{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T05:06:13Z","timestamp":1791435973700,"version":"4.3.3"},"reference-count":62,"publisher":"American Physiological Society","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2008,10]]},"abstract":"<jats:p>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 \u00b1 4.2 yr, height 1.67 \u00b1 0.07 m, mass 61.6 \u00b1 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 \u00b1 7.3 yr, height 1.63 \u00b1 0.05 m, mass 62.5 \u00b1 5.9 kg) participated in this study. Non-MOCP users were tested at the time of lowest (menstruation) and highest (\u2248ovulation) 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 &lt; 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.<\/jats:p>","DOI":"10.1152\/japplphysiol.01281.2007","type":"journal-article","created":{"date-parts":[[2008,6,19]],"date-time":"2008-06-19T21:22:18Z","timestamp":1213910538000},"page":"1035-1043","source":"Crossref","is-referenced-by-count":101,"title":["Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo"],"prefix":"10.1152","volume":"105","author":[{"given":"Adam L.","family":"Bryant","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ross A.","family":"Clark","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simon","family":"Bartold","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aron","family":"Murphy","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kim L.","family":"Bennell","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erik","family":"Hohmann","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sonya","family":"Marshall-Gradisnik","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Craig","family":"Payne","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kay M.","family":"Crossley","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","unstructured":"Alexander RM\n                      , Vernon A.\n                      The dimensions of the knee and ankle muscles and the forces they exert.\n                      J Hum Mov Stud\n                      1\n                      : 115\u2013123, 1975."},{"key":"R2","unstructured":"Alnaqueeb MA\n                      , Goldspink G.\n                      Changes in fiber type, number and diameter in aging muscles.\n                      J Anat\n                      152\n                      : 31\u201345, 1986."},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1177\/0363546505275149"},{"key":"R4","unstructured":"Bradley M\n                      , Schumann B.\n                      Examination of urine. In:\n                      Clinical Diagnosis and Management by Laboratory Methods\n                      , edited by Henry JB. Philadelphia, PA: Saunders, 1984, p. 380\u2013387."},{"key":"R5","doi-asserted-by":"publisher","DOI":"10.1080\/02841850600854936"},{"key":"R6","doi-asserted-by":"publisher","DOI":"10.2165\/00007256-200737070-00001"},{"key":"R7","unstructured":"Bush IE\n                      .\n                      Determination of estrogens, androgens, progesterone, and related steroids in human plasma and urine. In:\n                      The Chromotography of Steroids\n                      , edited by Bush IE. New York: Pergamon, 1961, p. 57\u2013139."},{"key":"R8","doi-asserted-by":"publisher","DOI":"10.1128\/MCB.00233-07"},{"key":"R9","doi-asserted-by":"crossref","unstructured":"Clark R\n                      , Child S, Crossley K, Bryant AL.\n                      Reliability of an in vivo measure of Achilles tendon strain.\n                      J Sci Med Sport\n                      10\n                      : 78, 2007.","DOI":"10.1016\/S1440-2440(07)70224-4"},{"key":"R10","doi-asserted-by":"publisher","DOI":"10.1007\/s00264-001-0326-0"},{"key":"R11","doi-asserted-by":"publisher","DOI":"10.1007\/s00167-006-0143-5"},{"key":"R12","doi-asserted-by":"publisher","DOI":"10.1136\/bjsm.2003.009886"},{"key":"R13","unstructured":"Ferin MJ\n                      .\n                      The menstrual cycle: an integrative view. In:\n                      Reproductive Endocrinology, Surgery, and Technology\n                      , edited by Adashi EY, Rock JA, Rosenwaks Z. Philadelphia, PA: Lippincott-Raven, 1996, p. 106."},{"key":"R14","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00775.2002"},{"key":"R15","doi-asserted-by":"publisher","DOI":"10.1016\/0010-7824(96)00136-9"},{"key":"R16","doi-asserted-by":"publisher","DOI":"10.1007\/BF00238560"},{"key":"R17","doi-asserted-by":"publisher","DOI":"10.1098\/rspb.2000.1361"},{"key":"R18","doi-asserted-by":"publisher","DOI":"10.1016\/S1050-6411(02)00003-2"},{"key":"R19","doi-asserted-by":"publisher","DOI":"10.1016\/S1050-6411(02)00002-0"},{"key":"R20","doi-asserted-by":"crossref","unstructured":"Hart DA\n                      , Archambault JM, Kydd A, Reno C, Frank CB, Herzog W.\n                      Gender and neurogenic variables in tendon biology and repetitive motion disorders.\n                      Clin Orthop Rel Res\n                      351\n                      : 44\u201356, 1998.","DOI":"10.1097\/00003086-199806000-00007"},{"key":"R21","unstructured":"Heitz NA\n                      , Eisenman PA, Beck CL, Walker JA.\n                      Hormonal changes throughout the menstrual cycle and increased anterior cruciate ligament laxity in females.\n                      J Athletic Training\n                      34\n                      : 144\u2013149, 1999."},{"key":"R22","doi-asserted-by":"crossref","unstructured":"Hill AV\n                      .\n                      The heat of shortening and the dynamic constraints of muscle.\n                      Proc R Soc Lond\n                      136\u2013195, 1938.","DOI":"10.1098\/rspb.1938.0050"},{"key":"R23","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1998.85.4.1230"},{"key":"R24","doi-asserted-by":"publisher","DOI":"10.1111\/j.1600-0838.1997.tb00121.x"},{"key":"R25","doi-asserted-by":"publisher","DOI":"10.1097\/00042752-200007000-00003"},{"key":"R26","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.2001.013459"},{"key":"R27","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7998.1988.tb02432.x"},{"key":"R28","doi-asserted-by":"publisher","DOI":"10.1152\/physrev.00031.2003"},{"key":"R29","doi-asserted-by":"publisher","DOI":"10.1249\/00003677-198401000-00006"},{"key":"R30","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-201X.2003.01097.x"},{"key":"R31","doi-asserted-by":"publisher","DOI":"10.1249\/01.mss.0000247006.24965.74"},{"key":"R32","doi-asserted-by":"publisher","DOI":"10.1016\/j.matbio.2004.07.004"},{"key":"R33","doi-asserted-by":"publisher","DOI":"10.1097\/00003677-200404000-00005"},{"key":"R34","doi-asserted-by":"publisher","DOI":"10.1016\/j.jbiomech.2005.10.035"},{"key":"R35","doi-asserted-by":"publisher","DOI":"10.1159\/000016708"},{"key":"R36","doi-asserted-by":"publisher","DOI":"10.1177\/036354659702500521"},{"key":"R37","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7793.1998.977bj.x"},{"key":"R38","doi-asserted-by":"publisher","DOI":"10.1016\/S0021-9290(02)00240-3"},{"key":"R39","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7793.2001.0277j.x"},{"key":"R40","doi-asserted-by":"publisher","DOI":"10.2106\/00004623-197658050-00001"},{"key":"R41","doi-asserted-by":"publisher","DOI":"10.1097\/00042752-200409000-00006"},{"key":"R42","doi-asserted-by":"publisher","DOI":"10.1152\/ajpendo.00300.2005"},{"key":"R43","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00797.2006"},{"key":"R44","doi-asserted-by":"crossref","unstructured":"Moller-Nielsen J\n                      , Hammar M.\n                      Women's soccer injuries in relation to the menstrual cycle and oral contraceptive use.\n                      Med Sci Sports Exerc\n                      21\n                      : 126\u2013129, 1989.","DOI":"10.1249\/00005768-198904000-00003"},{"key":"R45","doi-asserted-by":"crossref","unstructured":"Movin T\n                      , Guntner P, Gad A, Rolf C.\n                      Ultrasonography-guided percutaneous core biopsy in Achilles tendon disorder.\n                      Scand J Med Sci Sports\n                      7\n                      : 244\u2013248, 1997.","DOI":"10.1111\/j.1600-0838.1997.tb00147.x"},{"key":"R46","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2001.90.5.1671"},{"key":"R47","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00624.2004"},{"key":"R48","doi-asserted-by":"publisher","DOI":"10.1159\/000083731"},{"key":"R49","doi-asserted-by":"crossref","unstructured":"O'Brien M\n                      .\n                      Structure and metabolism of tendons.\n                      Scand J Med Sci Sports\n                      7\n                      : 55\u201361, 1997.","DOI":"10.1111\/j.1600-0838.1997.tb00119.x"},{"key":"R50","unstructured":"Pichler W\n                      , Tesch NP, Schwantzer G, Fronhofer G, Boldin C, Hausleitner L, Grechenig W.\n                      Differences in length and cross-section of semitendinosus and gracilis tendons and their effect on anterior cruciate ligament reconstruction: a cadaver study.\n                      J Bone Joint Surg\n                      90\n                      : 516\u2013519, 2008."},{"key":"R51","doi-asserted-by":"publisher","DOI":"10.1002\/mus.10392"},{"key":"R52","unstructured":"Romani W\n                      , Curl LA, Lovering R.\n                      The effect of endogenous estradiol levels at three phases of the menstrual cycle on anterior cruciate ligament stiffness in active females.\n                      J Athletic Training\n                      2\n                      : S62, 2001."},{"key":"R53","doi-asserted-by":"publisher","DOI":"10.1034\/j.1600-0838.2002.120205.x"},{"key":"R54","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1996.sp021381"},{"key":"R55","doi-asserted-by":"crossref","unstructured":"Sneader W\n                      .\n                      Hormone analogues. In:\n                      Drug Discovery: A History.\n                      Hoboken, NJ: Wiley, 2005, p. 188\u2013225.","DOI":"10.1002\/0470015535"},{"key":"R56","doi-asserted-by":"publisher","DOI":"10.1016\/j.contraception.2005.03.005"},{"key":"R57","doi-asserted-by":"publisher","DOI":"10.1007\/BF02425495"},{"key":"R58","doi-asserted-by":"publisher","DOI":"10.1152\/ajpendo.00367.2005"},{"key":"R59","doi-asserted-by":"crossref","unstructured":"Westh E\n                      , Kongsgaard M, Bojsen-Moller J, Aagaard P, Hansen M, Kjaer M, Magnusson SP.\n                      Effect of habitual exercise on the structural and mechanical properties of human tendon, in vivo, in men and women.\n                      Scand J Med Sci Sports\n                      18\n                      : 23\u201330, 2008.","DOI":"10.1111\/j.1600-0838.2007.00638.x"},{"key":"R60","unstructured":"Whiting AC\n                      , Zernicke RF.\n                      In:\n                      Biomechanics of Musculoskeletal Injury.\n                      Champaign, IL: Human Kinetics, 1998."},{"key":"R61","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1994.76.6.2714"},{"key":"R62","doi-asserted-by":"publisher","DOI":"10.1177\/03635465020300020601"}],"container-title":["Journal of Applied Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/japplphysiol.01281.2007","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,8]],"date-time":"2019-09-08T18:19:57Z","timestamp":1567966797000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/japplphysiol.01281.2007"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2008,10]]},"references-count":62,"journal-issue":{"issue":"4","published-print":{"date-parts":[[2008,10]]}},"alternative-id":["10.1152\/japplphysiol.01281.2007"],"URL":"https:\/\/doi.org\/10.1152\/japplphysiol.01281.2007","relation":{},"ISSN":["8750-7587","1522-1601"],"issn-type":[{"value":"8750-7587","type":"print"},{"value":"1522-1601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2008,10]]}}}