title: Time course of changes in the human Achilles tendon properties and metabolism during training and detraining in vivo.
abstract: The purpose of this study was to investigate the time course of changes in human tendon properties and metabolism during resistance training and detraining. Nine men (21-27 years) completed 3 months of isometric plantar flexion training and another 3 months of detraining. At the beginning and on every 1 month of training and detraining periods, the stiffness, blood circulation (blood volume and oxygen saturation), serum procollagen type 1 C-peptide (P1P; reflects synthesis of type 1 collagen), echointensity (reflects collagen content), and MRI signal intensity (reflects collagen structure) of the Achilles tendon were measured. Tendon stiffness did not change until 2 months of training, and the increase (50.3%) reached statistical significance at the end of the training period. After 1 month of detraining, tendon stiffness had already decreased to pre-training level. Blood circulation in the tendon did not change during the experimental period. P1P increased significantly after 2 months of training. Echointensity increased significantly by 9.1% after 2 months of training, and remained high throughout the experiment. MRI signal intensity increased by 24.2% after 2 months and by 21.4% after 3 months of training, but decreased to the pre-training level during the detraining period. These results suggested that the collagen synthesis, content, and structure of human tendons changed at the 2-month point of training period. During detraining, the sudden decrease in tendon stiffness might be related to changes in the structure of collagen fibers within the tendon.
authors: Department of Life Science (Sports Sciences), University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan. kubo@idaten.c.u-tokyo.ac.jp
authors: Keitaro
authors: K
authors: Kubo
authors: Toshihiro
authors: T
authors: Ikebukuro
authors: Akira
authors: A
authors: Maki
authors: Hideaki
authors: H
authors: Yata
authors: Naoya
authors: N
authors: Tsunoda
mesh_terms: D000125:Achilles Tendon / Q000033:anatomy & histology* / Q000502:physiology*; D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D002096:C-Peptide / Q000097:blood*; D003094:Collagen / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010809:Physical Fitness / Q000502:physiology*; D055815:Young Adult
chemical_list: D002096:C-Peptide; D003094:Collagen; D010100:Oxygen