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This Article Full Text Full Text (PDF) All Versions of this Article: 586/1/97    most recent jphysiol.2007.140434v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Morse, C. I. Articles by Jones, D. A. Search for Related Content PubMed PubMed Citation Articles by Morse, C. I. Articles by Jones, D. A. Related Collections Skeletal Muscle and Exercise

¹ Institute for Biophysical and Clinical Research into Human Movement (IRM), Manchester Metropolitan University, Hassall Road, Alsager, Cheshire ST7 2HL, UK
² School of Sport and Exercise Sciences, the University of Birmingham, Birmingham, UK

Passive stretching is commonly used to increase limb range of movement prior to athletic performance but it is unclear which component of the muscle–tendon unit (MTU) is affected by this procedure. Movement of the myotendinous junction (MTJ) of the gastrocnemius medialis muscle was measured by ultrasonography in eight male participants (20.5 ± 0.9 years) during a standard stretch in which the ankle was passively dorsiflexed at 1 deg s^–1 from 0 deg (the foot at right angles to the tibia) to the participants' volitional end range of motion (ROM). Passive torque, muscle fascicle length and pennation angle were also measured. Standard stretch measurements were made before (pre-) and after (post-) five passive conditioning stretches. During each conditioning stretch the MTU was taken to the end ROM and held for 1 min. Pre-conditioning the extension of the MTU during stretch was taken up almost equally by muscle and tendon. Following conditioning, ROM increased by 4.6 ± 1.5 deg (17%) and the passive stiffness of the MTU was reduced (between 20 and 25 deg) by 47% from 16.0 ± 3.6 to 10.2 ± 2.0 Nm deg^–1. Distal MTJ displacement (between 0 and 25 deg) increased from 0.92 ± 0.06 to 1.16 ± 0.05 cm, accounting for all the additional MTU elongation and indicating that there was no change in tendon properties. Muscle extension pre-conditioning was explicable by change in length and pennation angle of the fascicles but post-conditioning this was not the case suggesting that at least part of the change in muscle with conditioning stretches was due to altered properties of connective tissue.

(Received 11 July 2007; accepted after revision 18 September 2007; first published online 20 September 2007)
Corresponding author C. I. Morse: Institute for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Alsager Campus, Hassall Road, Alsager, Cheshire ST7 2HL, UK. Email: c.morse{at}mmu.ac.uk