Journal article
Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo
Journal of Applied Physiology, Vol.105(4), pp.1035-1043
2008
Abstract
The purpose of this study was to elucidate the effect of normal fluctuating [non-monophasic oral contraceptive pill (MOCP) users] and low, consistent (MOCP users) endogenous plasma estrogen levels on the strain behavior of the Achilles tendon in vivo. Twenty women (age 28.0±4.2 yr, height 1.67±0.07 m, mass 61.6±6.8 kg) who had been using the MOCP for at least 12 mo together with 20 matched women who were non-MOCP users (age 31.9±7.3 yr, height 1.63±0.05 m, mass 62.5±5.9 kg) participated in this study. Non-MOCP users were tested at the time of lowest (menstruation) and highest (≈ovulation) estrogen, whereas MOCP users, who exhibited constant and attenuated endogenous estrogen levels, were tested at day 1 and day 14 of their cycle. At each test session, maximal isometric plantarflexion efforts were performed on a calf-raise apparatus while synchronous real-time ultrasonography of the triceps surae aponeurosis was recorded. Achilles tendon strain (%) was calculated by dividing tendon displacement during plantarflexion by resting tendon length. Repeatedmeasures ANOVA revealed a significant (P < 0.05) main effect of subject group with significantly lower Achilles strain (25.5%) in the MOCP users compared with the non-MOCP users. In conclusion, acute fluctuations in plasma estrogen across the menstrual cycle in non-MOCP users did not alter the strain behavior of the Achilles tendon. Conversely, long-term exposure to attenuated estrogen in MOCP users resulted in a decrease in Achilles tendon strain, which is thought to be attributed to the effects of endogenous estrogen on collagen synthesis. These findings have a number of important functional and clinical implications. Copyright © 2008 the American Physiological Society.
Details
- Title
- Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo
- Authors
- A L Bryant (Author) - University of MelbourneRoss Clark (Author) - University of MelbourneS Bartold (Author) - University of Staffordshire, United KingdomA Murphy (Author) - University of Technology SydneyK L Bennell (Author) - University of MelbourneE Hohmann (Author) - Rockhampton Base HospitalS Marshall-Gradisnik (Author) - Bond UniversityC Payne (Author) - La Trobe UniversityK M Crossley (Author) - University of Melbourne
- Publication details
- Journal of Applied Physiology, Vol.105(4), pp.1035-1043
- Publisher
- American Physiological Society
- Date published
- 2008
- DOI
- 10.1152/japplphysiol.01281.2007
- ISSN
- 8750-7587
- Organisation Unit
- University of the Sunshine Coast, Queensland; School of Health and Sport Sciences - Legacy; School of Health and Behavioural Sciences - Legacy; School of Health - Public Health
- Language
- English
- Record Identifier
- 99450598702621
- Output Type
- Journal article
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- Sport Sciences
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