The External Validity of a Novel Contract-Relax Stretching Technique on Knee Flexor Range of Motion

Anthony D Kay, J Dixon, L D Bligh, Anthony J Blazevich

Research output: Contribution to JournalArticlepeer-review


Introduction: Compromised joint range of motion (ROM) can negativelyaffect the capacity to perform activities of daily living in clinicalpopulations.  Recently, similar improvementsin dorsiflexion ROM were reported following dynamometry-based contract-relax(CR) stretching and modified CR stretching technique (stretch-return-contract[SRC]) where the contraction phase was performed ‘off stretch’.  As neither the impact of SRC on other musclegroups nor the ecological validity of SRC performed in an applied environment havebeen tested, the acute effects of both techniques in dynamometry- (CRdynaand SRCdyna) and field-based (CRfield and SRCfield)environments were compared in the hamstring muscle group.  

Methods:Seventeen participants performed each of the four stretching conditions on separatedays in a randomised order. Before and after the stretches, knee extension ROM and passive knee flexor moment were recorded on an isokineticdynamometer.  

Results: Significant (P<0.01)increases in knee extension ROM (4.6-5.2°) and elastic potential energy storage(12.0-23.6%) and decreases in the slope of the passive moment-angle relation (8.9-12.2%)occurred in all conditions.  Significantincreases in peak passive joint moment were observed after field- (14.3-14.8%)but not dynamometry-based (4.6-6.6%) stretches. No difference (P>0.05) inany measure was found between conditions.  

Conclusions:These data confirm the acute efficacy of the SRC technique in the hamstringmuscle group and demonstrate its ecological validity in an applied environmentin healthy participants.  As the field-basedSRC technique was performed without partner assistance, when compared with classicalPNF it represents an equally effective and practical stretching paradigm to supportathletic and clinical exercise prescription.

Original languageEnglish
Pages (from-to)74-82
Number of pages9
JournalScandinavian Journal Of Medicine & Science in Sports
Issue number1
Early online date3 Oct 2019
Publication statusPublished - 5 Dec 2019

Bibliographical note

© 2019 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.


  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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