Oxandrolona e Propranolol em Pacientes Queimados

Propranolol and Oxandrolone Therapy Accelerated Muscle Recovery in Burned Children Tony Chao123 Craig Porter14 David N Herndon145 Aikaterina Siopi16 Henry Ideker17 Ronald P Mlcak5 Labros S Sidossis18 and Oscar E Suman145 1Metabolism Unit Shriners Hospitals for Children Galveston TX 2Division of Rehabilitation Sciences Department of Preventive Medicine and Community Health University of Texas Medical Branch Galveston TX 3Damage Control Resuscitation Task Area US Army Institute of Surgical Research Ft Sam Houston TX 4Department of Surgery University of Texas Medical Branch Galveston TX 5Wellness Center Shriners Hospital for Children Galveston TX 6School of Physical Education and Sport Science Aristotle University of Thessaloniki Thessaloniki Greece 7School of Medicine University of Texas Medical Branch Galveston TX 8Department of Kinesiology and Health Rutgers University New Brunswick NJ Abstract IntroductionSevere burns result in prolonged hypermetabolism and skeletal muscle catabolism Rehabilitative exercise training RET programs improved muscle mass and strength in severely burned children The combination of RET with βblockade or testosterone analogues showed improved exerciseinduced benefits on body composition and muscle function However the effect of RET combined with multiple drug therapy on muscle mass strength cardiorespiratory fitness and protein turnover are unknown In this placebocontrolled randomized trial we hypothesize that RET combined with oxandrolone and propranolol Oxprop will improve muscle mass and function and protein turnover in severely burned children compared to burned children undergoing the same RET with a placebo MethodsWe studied 42 severely burned children 7 17 years with severe burns over 30 of the total body surface area Patients were randomized to placebo 22 control or to Oxprop 20 and began drug administration within 96 hours of admission All patients began RET at hospital discharge as part of their standardized care Muscle strength Nm power W VO2peak body composition and protein fractional synthetic FSR and breakdown FBR rates were measured pre PRE and postRET POST Corresponding Author Tony Chao Metabolism Unit Shriners Hospitals for ChildrenGalveston 815 Market Street Galveston TX 77550 Tel 409 7706676 Fax 409 7706919 Email tochaoutmbedu Conflicts of Interest The authors have no conflicts of interests to declare HHS Public Access Author manuscript Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Published in final edited form as Med Sci Sports Exerc 2018 March 503 427435 doi101249MSS0000000000001459 Author Manuscript Author Manuscript Author Manuscript Author Manuscript ResultsMuscle strength and power lean body mass and VO2peak increased with RET in both groups p001 The increase in strength and power was significantly greater in Oxprop vs control p001 and strength and power was greater in Oxprop over control POST RET p005 FSR was significantly higher in Oxprop than control post RET p001 resulting in improved protein net balance POST RET p005 ConclusionRET improves body composition muscle function and cardiorespiratory fitness in children recovering from severe burns Oxprop therapy augments RETmediated improvements in muscle strength power and protein turnover Keywords Oxandrolone propranolol burns pediatric rehabilitation exercise Introduction Severe burns encompassing over 30 of the total body surface area TBSA result in acute critical illness associated with profound metabolic dysregulation 13 Increased proteolysis compounded by prolonged bed rest results in muscle cachexia and loss of function 46 Altered body composition and reduced function can persist for several years after burn injury 7 Indeed difficulty walking running feeling of weakness and fatigue have been reported in burn patients as much as 17 years post injury 8 underscoring the importance of finding therapeutic strategies that restore muscle mass and function in survivors of severe burn injury A structured rehabilitative exercise therapy RET program has been shown to be a safe and effective approach to rehabilitate burned patients 9 Those who participated in chronic resistive and aerobic exercise improved skeletal muscle strength increased lean body mass and improved joint range of motion 10 11 Exercise has also been shown to improve pulmonary function 12 and cardiorespiratory performance 13 in severely burned children The combination of RET with longterm drug therapy has also been studied as a strategy to hasten rehabilitation of massively burned individuals Oxandrolone is a testosterone analog that promotes lean body mass accretion and shorten the hospitalization period in severely burned individuals 1416 Interestingly when combined with RET oxandrolone therapy increased lean body mass LBM to a greater degree than in patients who exercised but did not take oxandrolone 17 The βadrenergic receptor blocker propranolol has been shown to be effective in reducing tachycardia and resting metabolic rate in burn patients 1821 Further propranolol also promotes the restoration of LBM in burned individuals by improving protein synthesis efficiency in the acute period post injury resulting in an improved protein net balance 19 22 Furthermore patients who were treated with propranolol during a RET program had a greater improvement in cardiorespiratory fitness than those who did not take propranolol 23 Collectively treatment with either oxandrolone or propranolol during an outpatient RET program has shown beneficial effects superior to RET alone in terms of restoring body muscle mass and function in severely burned children Oxandrolone treatment combined with exercise promoted lean body mass accretion above that of exercise alone but did not Chao et al Page 2 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript effect on cardiorespiratory function 17 Conversely propranolol treatment combined with exercise showed improved cardiorespiratory function above that of exercise alone but had no beneficial effects on muscle strength 23 The impact of the combined use of oxandrolone and propranolol with a hospitalbased outpatient RET program on muscle mass and function in severely burned children remains unknown We hypothesize that combined use oxandrolone and propranolol will augment the beneficial effects of outpatient RET on lean body mass strength and aerobic fitness in severely burned children To further progress burn care the purpose of this study is to determine the effects of oxandrolone and propranolol Oxprop treatment during a 6week RET program in severely burned children Methods and materials Patients This study was approved by the Institutional Review Board at the University of Texas Medical Branch and registered with clinicaltrialsgov NCT00675714 Written informed consent was obtained from the parents or legal guardians of severely burned children 7 17 years old with severe burns over 30 of the TBSA who were admitted to the Shriners Hospitals for Children Galveston between 2013 to 2016 All patients received standard acute burn care that included nutritional support guided by the patients injury characteristics and resting energy expenditure early wound excision and skin grafting as well as comprehensive antibiotics and analgesic therapy Patients who consented to this study were randomized into a control group receiving the standard of care and a placebo or the Oxprop group where they received the standard of care and oxandrolone and propranolol Administration of Oxprop drugs began within 96 hours after admission and continued through the course of their hospitalization period A metabolic study to determine protein turnover and DEXA scan were conducted within four days of the discharge date At hospital discharge all patients were enrolled into a 6week inhospital RET program Prior to commencing this RET program all patients underwent baseline PRE testing for strength peak torque and aerobic capacity VO2peak In our hospital RET has been a standard component of the outpatient rehabilitation of severely burned children over the age of 7 The control group participated in the standard 6week RET program while the Oxprop group participated in the 6week RET program and continued administration of oxandrolone and propranolol At the completion of the 6week RET program the same metabolic study DEXA scan and strength and aerobic capacity tests were repeated within five days to determine postexercise measurements POST Drug administration Oxandrolone was administered at 01 mgkg1 BTG Pharmaceuticals Iselin NJ twice a day during the patients entire stay in hospital and throughout the exercise training program Propranolol was administered at a dose of 033 mgkg1 of body weight every four hours 198 mgkg1day1 This dose was adjusted to achieve an approximate 20 decrease from admission heart rate for each patient Propranolol and oxandrolone administration began within 96 hours postadmission and continued through the acute hospitalization period and outpatient exercise program Chao et al Page 3 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Rehabilitative Exercise Training All subjects participated in a training program that was individualized to each patient in terms of frequency intensity duration and mode of exercise The training program included both resistive and aerobic components 9 13 24 25 All exercise sessions were supervised by an exercise specialist and followed the standards and guidelines set forth by the American College of Sports Medicine ACSM and the American Academy of Pediatrics 26 27 All patients in this study participated in a 6weeks rehabilitation exercise program that began within a week of hospital discharge Resistive exercise Eight different resistive exercises were used bench press squats shoulder press leg press biceps curl leg curl triceps extension and calf raises Training apparatus were modified to accommodate the injury characteristics of each patient All exercises were performed on resistance machines or utilized freeweights Subjects performed three sets of upper and lower body exercises with a twominute rest interval between each set Resistive exercise sessions were performed on nonconsecutive days No other organized strength training types of activities were permitted outside of the supervised session However there were no limitations on their normal daily activities Subjects were familiarized with the exercise equipment and taught proper techniques during the first week The intensity for the first week was set to target a maximal effort at 15 20 repetitions per set Intensity increased in their second week to achieve maximal effort at 8 12 repetitions per set which continued for the remaining sessions Adjustments in the load were made as applicable when the subject could consistently exceed 12 repetitions per set Aerobic exercise Aerobic exercise was performed on a treadmill rowing machine or cycle ergometer for approximately 20 45 minutes at least thrice weekly The intensity was set at 60 75 of their heart rate reserve HRR which was determined during a modified Bruce treadmill test 28 29 Each session started with a fiveminute warmup and subjects were asked for their rate of perceived exertion RPE on a 10point scale at 10 15 20 and 25 minutes into the exercise session Heart rate was monitored during the session using an Imara HRM wrist monitor Nike Beaverton OR The exercise intensity was adjusted according to the exercise heart rate and RPE Body composition LBM was quantified by Dual Emission XRay Absorptiometry DEXA images were analyzed with QDR 4500A software Hologics Waltham MA This method has a 2 3 margin of error for human body composition 30 Wholebody scans were performed per the manufacturers instructions Assessment of resting energy expenditure Resting energy expenditure REE of burned patients were determined by indirect calorimetry Sensor Medics Vmax 29 Yorba Linda CA REE was calculated from whole Chao et al Page 4 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript body oxygen consumption and carbon dioxide production rates using the Weir equation 31 This measured value was compared to the predicted REE predicted which was calculated using the HarrisBenedict equation 32 This is a standard method used by our group for estimating the degree of hypermetabolism in burned children Assessment of muscle protein turnover Skeletal muscle protein synthesis and breakdown were measured utilizing stable isotope tracers of phenylalanine Lring13C6 phenylalanine 99 enriched and L15N phenylalanine 99 enriched Cambridge Isotopes Cambridge MA 33 34 Briefly following a baseline blood draw bolus injections of stable isotope tracers were injected at time 0 and 30 minutes of the protocol Blood draws were taken periodically for one hour 33 Skeletal muscle biopsies were taken from the m vastus lateralis at 10 and 60 minutes following the injection of the first isotope bolus Muscle biopsies samples were snap frozen in liquid nitrogen and stored at 80C for future analysis Blood samples were centrifuged and plasma stored at 80C for future analysis Isotope enrichments were determined by gas chromatography mass spectrometry GCMS Skeletal muscle fractional synthesis FSR and breakdown FBR rates were calculated by the precursorproduct method 33 34 Assessment of cardiovascular exercise capacity Cardiovascular exercise capacity VO2peak test was performed utilizing a treadmill test modified Bruce Protocol 28 29 The rates of O2 uptake VO2 CO2 production VCO2 and minute ventilation VE were measured using the Medgraphic CardiO2 Combined O2ECG Exercise System St Paul Mn 11 Inspired and expired gas flow and volume were measured continuously through a hose attached to a facemask The treadmill speed was set at 17 mph at the start of the test with a 0 grade elevation Afterwards the speed and elevation increased every three minutes Subjects were constantly encouraged to give their maximal effort The test ended once volitional fatigue was achieved or the subject had an unwillingness to exercise further However the peak effort was based on an exercise heart rate above 190 bpm respiratory exchange ratio greater than 110 unsteady gait or a plateau in VO2 Assessment of muscle function Muscle strength test were performed using a Biodex dynamometer Shirley NY The isokinetic test was performed on the dominant leg and tested at an angular velocity of 150s 1 Patients were seated and stabilized with straps across the midthigh pelvis and trunk following the guidelines of the Biodex MultiJoint System 3 Testing and Rehabilitation System Users Guide The test administrator first demonstrated the test followed by an explanation to the subject followed by one practice set where the subject can be familiar with the movement without any load The subject was asked to perform 10 maximal voluntary muscle contractions at full knee flexion and extension without rest between each repetition A twominute rest period was given and the same test was performed for a second time Peak torque Newton meter Nm and average power Watts W was calculated using the Biodex Software System The highest value of the two trials was recorded Chao et al Page 5 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Statistical analysis All data are presented as group means SEM unless stated otherwise DAgostinoPearson omnibus normality test was conducted on each group data set Differences between group means were analyzed by unpaired ttests and differences within group means were analyzed by paired ttests Nonparametric analyses were conducted between and within groups on nonnormal datasets Statistical significance was reached when p005 Statistical analyses were performed using Graphpad Prism version 7 GraphPad Software La Jolla CA Results We consented 47 patients into the study n25 control and n22 Oxprop Five patients were lost due to noncompliance issues n3 control and n2 Oxprop We studied 42 severely burned pediatric patients n22 controls and n20 Oxprop PRE and POST RET There were sixteen males and six females in the placebo control group with sixteen males and four females the Oxprop group Age 11 3 vs 12 4 y p005 burn severity 47 12 vs 44 10 TBSA p005 and the total number of days they exercised 25 5 vs 27 3 days p005 were similar between control and Oxprop respectively No adverse events were reported as a result of this study Body composition All body mass and composition measures are shown in Table 1 Total body mass increased from PRE to POST in control 384 20 vs 405 22 kg p001 and Oxprop 446 29 vs 473 32 kg p 001 groups Lean mass also increased from PRE to POST in control 266 17 vs 284 17 kg p00 1 and Oxprop 300 19 vs 319 20 kg p001 groups Similarly BMI increased from PRE to POST in control 180 05 vs 191 05 kgm2 p001 and Oxprop 192 07 vs 210 08 kgm2 p005 groups Also BMI in Oxprop was greater than control PRE 180 05 vs 192 07 kgm2 p001 and POST RET 191 05 vs 210 08 kgm2 p005 We determined the LBM Index LBMI by calculating the total amount of lean mass kg divided by height m2 LBMI significantly improved from PRE to POST in control 123 03 vs 132 03 kgm2 p001 and Oxprop 137 04 vs 143 04 kgm2 p001 treated children Additionally LBMI in Oxprop was significantly greater than control at PRE 123 03 vs 137 04 kgm2 p005 and POST RET 132 03 vs 143 04 kgm2 p005 Lean mass as a percentage of total body mass was similar at PRE and POST timepoints in both groups The magnitude of change in total body mass LBM BMI or LBMI were also not different between control and Oxprop groups Resting energy expenditure We calculated the degree of hypermetabolism in patients as a ratio of calculated REE measured by respiratory gas exchange to predicted REE estimated by the HarrisBenedict equation REE differed significantly from PRE to POST RET in control 148 6 vs 122 7 predicted p001 and in Oxprop treated patients 121 6 vs 102 3 predicted p005 Fig 1A Furthermore Oxprop treated patients had a significantly lower REE than the control group at both PRE 148 6 vs 121 6 predicted p001 and POST 122 7 Chao et al Page 6 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript vs 102 3 predicted p001 timepoints The change in REE from PRE to POST was not different between groups Fig 1B Resting heart rate Resting heart rate RHR was reduced from PRE to POST in control 120 3 vs 110 3 bpm p005 and Oxprop 102 3 vs 92 4 bpm p005 groups Additionally RHR was significantly lower in the Oxprop group compared to control at both the PRE 120 3 vs 102 3 bpm p001 and POST 110 2 vs 92 4 bpm p0001 timepoints Fig 2A However the magnitude of change from PRE to POST were not significantly different between groups 9 3 vs 10 4 bpm p005 Fig 2B Muscle protein turnover FSR did not significantly change from PRE to POST in control 017 003 vs 007 001 h1 p005 or Oxprop treated patients 009 001 vs 011 009 h1 p005 FSR was not significantly different in control vs Oxprop at PRE 017 003 vs 009 001 h1 respectively p005 However FSR was significantly higher in the Oxprop vs control at POST 011 009 vs 007 001 h1 respectively p001 Fig 3A Control patients showed improvement in FBR from PRE to POST 035 006 vs 019 004 h1 p 005 FBR was not significantly changed in Oxprop from PRE to POST 014 001 vs 011 002 h1 p005 However FBR was significantly lower at PRE in Oxprop vs control 014 001 vs 035 006 h1 respectively p001 Fig 3B FBR tended to be lower in Oxprop vs control at POST 011 002 vs 019 004 h1 respectively p006 but it was not statistically significant Protein net balance was determined by subtracting FBR from FSR No improvement was found from PRE to POST in control 018 006 vs 012 004 h1 p005 or Oxprop 005 002 vs 001 003 h1 p005 Protein net balance was less negative in Oxprop group compared to the control group at the PRE 005 002 vs 018 006 h1 respectively p005 and POST RET 001 003 vs 012 004 h1 respectively p005 timepoints Fig 3C Cardiorespiratory fitness VO2peak significantly increased from PRE to POST in control 239 16 vs 298 14 mlkg1min1 p0001 and Oxprop 243 16 vs 310 17 mlkg1min1 p0001 groups No significant differences were found in the change of VO2peak 63 12 vs 71 12 mlkg1min1 p005 and no differences in absolute values were found between groups at PRE 239 16 vs 243 16 mlkg1min1 p005 and POST 298 14 vs 310 17 mlkg1min1 p005 timepoints Muscle strength Absolute muscle strength significantly improved from PRE to POST in control 359 37 vs 503 41 Nm p0001 and Oxprop 463 58 vs 698 71 Nm p0001 groups Fig 4A No significant differences in strength were seen between control and Oxprop at PRE 359 37 vs 463 58 Nm p005 but strength was significantly greater in Oxprop than control POST RET 503 41 vs 698 71 Nm p005 The change from PRE to POST was significantly greater in Oxprop vs control 223 20 vs 144 15 Nm Chao et al Page 7 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript respectively p001 Fig 4B Similar results were found when absolute strength was normalized to body weight Relative muscle strength improved from PRE to POST in both control 091 006 vs 122 004 Nmkg1 p0001 and Oxprop 099 008 vs 141 008 Nmkg1 p0001 No differences in relative or absolute strength were found between groups at PRE p005 but Oxprop treated patients had higher relative strength than control POST RET 141 008 vs 122 004 Nmkg1 respectively p 05 Fig 4C The improvement in relative strength with RET was significantly greater in Oxprop compared to control 031 003 vs 040 003 Nmkg1 p005 Fig 4D Muscle power Average muscle power significantly improved from PRE to POST in control 449 59 vs 616 55 W p0001 and Oxprop 581 76 vs 898 103 W p0001 Fig 5A There were no significant differences in average power at PRE between control and Oxprop 449 59 vs 581 76 W respectively p005 However power was significantly greater in Oxprop vs control POST RET 898 103 vs 616 55 W respectively p005 The magnitude of change was significantly greater in Oxprop vs control 167 21 vs 308 27 W p001 Fig 5B Discussion Severe burn injury results in an extreme pathophysiological stress response characterized by increased REE elevated HR and a marked loss of skeletal muscle mass and function 24 6 35 Severe muscle cachexia increases morbidity and mortality in burn survivors 36 37 Individuals with severe burns have reduced functional capacity long after their skin wounds have healed 7 Therefore it is imperative to develop new rehabilitation strategies that hasten the restoration of skeletal muscle mass and function following severe burns Our study shows for the first time that pharmacological treatment with the combination of oxandrolone and propranolol Oxprop augments the beneficial effects of outpatient exercise therapy in children recovering from severe burns This suggests that longterm therapy with Oxprop and exercise may hold value in improving outcomes in severely burned children In line with our previous observations propranolol and oxandrolone treatment blunt the hypermetabolic response to severe burns Specifically RHR and REE were significantly lower in the Oxprop group compared to control at PRE and POST exercise training While the effect of Oxprop on HR was undoubtedly the result of βblockade on the receptors on cardiomyocytes the decrease in REE may be mediated by both propranolol and oxandrolone since these drugs have both been shown to independently lower REE in severely burned children 18 19 38 We should note that the current study was not designed to test this hypothesis Our control and Oxprop treated groups showed significant improvement in body composition following RET Furthermore both groups exhibited significant improvement in functional performance in terms of absolute and relative strength and average power production The improvement seen in both groups after exercise supports the utility of RET in severely burned individuals Although we did not have a nonexercising group to compare the data and account for the effect of time as patients convalesce previous randomized Chao et al Page 8 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript studies suggest that improvements in muscle mass and strength in the first few months post burn injury are significantly augmented in patients who participate in an exercise program compared to those who do not 9 13 39 Although beneficial effects in body composition were seen in both control and Oxprop after RET changes in various parameters of body composition were largely not different between groups However BMI and LBMI were significantly higher in Oxprop than control at PRE and POST RET suggesting that Oxprop therapy may improve the maintenance of lean mass during their acute hospitalization period and through the duration of the study However we did not find significant differences in total or lean mass with the addition of Oxprop therapy with RET In a previous study oxandrolone and RET increased LBM in burned children to greater degree that in burned children receiving RET alone 17 In that particular study the placebo and nonexercise group showed no change in lean mass the placebo and exercise group had 58 increase in lean mass the oxandrolone with no exercise showed 54 increase in lean mass and the oxandrolone with exercise showed 131 increase in lean mass 17 Both of our groups showed a 68 and 63 increase in control and Oxprop respectively The increase in lean mass of our subjects appear to be greater than the group who had no exercise or oxandrolone but similar to the oxandrolone only group and placebo with exercise groups of the study by Przkora et al 17 However that exercise program persisted for 12weeks and was performed at six to ninemonths postinjury Since that study protocol was double the length of this exercise training program employed in the current protocol and was also performed at a later time frame postinjury it may offer an explanation for the reason we did not find a greater increase in lean mass in our Oxprop group over control We observed time and drug effect on skeletal muscle protein turnover There was a reduction in FSR in the control group which is in agreement with the previous findings of Hardee et al where FSR significantly decreased following 12 weeks of exercise training 13 Conversely our Oxprop group showed a significant increase in FSR following RET suggesting that it is Oxprop itself that promoted skeletal muscle synthesis in burn rehabilitation and not exercise Skeletal muscle FBR was greater in the control versus Oxprop group prior to RET FBR tended to decrease after RET in both groups although not statistically significant The trend in reduction of both FSR and FBR in our control group may indicate the reduction in overall protein turnover as a result of the gradual reduction in hypermetabolism and protein turnover associated with the longterm healing process 40 Perhaps of most importance protein net balance tended to improve ie become more positive in both groups Interestingly though protein net balance was significantly greater at both time points in the Oxprop group providing evidence of a nitrogen sparing effect of this treatment strategy in catabolic burned children The nitrogen sparing effect of Oxprop therapy appeared to be time dependent Prior to RET Oxprop had a pronounced impact on nitrogen balance by blunting the rates of muscle proteolysis FBR In contrast POST RET Oxprop arguably had a greater effect on improving nitrogen balance by increasing the FSR of new proteins As we discussed previously in the first few months post burn injury the FSR of muscle proteins is likely influenced by the elevated FBR which continuously saturates intracellular free pool of Chao et al Page 9 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript amino acids 33 However as muscle FBR declines in the months following burn injury this effect on muscle FSR is perhaps lost This may offer an explanation as to why Oxprop exerts an anticatabolic effect at the first study timepoint 20 days post injury and an anabolic effect at the second timepoint 106 days post injury Our protein turnover data suggests that the protein net balance in skeletal muscle is improved over time with RET and the addition of Oxprop therapy augments this improvement We did not find any differences in VO2peak in the Oxprop versus control group at PRE or POST RET nor was the improvement over time different between groups Previously data suggest that while oxandrolone does not augment RET mediated improvements in VO2peak in burned children 17 administration of propranolol during RET resulted in a greater improvement in VO2peak in burned children 36 increase in VO2peak when compared to children who underwent RET without propranolol 22 increase in VO2peak 23 It was speculated that this effect may be attributed to the reduced capillary blood flow allowing greater gas exchange in exercising muscles 23 Again the RET program in this study was 12weeks unlike the 6week RET program employed in the current study Further in a recent study comparing six vs twelve weeks of RET in burned children found that relative VO2peak in 12weeks trained patients was significantly greater than patients who participated in 6weeks exercise training 39 Thus although we found an improvement in cardiorespiratory fitness in both control 247 increase in VO2peak and Oxprop 276 increase in VO2peak treated patients in the current study it is conceivable that the differences in RET program duration training explain the discrepancy between our current data and our previously published work 23 Perhaps a significant difference in the amount of VO2peak increase between our control and Oxprop group might be found if the exercise period was doubled to 12weeks In the current study RET alone resulted in a significant improvement in absolute and relative muscle strength and average muscle power Previous work has shown that propranolol 23 or oxandrolone 17 administered during RET did not further improve muscle function when compared to RET alone In those previous studies they found that after 12weeks of exercise with oxandrolone muscle strength increased by 483 17 whereas strength increased by 50 when exercise was combined with propranolol 23 In our study we found that strength increased by 508 when the combination of oxandrolone and propranolol was utilized with exercise Again it should be noted that it is not an equal comparison with our current study and those referenced studies because they tested patients at approximately six to ninemonths postburn using a 12week RET program whereas we tested our patients approximately one month postburn using a 6week RET program However our current data suggests that combined treatment with oxandrolone and propranolol Oxprop augments the improvement in muscle function brought about by exercise over the current standard of care Further muscle function was subsequently greater in the Oxprop group compared to control after RET suggesting that functional capacity may be restored to a greater degree when Oxprop therapy is combined with exercise There are some limitations to our study First we did not have an oxandrolone alone and propranolol alone group We previously determined the individual effects of oxandrolone with exercise 17 and propranolol with exercise 23 With the resources that were available Chao et al Page 10 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript for this study it was only feasible to study the effects of combined use of Oxprop versus standard of care Therefore our approach in the current study was to compare a new treatment strategy oxandrolone propranolol early exercise versus the current standard of care early exercise only on clinical and functional outcomes Secondly our protein turnover analysis only provides a snapshot of the rates of protein synthesis and breakdown in the fasted state Also nutrition and physical activity were not directly monitored during the intervention Changes in weight and body composition can be influenced by diet Finally physical activity outside of exercise sessions was not quantified in the current study Despite these limitations our data show that in freeliving patients the combined treatment of oxandrolone and propranolol blunts hypermetabolism and augments the beneficial effect of a 6week RET program When undertaking this clinical trial standard burn care at our institution did not include propranolol or oxandrolone therapy Previously clinical trials have shown that propranolol attenuates hypermetabolism in burn patients 19 22 while improving aerobic exercise capacity in burned children when combined with exercise 23 Previous studies have also demonstrated an anabolic effect of oxandrolone on muscle mass following severe burns 16 as well as an additive effect in restoring muscle mass after burn injury when provided during a rehabilitative exercise regime 17 The novelty of this study was in demonstrating a beneficial effect of Oxprop therapy over standard of care in restoring body composition and function during a RET regime performed immediately after hospital discharge To summarize in agreement with previous studies 13 17 23 24 we show that and early outpatient exercise rehabilitation program improves body composition muscular function and cardiorespiratory fitness in burned children For the first time we show that the addition of Oxprop therapy with exercise further blunted hypermetabolism and improved skeletal muscle protein turnover in burned children Further in combination with a 6week RET program the addition of Oxprop treatment augmented RETinduced improvements in muscle mass and function in burned children Therefore combined longterm drug therapy with testosterone analogues and βblockers with exercise may be of benefit in hastening the rehabilitation of severely burned individuals Acknowledgments We would like to thank Clark Andersen for assisting us with the statistical analyses Ileanna Gutierrez Shauna Glover and Angie Agudelo for their work with the children in the Wellness Center Source of Funding The results of the present study do not constitute endorsement by ACSM The results of the study are presented clearly honestly and without fabrication falsification or inappropriate data manipulation This study was funded by the National Institutes of Health P50 GM060338 R01 GM56687 R01 HD049471 R01 AR049877 P30 AG024832 T32 GM008256 NIDILRR 90DP00430100 Shriners Hospitals for Children 84080 84090 71006 71009 85310 TC was supported in part by an appointment to the Postgraduate Research Participation Program at the US Army Institute of Surgical Research administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US Department of Energy and USAMRMC Chao et al Page 11 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript AS was funded by the Greek State Scholarships Foundation and the European Program Education and Lifelong Learning European Social Fund ESF NSRF 20072013 References 1 Williams FN Herndon DN Hawkins HK et al The leading causes of death after burn injury in a single pediatric burn center Critical Care 2009 136doi 101186cc8170 2 Jeschke MG Chinkes DL Finnerty CC et al Pathophysiologic response to severe burn injury Annals of Surgery 2008 2483387400 DOI 101097SLA0b013e3181856241 PubMed 18791359 3 Hart DW Wolf SE Mlcak R et al Persistence of muscle catabolism after severe burn Surgery 2000 12823129 DOI 101067msy2000108059 PubMed 10923010 4 Hart DW Wolf SE Chinkes DL et al Determinants of skeletal muscle catabolism after severe burn Annals of Surgery 2000 232445563 DOI 1010970000065820001000000001 PubMed 10998644 5 Ferrando AA Lane HW Stuart CA DavisStreet J Wolfe RR Prolonged bed rest decreases skeletal muscle and whole body protein synthesis American Journal of PhysiologyEndocrinology and Metabolism 1996 2704E627E33 6 Alloju SM Herndon DN McEntire SJ Suman OE Assessment of muscle function in severely burned children Burns 2008 3444529 DOI 101016jburns200710006 PubMed 18243565 7 StPierre DMM Choiniere M Forget R Garrel DR Muscle strength in individuals with healed burns Archives of Physical Medicine and Rehabilitation 1998 79215561 DOI 101016 s0003999398902921 PubMed 9473996 8 Holavanahalli RK Helm PA Kowalske KJ LongTerm Outcomes in Patients Surviving Large Burns The Musculoskeletal System Journal of Burn Care Research 2016 37424354 DOI 101097bcr0000000000000257 PubMed 26056761 9 Porter C Hardee JP Herndon DN Suman OE The Role of Exercise in the Rehabilitation of Patients with Severe Burns Exercise and Sport Sciences Reviews 2015 4313440 DOI 101249jes 0000000000000029 PubMed 25390300 10 Neugebauer CT Serghiou M Herndon DN Suman OE Effects of a 12Week Rehabilitation Program With Music Exercise Groups on Range of Motion in Young Children With Severe Burns Journal of Burn Care Research 2008 29693948 DOI 101097BCR 0b013e31818b9e0e PubMed 18849852 11 Suman OE Spies RJ Celis MM Mlcak RP Herndon DN Effects of a 12wk resistance exercise program on skeletal muscle strength in children with burn injuries Journal of Applied Physiology 2001 913116875 PubMed 11509512 12 Suman OE Mlcak RP Herndon DN Effect of exercise training on pulmonary function in children with thermal injury Journal of Burn Care Rehabilitation 2002 23428893 DOI 10109701bcr0000020443043896b PubMed 12142585 13 Hardee JP Porter C Sidossis LS et al Early Rehabilitative Exercise Training in the Recovery from Pediatric Burn Medicine and Science in Sports and Exercise 2014 46917106 DOI 101249 mss0000000000000296 PubMed 24824900 14 Wolf SE Edelman LS Kemalyan N et al Effects of oxandrolone on outcome measures in the severely burned A multicenter prospective randomized doubleblind trial Journal of Burn Care Research 2006 2721319 DOI 10109701bcr0000202620557514f PubMed 16566555 15 Wolf SE Thomas SJ Dasu MR et al Improved net protein balance lean mass and gene expression changes with oxandrolone treatment in the severely burned Annals of Surgery 2003 237680111 DOI 1010970000065820030600000008 PubMed 12796576 16 Hart DW Wolf SE Ramzy PI et al Anabolic effects of oxandrolone after severe burn Annals of Surgery 2001 233455664 DOI 1010970000065820010400000012 PubMed 11303139 17 Przkora R Herndon DN Suman OE The effects of oxandrolone and exercise on muscle mass and function in children with severe burns Pediatrics 2007 1191E109E16 DOI 101542peds 20061548 PubMed 17130281 Chao et al Page 12 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript 18 Baron PW Barrow RE Pierre EJ Herndon DN Prolonged use of propranolol safely decreases cardiac work in burned children The Journal of burn care rehabilitation 1997 1832237 DOI 1010970000463019970500000008 PubMed 9169945 19 Herndon DN Hart DW Wolf SE Chinkes DL Wolfe RR Reversal of catabolism by betablockade after severe burns New England Journal of Medicine 2001 3451712239 DOI 101056 NEJMoa010342 PubMed 11680441 20 Williams FN Herndon DN Kulp GA Jeschke MG Propranolol decreases cardiac work in a dose dependent manner in severely burned children Surgery 2011 14922319 DOI 101016jsurg 201005015 PubMed 20598332 21 Flores O Stockton K Roberts JA Muller MJ Paratz JD The efficacy and safety of adrenergic blockade after burn injury A systematic review and metaanalysis Journal of Trauma and Acute Care Surgery 2016 80114655 DOI 101097ta0000000000000887 PubMed 26517779 22 Herndon DN Rodriguez NA Diaz EC et al LongTerm Propranolol Use in Severely Burned Pediatric Patients A Randomized Controlled Study Annals of Surgery 2012 256340211 DOI 101097SLA0b013e318265427e PubMed 22895351 23 Porro LJ AlMousawi AM Williams F Herndon DN Mlcak RP Suman OE Effects of Propranolol and Exercise Training in Children with Severe Burns Journal of Pediatrics 2013 1624799doi 101016jjpeds201209015 PubMed 23084706 24 AlMousawi AM Williams FN Mlcak RP Jeschke MG Herndon DN Suman OE Effects of Exercise Training on Resting Energy Expenditure and Lean Mass During Pediatric Burn Rehabilitation Journal of Burn Care Research 2010 3134008 DOI 101097BCR 0b013e3181db5317 PubMed 20354445 25 Diego AM Serghiou M Padmanabha A Porro LJ Herndon DN Suman OE Exercise Training After Burn Injury A Survey of Practice Journal of Burn Care Research 2013 346E311E7 DOI 101097BCR0b013e3182839ae9 PubMed 23511288 26 Nelson MA Goldberg B Harris SS et al RISKS IN DISTANCE RUNNING FOR CHILDREN Pediatrics 1990 865799800 PubMed 2235238 27 Small EW McCambridge TM Benjamin HJ et al Strength training by children and adolescents Pediatrics 2008 121483540 DOI 101542peds20073790 PubMed 18381549 28 Cumming GR Everatt D Hastman L Bruce treadmill test in children normal values in a clinic population Am J Cardiol 1978 4116975 Epub 19780101 PubMed 623008 29 Bruce RA McDonough JR Stress testing in screening for cardiovascular disease Bull N Y Acad Med 1969 45121288305 Epub 19691201 PubMed 5261245 30 Haarbo J Gotfredsen A Hassager C Christiansen C Validation of bodycomposition by dual energy xray absorptiometry DEXA Clinical Physiology 1991 11433141 DOI 101111j 1475097X1991tb00662x PubMed 1914437 31 Weir JBD New methods for calculating metabolic rate with special reference to protein metabolism Journal of PhysiologyLondon 1949 1091219 32 Roza AM Shizgal HM The HarrisBenedict equation reevaluated resting energyrequirements and the body cell mass American Journal of Clinical Nutrition 1984 40116882 PubMed 6741850 33 Chao T Herndon DN Porter C et al SKELETAL MUSCLE PROTEIN BREAKDOWN REMAINS ELEVATED IN PEDIATRIC BURN SURVIVORS UP TO ONEYEAR POST INJURY Shock 2015 445397401 DOI 101097shk0000000000000454 PubMed 26263438 34 Zhang XJ Chinkes DL Wolfe RR Measurement of muscle protein fractional synthesis and breakdown rates from a pulse tracer injection American Journal of PhysiologyEndocrinology and Metabolism 2002 2834E753E64 DOI 101152ajpendo000532002 PubMed 12217893 35 Jeschke MG Gauglitz GG Kulp GA et al LongTerm Persistance of the Pathophysiologic Response to Severe Burn Injury Plos One 2011 67doi 101371journalpone0021245 36 Chang DW DeSanti L Demling RH Anticatabolic and anabolic strategies in critical illness A review of current treatment modalities Shock 1998 10315560 DOI 1010970002438219980900000001 PubMed 9744642 Chao et al Page 13 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript 37 Wolfe RR The underappreciated role of muscle in health and disease American Journal of Clinical Nutrition 2006 84347582 PubMed 16960159 38 Porro LJ Herndon DN Rodriguez NA et al FiveYear Outcomes after Oxandrolone Administration in Severely Burned Children A Randomized Clinical Trial of Safety and Efficacy Journal of the American College of Surgeons 2012 2144489502 DOI 101016jjamcollsurg 201112038 PubMed 22463890 39 Clayton RP Wurzer P Andersen CR Mlcak RP Herndon DN Suman OE Effects of different duration exercise programs in children with severe burns Burns 2016 Epub 20161203 doi 101016jburns201611004 40 Diaz EC Herndon DN Porter C Sidossis LS Suman OE Borsheim E Effects of pharmacological interventions on muscle protein synthesis and breakdown in recovery from burns Burns 2014 Epub 20141204 doi 101016jburns201410010 Chao et al Page 14 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Figure 1 Resting energy expenditure in control and Oxprop treated children with severe burns PRE and POST exercise training A Resting energy expenditure REE was measured by indirect calorimetry and compared to the predicted value by HarrisBenedict equation Change in REE B was determined by substracting POST REE from PRE p005 vs PRE p001 vs PRE p005 vs control p001 vs control Chao et al Page 15 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Figure 2 Resting heart rate in children with severe burns in control and Oxprop PRE and POST exercise A The change in resting heart rate was determined by the difference seen POST minus PRE B Bpm beats per minute p005 vs PRE p001 vs control Chao et al Page 16 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Figure 3 Skeletal muscle protein turnover in control and Oxprop treated children with severe burns PRE and POST 6weeks outpatient exercise training Protein synthesis A breakdown B and net balance C were measured utilizing stable isotope tracers of phenylalanine FSR fractional synthesis rate FBR fractional breakdown rate p005 vs PRE p005 vs control p001 vs control Chao et al Page 17 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Figure 4 Muscle strength in control and Oxprop treated patients PRE and POST 6weeks exercise training by absolute strength A or relative strength C The change in absolute strength B and relative strength D was calculated by subtracting PRE from POST measures p0001 vs PRE p005 vs control Chao et al Page 18 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Figure 5 Muscle power in control and Oxprop treated children with severe burns PRE and POST 6 weeks exercise training program A Change in strength was determined by subtracting PRE from POST measures B p 0001 vs PRE p 001 vs control Chao et al Page 19 Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01 Author Manuscript Author Manuscript Author Manuscript Author Manuscript Author Manuscript Author Manuscript Author Manuscript Author Manuscript Chao et al Page 20 Table 1 DEXA analysis Control n22 Oxprop n20 PRE POST PRE POST Total body mass kg 384 20 405 22 446 29 473 32 Lean mass kg 266 17 284 17 300 19 319 20 Lean mass 69 2 70 1 69 2 69 1 BMI 180 05 191 05 192 07 210 08 LBMI 123 03 132 03 137 04 143 04 Values are mean SE BMI Body mass index LBMI Lean body mass index p001 vs PRE p005 vs control Med Sci Sports Exerc Author manuscript available in PMC 2019 March 01