Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo

Bryant, Adam L., Clark, Ross A., Bartold, Simon, Murphy, Aron, Bennell, Kim L., Hohmann, Erik, Marshall-Gradisnik, Sonya, Payne, Craig and Crossley, Kay M. (2008) Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo. Journal of Applied Physiology, 105 4: 1035-1043. doi:10.1152/japplphysiol.01281.2007

Author Bryant, Adam L.
Clark, Ross A.
Bartold, Simon
Murphy, Aron
Bennell, Kim L.
Hohmann, Erik
Marshall-Gradisnik, Sonya
Payne, Craig
Crossley, Kay M.
Title Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 8750-7587
Publication date 2008-10
Sub-type Article (original research)
DOI 10.1152/japplphysiol.01281.2007
Volume 105
Issue 4
Start page 1035
End page 1043
Total pages 9
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Language eng
Formatted 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. Repeated-measures 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.
Keyword Strain
Anterior cruciate ligament
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Health and Rehabilitation Sciences Publications
School of Medicine Publications
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Citation counts: TR Web of Science Citation Count  Cited 40 times in Thomson Reuters Web of Science Article | Citations
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