doi: 10.2522/ptj.20060182 Originally published online May 15, 2007 2007; 87:888-898. PHYS THER. Diane D Allen Movement in the Movement Continuum Theory Proposing 6 Dimensions Within the Construct of http://ptjournal.apta.org/content/87/7/888 found online at: The online version of this article, along with updated information and services, can be Collections Motor Control and Motor Learning Kinesiology/Biomechanics in the following collection(s): This article, along with others on similar topics, appears e-Letters "Responses" in the online version of this article. "Submit a response" in the right-hand menu under or click on here To submit an e-Letter on this article, click E-mail alerts to receive free e-mail alerts here Sign up by guest on March 11, 2012 http://ptjournal.apta.org/ Downloaded from
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doi: 10.2522/ptj.20060182Originally published online May 15, 2007
2007; 87:888-898.PHYS THER. Diane D AllenMovement in the Movement Continuum TheoryProposing 6 Dimensions Within the Construct of
http://ptjournal.apta.org/content/87/7/888found online at: The online version of this article, along with updated information and services, can be
Collections
Motor Control and Motor Learning Kinesiology/Biomechanics
in the following collection(s): This article, along with others on similar topics, appears
e-Letters
"Responses" in the online version of this article. "Submit a response" in the right-hand menu under
or click onhere To submit an e-Letter on this article, click
E-mail alerts to receive free e-mail alerts hereSign up
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Proposing 6 Dimensions Within theConstruct of Movement in theMovement Continuum TheoryDiane D Allen
Background and PurposeThe Movement Continuum Theory (MCT) provides a potential basis for movementassessment and intervention, but “movement” lacks specificity. The purposes of thisstudy were to propose and evaluate a subdivision of movement into multipledimensions.
SubjectsA convenience sample of 318 adults completed a 24-item self-report measure ofmovement ability.
MethodsA multimethod approach was used to identify, operationalize, and test a multidimen-sional model of movement. Data analysis included a comparison of the fit of uni-dimensional and multidimensional models using item response theory methods andinspection of response patterns.
ResultsA model specifying 6 dimensions—flexibility, strength, accuracy, speed, adaptability,and endurance—fit respondent data significantly better than the unidimensionalmodel, even with high pair-wise correlations between dimensions. Response patternsshowed large differences rather than uniform scores across dimensions for over halfof the respondents.
Discussion and ConclusionSubdividing movement into the proposed dimensions fits the data and potentiallystrengthens the usefulness of the MCT as a theoretical foundation for managingmovement effectively.
DD Allen, PT, PhD, is Adjunct As-sociate Professor, Department ofPhysical Therapy, Samuel MerrittCollege, Oakland, Calif, and Post-Doctoral Fellow, Health and Dis-ability Research Institute, BostonUniversity, Boston, Mass. Addressall correspondence to Dr Allen at:[email protected].
[Allen DD. Proposing 6 dimen-sions within the construct ofmovement in the Movement Con-tinuum Theory. Phys Ther.2007;87:888–898.]
The Movement Continuum The-ory (MCT),1 first published in1995, establishes links among
movement sciences, the movementcapability of individuals, and the roleof movement specialists in maximiz-ing people’s movement capability.The MCT1 presents movement as thecentral unifying construct for the as-sessment and management of move-ment and movement disorders in-stead of the common clinicalpractice of focusing on function ordisability.2 Its authors proposed it asa possible grand theory of physicaltherapy,1 but the MCT and its prin-ciples can enhance the understand-ing of movement and potential inter-ventions by other professions aswell.
Despite broad relevance and a needfor theoretical foundations for clini-cal practice,1,3 the MCT has inspiredlittle empirical research since its in-troduction. In a search of CINAHLand MEDLINE databases as of August2005, none of the 24 articles refer-ring to the MCT since its publicationcontained accounts of prospectivetesting of the MCT or any hypothe-ses stemming from it.
This study initiates testing of theMCT in a direction that could easethe application of this theory to em-pirical research. In this study, theconstruct of movement is subdividedinto multiple components or dimen-sions that may prove more readilymeasurable than the singular genericmovement construct presented inthe MCT. A multidimensional modelsuch as the model proposed heremay stimulate both the generation oftestable hypotheses and the associa-tion of current evidence of effective-ness with a unified theory. A multi-dimensional model of movementalso may promote the characteriza-tion of people’s different movementabilities, enhancing the specificitywith which clients and movementspecialists can pinpoint deficits and
identify appropriate interventions.The purposes of this study were topropose a multidimensional modelof movement as an extension of theMCT and to perform an initial evalu-ation of this new model ofmovement.
Literature ReviewThe MCT presents 3 general and 6physical therapy principles that linkmovement science with movementcapability and clinical practice.1 Inessence, movement, defined as anactual change in position, occurs atmultiple interacting levels along acontinuum from microscopic to thelevel of a person acting in society.Each level is influenced by physical,social, psychological, and environ-mental factors. Physical agents andtherapeutic exercise generally haveentry points at the tissue level orhigher, but because the levels inter-act, these interventions can affectmolecular and cellular movement aswell as body part and person move-ment. The MCT specifies that eachperson has maximum, current, andpreferred movement capabilities. If amovement specialist successfully ad-dresses movement problems with apatient or client, then current move-ment capability will increase and thegap between current and preferredmovement capabilities will narrow.1
Testing the principles presented bythe MCT requires an assessment ofpeople’s current and preferredmovement capabilities and the effectof intervention on them. The con-struct of movement as presented inthe MCT, however, is too generic forclinical assessment. Specifying subdi-visions or dimensions of movementmay assist in identifying clinicallymeasurable constructs that have adefinitive relationship to the move-ment capabilities presented in theMCT. Because the MCT already pre-sents a framework for identifyingwhat part of the person moves (eg,at the tissue, body part, or person
level on the continuum) and for iden-tifying physical, psychological, so-cial, and environmental factors thatinfluence the movement,1 these as-pects of observable behavior do notrequire redundant description. Onlythe movement itself requires furtherspecification.
The specification of multiple subdi-visions or dimensions of movementhas support in the movement sci-ence and clinical literature. Clinical4
and motor control5 sources presentstrength, flexibility, proprioception,and coordination as candidates forintervention following orthopedic orneurologic pathology. Some of thesesensorimotor aspects overlap withthe list that Hedman et al6 compiledas the “components of movement”or that Majsak7 identified as con-straints delineating the “range ofmovement behaviors.” Additionaloverlap and alternative ways of spec-ifying aspects of movement appearin Craik’s discussion of issues for de-fining normal motor behavior8 andthe classification that Scheets et al9
formulated for diagnosing impair-ment of the movement system. Eachof the movement aspects and com-ponents mentioned in these sourcescould contribute to a multidimen-sional model of movement.
Phases of StudyThis article describes 3 phases of amultimethod study. The purposeswere to formulate and evaluate amultidimensional model of move-ment to extend the MCT. In the iden-tification phase, components ofmovement from the literature wereevaluated on the basis of a set ofcriteria for inclusion into an econom-ical model. In the operation phase,the set of dimensions and the MCTformed the basis of a new measureconstructed to incorporate both ge-neric and multidimensional con-structs of movement. In the testphase, data were collected with thenew measure. The proposed multi-
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dimensional model then was com-pared with a unidimensional modelof movement and with a multidimen-sional model with randomly attrib-uted dimensions. Because the phasesnecessarily occurred sequentially,the results follow the method foreach phase in sequence.
Identification Phase:Method and ResultsGenerating the set of potential move-ment dimensions consisted of settingevaluative criteria, identifying fromliterature sources common featuresof movement to propose as candi-dates, and comparing those candi-dates with the criteria to ensurealignment. The criteria for potentialdimensions of movement to extendthe MCT included the following:
(1) Descriptive: The complete set ofdimensions, with an added refer-ence to the body parts or sub-stances doing the moving,should fully describe normal hu-man movement, a series ofmovements, or actively holdinga position against a force.
(2) Efficient: The set of dimensionsshould describe movement effi-ciently, subsuming related con-cepts, with the fewest numberof separate dimensions whilecompletely describing movement.
(3) Distinct: The dimensions shouldidentify observable features ofmovement distinct from the partof the body doing the moving ordifferent physical, psychologi-cal, social, or environmental fac-tors that influence movement.
(4) Measurable: The dimensionsshould be measurable.
(5) Understandable: The dimensionsshould make sense to bothmovement specialists and theirpatients or clients.
A comparison of possible movementdimensions with the criteria led tothe addition, modification, or elimi-nation of candidates. Tables 1 and 2show comparisons of the first 4 cri-teria with the proposed (Tab. 1) andsome of the rejected (Tab. 2) candi-dates for movement dimensions. Thefifth criterion implies that peoplecan differentiate among and use thevarious dimensions in their observa-tions and descriptions of movement.Testing this implication or otherwiseproviding evidence of understandingof any of the movement dimensionswill require empirical data.
The resulting set of dimensions in-cludes flexibility, strength (force ex-erted), accuracy, speed, adaptability,and endurance. These 6 dimensionsdescribe observed movement com-prehensively and efficiently (criteria1 and 2). The proposed dimensionsof flexibility, strength, and speed ap-ply to all human movement; accu-racy applies specifically to purpose-ful movement; and adaptability andendurance apply to movement whenencountering unexpected obstaclesor when approaching the limits of aperson’s capacity. All of these dimen-sions have direct relationships withbut remain distinct from the physi-cal, psychological, social, and envi-ronmental factors that influencemovement (criterion 3). Each candi-date dimension can be measuredclinically (criterion 4). Although fur-ther research may justify modifica-tion of this set, these 6 dimensionsprovide a starting point for charac-terizing movements readily observedby movement specialists and theirpatients or clients (toward criterion5). In addition, these 6 dimensionspresent interesting possibilities forcategorizing movement abilitiesmaximized by athletes or performingartists or diminished in people witha particular pathologic condition(Tab. 3).
Operation Phase:Method and ResultsThe next step in determining theusefulness of this set of dimensionswas to construct or locate measuresfor assessing movement. If the samemeasure could evaluate both genericand multidimensional movements,then it would facilitate the directcomparison of a generic or overallidea of movement with the dimen-sions of movement proposed in themodel. In addition, because the MCTand the proposed model apply to abroad range of ability levels and tothe movements of people with orwithout pathologic conditions, theideal measure for comparing genericand multidimensional constructswould apply to a similar range. Manymeasures of movement exist for test-ing individual dimensions, specificdiagnostic groups, or particular bodyparts exist, but few existing mea-sures assess generic movement abil-ity or apply to multiple groups oracross the proposed dimensions.
Generation of the self-report Move-ment Ability Measure (MAM) opera-tionalized the MCT and the proposedmodel and facilitated direct compar-ison of unidimensional and multi-dimensional models of movement.For addressing a generic or uni-dimensional construct of movement,all items in the MAM were given asimilar item construction and stan-dard levels of item responses. If peo-ple marked every item with the samelevel of response, then a genericmovement construct could specifytheir movement ability quite ade-quately. For addressing a multi-dimensional construct of movement,variations in the wording of items inthe MAM referred specifically to the6 proposed dimensions of move-ment. If people marked items associ-ated with one dimension quite differ-ently from items associated withother dimensions, then specificationof their ability on that dimension
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could enhance the description oftheir movement ability.
The self-report format allowed sub-jects to interpret movement as awhole or differentiate movement di-mensions within the context of theirown lives. The MAM placed minimalconstraints on subject interpreta-tion. In avoiding the specification oftasks that may have limited relevanceacross groups, the MAM also appliedto a broad range of subjects acrossmovement ability levels and with orwithout pathologic conditions.
The MAM was developed and testedfor reliability and for content andconstruct validity with proceduresrecommended by Wilson10; evi-dence of reliability and validity is pre-sented elsewhere (see the article byAllen on the validity and reliability ofthe Movement Ability Measure inthis Special Series).11 Each item inthe MAM consisted of 6 statementsindicating levels of movement abil-ity. Respondents were instructed tochoose the statement that mostclosely matched how they thoughtthey moved now and how they
would like to be able to move. Threesample items and instructions areshown in Figure 1. The MAM in-cluded 4 items for each of the 6 di-mensions, for a total of 24 items. Thesame instructions applied to allitems. Consistency of responsesacross items was high, with personseparation reliability ranging from.92 to .96 for the 6 dimensions andequaling .98 for the whole measure.
Test Phase: MethodFor the test phase, a heterogeneoussample of people completed the
Table 1.Proposed Movement Dimensions Aligned With 4 Criteria
Direction and timing ofdisplacement,coordination,6,7,9 timingand sequencing,7,9
fractionating orisolating movement,9
and selective capacity6
Cerebellar integrity andneuromuscular integrity
Distance between result ofmovement and target; errorscores; distance or numberof deviations from targettrajectory; and synchronywith a timing target,cadence, andelectromyographic timing
MAM. The expectation was thatmost people who move normallymight perceive themselves to haveabout the same level of movementability on all 6 dimensions; therefore,a unidimensional model would fitthe data very well. If people perceivedifferences in the effects of differentdimensions on their movement abil-ity, then they might respond quitedifferently to items associated withthose dimensions. In this situation, a
multidimensional model would fitthe data better than a unidimensionalmodel. The proposed multidimen-sional model was compared with aunidimensional model and with amultidimensional model in whichitems were randomly assigned todimensions.
Recruitment of volunteers to re-spond to the MAM targeted a broadspectrum of groups in order to ob-
tain a heterogeneous representationof movement abilities. Adults volun-teered from religious and commu-nity groups, personal contacts, a col-lege sports team, physical therapyoutpatient clinics, and a senior dayactivity event. In addition to theMAM, respondents completed acover sheet of information abouthealth status and any movementproblems. Respondents were in-formed that completing and return-ing the questionnaire constitutedconsent for their (anonymous) re-sponses to be included in the study.
The data were analyzed with itemresponse theory (IRT) methods12
and ConQuest13,* software, and onlythe “now” responses to items wereanalyzed. Two models were com-pared. One model assigned all itemsto 1 dimension in a unidimensionalconstruct; the other assigned itemsto the 6 dimensions in a multidimen-sional construct. Fit was analyzed onthe basis of the differences in the
* Australian Council for Educational Research,Hawthorn, Victoria, Australia.
Table 3.Proposed Dimensions and Sample Activities or Pathologies Relevant to Each
Sensory or perceptual loss fromauditory, visual, vestibular, orsomatosensory systems
Endurance Running a marathon, singing anopera
Cardiovascular or pulmonary diseases
Table 2.Representative Movement Features Not Aligned With Criteria
Feature of Movement Unmet Criteria
Posture6,7 Efficient and distinct: posture, when active, as during holding of aposition against a force such as gravity, can be describedadequately with a combination of other dimensions; whenpassive, it influences but does not describe subsequentmovement
Balance6 Efficient: balance is a complex set of sensorimotor activities thatcan be described with a combination of the proposeddimensions, such as adaptability, strength, and flexibility
Cognitive capacity,6 psychological capacity,6 ability to learn,9
and motivation and alertness7
Distinct and descriptive: these psychological factors influencemovement and the intention behind movement but do notdescribe movement itself
Pain6 Distinct and descriptive: pain, perhaps a physical or psychologicalfactor influencing movement, does not describe movementitself
Alignment, center of mass, and base of support7 Distinct and descriptive: these physical (biomechanical) factorsinfluence movement but do not describe movement itself
Proprioception,4 sensory modalities,9 perception of vertical,9
perception of motion,9 and sensory information6
Distinct and descriptive: sensation and perception are physicaland psychological factors that influence the ability to learnmovement or to adapt to an environment but do not describemovement itself
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deviances and the numbers of pa-rameters (obtained from ConQuest)by use of the G2 likelihood ratio sta-tistic. For a more complex (multidi-mensional) model to fit better thana simpler nested (unidimensional)model, it must result in a lower de-viance (a measure of lack of fit of thedata to the model) than can be ac-counted for simply by the greaternumber of parameters estimated.The difference between the devi-ances for the 2 models functions likea chi-square distribution with the dif-ference in the number of parametersas the degrees of freedom. Correla-tions also were obtained for each pairof dimensions in the multidimensionalmodel.
To assess whether any multidimen-sional model would fit better thanthe unidimensional model for thesedata, a random multidimensionalmodel was generated, with items as-signed randomly, but without repli-cation, to generic dimensions. Thatis, no more than one item from anyproposed dimension was allowedper generic dimension. This randommultidimensional model also wascompared with the unidimensionalmodel with the G2 likelihood ratiostatistic as described previously.
In addition to the comparisons ofmodels with the G2 statistic, the pat-terns of responses of individual re-spondents were examined. Examin-ing uniform or uneven patterns ofresponses across dimensions mightprovide insight into the constructs inthe proposed model. A sum ofsquares indicator, DI, was calculatedto indicate the sizes of the differ-ences in responses across dimen-sions.14 For this calculation, move-ment levels and respondent abilities(�) were examined in logits, the logof the odds of choosing the state-ment indicating a given level ofmovement ability within each item.The DI sums differences from move-ment ability estimates across the 6
dimensions (d) for each person p, asfollows:
DIp � �d � 1
6
���� � �d�2�
If the sum of the squared deviationsfrom an average estimate is low, thenthat person perceives his or hermovement to be about the sameacross all 6 dimensions. If DIp ishigh, then that person perceives
movement ability on at least one ofthe dimensions to be quite differentfrom the average of the rest. Repre-sentative respondents with low andhigh DI values were selected; move-ment ability plots (MAPs) depictedthe asymmetry of dimensions forthese selected respondents with lowand high DI values. Designation oflow and high DI values within anyparticular study is arbitrary.15 Forthis study, the lowest and highestaverage logits for any dimension
Figure 1.Example of 3 Movement Ability Measure items directed toward the dimensions offlexibility, speed, and strength. Respondents were instructed to choose the one state-ment within each box that most closely described their usual ability to move now, thisweek, and the one statement that most closely described the ability that they would liketo have even if they had to work hard for it. They were instructed to mark one numberon the left (Now) and one number on the right (Would Like) for each set of 6statements.
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were inspected for each respondent;the DI cutoff was assigned to thevalue above which all respondentshad differences from their lowest totheir highest dimensions that werelarge enough to be outside of a 98%confidence interval.
Test Phase: ResultsA total of 318 adults completed theMAM. Respondent ages ranged from18 to 101 years, with modes (10each) at ages 49 and 76. Women con-stituted 206 (65%) of the respon-dents; 178 (56%) acknowledged atleast a little movement difficulty inthe previous week. Forty-six respon-dents (14%) indicated that they werestarting or undergoing physical ther-apy at the time of responding to theMAM.
With items specifically assigned to 6corresponding dimensions, the mul-
tidimensional model fit significantlybetter than the unidimensionalmodel (�2
25�280.9, P�.0001), evenwith high internal consistency acrossall items (Cronbach ��.94) and highcorrelations between pairs of dimen-tions (r�.87–.99). In contrast, whenitems were randomly assigned to 6generic dimensions, the multidimen-sional model fit no differently thanthe unidimensional model (�2
25�23.3, P�.56).
When response patterns were exam-ined with the DI statistic (mean�9.25 logits2, standard deviation�11.62), 5.3 logits2 was designated asthe cutoff between low and high. Noperson who had a DI value abovethis cutoff had less than 2.5 logitsbetween the lowest and the highestaverage dimension estimates. At 2.5logits, the lowest and highest aver-age dimension estimates were out-
side of their respective 98% confi-dence intervals (standard errors foraverage dimension estimates wereabout 1 logit), and the spread signi-fied at least 0.5 and up to 1.25 move-ment ability level differences be-tween the dimensions. At a DI valueof 5.3, 165 (52%) of the respondentsshowed differences between the di-mensions of movement rather than auniform average across dimensions.Movement ability plots of samplecases (Figs. 2, 3, 4, 5, 6, and 7) cho-sen to represent low and high DIvalues depict dimensional abilities inlogits along 6 respective axes in ahexagon (range for all axes��11 to�9 logits). Greater asymmetry indi-cates larger differences between di-mensions. Demographic informationis provided when known from re-sponses and comments on com-pleted questionnaires.
Discussion and ConclusionThe 3 phases of this study resulted ina proposed set of dimensions to ex-tend the construct of movementwithin the MCT. The proposed di-mensions included aspects of move-ment that were described in the lit-erature and that were aligned withevaluative criteria. Testing the pro-posed dimensions required the con-struction of a new measure targetingthese movement constructs alongwith a generic movement construct.Model comparisons carried out withdata obtained with the new measureshowed that the proposed multidi-mensional model fit better than aunidimensional model.
Despite the dimension-specificwording of the MAM, many respon-dents provided no discernible indica-tion that their movement was differ-ent across dimensions. For them,responses across the dimensions in-dicated about the same level ofmovement ability, although thatmovement ability might have beenlow or high, as shown in Figures 2and 3. The associated demographic
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Figure 2.Respondent 201 reported low movement ability (low logit values) on all dimensions.This respondent was an 86-year-old woman who reported that she was “clumsy” andhad low back problems. The sum of the squared deviations from an average dimen-sional logit value, DI201�0.47 logit2.
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data indicated that symmetry in re-sponses across dimensions mighthave been associated with debilita-tion or physical capability in general.
For more than half of the respon-dents in this study, MAM responseswere different across dimensions.Some respondents showed excep-tionally low levels of ability on somedimensions (Figs. 5 and 7), andothers showed exceptionally highlevels of ability on 1 or 2 dimensions(Fig. 6). These responses imply suf-ficient understanding of the dimen-sions in the MAM to reflect con-sistent differences (with personseparation reliability ranging from.92 to .96) across designated groupsof items. This is initial evidence thatthis set of dimensions may meet cri-terion 5. Determining whether suchdifferences across dimensions haveclinical meaning depends on futureresearch. Comparing the demo-graphic data to the MAPs suggested alink between responses and respon-dent characteristics rather than ei-ther uniform or random responses toitems.
Although these results provide someinitial evidence supporting the sub-division of the movement constructof the MCT into the 6 proposed di-mensions, validation of the proposedmodel requires further research. Forexample, the MAM deliberately al-lowed respondents to interpretitems without specifying standardtasks; this property increased its ap-plicability across individuals with dif-ferent experiences of functional ac-tivities but restricted the absolutecomparison of one individual withanother or of MAM responses withinstrumented measures. To deter-mine whether differences in per-ceived movement ability correlatewith measurable differences in di-mensions, future research might ex-amine the association between MAMresponses and performance-basedmeasures or clinicians’ judgments of
4
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Figure 3.Respondent 244 reported high movement ability on all dimensions. This respondentwas a 72-year-old man who was healthy. The sum of the squared deviations from anaverage dimensional logit value, DI244�3.15 logits2.
4
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Figure 4.Respondent 39 reported higher movement ability on flexibility, strength, and endur-ance and lower movement ability on accuracy, speed, and adaptability. This respondentwas a 65-year-old man. The sum of the squared deviations from an average dimensionallogit value, DI39�28.22 logits2.
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movement ability. To determinewhether the magnitude of perceivedmovement ability has meaning, fu-ture research might examine groupdata for each dimension and com-pare healthy control subjects withsubjects who have identified defi-ciencies. To explore the possibleclinical meaning of the proposed di-mensionality, future research mightexamine people before and aftertherapy to determine whether thosewho respond well to therapy startedwith a generic lack of movementability across all dimensions or a spe-cific and predictable lack of move-ment ability in one dimension or afew dimensions. Further researchalso might indicate that MAPs revealidentifiable patterns of asymmetryfor certain clinical groups.
Asymmetry across different dimen-sions should follow predictable pat-terns according to the proposed mul-tidimensional model of movement.For example, athletes should testhigher in predictable subsets ofthese dimensions, depending on therequirements of their specific sport-ing events, as proposed in Table 3.Likewise, patients should test lowerin predictable ways if they have di-agnoses affecting 1 or several desig-nated dimensions. Furthermore, ifthese dimensions extend the MCT,then patients should improve in af-fected dimensions upon successfulcompletion of a clinical intervention.If research confirms predictable pat-terns among the dimensions relatedto athletic ability or pathology-related disability, then characteriza-tion of movement ability along thedimensions may prove useful in de-termining prognosis and planningfor client intervention.
A common alternative statisticalmethod for determining dimension-ality, factor analysis, proved unhelp-ful in this study. Exploratory or con-firmatory factor analysis of aninstrument relies on a lack of corre-
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Figure 5.Respondent 186 reported moderate movement ability on adaptability and much lowermovement ability on the other dimensions, especially flexibility. This respondent was a76-year-old woman who had had a stroke. The sum of the squared deviations from anaverage dimensional logit value, DI186�68.34 logits2.
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Figure 6.Respondent 316 reported higher movement ability on endurance and moderate move-ment ability on the other dimensions. This respondent was a 25-year-old woman whowas a long-distance runner. The sum of the squared deviations from an averagedimensional logit value, DI316�29.35 logits2.
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lation between groups of items ordimensions to determine whetherdifferent factors are represented. Forperceived movement ability as as-sessed with the MAM, the dimen-sions had an extremely high pair-wise correlation that negatedconfirmation of factors with factoranalysis. Choosing IRT methods totest dimensionality proved more use-ful in this study because these meth-ods estimate item and respondent lo-cations on the same (logit) scale onthe basis of all of the recorded re-sponses to all of the items. Thus, IRTmethods retain the distinctions be-tween items and groups of itemsmade by individual respondentsrather than subsuming all of thosedifferences in pooled correlationdata across a sample.
Although the MCT describes move-ment at all levels, from the molecularand cellular levels to the level of aperson acting in society, the MAMincorporates the 6 dimensions ofreadily perceivable movement only.Further research is needed to deter-mine whether these 6 dimensionsapply to the molecular and cellularlevels of the continuum described bythe MCT or whether separate move-ment descriptors are more applica-ble for these levels.
Although numerous discussions withprofessional informants helped re-fine the set of dimensions describedhere and although these dimensionsmet the evaluative criteria, the liter-ature search for movement dimen-sion candidates was neither exhaus-tive nor systematic. Further researchmay provide support for the exclu-sivity of these dimensions or providesome other criteria for accepting dif-ferent dimension candidates. Re-search also may modify the conceptsof these dimensions, splitting someinto smaller subdivisions or mergingothers on the basis of some alterna-tive criteria. It is hoped that the iden-tification of the 6 dimensions in this
study will promote discussion ofmovement and all of its possibledimensions.
The subjects in this study were not arandomized sample; subjects whovolunteered to complete the self-report measure may have self-selected either because they thoughtthey moved well or because theywere conscious of movement prob-lems. Neither of these motivationswas thought to bias the results par-ticularly, as this study focused on di-mensionality and not the level ofmovement ability.
An alternative to the disablementmodels described as the basis ofthe Guide to Physical TherapistPractice,2 the MCT1 presents a po-tential grand theory of physicaltherapy3 that also could be relevantto movement specialists in otherprofessions. Without testable hy-
potheses, however, the MCT willfail to provide a foundation for as-sessment and intervention. The pro-posed multidimensional model maypromote hypothesis generation be-cause the specificity of the dimen-sions makes measuring movementwith the MCT more concrete.Strength, for example, as a dimen-sion within the movement con-struct of the MCT, has links amongthe assessment of strength in thelaboratory, the problems of weak-ness, and the intervention used toimprove current ability to gener-ate force. Characterizing movementcapabilities across dimensions andtesting any narrowing of the gap be-tween current and preferred move-ment capabilities as a result of inter-vention become possible.
If the research suggested in this dis-cussion further supports the MCTand the proposed dimensions of
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Figure 7.Respondent 309 reported low movement ability on flexibility and strength and mod-erate movement ability on the other dimensions. This respondent was a 40-year-oldman with limited neck and arm function because of impingement. The sum of thesquared deviations from an average dimensional logit value, DI309�123.02 logits2.
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movement, it will have implicationsaffecting research, education, andclinical practice. In research, theMCT and dimensions of movementcould provide a framework for re-vealing relationships among flexibil-ity, strength, and speed, for exam-ple, providing a needed unificationfor effectiveness evidence. In educa-tion, a focus on movement dimen-sions provides a natural link betweenbasic and movement sciences andthe movement deficits associatedwith particular pathologic condi-tions, perhaps improving studentunderstanding of assessment and in-tervention relationships across diag-nostic groups. In clinical practice,the dimensions of movement mayhelp patients and movement special-ists more readily specify and focusassessment and intervention on thedimensions having the most diffi-culty. Across all areas, disseminationand use of the MCT and dimensionsof movement could enhance effec-tiveness in investigating and manag-ing movement. Although this studyaddressed only the initial testingof the proposed multidimensionalmodel of movement and the MCT,the potential usefulness of thistheory makes further researchworthwhile.
The author acknowledges Mark Wilson forsparking the original idea of dimensions ofmovement and for his direction in the meth-
odology of testing. The author also thanksRick Allen for support and editing advicethroughout the process of conceptualizing,testing, and writing.
A version of this study was presented as aposter at the Combined Sections Meeting ofthe American Physical Therapy Association;February 1–5, 2006; San Diego, Calif. Thisstudy was completed as part of the author’sdoctoral dissertation at the University of Cal-ifornia, Berkeley.
The Committee for the Protection of HumanSubjects at the University of California,Berkeley, designated this study exempt fromfurther review.
This article was received June 27, 2006, andwas accepted March 1, 2007.
DOI: 10.2522/ptj.20060182
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