patients on the WTQ schedule, relative toatients in the WTT group and the control group, wouldecover greater aerobic capacity because of the gradual andonsistent increase in aerobic training over the 12 weeks.

METHODS

articipantsParticipants were recruited from among adult patients admitted

o the Johns Hopkins Burn Center in Baltimore, from September999 to May 2006. Criteria for participation were that the patient1) sustained a burn injury serious enough to require hospitaliza-ion, (2) was at least 18 years of age, (3) was English-speaking,nd (4) had the capacity to undergo consent procedures as outlinedy the Johns Hopkins University Institutional Review Board.atients were excluded if they were unable to provide informedonsent because of cognitive impairment (eg, delirium, psychosis,ini-Mental State Examination score �23/30), or if they had had

ny cardiac insult within the past 6 months involving myocardialnfarction (MI), unstable angina, congestive heart failure, or pace-aker placement (American College of Sports Medicine [ACSM]

riteria for early termination of a stress test including acute MI,oderate-to-severe angina, drop in systolic blood pressure, seri-

us arrhythmias [second- or third-degree arteriovenous block, c

ustained ventricular ectopic beats], electrocardiographic changesrom baseline greater than 2mm ST depression or elevation, orncreasing chest pain).23 The number of eligible patients whoither were not approached for participation or chose not toarticipate was not recorded during the lengthy recruitment pe-iod.

tudy DesignSubjects were randomly assigned to 1 of 3 groups: standard

unctional restoration (SFR; control group), WTQ, or WTT. Aandomized sequence was generated by Excela (no restrictions)o ensure random allocation of participants. The sequence wasoncealed from consent-designee research staff using an elec-ronic password-protected document. A project instructorGM-R) generated and protected the randomized sequence;articipants were recruited and consented by the researchroject coordinator (MGB), and the instructor (GM-R) thenssigned participants to their groups according to the random-zed sequence. The SFR protocol is the standardized burnehabilitation protocol tailored to the needs of each patient athe Johns Hopkins Burn Center. It includes such therapies asOM, massage, splinting, stretching, strengthening, and func-

ional training for ambulation and activities of daily livingADLs). SFR group participants underwent maximal aerobicapacity (V̇O2max) stress tests at baseline and at 12 weeks.dditionally, these participants were examined biweekly

hroughout the intervention by a physical or occupational ther-pist, who measured quadriceps and hamstring strength, pinchnd grip strength, active ROM at all affected burn joints, andelf-selected walking speed. Participants and a supervisinghysician (BJD) who assessed the outcomes of the stress testsere blinded to group assignments.All participants received SFR; participants in the WTQ andTT were required to augment their usual care by adhering totreadmill ambulation schedule. After the baseline cardiovas-

ular stress test, subjects in the WTT and WTQ groups partic-pated in treadmill exercise sessions 3 times a week throughouthe 12-week protocol. Participants’ target exercise heart ratesere calculated according to their age-predicted maximal heart

ate and their maximal stress heart rate, which was recordeduring the initial stress test. The target exercise heart rate wasalculated as 60% of the participant’s heart rate reserve (max-mal exertion). WTQ participants gradually intensified theirxercise program by increasing their target exercise heart ratend time according to preset quotas, whereas WTT participantsere instructed to tolerate the aerobic exercise at their targeteart rate for as long as possible. All exercise sessions wereapped at 30 minutes.

xercise TestingMaximal aerobic capacity (V̇O2max) tests were conducted at

he Johns Hopkins Bayview General Clinical Research Cen-er’s Exercise and Body Composition Lab. The testing processas explained to the subjects on their arrival for each test. Arief medical history and resting 12-lead electrocardiographere reviewed before they were permitted to begin the test.We used a modified BRUCE protocol24 at each assessment.

he BRUCE protocol is accepted by ACSM23 as standard proce-ure for ambulatory stress testing and is based on the seminalork of cardiologist Robert Bruce in the early 1970s.23 Theodified workload began at 2.7km (1.7mph), 0% grade and was

ncreased every 3 minutes at 1.7 mph to 5% grade and 1.7 mph,0% grade before the conventional BRUCE protocol was begun.e used this multistage protocol because of the limited functional

apacity of burn survivors; it does not expose subjects to large and

Arch Phys Med Rehabil Vol 88, Suppl 2, December 2007

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S20 AUGMENTED EXERCISE IN BURN INJURY, de Lateur

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nequal increments in workload.23 A 30-second sample of restingases was collected before subjects began the 30-second warm-uperiod at 1.6km (1.0mph). Blood pressure measurements wereaken with a manual mercury sphygmomanometer every 3 min-tes, concurrent with the end of each stage. Electrocardiographicnd heart rate activity were continually monitored throughout theest. Subjects graded their overall body exertion using the Borgatings of perceived exertion scale25 at the end of each stage of therotocol.

The subjects were given verbal encouragement during the test.hey were instructed to exercise until they reached a level ofaximal overall body fatigue. To facilitate a true measurement of

heir maximal exercise capacity, they were discouraged fromeaning on the treadmill’s handrails. The test continued until theatient was exhausted, or until there were apparent indications forerminating the test.23 Heart rate, blood pressure, and electrocar-iographic activity were monitored during exercise and recoveryntil they returned close to resting levels.

The primary outcome measure of aerobic capacity was the

RAND

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rch Phys Med Rehabil Vol 88, Suppl 2, December 2007

nd oxygen uptake (V̇O2), carbon dioxide production (V̇CO2),nd respiratory quotient were measured using the SensorMed-cs Vmax 229 metabolic system.b V̇O2max was calculated byveraging the computer-selected “peak zone,” which was theast 30 seconds of the final stage. The anaerobic threshold wasetermined using the V-slope technique,26 which is a compo-ent of the Vmax 229 software. These results were then con-rmed by graphs that plotted V̇CO2 as a function of V̇O2. Thislot created 2 lines intersecting where metabolic acidosis oc-urs, determining the V̇O2max.

RESULTS

escriptive DataSample characteristics. The total sample included 35 par-

icipants who completed all 12 weeks of the exercise program,s indicated by baseline and postintervention cardiovasculartress tests. Figure 1 illustrates the flow of participants throughach stage of the study. The average number of days � stan-

ZED (N=58)

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S21AUGMENTED EXERCISE IN BURN INJURY, de Lateur

tart of their participation in the study was 37.5�23.3 (range,�122). There were no significant differences in sex (Pearson2 test�1.79, P�.41), age (t�1.26, P�.21), employment sta-

us (Pearson �2 test�3.40, P�.33), type of burn injury (Pear-on �2 test�6.2, P�.29), or TBSA burned (t��.99, P�.33).lso, there were no significant differences between participantsho completed the study protocol (completers; n�35/58

60%]) and participants who agreed to participate but did notomplete the protocol (noncompleters; n�23/58 [40%]). Sex,ge, type of burn injury, average TBSA, and employmenttatus for completers are presented in table 1. Among theompleters, there were no significant differences in TBSAF�.24, P�.79), type of burn injury (Pearson �2 test�4.90,�.557), age (F�1.26, P�.30), or weight (F�.94, P�.40)etween treatment groups at baseline. Group differences in sexere not significant (Pearson �2 test�4.76, P�.09).

reatment EffectsPhysiologic characteristics. Tables 2 and 3 show the sample

nd group averages for physiologic variables collected duringhe baseline and post-test cardiovascular stress tests. Thereere no significant differences at baseline between groupembers in weight (F�.87, P�.43), resting heart rate (F�.34,�.72), maximum heart rate (F�1.95, P�.16), and absolute

˙ O2 (F�.68, P�.51). Likewise, there were no significant dif-erences between groups at the 12-week post-test in weightF�.20, P�.82), resting heart rate (F�.25, P�.78), maximumeart rate (F�.31, P�.73), and absolute V̇O2 (F�.07, P�.93).

Within-group effects. Over the course of the exercise pro-ram (from baseline to post-test assessment periods), WTQt��3.60, P�.01) and WTT (t��3.17, P�.01) groups dis-layed significant improvement in aerobic capacity, as mea-

Table 1: Group Dem

Group NMean Age � SD

(y)Sex

(% male)

All groups 35 38.0�13.3 74

SFR 11 34.9�14.5 82

WTT � SFR 11 43.5�8.9 91

WTQ � SFR 13 35.4�14.8 54

Table 2: Baseline Gro

Group NMean Weight � SD

(kg)

Mean RestHeart Rate �

(bpm)

All groups 35 82.2�20.4 85.3�15SFR 11 88.0�20.9 84.6�15WTT � SFR 11 82.9�17.2 88.5�15WTQ � SFR 13 76.6�22.5 83.1�16

Based on 34 participants.Based on 12 participants.

ured by V̇O2max. The SFR group did not show significantmprovement in aerobic capacity (t��1.39, P�.19) (fig 2).

Between-group effects. WTQ and WTT participants dem-nstrated significantly greater improvements in aerobic capac-ty, as measured by V̇O2max, in comparison with the SFRroup (F�4.6, P�.05). The WTQ and WTT group members’mprovements in aerobic capacity did not differ significantlyrom each other (F�.014, P�.907).

DISCUSSIONThis study demonstrates for the first time in adult burn

atients that aerobic conditioning in combination with standardunctional restoration therapy is superior to standard functionalestoration alone. Although the 2 experimental exercise treat-ent groups appeared slightly less fit than the control group at

aseline, this difference was not statistically significant. Addi-ionally, both groups taking part in the experimental exercisereatment improved dramatically during the study, crossingver the line of progression of the SFR group, which did nothow significant improvement in aerobic capacity.

Aerobic capacity is an important aspect of burn rehabilita-ion. By participating in the treadmill-walking program, the

TT and WTQ subjects significantly increased their V̇O2max.hus, burn survivors who participate in a regular exercise

outine are more likely to realize health-related benefits such asmproved flexibility, balance, stamina, and musculartrength,27 all of which are crucial in returning to an active andndependent lifestyle. Physical activity has several additionalotential benefits, such as decreased anxiety and depressionnd enhanced feelings of well-being27 resulting from the re-ease of endorphins secreted during muscular activity, as wells through other mechanisms.

phic Characteristics

Mean TBSA � SD(%)

Burn Type(% of population)

PercentageEmployed atTime of Burn

19.3�15.7 Flame: 60 77Scald: 28Electrical: 9Chemical: 3

21.6�19.4 Flame: 73 64Scald: 27

16.8�9.8 Flame: 46 73Scald: 36Electrical: 9Chemical: 9

19.5�17.2 Flame: 62 92Scald: 23Electrical: 15

tress Test Statistics

Mean MaximumHeart Rate � SD

(bpm)Mean

V̇O2max � SD Absolute V̇O2

163.2�22.1 21.7�7.0 1809.0�687.5*167.6�20.9 23.2�8.6 1993.7�865.3152.5�24.3 21.2�5.8 1787.4�611.8168.5�19.5 20.8�6.7 1659.5�581.2†

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Results of this study suggest that without aerobic exercise,econditioned burn survivors will not achieve the same gains inerobic capacity as patients who participate in an exercise-raining program. Moreover, a decrease in cardiorespiratorytness is a health-related concern for all people, whether or not

hey have a major burn injury; low levels of fitness are asso-iated with a markedly increased risk of premature death fromny number of causes, but specifically from cardiovascularisease.28 Additionally, when movement and exercise are lim-ted, ROM can be diminished, which often causes muscular andoint contractures and a decrease in quality of life among burnurvivors.

The fact that WTT and WTQ groups did not differ from eachther after training suggests that the quotas may have been setoo conservatively (ie, too low) for the WTQ subjects, or thathe subjects in the WTT group may have exerted themselvesore than was anticipated a priori. We set the quotas conser-

atively because of concerns expressed by institutional reviewommittees that vigorous exercise might aggravate the hyper-etabolic state of these patients. Additionally, it is reasonable

o be concerned that temperature regulation might be problem-tic in patients with burn injuries (hence limiting the utility ofn aerobic exercise program). McEntire et al29 found, however,hat exercise at moderate intensities conducted for 20 minutest room temperature was safe in children with up to 75% ofBSA burns. Similarly, in this study there was no evidence thatxercise was unsafe for participants during protocol trainingessions or during maximal stress testing. Specifically, if aer-bic training exacerbated hypermetabolism, it would be ex-

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Table 3: Group Stress

Group NMean Weight � SD

(kg)

Mean ResHeart Rate

(bpm)

All groups 35 85.8�23.6 79.8�14SFR 11 89.6�30.3 77.5�9.WTT � SFR 11 86.1�17.9 80.9�15WTQ � SFR 13 82.5�22.9 80.9�18

Based on 34 participants.Based on 12 participants.

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rch Phys Med Rehabil Vol 88, Suppl 2, December 2007

ected that chest discomfort, shortness of breath, or palpita-ions would have resulted in either the participant or thehysician stopping the exercise session early. Chest pain, dys-nea, and tachycardia were not limiting factors in the stressests, however. To the contrary, and perhaps not surprisinglyiven the muscle wasting and deconditioning in these patients,eg discomfort or leg muscle fatigue were the most commonimiting factors. It should be noted that for safety purposes, ahysician (BJD or BJK) was present throughout every tread-ill test.

tudy LimitationsLimitations of this study include the relatively small total

ample size. The findings were so robust, however, that weelieve concerns about the sample size are partially negated.nother concern is that patients with burns of all sizes and

everity were permitted to participate. Again, however, theffect sizes were robust even among subjects with smaller andess severe burns who were likely to have lost less muscle massnd aerobic capacity during hospitalization. This suggests thathe exercise programs may have even more relevance foreople with more serious burn injuries (eg, burns involvingore than 30% of TBSA, inhalational injury, amputations).nother potential limitation is that subjects were recruited fromnly 1 regional burn center, thereby limiting generalizability.A final concern is the disproportionate manner in which

esults may have been affected by sex differences in groupembership. Recent evidence suggests that women and men

enerally differ in their metabolic responses to incrementalxercise,30 and that sex differences in pulmonary function andxercise capacity limit aerobic capacity and exercise tolerancen women.31 Such findings suggest that in future investigations,t would be reasonable to control for potential confounders bytratifying the treatment groups according to sex during ran-omization.

CONCLUSIONSOur results show that a moderate, 30-minute treadmill walk-

ng program performed 3 times a week for 12 weeks, whetheratient-limited or experimenter-limited, combined with cus-omary postburn care, significantly improves aerobic fitness,hereas customary care alone does not. Important directions

or further research include conducting trials with greater num-ers of participants and more intensive exercise protocols thatllow for comparison of the effectiveness of differing exerciserograms for adult burn survivors. It is also important tonvestigate alternative therapies that might achieve the sameenefits. For instance, in a placebo-controlled, randomized trialith severely burned children, the administration of growthormone from hospital discharge to 12 months postburn sig-ificantly improved the height, weight, LBM, bone mineral

t Statistics Post-Test

Mean MaximumHeart Rate � SD

(bpm)Mean

V̇O2max � SD Absolute V̇O2

168.4�17.6 25.7�6.1 2215.3�647.7*171.2�18.6 24.7�7.3 2215.1�750.6165.2�17.9 26.5�4.3 2269.3.4�533.6168.9�17.3 25.8�6.6 2166.0�694.3†

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S23AUGMENTED EXERCISE IN BURN INJURY, de Lateur

reatment group compared with children who received a pla-ebo.32 Future research should attempt to replicate these resultsith adults to discern whether the effects are generalizable to

n adult burn population. Another avenue for investigation isn analysis of the relation between aerobic capacity and burn-pecific functional outcomes, such as the ability to return torevious employment, perform ADLs, live independently, andegulate body temperature. Finally, clinical implications fromhis study suggest that rehabilitation professionals should con-ider including aerobic training in physical therapy regimens torovide patients with unique physiologic benefits in recoveringrom burn injury.

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Arch Phys Med Rehabil Vol 88, Suppl 2, December 2007