Original research Reliable lower limb musculoskeletal profiling using easily operated, portable equipment Andrew Miller * , Robin Callister School of Biomedical Sciences, University of Newcastle, Callaghan, NSW 2308, Australia article info Article history: Received 25 February 2008 Received in revised form 9 July 2008 Accepted 31 October 2008 Keywords: Reliability Musculoskeletal Functional movement Vertical jump Video analysis abstract Objectives: Jumping performance and movement-based screening tests are commonly performed on athletes pre-season. Little is known regarding the test-retest reliability of performance tests and asso- ciated movement patterns using easily operated, portable and cost effective equipment. The purpose of this study was to establish the test-retest reliability of performance and video-derived movement characteristics of six screening tests measured simultaneously using a contact mat and two-dimensional video analysis. Methods: Twenty-four subjects (17 male/7 female) were tested on three occasions 5–12 days apart to establish test-retest reliability of the measurement tools used. The tests used were anterior step-up, double and single-leg countermovement jumps, double and single-leg reactive (drop) jumps, and single- leg side springs. Results: Measures of performance demonstrated less variability (mean-typical error expressed as a coefficient of variation, CV 2.8–4.3%) and higher reliability (intraclass correlation coefficients, ICC 0.98– 0.99) for floor-based tests (preceding values) than drop tests (CV 10.3–13.2%, ICC 0.83–0.85). All video- derived movement characteristics demonstrated low variability (CV 3.2–4.8%), but lower rank order repeatability (ICC 0.43–0.79). Conclusion: The findings suggest that screening tests performed from the floor and measured simulta- neously using a contact mat and two-dimensional movement analysis are reliable, and trialling these tests for the pre-season screening of athletes is supported. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Strategies to reduce sports injury risk include identifying athletes with characteristics indicative of greater risk of injury and implementing specific training programs to alter these character- istics and reduce injury risk (Meeuwisse, 1994). Prior to the establishment of a relationship between a proposed factor and injury risk, the choice of characteristics to use in the screening of athletes is often based on reasonable assumptions about deficits in performance or movement patterns and a particular injury, which are subsequently trialled in prospective cohort studies in which potential injury risk factors are measured and athletes followed over time (Finch, 2006; Murphy, Connolly, & Beynnon, 2003). The first step in the development of such screening procedures is to establish that the methods used to evaluate potential injury risk factors are reliable prior to conducting prospective studies (Gabbe, Bennell, Wajswelner, & Finch, 2004). The reliability of a test is the reproducibility of the measurement values over multiple test sessions and has the following charac- teristics. With repeated assessments on multiple people there is no change in the means of the sessions (differences may indicate learning effects), there is small within-subject variation over the sessions, and there is a high test-retest correlation among the sessions (Hopkins, 2000). Hopkins recommends a minimum of three measurement trials on different days for assessment of reli- ability. It is also important that the population used for the deter- mination of reliability is representative of the population to be used for subsequent investigation. Since the 1990s there has been an increasing emphasis on functional movement tests as candidate assessments for injury risk screening (Cordova & Armstrong, 1996). Jumping and landing tasks have commonly been used (Walsh, Ford, Bangen, Myer, & Hewett, 2006). Side-to-side strength imbalance has also attracted interest over recent times (Askling, Karlsson, & Thorstensson, 2003; Crois- ier, Forthomme, Namurious, Van-Derthommen, & Crielaard, 2002; Negrete, Schick, & Cooper, 2007; Newton et al., 2006; Orchard, * Corresponding author. Tel.: þ61 (02) 4921 6311; fax: þ61 (02) 4921 7407. E-mail addresses: [email protected](A. Miller), robin.callister@ newcastle.edu.au (R. Callister). Contents lists available at ScienceDirect Physical Therapy in Sport journal homepage: www.elsevier.com/ptsp 1466-853X/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ptsp.2008.10.003 Physical Therapy in Sport 10 (2009) 30–37
Transcript
lable at ScienceDirect
Physical Therapy in Sport 10 (2009) 30–37
Contents lists avai
Physical Therapy in Sport
journal homepage: www.elsevier .com/ptsp
Original research
Reliable lower limb musculoskeletal profiling using easily operated,portable equipment
Andrew Miller*, Robin CallisterSchool of Biomedical Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
a r t i c l e i n f o
Article history:Received 25 February 2008Received in revised form9 July 2008Accepted 31 October 2008
1466-853X/$ – see front matter � 2008 Elsevier Ltd.doi:10.1016/j.ptsp.2008.10.003
a b s t r a c t
Objectives: Jumping performance and movement-based screening tests are commonly performed onathletes pre-season. Little is known regarding the test-retest reliability of performance tests and asso-ciated movement patterns using easily operated, portable and cost effective equipment. The purpose ofthis study was to establish the test-retest reliability of performance and video-derived movementcharacteristics of six screening tests measured simultaneously using a contact mat and two-dimensionalvideo analysis.
Methods: Twenty-four subjects (17 male/7 female) were tested on three occasions 5–12 days apart toestablish test-retest reliability of the measurement tools used. The tests used were anterior step-up,double and single-leg countermovement jumps, double and single-leg reactive (drop) jumps, and single-leg side springs.
Results: Measures of performance demonstrated less variability (mean-typical error expressed asa coefficient of variation, CV 2.8–4.3%) and higher reliability (intraclass correlation coefficients, ICC 0.98–0.99) for floor-based tests (preceding values) than drop tests (CV 10.3–13.2%, ICC 0.83–0.85). All video-derived movement characteristics demonstrated low variability (CV 3.2–4.8%), but lower rank orderrepeatability (ICC 0.43–0.79).
Conclusion: The findings suggest that screening tests performed from the floor and measured simulta-neously using a contact mat and two-dimensional movement analysis are reliable, and trialling thesetests for the pre-season screening of athletes is supported.
� 2008 Elsevier Ltd. All rights reserved.
1. Introduction
Strategies to reduce sports injury risk include identifyingathletes with characteristics indicative of greater risk of injury andimplementing specific training programs to alter these character-istics and reduce injury risk (Meeuwisse, 1994). Prior to theestablishment of a relationship between a proposed factor andinjury risk, the choice of characteristics to use in the screening ofathletes is often based on reasonable assumptions about deficits inperformance or movement patterns and a particular injury, whichare subsequently trialled in prospective cohort studies in whichpotential injury risk factors are measured and athletes followedover time (Finch, 2006; Murphy, Connolly, & Beynnon, 2003). Thefirst step in the development of such screening procedures is toestablish that the methods used to evaluate potential injury risk
factors are reliable prior to conducting prospective studies (Gabbe,Bennell, Wajswelner, & Finch, 2004).
The reliability of a test is the reproducibility of the measurementvalues over multiple test sessions and has the following charac-teristics. With repeated assessments on multiple people there is nochange in the means of the sessions (differences may indicatelearning effects), there is small within-subject variation over thesessions, and there is a high test-retest correlation among thesessions (Hopkins, 2000). Hopkins recommends a minimum ofthree measurement trials on different days for assessment of reli-ability. It is also important that the population used for the deter-mination of reliability is representative of the population to be usedfor subsequent investigation.
Since the 1990s there has been an increasing emphasis onfunctional movement tests as candidate assessments for injury riskscreening (Cordova & Armstrong, 1996). Jumping and landing taskshave commonly been used (Walsh, Ford, Bangen, Myer, & Hewett,2006). Side-to-side strength imbalance has also attracted interestover recent times (Askling, Karlsson, & Thorstensson, 2003; Crois-ier, Forthomme, Namurious, Van-Derthommen, & Crielaard, 2002;Negrete, Schick, & Cooper, 2007; Newton et al., 2006; Orchard,
Mid thigh (anterior) Midpoint of the tip of anterior superior iliac spine and midpatella landmarks
Mid patella Midpoint of anterior/superior and medial/lateral borders ofpatella
Distal anterior tibialmargin
Anterior tibial margin at the minimum girth superior to theSphyrion tibiale
Fig. 1. Subject marking.
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–37 31
Marsden, Lord, & Garlick, 1997; Yamamoto, 1993) both as a perfor-mance indicator and/or injury risk factor. However, publishedevidence of the reliability of many of these types of tests is lackingor insufficient. Studies have investigated the performance reli-ability of the countermovement vertical jump (Aragon-Vargas,2000; Arteaga, Dorado, Chavarren, & Calbet, 2000; Carlock et al.,2004; Markovic, Dizdar, Jukic, & Cardinale, 2004; Moir, Sanders,Button, & Glaister, 2005), drop vertical jump (Walsh et al., 2006)and single-leg vertical jump (Cordova & Armstrong, 1996; Flanagan& Harrison, 2007; Gustavsson et al., 2006; Newton et al., 2006;Risberg, Holm, & Ekeland, 1995) but there are no reliability data forsingle-leg drop jumps or maximum side-spring tests.
Few studies (Arteaga et al., 2000; Gustavsson et al., 2006) haveperformed more than two trials to demonstrate reliability, andmany (Carlock et al., 2004; Flanagan & Harrison, 2007; Markovicet al., 2004; Walsh et al., 2006) have used only single sessions, withmultiple trials within that session. Of the investigations establish-ing reliability across more than two trials, Arteaga (Arteaga et al.,2000) reported negligible learning effects for double-leg counter-movement jumps and drop jumps using a contact mat measure-ment device, and Gustavsson (Gustavsson et al., 2006) reportedsingle-leg vertical jump tests using a laser timing device as reliable(ICC: 0.89–0.97). Risberg (Risberg et al., 1995) concluded that thesingle-leg countermovement vertical jump measured using a Ver-tec measurement device had too much variation to be recom-mended (CV¼ 7.0% dominant, 7.7% non-dominant), using a twotrial test-retest design.
The protocols used for establishing the reliability of jump-basedtests may also vary substantially. For example, jumps may be per-formed with hands on hips, hands free, or from differing dropheights, use different measurement techniques such as contactmats, lasers, force plates, or Vertec, and perform different types ofjumps such as countermovement, drop, single or double-legvertical jumps. It is desirable that injury risk screening protocols aredeveloped that are easily performed and measured, cost effectiveand use portable equipment in order to increase their utility withlarger numbers of athletes.
Assessment of movement patterns by kinematic analysis iswidely advocated for injury risk factor evaluation. Three-dimen-sional kinematic analysis is the gold standard (McLean et al., 2005)but this limits the number of athletes that can be tested efficientlyand cost-effectively. With a move towards real world screening oflarger numbers of athletes, two-dimensional analysis is portable,more time efficient and cost effective. Two-dimensional movementanalysis has been validated against three-dimensional analysis forseveral functional movement tests (McLean et al., 2005), howeverlittle is known regarding the reliability of these movement testsacross multiple sessions using two-dimensional analysis.
To date, only the reliability of the double-leg drop jump test hasbeen reported using two-dimensional analysis (McLean et al.,2005). With jumping and landing tasks common in functional andperformance screening for locomotion-based team sport athletes;and dynamic valgus movements suggested as the major mecha-nism for ACL injury (Olsen, Mykleburst, Engebretsen, & Bahr, 2004),investigation of the two-dimensional medial/lateral knee actionsduring these movements for further use in large scale prospectivetesting is warranted.
The purpose of this study was to investigate the reliability of sixsimple movement tasks in which an objective performancemeasure and two-dimensional movement pattern recordings wereobtained simultaneously. The tests are easily performed, and theequipment used is easily operated, cost effective and portable.These tests could potentially form a battery of lower extremityassessment tools to be used in building a lower extremity profile ofathletes during pre and mid season screening, or for prospectivepre-season screening.
2. Methods
2.1. Participants
Seventeen males and seven females (University PhysicalEducation and TAFE Personal Training students) volunteered toparticipate in the study. The mean (95% CI) age of participants was23.7 (21.2–26.3) years and 21 of 24 subjects were right leg domi-nant. All participants were physically active and were not restrictedby any current injury at the time of the study. They participated ina range of competitive locomotion-based team and individualsports, at a variety of competition levels from recreational toprofessional. The study was approved by the University of New-castle Human Research Ethics Committee and written informedconsent was obtained from all participants prior to data collection.
2.2. Procedures
Subjects attended three testing sessions 5–12 days apart. Withsubject standing, major lower limb landmarks (Table 1 and Fig. 1)were identified and marked (1 cm square) using a permanentmarker pen. All subjects were marked, instructed, recorded andmeasured by one previously inexperienced tester for all threesessions. Inter-rater reliability was not investigated in this study. Allsubjects performed a common warm-up procedure containingbalance and specific jump/landing movements prior to testing. The
15 cm
contact mat
58 cm
functionalmovement box
video camera
2.9 m
contact mat
side view 15 cm
2.9 m
video camera
top view
Fig. 2. Equipment setup – functional movement testing.
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–3732
tests (anterior step-up, vertical jumps, side springs) are describedbelow, and practice trials for each test were performed for famil-iarisation prior to data collection at all test sessions.
All vertical jumps were performed on a 70 cm� 100 cmcomputer-interfaced contact mat (Kinematic Measurement System(KMS), Fitness Technologies, Adelaide, Australia) and maximumpower relative to body weight (W/kg) was measured for all verticaljumps. A line marked metrically for 3 m at 90� to a central line wasused for side-spring measurement. Kinematic data were filmedusing a single, anteriorly positioned video camera (PanasonicNV-GS180) on a spirit level tripod (Slick, 88S); a ceiling held plumbline was used to calibrate true vertical during subsequent videoanalysis (Dartfish Connect v4.9, Dartfish, Fribourg, Switzerland).The equipment setup for functional movement testing is shown inFig. 2.
2.2.1. Anterior step-upThe amount of compensatory movement required to support
the entire body weight on a single leg during a step up onto a 30 cmbox was assessed. Subjects were instructed to keep the non-working leg locked straight and to shift all weight to the workingleg as early as possible, stepping onto the box at a smoothcontrolled pace. Arms were extended anteriorly at shoulder heightthroughout the movement. Subjects were given as many efforts asrequired to perform the task within the criteria stated. A test was
Fig. 3. Single-leg vertic
repeated if: a) the non-working knee or ankle assisted the workingleg in upwards movement, b) the subject rocked forward onto theworking leg using momentum to assist the upward movement, orc) the subject lost balance during the movement.
2.2.2. Vertical jumpsCountermovement and reaction (drop) jumps were performed
using double and single legs. Subjects performed three repetitionsof each jump, with 20–30 s rest between repetitions. Foot place-ment zones were taped onto the drop box (30 cm) and contact matto ensure subjects started each repetition in the same location.Hands were placed on hips for all jump tests, with subjectsinstructed to keep the leg(s) straight underneath their body whilstin the air. Failure to comply with any of the protocols during a testresulted in a repeat of the individual repetition and removal of theinitial score from results.
2.2.2.1. Countermovement jumps. Three maximum effort double-leg countermovement vertical jumps (DCMJ) as described byArteaga (Arteaga et al., 2000) were performed, followed by threesingle-leg countermovement jumps (SCMJ) with each leg. Subjectswere instructed to keep the thigh of the non-working leg parallel tothe floor, with the knee at 90�. Fig. 3 demonstrates the startingposition and sequence of the single-leg countermovement verticaljump.
al jump sequence.
Fig. 4. Single-leg reactive (drop) jump sequence.
Fig. 5. Single-leg side-spring sequence.
Table 2Measurements recorded per test.
Test Video analysis KMS Floorruler
ANQ Thigh tohorizontal
Relative power(W/kg)
Cm
Doubleleg
Countermovementvertical jump
U
Drop vertical jump U
Singleleg
Anterior step-up U U
Countermovementvertical jump
U U U
Drop vertical jump U U U
Side spring U U U
ANQ (ankle, knee, quadriceps angle): formed by the distal anterior tibial margin, midpatella and mid thigh markers.Thigh angle to horizontal: formed by mid patella and mid thigh (anterior) markers,measured to horizontal.
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–37 33
2.2.2.2. Reactive (drop) jumps. Subjects performed a double-legdrop vertical jump (DDJ) from a 30 cm box height. A small double-leg jump off the edge of the box was used to initiate the test, withsubjects instructed to spring as quickly as possible off the contactmat and gain as much height as possible. Similarly, a small single-leg hop off the edge of the 30 cm box was used to initiate single-legdrop jumps (SDJ), with subjects springing off the mat and landingon the same leg in a balanced, stable position. Subjects wereinstructed to keep the thigh of the non-working leg parallel to thefloor, with the knee at 90�. Three trials were performed for each leg.Fig. 4 demonstrates the starting position and sequence of thesingle-leg drop vertical jump.
2.2.2.3. Single-leg side spring (SSS). A lateral, single-leg jump fordistance was performed off each leg (Fig. 5), with subjectsrequired to land on the opposite (non-working) leg, finishing ina balanced position. The distance from the centre line to theinstep of the landing leg was measured to the nearest 0.1 cm. Ifbalance was lost on landing, or no part of the foot landed on themeasurement line, the trial was repeated. Three trials were per-formed for each leg.
2.3. Measurements
A summary of the data obtained from each test is provided inTable 2. Relative jump power was calculated from the flight time offthe mat for both countermovement and drop vertical jumps.Kinematic data were obtained from all single-leg tests.
Measurement of the anterior step-up was taken at the first frame ofupward movement involving the subject’s non-working iliac spine(Fig. 6). The subject’s full weight is on the working leg, and anycompensatory movements of the hip and/or knee required tocomplete the task have been performed. Single-leg jumpingmovement angles were measured at the first frame of kneeextension after countermovement had been performed (Figs. 7and 8). The best performance of the three efforts was examined forkinematic measurement.
Fig. 6. Anterior step-up measurement.
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–3734
2.4. Data management and analysis
All data were exported from the KMS system or entered intoMicrosoft Excel (Microsoft Windows XP professional, Version5.1.2600) for data management. All data were analysed using reli-ability spreadsheets by Hopkins (Hopkins, 2006). The effects ofrandom and systematic change through sampling error andfamiliarisation were assessed using change in the mean (%) with95% confidence intervals between trials. Within-subject variationwas determined using typical error expressed as a coefficient ofvariation (%) as follows: typical error¼ [(sdiff/O2)/mean]/100where sdiff is the standard deviation of difference scores betweentwo trials. This measure represents technical and biological sourcesof error in measurement. Rank order repeatability of the resultsamong trials was investigated using intraclass correlation coeffi-cients (ICC, r). The ‘minimum-raw-change required’ was deter-mined to give an indication of the magnitude of change in a valueneeded for a meaningful change in the tested group mean with 95%
Fig. 7. Single-leg jump
confidence. This figure was calculated using the trial one test meanmultiplied by the percentage typical error between trials one andtwo (upper 95% CI). As this investigation was designed purely toinvestigate the reliability of the measures used, the single-leg datafrom left and right sides were treated as two individuals foranalysis.
3. Results
Descriptive statistics for the performance measures are pre-sented in Table 3. All tests performed from the floor (DCMJ, SCMJand SSS) demonstrated better reliability than the reactive (drop)tests (DDJ, SDJ) as indicated by smaller percentage changes inmeans and mean-typical errors, as well as higher ICC values.
Descriptive statistics for the kinematic measures are presentedin Table 4. Higher values indicate more stable movement and lessmedial movement of the knee. All test measures demonstratedtrivial to small changes in the mean values between trials. ICC
test measurement.
Fig. 8. Side-spring measurement.
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–37 35
values (r) were considered strong to very strong (r¼ 0.5–0.7)(Hopkins, 2006).
4. Discussion
All of the tests performed in this investigation are simple,portable and inexpensive procedures that can be used in the pre-season screening of large groups of athletes in a variety of settings.Simplicity in measurement usually involves an increase in thevariability of recorded measures; however excellent test-retestresults were obtained for most of the tests in this study. Although itis up to researchers to determine the level of variability in testmeasures they consider acceptable, desirable values for reliabilitymeasures are a change in the mean between trials 1 and 2 less than5%, typical error of less than 5% and ICC levels above 0.6. A summaryof the tests that met these criteria in this study is provided inTable 5. The reliability of the performance scores from both the
Table 3Test–retest reliability of performance measures.
Mean Change inmean (%)
95% CI Tea
Trial 1 Trial 2 Trial 3
Max vert jumpAvg rel power
(W/kg)13.7 13.7 13.8 Trial 2–1 0.10 �1.95 to 2.20
3–2 0.58 �1.11 to 2.31
Drop vert jumpAvg rel power
(W/kg)13.1 13.7 14.0 Trial 2–1 5.87 �0.57 to 12.73 1
single-leg and double-leg countermovement jump tests and theside-spring tests indicate they can be recommended as reliablescreening or performance evaluation tests. The single-leg step-up,countermovement jump and side-spring kinematic results are alsosufficiently reliable to justify investigating their effectiveness asscreening tests.
The typical error evaluation indicates the consistency of indi-viduals’ scores on repeated measures. Smaller percentages indicategreater consistency. Consequently, small changes in such a variablemay be functionally meaningful. The minimum-raw-change-required values listed in Tables 3 and 4 for each variable providecriterion values for the change in values required for meaningfulchange with an intervention or for identifying a true differencebetween groups, for example, if comparing injured and uninjuredathletes.
The ICC values for the performance scores were consistentlyhigher than those for the kinematic values. This primarily reflectsthe limited range of values obtained from healthy individuals onthe kinematic measures where variations of only one or twodegrees can change the rank order of participants. This highlightsthe problems with sole reliance on ICC values for determiningreliability. All the mean-typical-error results for the kinematicmeasures were less than 5% indicating excellent test-retest reli-ability for individuals.
Improved values in the mean for a variable between trialsusually indicate a learning effect. Improvements between trials oneand two but not subsequent trials suggest a familiarisation sessionwould be beneficial to improve the accuracy of the values obtained.In this study, substantial improvements between the first two trialswere observed for the drop jump tests, particularly the double-legged drop jump test.
A number of studies have determined the reliability of therelative power values obtained on the DCMJ test. Using a singlesession retest design, Markovic (Markovic et al., 2004) reportedfigures of 2.8% for CV and 0.98 for ICC, with Carlock (Carlock et al.,2004) reporting similar ICC values. The current study observedmarginally higher (3.2%) mean-typical error as CV values acrossthree test sessions, and Artega (Arteaga et al., 2000) reportedhigher CV values (6.3%) across six separate testing sessions. Notsurprisingly, this suggests that there is more variability whenthere is more time between tests. Alternatively, differences instatistical methodology could explain the difference, as the
ypicalrrors CV (%)
95% CI Mean-typicalerror asCV (%)
95% CI ICC (r) 95% CI Minimum-raw-changerequired(W/kg)
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–3736
method of calculating CV employed by Artega (Arteaga et al.,2000) differed to that described by Hopkins (2000) and used byboth this study and Markovic (Markovic et al., 2004). This possi-bility was investigated by analysing the data from the current studyusing the method of Artega, and this demonstrated a negligibledifference between the CV (%) values produced using the twomethods.
The ICC values for DDJ relative power were identical to thosepreviously reported by Walsh (Walsh et al., 2006) (r¼ 0.84), whoused a portable force plate and single session retest design. Thismeasure did however demonstrate typical error of 11% (95% CI:8.52–15.90%) between trials one and two, making its use in eval-uating performance questionable. The reactive (drop) jump resultswere consistently more variable than the countermovement jumpresults, clearly indicating that the drop jumps are inferior in termsof reliability. The magnitude of the typical error influences the sizeof the minimum difference between two values that is meaningfuleither in test-retest situations or when comparing groups. For the
Table 5Acceptable testing procedures and measures.
Side spring CM: 0.16% CM: 1.65% CM: 2.6%MTE: 4.3% MTE: 3.8% MTE: 2.8%ICC: 0.75 ICC: 0.73 ICC: 0.84
CM: change in mean (trial 1–2); MTE: mean-typical error %; ICC: intraclass corre-lation coefficient r (average of between trial results).
DDJ, a change of 2.1 W/kg (147 W for a 70 kg person) or 16% ofinitial value is required before the change would be regarded asmore than normal variation with 95% confidence.
Two previous studies by Gustavsson (Gustavsson et al., 2006)and Risberg (Risberg et al., 1995) have evaluated the reliability ofSCMJ relative power. These studies reported ICC values rangingfrom 0.89 to 0.97 and CV values ranging 4.0% to 7.7%, supporting thefindings from the current study. No reliability studies have beenpublished previously on SDJ relative power, SSS distance or kine-matic measures for step-up, SCMJ, SDJ and SSS.
This study has demonstrated that most of the tests evaluated arereliable, however limitations must be recognised. Inter-rater reli-ability was not investigated as one investigator provided all theinstructions to participants in this study and performed all thekinematic analyses. The procedures used are relatively simple, withmost measures collected electronically at the time of testing,making instruction of the subject the major source of variability.With appropriate training, we believe high inter-rater reliabilitywill be established for these tests but further investigation isrequired to establish this. The subject group included both malesand females, with no separate analysis of reliability for each gendergroup. The participants were young adults, with no indication ofhow results may vary across an older or younger population.Although the validity and clinical relevance of these performanceand kinematic measures are yet to be determined, ensuring that themeasures used in such clinical studies are of high reliability allowsmore effective investigation of performance levels and relation-ships to the functional demands of the athlete (performance and/orinjury reduction).
5. Conclusion
This study has established the reliability of a battery ofscreening procedures in which performance and two-dimensionalmovement patterns data are obtained simultaneously using easilyoperated, portable equipment. A laboratory environment is notrequired to conduct these tests. Quantifying the measurements
A. Miller, R. Callister / Physical Therapy in Sport 10 (2009) 30–37 37
with minimal time demands is possible due to the ease of useof the new movement measurement software. One investigatorconducted and analysed all tests in this study, and although thisinvestigator had no prior experience at conducting these tests,intra-rater reliability was established for many of the procedures.Inter-rater reliability remains to be established and further inves-tigation of the validity of these procedures for use in performanceand injury or rehabilitation screening is recommended.
Conflict of Interest
The authors perceive no conflict of interest in this study.
Ethical Approval
University of Newcastle Human Research Ethics Committee,Approval No. H-252-0706.
Funding
This project was funded by the University of Newcastle and theN.S.W Research and Injury Prevention Scheme.
Acknowledgements
This project was funded by the University of Newcastle and theN.S.W Research and Injury Prevention Scheme.
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