Balance, Body Motion, and Muscle Activity After High-Volume Short-Term Dance-Based Rehabilitation in Persons With Parkinson Disease: A Pilot Study

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1 RESEARCH ARTICLES Blnce, Body Motion, nd Muscle Activity After High-Volume Short-Term Dnce-Bsed Rehbilittion in Persons With Prkinson Disese: A Pilot Study J. Lucs McKy, PhD, MSCR, Len H. Ting, PhD, nd Mdeleine E. Hckney, PhD Bckground nd Purpose: The objectives of this pilot study were to (1) evlute the fesibility nd investigte the efficcy of 3-week, high-volume (45 minutes per week) Adpted Tngo intervention for community-dwelling individuls with mild-moderte Prkinson disese (PD) nd (2) investigte the potentil efficcy of Adpted Tngo in modifying electromyogrphic (EMG) ctivity nd center of body mss (CoM) displcement during utomtic posturl responses to support surfce perturbtions. Methods: Individuls with PD (n = 26) were recruited for highvolume Adpted Tngo (15 lessons, 1.5 hour ech over 3 weeks). Twenty prticipnts were ssessed with clinicl blnce nd git mesures before nd fter the intervention. Nine prticipnts were lso ssessed with support-surfce trnsltion perturbtions. Results: Overll dherence to the intervention ws 77%. At posttest, pek forwrd CoM displcement ws reduced (4. ±.9 cm, pretest, vs 3.7 ± 1.1 cm, posttest; P =.3; Cohen s d =.3) nd correlted to improvements on Berg Blnce Scle (ρ =.68; P =.4) nd Dynmic Git Index (ρ =.75; P =.3). Overll ntgonist onset time ws delyed (27 ms; P =.2; d =.9) nd durtion ws reduced (56 ms, 39%, P =.2; d =.45). Reductions in EMG mgnitude were lso observed (P <.5). Discussion nd Conclusions: Following prticiption in Adpted Tngo, chnges in kinemtic nd some EMG mesures of perturbtion responses were observed in ddition to improvements in clinicl mesures. We conclude tht 3-week, high-volume Adpted Tngo is fesible nd represents vible lterntive to longer durtion dpted dnce progrms. The Wllce H. Coulter Deprtment of Biomedicl Engineering, Emory University, nd the Georgi Institute of Technology (J.L.M., L.H.T.), Atlnt VA Center of Excellence for Visul & Neurocognitive Rehbilittion (M.E.H.), nd Deprtment of Medicine, Division of Generl Medicine nd Geritrics, Emory University School of Medicine (M.E.H.), Atlnt, GA. None of the uthors hve potentil conflicts of interest to be disclosed. This work hs been previously published in n bstrct form t the Interntionl Society for Posture nd Git Reserch. Supplementl digitl content is vilble for this rticle. Direct URL cittion ppers in the printed text nd is provided in the HTML nd PDF versions of this rticle on the journl s Web site ( Correspondence: J. Lucs McKy, PhD, MSCR, Emory Rehbilittion Hospitl, Room R154, 1441 Clifton Rd, Atlnt, GA 3322 (j.lucs.mcky@ emory.edu). Copyright C 216 Acdemy of Neurologic Physicl Therpy, APTA. ISSN: /16/ DOI: 1.197/NPT.15 Video Abstrct vilble for more insights from the uthors (see Supplementl Digitl Content 1, Key words: dnce therpy, electromyogrphy, exercise therpy, humn movement system, posturl blnce (JNPT 216;4: ) INTRODUCTION Blnce problems re common in Prkinson disese (PD) nd re chllenging to tret. 1,2 Improvements on clinicl mesures of blnce nd git hve been demonstrted fter severl rehbilittive exercise progrms for individuls with PD, 3-6 including Adpted Tngo dnce. 7,8 Adpted Tngo elicits cliniclly mesured blnce improvements tht re superior to exercise, 9 nonprtnered dnce, 7 other dnce-bsed nd mrtil rts bsed interventions, 1,11 no intervention, 8,11 nd helth eduction. 12 Recently, the importnce of rehbilittion volume hs received incresed ttention. 13,14 In PD, high-volume rehbilittion my be prticulrly effective, s individuls exhibit superior increses in git speed fter highervolume/low-intensity exercise therpy (12 weeks, 15 minutes per week, 4%-5% of hert rte reserve) compred with lower-volume/high-intensity exercise therpy (12 weeks, 9 minutes per week, 7%-8% of hert rte reserve) with comprble overll work. 14 Furthermore, exercise therpy of t lest 18 minutes per week is required to improve git speed in older dults. 15 Recently, 45 minutes per week hs been demonstrted to be the upper threshold of exercise volume (ie, the sweet spot) required for lowered mortlity risk (by 39%), compred with sedentry older dults. 16 Previously, individuls with PD demonstrted functionl improvements fter 2 weeks of high-volume (45 minutes per week) Adpted Tngo trining. 17 Although these improvements re promising, it is unknown if longer-term therpy (ie, 3 weeks) with similr volume is fesible nd possibly more effective. Also, it is unknown whether clinicl chnges fter Adpted Tngo re ssocited with ltertions in responses to posturl perturbtions ssessed in lbortory setting, common prdigm in humn neurophysiology reserch Previous studies in popultions other thn PD suggest tht improvements in clinicl mesures of blnce fter rehbilittion my be ssocited with improved kinemtic nd electromyogrphic (EMG) mesures during blnce nd git For exmple, 3 weeks of high-volume JNPT Volume 4, October

2 McKy et l JNPT Volume 4, October 216 (45 minutes per week) Ti Chi trining dvnced gonist muscle ctivtion onset times nd reduced co-contrction in response to support-surfce perturbtions during wlking in mildly blnce-impired older dults whose blnce hd only slightly improved, s mesured by 2-point increse on the Berg Blnce Scle (BBS). 22 In individuls with poststroke hemipresis, gility exercise therpy (1 weeks, 18 minutes per week) improved git speed, nd reduced muscle ctivtion onset times in response to support-surfce perturbtions during stnding. 23 Locomotor rehbilittion lso improved timing of nkle plntr flexors during git in hemipretic individuls (12 weeks, 12 minutes per week). 24 However, it is unknown whether chnges in clinicl mesures fter Adpted Tngo, dnce-bsed rehbilittion, which my ddress PD impirments through different mechnisms thn Ti Chi nd gility exercise, 25 would be ssocited with chnges in muscle ctivity or kinemtic mesures during posturl responses. Electromyogrphic nd kinemtic bnormlities during responses to support surfce trnsltion perturbtions in PD 18,2 differ from those of older dults 22 nd stroke survivors. 23,24 During trnsltion perturbtions of the support surfce, the center of mss (CoM) is displced nd medium- ( 8 ms) nd long-ltency ( 1 ms) corrective responses re generted in leg nd trunk muscles, referred to s the utomtic posturl response. 19 Unlike the delyed responses in blnceimpired older dults 22 nd in individuls with poststroke hemipresis, 23,24 in individuls with PD, utomtic posturl response onset ltency is typiclly norml or erlier thn norml in gonist muscles 18 nd typiclly erlier thn norml in ntgonist muscles, leding to inpproprite co-contrction. 18,2 Prkinson disese is lso ssocited with incresed totl CoM displcement during perturbtion responses. 26 We initited this investigtion becuse, to the best of our knowledge, no studies hve exmined chnges in posturl responses in PD before nd fter Adpted Tngo. The primry objectives of this pilot study were to determine the fesibility nd investigte the efficcy of 3 weeks of high-volume (45 minutes per week) Adpted Tngo in improving clinicl mesures of blnce nd git in communitydwelling individuls with PD. We performed repetedmesures observtionl study of high-volume Adpted Tngo with durtion incresed to 3 weeks to estimte dherence nd investigte efficcy. We predicted tht (1) 3-week high-volume Adpted Tngo would be fesible for individuls with mildmoderte PD, s demonstrted by dherence with 95% confidence intervl lower bound of 6% or more, (2) clinicl mesures of blnce nd disese severity would improve from pretest to posttest nd be retined for t lest 1 month, on the bsis of results from previous studies demonstrting retention for 2 months, 8,12 nd (3) clinicl mesures would be stble over 1 month before pretest, when tested in subset of prticipnts. The secondry, explortory objectives of this pilot study were to evlute posturl responses before nd fter Adpted Tngo to exmine the fesibility of nd utility of using kinemtic nd EMG outcome mesures in this type of intervention. We llocted convenience smple of intervention prticipnts to receive dditionl perturbtion response testing t pretest nd posttest. Muscle onset time mesurements hve been demonstrted to be stble cross multiple dys in helthy young individuls 27 nd cross multiple months in individuls with PD. 28 Thus, we determined tht we would consider rndomized tril to be fesible nd justified if we obtined preliminry efficcy evidence, s determined by reductions in CoM displcement or in ntgonist muscle onset time, durtion, or mgnitude. To further investigte preliminry evidence of efficcy, we lso exmined ssocitions between chnges in clinicl mesures nd chnges in CoM displcement or in muscle ctivity mesures fter Adpted Tngo. METHODS Study Design This study ws repeted-mesures, observtionl study without control group. A double bseline procedure ws employed to improve internl vlidity of clinicl outcomes. Multiple posttest periods were used to ssess stbility of observed chnges in clinicl outcome mesures. A convenience smple of study prticipnts ws llocted to dditionl perturbtion testing before nd fter the intervention. Prticipnts nd Setting Prticipnts were recruited t PD outrech events, senior centers, nd the Emory Movement Disorders clinic. Prticipnts met the following inclusion criteri: Hoehn & Yhr stges I-IV, dignosis of definite idiopthic PD, 29 ge 35 yers or greter. Exclusion criteri were deep brin stimultion, other significnt comorbidities, or significnt musculoskeletl impirment s determined by the investigtors. Prticipnts were observed for outcome mesures on 3 seprte occsions. All prticipnts were ssessed within 1 week before (pretest) nd within 1 week fter (posttest) the intervention. Prticipnts recruited erly in the tril (n = 7) were ssessed 1 month before the beginning of the intervention (1-month pretest) to estblish double bseline for these prticipnts nd exmine stbility of clinicl mesures. Prticipnts recruited lter in the tril (n = 13) were observed in follow-up ppointment, 1 month fter the intervention s cesstion (1-month post). The double bseline ws conducted to exmine the stbility of mesures between 1-month pretest nd pretest: time period ( 1 month) tht ws similr to the intervention time period of 3 weeks. The 1-month posttest (follow-up) ws used to detect retention (or loss) of chnges between posttest nd 1-month posttest lso over period of time tht ws similr to the interventionl time period. Adpted Tngo clsses nd clinicl ssessments were performed in lrge multipurpose room on university cmpus. Perturbtion response ssessments were performed in dedicted blnce lbortory elsewhere on cmpus. Prticipnts provided written informed consent ccording to protocols pproved by institutionl review bords t Emory University nd the Georgi Institute of Technology. Three-Week High-Volume Adpted Tngo Intervention Prticipnts received high-volume, moderte-intensity Adpted Tngo, tught by professionl dnce instructor, 3 nd were to complete fifteen 9-minute Adpted Tngo sessions in 3 weeks. Clsses were designed to induce expenditure of 3 or more metbolic equivlents of tsk (METs) per minute, 258 C 216 Acdemy of Neurologic Physicl Therpy, APTA

3 JNPT Volume 4, October 216 Blnce fter Dnce Rehbilittion s per estimtes for typicl bllroom dnce, which is considered light- to moderte-intensity exercise by the US Centers for Disese Control nd Prevention. 31 Clsses begn with stnding wrm-ups to upbet music nd continued with dncing to commercil music selections. Prticipnts spent equl time leding nd following dnce steps, performed in n dpted bllroom frme, holding forerms, nd clsses were progressive. (See Video Abstrct, Supplementl Digitl Content 1, for n exmple of the dpted bllroom frme.) Individuls with PD were coupled with individuls without PD. Prticipnts spent one third of clss working on rhythmic entrinment to the bet during the wrm-ups, such s tpping of toes or heels, or sequentilly opening nd closing the hnds. Furthermore, the prticipnts spent mple time (ie, 2-3 minutes) simply wlking to vrious tngo rhythms intended to enhnce their musiclity, tht is, the bility to control the git cycle in more complex rhythm thn typicl git. As in previous studies, 7,9,1,12 prticipnts were llowed to tke breks s needed throughout the clsses to decrese ftigue. Outcome Mesures Clinicl Blnce nd Git Mesures Assessments were dministered in the sme order t ech evlution to minimize the effects of ftigue on mesurements. Prticipnts were ssessed for generl helth nd were observed t ech visit with clinicl mesures including Prkinson disese severity (Unified Prkinson Disese Rting Scle [UPDRS] motor subscle III 32 ), dyskinesi (totl of scores -4 for ech limb nd fce), the BBS 33, Dynmic Git Index (DGI 34 ), Fullerton Advnced Blnce Scle (FAB 35,36 ), the 2-footed Jump test, test of neuromusculr synergies nd musculoskeletl helth, 37 6-minute wlk test (6MWT 38 ), functionl rech (FR 39 ), Single/Dul Timed Up nd Go (TUG 34 ), fst nd preferred git speed, nd cdence were mesured using stopwtch over 2 pth. 4 The Activities-Specific Blnce Confidence questionnire (ABC 41 ) nd the Freezing of Git questionnire (FOG 42 ) were lso dministered. Fullerton Advnced Blnce Scle ws recently vlidted in community-dwelling individuls with PD 36 nd ws used to void BBS ceiling effects. For ech prticipnt, ll ssessments occurred t stndrdized time of dy coinciding with selfdetermined optiml ON period to minimize phrmcologiclly relted motor fluctutions. Clinicl blnce nd git mesures were performed by n experienced rehbilittion scientist or by trined reserch ssistnts. An experienced rehbilittion scientist certified by the Movement Disorders Society dministered the UPDRS-III. To minimize the vribility of individul UPDRS items, including the retropulsion test, 43 the sme rehbilittion scientist dministered the exmintion t ech observtion. Clinicl dt were entered nd cross-verified by reserch ssistnts. Response to Perturbtion A convenience smple of the study prticipnts ws llocted to receive dditionl perturbtion response ssessments within 2 weeks before (pretest) nd within 2 weeks fter (posttest) the intervention. These prticipnts were ssessed t stndrdized time of dy (either 9 AM or 1 PM) coinciding s closely s possibly to the prticipnts self-determined ON time. While wering sfety hrness, prticipnts stood with ech foot on 6-xis (3D ground-rection forces nd moments) force plte (OR6-6; AMTI, Wtertown, Msschusetts) embedded in custom perturbtion pltform tht trnslted in the horizontl plne. They were instructed to cross their rms over their chest, to focus on lndscpe scene 3 m hed, nd to mintin blnce with their feet in plce but to tke protective steps if necessry. Three perturbtions were induced in ech of the forwrd (displcing the CoM nterior towrd the toes) nd bckwrd (displcing the CoM posterior towrd the heels) directions of body swy. 19 These perturbtions were induced within set of 36 perturbtions spnning ll directions in the horizontl plne nd delivered in rndom order. At pretest, 3 to 6 test perturbtions were delivered to select the highest perturbtion level ech prticipnt could mintin blnce without stepping. These perturbtions were excluded from nlysis to control for strtle effects. 44 Prticipnts PR7 nd PR9 ( PR designtes Perturbtion Response ) used level 4 (pek displcement 1 cm; pek velocity /s; pek ccelertion.2 g; 7-ms totl durtion); ll others used level 3 (7.5 cm; 15 cm/s;.1 g; 7 ms). Self-selected stnce width ws mesured t pretest nd subsequently enforced t posttest. (See Video Abstrct, Supplementl Digitl Content 1, for the video of the perturbtion pprtus.) Pltform kinemtics, surfce EMG, nd ground-rection forces were smpled t 18 Hz nd processed in Mtlb (The MthWorks, Ntick, Msschusetts). Trils with stepping responses or rm movement were excluded from nlysis. Ground rection forces were low-pss filtered (1 Hz, thirdorder zero-lg Butterworth filter), nd CoM ccelertion in the medil-lterl nd nterior-posterior directions ws clculted by dding horizontl-plne ground rection force components t ech foot nd dividing by prticipnt mss (ccelertion = force/mss). 19,45,46 Becuse estimtes of CoM position from kinemtic mrker dt were unrelible, we then integrted the ccelertion twice, ssuming zero initil velocity nd zero initil displcement t the onset of the perturbtion, to rrive t the displcement of the CoM Liner trends were removed from ccelertion signls before integrtion to void introducing integrtion constnts in velocity signls, nd computed velocity nd displcement signls were set to zero t perturbtion onset to enforce the ssumed initil conditions. Surfce EMG (Konigsberg Instruments, Psden, Cliforni) ws collected from leg nd trunk muscles, high-pss filtered (35 Hz, third-order zero-lg Butterworth filter), demened, rectified, nd low-pss filtered (4 Hz). 48,52,53 EMG ws nlyzed from nkle muscles tibilis nterior (TA) nd medil gstrocnemius (MG), recorded bilterlly. 22,54 During bckwrd swy, gonist TA is lengthened nd ntgonist MG is shortened. During forwrd swy, gonist MG is lengthened nd ntgonist TA is shortened. To minimize vribility in electrode plcement between pretest nd posttest, silver/silver chloride disc electrodes were plced t 2-cm interelectrode distnce ccording to stndrd EMG electrode plcement guidelines 19,55 by the sme experimenter t ech ssessment. Electromyogrphic records from ech tril were normlized to the mximum vlue observed during ech ssessment fter verging cross similr trils nd cross 5-ms bins. C 216 Acdemy of Neurologic Physicl Therpy, APTA 259

4 McKy et l JNPT Volume 4, October 216 Before sttisticl nlysis, computed CoM displcement signls in the nterior-posterior direction nd normlized EMG signls from ech recorded muscle were verged cross similr trils for ech prticipnt t ech ssessment. The pek of ech verge CoM displcement signl ws clculted. Onset nd offset times of ech verge EMG signl were clculted with computer progrm nd corrected s necessry (14 records, 11%). For ech verge EMG signl, the first smple within window between 8 nd 3 ms fter perturbtion onset to cross threshold of M + 6 SD ws first identified. Onset time ws then determined s the lst smple prior to the threshold-crossing smple for which the preceding 1 smples were ll less thn M + 2 SD. Offset time ws determined s the first smple subsequent to the thresholdcrossing smple for which the following 1 smples were ll less thn M + 2 SD. To void including responses to pltform decelertion, 54 offset times were truncted to the erlier of 28 ms fter EMG onset or 45 ms fter perturbtion onset. The durtion of ech verge EMG signl ws clculted s offset time onset time. The mgnitude of ech verge EMG signl ws clculted by verging over window 8 to 45 ms fter perturbtion onset fter removing bckground level. 18,2 After ll processing, kinemtic nd EMG dt of ech prticipnt were summrized s dt set contining 13 vribles (CoM displcement, 1 vrible, nd 3 vribles [Onset, Durtion, nd Mgnitude] for ech of the 4 muscles nlyzed [TA from the left nd right leg nd MG from the left nd right leg], for totl of 13 vribles) for ech level of the independent vribles Time [pretest, posttest], Perturbtion Direction [forwrd, bckwrd], nd Perturbtion Level [3, 4]). Smple Size Smple size for the intervention (n = 26) ws selected to chieve effect sizes in clinicl blnce nd git mesures comprble with previous 2-week intervention (conducted with n = 14) 17 fter llowing for pproximtely 4% ttrition, given the longer term of the intervention. Smple size for the group of prticipnts llocted to posturl response testing (n = 1) ws selected on the bsis of previous literture demonstrting the fesibility of identifying effects of interest in EMG nd kinemtic mesurements of individuls with PD in cross-sectionl 56 nd longitudinl 57 studies. Sttisticl Anlyses Descriptive Anlyses nd Effect Sizes Descriptive sttistics were clculted for ll outcomes t ech time point. Mgnitude effect sizes representing chnges from pretest to posttest were clculted with Cohen s d, 58 which describes the difference in mens scled to units of stndrd devition, in this cse tken from pretest. Smpling nd Stbility of Clinicl Mesures t Pretest To test tht prticipnts llocted to perturbtion response testing represented n unbised smple of the study popultion, bseline demogrphic chrcteristics were compred between perturbtion response prticipnts nd the rest of the study prticipnts with 1-wy nlyses of vrince (ANOVAs) (Group [lloction to perturbtion response testing vs nonlloction to perturbtion response testing]) or Kruskl- Wllis 1-wy ANOVAs on rnks for nonprmetric dt. To estblish test-retest stbility of clinicl blnce nd git mesures in this cohort, intrclss correltion coefficients were clculted between 1-month pretest (screening) nd pretest. Intrclss correltion coefficient vlues more thn.75 nd more thn.4 were chrcterized s excellent nd fir to good, respectively. Sttisticl Anlyses of Chnges in Clinicl Mesures Across Pretest, Posttest, nd Follow-up To investigte the efficcy of the intervention in improving clinicl mesures of blnce nd git, repeted-mesures ANOVAs (time [pretest, posttest, follow-up]), with Holms- Sidk post hoc tests determined significnce of chnges in clinicl mesures between pretest, posttest, nd follow-up. Greenhouse-Geisser corrections to degrees of freedom were pplied when sphericity ws violted s per Muchly s Test. The lst observtion ws crried forwrd in cses of missing dt. Additionl pired t tests on individul UPDRS-III items nd on verge tremor score (the verge of the scores of items III.2 nd III.21; cf 59 ) were performed post hoc to identify items tht chnged from pretest to posttest. Sttisticl Anlyses of Chnges in Posturl Responses From Pretest to Posttest To investigte the potentil efficcy of the intervention in ltering CoM displcement nd muscle ctivity during perturbtion responses, seprte repeted-mesures ANOVAs (time [pretest, posttest], with perturbtion level [3, 4] included s covrite) were initilly run. Perturbtion level ws entered s covrite in these nlyses to control for the potentil effects of perturbtion level on CoM displcement nd muscle ctivity demonstrted in previous studies. 19,27 No sttisticl testing of differences between perturbtion levels 3 nd 4 ws performed. These ANOVAs determined the significnce of chnges in pek CoM displcement nd in onset time, durtion, nd mgnitude of ech recorded muscle (TA-L, TA-R, MG-L, MG-R) in ech perturbtion direction. Chnges in Posturl Responses Bsed on Pooled EMG Dt Secondry univrite ANOVAs were lso conducted on EMG vribles onset time, durtion, nd mgnitude fter recoding dt from individul muscles s either TA or MG, or s gonist or ntgonist. In these nlyses: (1) Dt from TA-L nd TA-R were pooled for nlysis s TA, nd dt from MG-L nd MG-R were pooled for nlysis s MG. Secondry ANOVAs (time [pretest, posttest] perturbtion level [3, 4] prticipnt [1-9]; with prticipnt s nested fctor within perturbtion level, nd Time Prticipnt interction term) were then conducted to determine significnce of chnges in onset time, durtion, nd mgnitude of TA nd MG in ech perturbtion direction. (2) Dt from MG during forwrd CoM perturbtions nd from TA during bckwrd CoM perturbtions were pooled for nlysis s gonists, nd dt from TA during forwrd CoM perturbtions nd from MG during bckwrd CoM perturbtions were pooled for nlysis s 26 C 216 Acdemy of Neurologic Physicl Therpy, APTA

5 JNPT Volume 4, October 216 Blnce fter Dnce Rehbilittion ntgonists. Secondry ANOVAs (time [pretest, posttest] perturbtion level [3, 4] prticipnt [1-9]; with prticipnt s nested fctor within perturbtion level, nd Time Prticipnt interction term) were then conducted to determine significnce of chnges in onset time, durtion, nd mgnitude of gonists nd ntgonists. Associtions Between Chnges in Clinicl Mesures nd Chnges in Posturl Responses To test whether improvements in clinicl mesures of blnce function fter Adpted Tngo were ssocited with ltertions in perturbtion responses nd to detect possible evidence of efficcy of the intervention in ltering CoM displcement nd muscle ctivity during perturbtion responses, ssocitions between chnges on BBS, FAB, nd DGI nd chnges in perturbtion response mesures were determined with Spermn correltion coefficients in complete cse nlysis. Sttisticl nlyses were performed using IBM SPSS 2 softwre (IBM Corp., Armonk, New York) nd SAS University Edition 9.2 (SAS Institute, Inc., Cry, North Crolin). All tests were performed with 2 tils nd considered significnt t P <.5. Summry sttistics re reported s M ± SD unless otherwise noted. RESULTS Prticipnt Flow nd Recruitment A flow chrt of prticipnts through the study is presented in Figure 1. Twenty-six prticipnts were recruited for the tril. Of these, 4 withdrew before pretest ssessment (fmily/helth issues, n = 1; lck of interest, n = 1; loss of contct/unknown, n = 1). These individuls were excluded from nlyses of outcome mesures s no dt were vilble, but they were included in estimtes of dherence to the intervention. Of the remining 22 prticipnts, 2 prticipnts withdrew before posttest (fmily/helth issues, n = 1; scheduling difficulties, n = 1); ll others completed ll plnned ssessments. Adherence to the intervention exceeded previously expected trgets (2/26 observed vs 15/26 expected), providing evidence tht 3-week high-volume Adpted Tngo is fesible. Overll dherence to the intervention ws 77%, with 95% confidence intervl (CI: 61%-93%). Adherence ws higher mong those who ttended t lest 1 clss (91% [95% CI: 78%-1%]). Posttest nd 1-month posttest dt were un- ENROLLMENT ALLOCATION FOLLOW-UP ANALYSIS Figure 1. the study. Allocted to perturbtion response testing (n=9) Withdrew during intervention (n=) Anlyzed (n=9) Assessed for eligibility (n=26) Withdrew before pretest (n=4) Fmily / helth issues (n=1) Lck of interest (n=1) Unknown (n=2) Allocted to Adpted Tngo (n=22) Not llocted to perturbtion response testing (n=13) Withdrew during intervention (n=2) Fmily / helth issues (n=1) Scheduling difficulties (n=1) Anlyzed (n=13) Digrm depicting flow of prticipnts through vilble for prticipnts who withdrew before posttest (n = 2). One-month posttest dt were not collected for those (n = 7) llocted to 1-month pretest (screening) ssessments. Prticipnts who completed t lest 1 clinicl ssessment were invited to prticipte in posturl response ssessments until the Adpted Tngo intervention begn nd enrollment for dditionl testing ws closed. Nine prticipnts were enrolled in posturl response testing. Demogrphic chrcteristics of the 22 prticipnts included in the finl nlysis (68% femle, 65.4 ± 12.8 yers) re summrized in Tble 1. Detiled chrcteristics of the 9 prticipnts llocted to dditionl posturl response testing re summrized in Tble 2. During the study, no dverse events or devitions from the intervention were observed. Two smll devitions from the perturbtion response ssessment protocol occurred. In one prticipnt (PR1), self-selected stnce width ws not correctly enforced. This prticipnt used 9.5-cm wider stnce width t posttest. These dt were retined in nlyses s stnce width minimlly ffects forwrd nd bckwrd perturbtions. 18 Becuse of equipment filure, only MG recorded from the right leg (MG-R) ws vilble t posttest for prticipnts PR4, PR5, nd PR6. Adpted Tngo clsses nd ll ssessments were conducted from August through October 211. Bseline Dt At pretest, no significnt effects of group (llocted to perturbtion response testing vs not llocted to perturbtion response testing) were identified in ge, sex, height, weight, disese durtion, UPDRS-III, Hoehn nd Yhr stge, or dyskinesi score. Correltionl nlyses showed very strong correltions between FAB nd BBS (r =.81; P <.1) nd between FAB nd DGI (r =.87; P <.1). Test-retest nlyses demonstrted tht clinicl mesures were stble over the month before tretment, with excellent intrclss correltion coefficient vlues (>.75) obtined for BBS (.93), DGI (.9), FR (.79), ABC (.94), nd FOG (.88) nd intrclss correltion coefficients chrcterized s fir to good (>.4) obtined for 6MWT (.6). Clinicl Mesures Descriptive sttistics, chnge scores, nd effect sizes for ll clinicl mesures re tbulted in Tble 3. At posttest, scores incresed on BBS (P <.1), FAB (P <.1), nd DGI (P =.1) (Figure 2). All significnt increses t posttest remined significnt t 1-month posttesting in post hoc tests (BBS, P <.1; FAB, P <.1; DGI, P =.4). Prticipnts lso incresed preferred nd fst cdence (preferred, P <.1; fst, P =.3) nd exhibited decresed UPDRS-III (motor subscle) totl scores (P <.1) from pretest to follow-up. Pired t tests performed post hoc on individul UPDRS-III items identified significnt improvements on posturl stbility (item III.3;.95 ±.58, pretest, vs.6 ±.68, posttest, M ± SD, P =.3), nd speech (item III.1; 1.18 ±.73, pretest vs 1. ±.79, posttest; P =.2). No chnges were observed on 6MWT (P =.11), FR (P =.48), ABC (P =.22), FOG (P =.38), git speed (preferred, P =.69; fst, P =.18), Jump (P =.6), or TUG (P =.3). C 216 Acdemy of Neurologic Physicl Therpy, APTA 261

6 McKy et l JNPT Volume 4, October 216 Tble 1. Vrible Chrcteristics of Prticipnts in the 3-Week High-Volume Adpted Tngo Rehbilittive Intervention All Prticipnts (n = 22) Prticipnts Allocted to Receive Perturbtion Response Testing (n = 9) Prticipnts Not Allocted to Receive Perturbtion Response Testing (n = 13) Age (M ± SD), y 65.4 ± ± ± Sex, n (%).65 Mle 7 (32%) 2 (22%) 5 (38%) Femle 15 (68%) 7 (78%) 8 (62%) Height (M ± SD), m 1.72 ± ± ±.12.6 Weight (M ± SD), kg 74.3 ± ± ± PD durtion (M ± SD), y 6.1 ± ± ± UPDRS III, M ± SD 3.4 ± ± ± H&Y,n(%).83 Stge1.5 1(4%) (%) 1(8%) Stge 2 12 (55%) 5 (56%) 7 (54%) Stge (18%) 1 (11%) 3 (23%) Stge 3 5 (23%) 3 (33%) 2 (15%) Dyskinesi score (M ± SD) 1.8 ± 2.5 b 2.1 ± 2.5 c 1.6 ± 2.5 d.65 Tremor score (M ± SD).4 ±.4.5 ±.7.3 ±.2.32 Abbrevitions: H & Y, modified Hoehn nd Yhr stge; PD, Prkinson disese; UPDRS III, Unified Prkinson s Disese Rting Scle Motor Subscle III. P vlues re from independent-smples t tests for continuous vribles or Fisher exct tests for ctegoricl vribles compring prticipnts llocted to receive perturbtion response testing with those not llocted to receive perturbtion response testing. b n = 19. c n = 7. d n = 12. P Tble 2. Detiled Chrcteristics of Prticipnts in the 3-Week High-Volume Adpted Tngo Rehbilittive Intervention Allocted to Receive Perturbtion Response Testing Prticipnt Age, y Sex Height, m Weight, kg PD Durtion, y UPDRS III (/18) H & Y Dysk (/2) Medictions PR1 68 M C/L, Ent., Rop. PR2 79 M C/L, Am. PR3 64 M C/L, Ent. PR4 81 M C/L, Ent., Rs. PR5 74 M C/L PR6 73 F C/L, Rs. PR7 36 M C/L PR8 81 F C/L, Rop. PR9 56 M C/L Abbrevitions: Am., mntdine; C/L, crbidop/levodop; Dysk, dyskinesi score; Ent., entcpone; H & Y, modified Hoehn nd Yhr stge; PD, Prkinson disese; Rs., Rsgiline; Rop., ropinirole; UPDRS III, Unified Prkinson s Disese Rting Scle Motor Subscle III. Posturl Responses Chnges in Posturl Responses From Pretest to Posttest Descriptive sttistics nd effect sizes for kinemtic nd individul EMG mesures re tbulted in Tble 4. At posttest, CoM displcement ws reduced during forwrd CoM perturbtions (P =.3) nd unchnged during bckwrd CoM perturbtions (P =.39) (Figure 3). Initil nlyses of individul muscles reveled significnt reductions in TA-L mgnitude (P =.2) nd MG-R mgnitude (P =.1) during forwrd CoM perturbtions nd no sttisticlly significnt chnges in onset, durtion, or mgnitude of ny individul muscles during bckwrd CoM perturbtions. Secondry Anlyses Using Pooled EMG Dt Descriptive sttistics nd effect sizes for pooled EMG mesures re tbulted in Tble 5. Secondry nlyses of EMG dt pooled cross legs reveled significnt delys in TA onset time (forwrd CoM perturbtions, P =.4; bckwrd, P =.3), TA durtion (forwrd, P =.2), nd MG onset time (bckwrd, P <.1). Secondry nlyses of EMG dt pooled cross legs nd cross perturbtion directions reveled significnt delys in ntgonist onset time (27 ms; P =.2), gonist onset time (1 ms, P <.5), nd significnt reduction in ntgonist durtion (56 ms, 39%, P =.2). Associtions Between Clinicl Chnges nd Chnges in Posturl Perturbtions Significnt correltions were identified between reductions in forwrd CoM displcement nd incresed BBS scores (ρ =.68; P =.4) nd DGI (ρ =.75; P =.3). No significnt correltions were identified between incresed BBS scores nd delyed ntgonist onset times (ρ =.78; P =.7), between reductions in forwrd CoM displcement nd incresed FAB scores (ρ =.49; P =.19), or between chnges in bckwrd CoM displcement nd improvements in BBS (ρ =.37; P =.33), FAB (ρ =.52; P =.15), or DGI (ρ =.21; P =.62). DISCUSSION The low ttrition observed here (2 of 22 prticipnts who begn the intervention) nd improvements observed in these individuls with mild-moderte PD on clinicl mesures of blnce, git, nd disese severity fter 3-week, high-volume 262 C 216 Acdemy of Neurologic Physicl Therpy, APTA

7 JNPT Volume 4, October 216 Blnce fter Dnce Rehbilittion Tble 3. Men Vlues (±SD) of Clinicl Mesures of Blnce nd Git Before nd After the 3-Week, High-Volume Adpted Tngo Rehbilittive Intervention Pretest (n = 2) Posttest (n = 2) Follow-up (n = 13) Chnge Scores (n = 2) Effect Size PD severity UPDRS-III (/18) b 3.4 ± ± ± 5.6 c 2.9 ± 5.4 d.47 Dyskinesi 1.7 ± 2.1 (n = 18) 1.3 ± ± ± 1.8 (n = 16).14 FOGB 5.2 ± ± ± 4.9 (n = 14).3 ± Sttic nd dynmic blnce BBS (/56) b 49.3 ± ± 3.5 c 54.4 ± 1.7 c 3.8 ± 4.2 e.59 FAB (/4) b 27.1 ± ± 5.3 c 31.6 ± 7.4 (n = 12) c 3.7 ± DGI (/24) b 19.1 ± ± 2.1 (n = 19) c 2.9 ± 2.6 (n = 12) c 1.8 ± 2.4 (n = 19) f.53 FR, m.3 ±.7.32 ±.7.3 ±.7.1 ±.6.14 ABC (/1) 77. ± 23. (n = 21) 79.6 ± ± 16.4 (n = 14) 2.9 ± 12.6 (n = 19).12 TUG, s 9.3 ± ± ± 3.6 (n = 12) 1. ± TUG cognitive, s 12.6 ± ± ± 6. (n = 12) 1.4 ± TUG mnul, s 11.3 ± ± ± 3.8 (n = 12).6 ± Two-Footed Jump, m.5 ±.39.6 ±.37 (n = 19).66 ±.47 (n = 12).9 ±.19 (n = 19).23 Git 6MWT, m ± ± ± 93.2 (n = 12) 32.4 ± 83. g.37 Preferred git speed, m/s 1.19 ± ± ±.19 (n = 12).2 ±.19 h.1 Preferred cdence, steps/min b 19.6 ± ± ± 8.1 (n = 12) c 6.1 ± Fst git speed, m/s 1.67 ± ± ±.31 (n = 12).9 ± Fst cdence, steps/min b ± 16.4 (n = 21) ± ± 15.4 (n = 12) c 7.6 ± 11.8 (n = 19).47 Abbrevitions: ABC, Activities-specific Blnce Confidence Scle; BBS, Berg Blnce Scle; DGI, Dynmic Git Index; FAB, Fullerton Advnced Blnce Scle; 6MWT, Six-Minute Wlk Test; FOGB, Freezing of Git questionnire B; FR, Functionl Rech; TUG, Timed Up nd Go test; UPDRS, Unified Prkinson s Disese Rting Scle. Vlues re shown s M ± SD t ech time point. Effect sizes (Cohen s d) re clculted s difference in mens between posttest nd pretest divided by stndrd devition t pretest. b Min effect of time (P <.5), repeted-mesures ANOVA with Holms-Sidk post hoc tests. c Significntly different from pretest. The lst observtion ws crried forwrd in cses of missing dt. d-h Where vilble, Miniml Cliniclly-Importnt Differences (MCIDs) re noted. d MCID = 2.5 points. 6 e MCID (estimted from blnce-impired older dults) = 7 points, 61 Miniml Detectble Chnge (estimted from PD) = 5 points. 62 f MCID (estimted from community-dwelling older dults) = 1.9 points. 63 g MCID (estimted from geritric individuls nd stroke survivors) = 47 m. 64 h MCID (estimted from geritric individuls nd stroke survivors) =.1 m/s Pre Pre UPDRS Post Follow up FAB Post Follow up Pre Pre BBS Post Follow up DGI Post Follow up Figure 2. Clinicl mesures of blnce nd git before nd fter the intervention. BBS, Berg Blnce Scle; DGI, Dynmic Git Index; FAB, Fullerton Advnced Blnce Scle; UPDRS, Unified Prkinson s Disese Rting Scle, motor subscle III. Brs nd error brs indicte M ± SD. The lst observtion ws crried forwrd in cses of missing dt. All mesures shown exhibited min effect of time (P <.5) in repetedmesures ANOVA. Superscript indictors ( ) indicte significnt differences from pretest determined with Holms-Sidk post hoc tests, P <.5. Adpted Tngo demonstrte tht the progrm volume is fesible nd my hve efficcy comprble with longer progrms with similr totl doses. This pilot study is the first to mesure utomtic posturl responses before nd fter Adpted Tngo. In convenience smple of the study prticipnts, we observed reductions in forwrd CoM displcement nd chnges in some mesures of EMG mgnitude nd timing fter Adpted Tngo. On the bsis of this, we consider subsequent rndomized Adpted Tngo tril with kinemtic nd EMG outcome mesures to be fesible nd justified. Benefits nd Fesibility of High-Volume Exercise in Persons With PD High-volume exercise (>18 minutes per week) is necessry to improve older dults git speed. 15 We observed overll dherence to the high-volume intervention of 77%, with 95% confidence intervl 61% to 93%, chieving the stted primry fesibility criterion of 6% nd demonstrting tht 3-week, high-volume Adpted Tngo is fesible in this popultion. After the intervention, we observed improvements in mesures of disese severity nd blnce (chnges: UPDRS, 2.9; BBS, 3.8) comprble to previous 2-week high-volume Adpted Tngo tril (UPDRS, 4.6; BBS 2.8) 17 nd to 2 previous longer durtion trils (ie, 2 hours over 13 weeks: UPDRS, 1.6; BBS, 3.9; 2 hours over 1 weeks: BBS, 3.6). 7,1 Miniml cliniclly importnt differences (MCIDs) hve not been estblished for mny of the outcome mesures used in this popultion. However, cliniclly significnt chnges were observed in UPDRS-III (2.9 points vs MCID ) nd mrginlly significnt chnges were observed in DGI (1.8 points vs MCID C 216 Acdemy of Neurologic Physicl Therpy, APTA 263

8 McKy et l JNPT Volume 4, October 216 Tble 4. Men Vlues (±SD) of Primry Kinemtic nd Electromyogrphic Mesures of Perturbtion Responses Before nd After the 3-Week, High-Volume Adpted Tngo Rehbilittive Intervention Pretest Posttest n M ± SD n M ± SD Effect Size Kinemtic CoM displcement, ± ± bckwrd (cm) CoM displcement, ± ± forwrd (cm) Individul muscle nlyses Bckwrd perturbtion TA-L onset, ms ± ± TA-L durtion, ms ± ± TA-L mgnitude, nu 9.48 ± ±.8.3 TA-R onset, ms ± ± 7.21 TA-R durtion, ms ± ± TA-R mgnitude, nu 9.5 ± ± MG-L onset, ms ± ± 22.7 MG-L durtion, ms 9 1 ± ± MG-L mgnitude, nu 9.14 ± ± MG-R onset, ms ± ± MG-R durtion, ms 9 58 ± ± MG-R mgnitude, nu 9.12 ± ± Forwrd perturbtion TA-L onset, ms ± ± TA-L durtion, ms 9 23 ± ± TA-L mgnitude, nu 9.11± ±.9.3 TA-R onset, ms ± ± TA-R durtion, ms 9 26 ± ± TA-R mgnitude, nu 9.11 ± ±.8.3 MG-L onset, ms ± ± 27. MG-L durtion, ms ± ± 96.1 MG-L mgnitude, nu 9.34 ± ± MG-R onset, ms ± ± 2.95 MG-R durtion, ms ± ± MG-R mgnitude, nu b 9.39± ±.9.28 Abbrevitions: MG, medil gstrocnemius; nu, normlized units; TA, tibilis nterior. P.5; b P.1, ANOVA. 1.9 in community-dwelling older dults. 63 ) While these results ostensibly support the benefits of the progrm, it is importnt to be extremely cutious in ny interprettion. The results of this pilot study will require repliction with more ppropritely powered smple size. Although the prticipnts exhibited 3.4-point improvement on BBS, this chnge is less thn the MCID of 7 points estblished in older dults with blnce impirments 61 nd lso less thn the Miniml Detectble Chnge (MDC) of 5 points estblished in individuls with PD. This cohort ws reltively higher functioning thn the reference popultion for the MDCs determined for the BBS in PD (49.3 ± 6.4 vs 42 ± 11.2); therefore, there my hve been some ceiling effects on this mesure. Improvements were observed on the more chllenging but lesser used FAB, nd smll improvements were observed in the posturl stbility UPDRS-III item (.35 points, comprble to the difference observed in this item between the OFF nd ON mediction sttes 65 ). However, clerly similr cohort would need to be recruited nd exmined in comprison to control group to mke definitive conclusions bout the efficcy of this high-volume but short-term dose of Adpted Tngo. Vigorous ongoing exercise tht increses hert rte nd oxygen uptke could be neuroprotective for individuls with PD 66 ;however, high-volume/low-intensity exercise therpy my be superior to low-volume/high-intensity exercise therpy for chnges in git speed. 14 We noted sustined gins 1 month fter the highvolume Adpted Tngo tretment ended, consistent with prior work demonstrting gins mintined over 1 month, 7 nd 3 months, 12 fter intervention cesstion. The 3-week Adpted Tngo protocol my be useful in crossover designs tht cn be completed in short overll time frme, which is beneficil for cdemic reserch studies tht rely on student volunteer personnel over the course of n cdemic semester. Electromyogrphic nd Kinemtic Mesures From Support-Surfce Perturbtion s Rehbilittion Outcome Mesures On the bsis of the observed reductions in forwrd CoM displcement nd chnges in ntgonist onset nd durtion, we consider subsequent rndomized tril of Adpted Tngo with kinemtic nd EMG outcome mesures to be fesible nd justified. Given the limited smple size, the observed chnges in muscle ctivity could be ttributed to chnce in mny cses. However, verge effect sizes observed in individul muscle nlyses were moderte (verge effect size.5), nd generlly comprble with those observed in UPDRS-III (.47), BBS (.59), FAB (.56), nd DGI (.53). Prticulrly becuse effect sizes re less susceptible to the influence of smll smple sizes thn P vlues, we interpret these results s evidence tht EMG nd kinemtic mesures would be fesible nd potentilly useful when pplied in lrger smple in this type of intervention. Associtions between chnges in clinicl mesures observed fter the intervention nd chnges in kinemtic mesures provided dditionl evidence tht lbortory-ssessed blnce mesures re fesible s objective rehbilittive outcomes for Adpted Tngo. Generlizbility The fesibility results obtined here pper generlizble to subsequent controlled trils without substntil modifictions to the bsic protocol. We nticipte tht subsequent rndomized tril would test the hypothesis tht CoM displcement would be reduced nd utomtic posturl response onset ltency would be delyed from pretest to posttest fter Adpted Tngo, compred to stndrd cre. The following modifictions could improve the precision of subsequent studies. A reduced number of clinicl outcomes, ll collected t the sme visit s posturl response testing, would improve the precision of correltionl nlyses nd reduce the potentil for ftigue effects. The posturl stbility UPDRS item hs known limittions in discriminting fllers from nonfllers 65 nd lower interrter relibility thn tests including the Push nd Relese test. 43 Blnce outcome mesures should be evluted crefully to improve externl vlidity nd to reduce prticipnt burden. At posttest, we did not observe reductions in bckwrd CoM displcement, despite reductions in forwrd CoM displcement, ltered ntgonist ctivity, nd improved posturl stbility s mesured by the UPDRS. This my reflect the incresed difficulty nd fewer biomechnicl strtegies vilble to recover blnce when flling bckwrd 264 C 216 Acdemy of Neurologic Physicl Therpy, APTA

9 JNPT Volume 4, October 216 Blnce fter Dnce Rehbilittion Forwrd Perturbtion CoM Displcement MG TA CoM Displcement Agonist (MG) EMG Antgonist (TA) EMG Pltform Position Forwrd Perturbtion Prticipnt PR8 (Hoehn & Yhr 3) Pretest Posttest nu.25 nu 8 ms Individul Tril Men Men Pek CoM displcement Men EMG onset or offset nu.25 nu ms CoM Displcement Agonist (MG) EMG Antgonist (TA) EMG Men EMG bckground level Men EMG between 8-45 ms 4 cm 3 ms Pre Forwrd Perturbtion Group Dt Post Onset Time Durtion Mgnitude 3 ms 3 ms 1. nu Pre Post Pre Post Pre Post 3 ms 1. nu Pre Post Pre Post Pre Post Bckwrd Perturbtion Bckwrd Perturbtion Prticipnt PR3 (Hoehn & Yhr 2.5) Bckwrd Perturbtion Group Dt CoM Displcement Pretest Posttest CoM Displcement CoM Displcement 4 cm Pre Post MG TA Agonist (TA) EMG Antgonist (MG) EMG Pltform Position nu.25 nu nu.25 nu ms ms Agonist (TA) EMG Antgonist (MG) EMG Onset Time Durtion Mgnitude 3 ms 3 ms 1. nu 3 ms. Pre Post Pre Post Pre Post b 3 ms 1. nu. Pre Post Pre Post Pre Post Figure 3. Exmples of center of mss (CoM) displcement nd muscle ctivity during utomtic posturl responses to forwrd (bove) nd bckwrd (below) perturbtions before nd fter the intervention. From left to right in ech row, crtoon describing perturbtion direction, exemplr dt of one prticipnt t pretest nd posttest, nd group dt cross prticipnts re shown. Shded regions in exemplr dt plots designte re under verge EMG curves 8 to 45 ms fter perturbtion onset. Note tht scle is reversed for ntgonist muscles, nd bsolute CoM displcement is shown s positive for both perturbtion directions. Brs nd error brs in group dt designte M ± SD. P <.5, b P <.1; ANOVA. in individuls with PD, who re prticulrly unstble during bckwrd swy. 2,67 Overll, the number of trils delivered in which foot, heel, or toe lift or rm fliling occurred ws reduced from 31% t pretest to 23% t posttest, suggesting tht perturbtions in both directions were less chllenging t posttest, possibly becuse of ltered posturl strtegies tht were not cptured in our nlyses of CoM displcement. A more complete kinemtic nd kinetic dt set, including vribles such s center of pressure nd stbility mrgin, 67 should be collected to better chrcterize posturl strtegies during perturbtion responses nd investigte this symmetric response. As posterior perturbtion responses nd the UPDRS C 216 Acdemy of Neurologic Physicl Therpy, APTA 265

10 McKy et l JNPT Volume 4, October 216 Tble 5. Men Vlues (±SD) of Secondry Pooled Electromyogrphic Mesures of Perturbtion Responses Before nd After the 3-Week, High-Volume Adpted Tngo Rehbilittive Intervention Pretest Posttest n M ± SD n M ± SD Effect Size TA, pooled Bckwrd perturbtion TA onset ± ± 8.75 TA durtion ± ± TA mgnitude ± ±.9.6 Forwrd perturbtion TA onset ± ± TA durtion ± ± TA mgnitude ± ±.8.31 MG, pooled Bckwrd perturbtion MG onset b ± ± MG durtion ± ± MG mgnitude ± ± Forwrd perturbtion MG onset ± ± MG durtion ± ± MG mgnitude ± ± Agonist, pooled TA, bckwrd; MG, forwrd Agonist onset ± ± Agonist durtion ± ± Agonist mgnitude ± ± Antgonist, pooled MG, bckwrd; TA, forwrd Antgonist onset ± ± 21.9 Antgonist durtion ± ± Antgonist mgnitude ± ± Abbrevitions: MG, medil gstrocnemius; nu, normlized units; TA, tibilis nterior. P.5; b P.1, ANOVA. posturl stbility item re correlted in the prcticlly defined 12-hour OFF, 67 but not in the ON, 68 mediction stte, testing should be performed in the prcticlly defined 12-hour OFF stte to improve the precision of correltionl nlyses 68 nd the discrimintory bility of clinicl mesures. 65,69 Limittions This pilot study hs severl limittions tht should be ddressed in subsequent controlled trils. Cution should be used in interpreting these results, given the smll effect sizes of most mesures, the potentil for Type II error, nd the lck of control group. Furthermore, the smll smple size left the study underpowered. Although we provide test-retest relibility findings tht demonstrte stbility of clinicl mobility mesures within these individuls with PD, the bsence of prllel control group for EMG nd kinemtic mesures prevents us from ttributing chnges in these mesures to the effects of the intervention. The study used lrge number of outcome mesures, which increses the likelihood of chnce findings. In prticulr, plusible mechnism for Adpted Tngo in improving speech (UPDRS-III item 1) is unknown. Prkinson disese is most often ssocited with hypokinetic dysrthri ttributed to decresed rnge of motion in the speech mechnism. 7 We observed improved preferred nd fst cdence fter the intervention, s well s improved speech these chnges my reflect common underlying mechnism. However, it is lso possible tht this unexpected finding is spurious nd should be interpreted with cution. The study lso used convenience smple of prticipnts for posturl response outcome mesures. Although these prticipnts did not differ in demogrphic mesures from the other prticipnts in the study, unknown selection bises my limit the generlizbility of these findings. Since the Adpted Tngo clsses represent form of group exercise, in future studies it would be vluble to ssess chnges in mesures of socil prticiption. 71 CONCLUSIONS These results demonstrte tht 3-week, high-volume Adpted Tngo rehbilittive intervention is fesible for individuls with mild-moderte PD nd tht rndomized Adpted Tngo trils using lbortory-ssessed mesures of posturl responses re fesible nd justified. ACKNOWLEDGMENTS The uthors thnk H. Brtlett, J. Binghm, S. Chvtl, J. Jilk, K. Krmer, M. McCll, C. Pope, A. Ruedrich, S. Sfvyni, H. Sohn, A. Adms, P. Dillrd, E. Renz, A. Robinson, nd A. Dftrin for ssistnce with experiments nd dt processing; K. Pirog Revill for ssistnce with recruitment, ssessment, nd study conduct; K. Lng for reserching clinicl instruments, nd the Georgi Tech/Georgi Stte Center for Advnced Brin Imging for providing spce for the intervention. This work ws supported in prt by NIH R21 HD , NSF EFRI , Tngo Under the Tent, Inc., nd by the Emory Udll Center. J.L.M. ws supported by the Atlnt Clinicl nd Trnsltionl Science Institute KL2-Mentored Clinicl nd Trnsltionl Reserch Progrm (NIH RR258, UL1TR454, nd KL2TR455). M.E.H. ws supported by the Deprtment of Veterns Affirs R&D service Creer Development Awrds E718M nd N87W. REFERENCES 1. Bloem BR, Grimbergen YAM, Crmer M, Willemsen M, Zwindermn AH. Prospective ssessment of flls in Prkinson s disese. JNeurol. 21;248(11): Melton LJ III, Leibson CL, Achenbch SJ, et l. Frcture risk fter the dignosis of Prkinson s disese: influence of concomitnt dementi. Mov Disord. 26;21(9): Fisher BE, Wu AD, Slem GJ, et l. The effect of exercise trining in improving motor performnce nd corticomotor excitbility in people with erly Prkinson s disese. Arch Phys Med Rehbil.28;89(7): Smni N, Corto E, Tinzzi M, et l. Effect of blnce trining on posturl instbility in ptients with idiopthic Prkinson s disese. Neurorehbil Neurl Repir. 21;24(9): Hirsch MA, Toole T, Mitlnd CG, Rider RA. The effects of blnce trining nd high-intensity resistnce trining on persons with idiopthic Prkinson s disese. Arch Phys Med Rehbil. 23;84(8): Li F, Hrmer P, Fitzgerld K, et l. Ti chi nd posturl stbility in ptients with Prkinson s disese. N Engl J Med. 212;366(6): C 216 Acdemy of Neurologic Physicl Therpy, APTA