scholes cj phd 1,2,3 mcdonald md phd 2 coolican mrj fracs 1 parker da fracs 1

www.sori.com.au

SydneyAustrali

a

SORI

Efficacy of Repetitive Stepping as a Efficacy of Repetitive Stepping as a Test of Quadriceps Fatigue: Test of Quadriceps Fatigue:

Comparison to Isokinetic ExerciseComparison to Isokinetic Exercise

Scholes CJ Scholes CJ PhDPhD1,2,31,2,3

McDonald MD McDonald MD PhDPhD22

Coolican MRJ Coolican MRJ FRACSFRACS11

Parker DA Parker DA FRACSFRACS11

Parker AW Parker AW PhDPhD33

11 Sydney Orthopaedic Research Institute Sydney Orthopaedic Research Institute22 School of Human Movement Studies, Queensland University of Technology School of Human Movement Studies, Queensland University of Technology

33Institute of Health & Biomedical Innovation, Queensland University of TechnologyInstitute of Health & Biomedical Innovation, Queensland University of Technology

Australian Orthopaedic AssociationAustralian Orthopaedic Association7070thth Annual Scientific Meeting Annual Scientific Meeting

Adelaide, 2010Adelaide, 2010

www.sori.com.auwww.sori.com.au

Conflict of InterestConflict of Interest

There is no conflict of interest in this research There is no conflict of interest in this research projectproject


Quadriceps FunctionQuadriceps Function

Strength and endurance critical Strength and endurance critical to knee functionto knee function

Implications of dysfunction Implications of dysfunction following surgeryfollowing surgery

Quadriceps avoidance Quadriceps avoidance (Lewek et (Lewek et al 2002)al 2002)

Joint loading Joint loading (Shelbourne et al 2004)(Shelbourne et al 2004)

Functional instability Functional instability (Hurd et al (Hurd et al 2007)2007)

Endurance improves Endurance improves performance of functional performance of functional activitiesactivities


IntroductionIntroduction

Dynamometry – ‘gold standard’Dynamometry – ‘gold standard’

LimitationsLimitations Cost (~$100k)Cost (~$100k) SpaceSpace Dedicated specialist personnelDedicated specialist personnel

Need for a clinical alternative Need for a clinical alternative


AimAim

Validate a functional protocol to induce and Validate a functional protocol to induce and quantify quadriceps fatigue compared to quantify quadriceps fatigue compared to isokinetic dynamometryisokinetic dynamometry


MethodsMethods

ParticipantsParticipants Male undergraduates Male undergraduates 20.620.6++2.5yrs2.5yrs 1.781.78++0.05m0.05m 72.372.3++8.8kg8.8kg

Repetitive Repetitive SteppingStepping

Additional WeightAdditional Weight Step HeightStep Height Start-end PosturesStart-end Postures SpeedSpeed


MethodsMethods

DynamometryDynamometry 50 Repetitions50 Repetitions

Concentric-EccentricConcentric-Eccentric

Range-of-motion 90Range-of-motion 9000

Speed 60Speed 6000/sec/sec


Methods - Fatigue Methods - Fatigue IndicatorsIndicators

Peak powerPeak power

Inverse Inverse dynamicsdynamics

Integrated Integrated torque/timtorque/timee


Methods - Fatigue Methods - Fatigue IndicatorsIndicators

Surface Surface ElectromyographyElectromyography

Wireless (Zerowire, Wireless (Zerowire, Italy)Italy)

VM, VL, RFVM, VL, RF Standardised Standardised

placementplacement


Methods - Mean FrequencyMethods - Mean Frequency


Results - Peak Power Results - Peak Power ProductionProduction


Results - Mean FrequencyResults - Mean Frequency


Results - Protocol Results - Protocol ComparisonComparison

*

* Significant difference between stepping and isokinetic

^

^Significant difference between muscles


DiscussionDiscussion

Stepping induced greater fatigue compared to Stepping induced greater fatigue compared to previous studies previous studies (Coventry et al 2006; Bonato et al 2001)(Coventry et al 2006; Bonato et al 2001)

Isokinetic exercise also induced greater fatigue Isokinetic exercise also induced greater fatigue compared to previous studies compared to previous studies (Molinari et al 2006)(Molinari et al 2006)

Combined eccentric-concentric actionCombined eccentric-concentric action

Differential isokinetic fatigue pattern agrees Differential isokinetic fatigue pattern agrees with previous studies with previous studies (Molinari et al 2006)(Molinari et al 2006)


DiscussionDiscussion

Lack of studies quantifying fatigue progression Lack of studies quantifying fatigue progression in quadriceps during functional taskin quadriceps during functional task

Parallel fatigue could be related to joint stability Parallel fatigue could be related to joint stability and balance during steppingand balance during stepping

Increased variability in power productionIncreased variability in power production Load sharing between hip and kneeLoad sharing between hip and knee


ConclusionsConclusions

Stepping protocol valid method to induce Stepping protocol valid method to induce quadriceps fatiguequadriceps fatigue

not as effective as isokinetic exercisenot as effective as isokinetic exercise

Potential future model for clinic-based fatigue Potential future model for clinic-based fatigue assessmentassessment


Future clinical toolFuture clinical tool Adjustments to the protocol to reduce variabilityAdjustments to the protocol to reduce variability

Validity and reliability for surgically-repaired kneesValidity and reliability for surgically-repaired knees Modify protocol for patient populationsModify protocol for patient populations Effects of rehabilitationEffects of rehabilitation

Clinical measurements – fatigue indicatorsClinical measurements – fatigue indicators Steps to exhaustionSteps to exhaustion Stepping frequencyStepping frequency


Thank You

scholes cj phd 1,2,3 mcdonald md phd 2 coolican mrj fracs 1 parker da fracs 1

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