title: Strain and elongation of the human semitendinosus muscle - tendon unit.
abstract: The semitendinosus (ST) consists of a long distal tendon and it is divided in two parts by a tendinous inscription (TI). The purpose of this study was to quantify strain and elongation of the TI and the distal tendon of ST. Fourteen subjects performed ramp isometric contractions of the knee flexors at 0°, 45° and 90° of knee flexion. Two ultrasound probes were used to visualize the displacement of the distal tendon and selected points across the TI and aponeuroses. Three-way analysis of variance designs indicated that: (a) strain and elongation of the ST distal muscle-tendon junction were higher than that of the aponeurosis - TI junction points (p < 0.05) (b) the long arm of the TI reach strain of 49.86 ± 7.77% which was significantly (p < 0.05) higher than that displayed by the short arm (28.35 ± 0.59%) (c) Strain of tendinous and TI-aponeuroses segments significantly increased from 90° to 0° of knee flexion while the inverse was observed for the TI arm length (p < 0.05). (d) Tendon strain was significantly higher than strain of the TI-aponeuroses segments at 45° and 90° of knee flexion while the opposite was observed at 0° of knee flexion. The arrangement of TI along ST length results in differential local strains, indicating that the mechanical properties of the ST muscle are affected by tendon, aponeuroses and tendinous inscription interactions.
authors.affiliation: Laboratory of Neuromechanics, Department of Physical Education and Sport Sciences at Serres, Aristotle University of Thessaloniki, Greece. Electronic address: ekellis@phed-sr.auth.gr.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Kellis
authors.forename: Glykeria
authors.initials: G
authors.lastname: Patsika
authors.forename: Evaggelos
authors.initials: E
authors.lastname: Karagiannidis
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003238:Connective Tissue / Q000502:physiology; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007717:Knee / Q000502:physiology; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology; D008297:Male; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D011187:Posture / Q000502:physiology; D012399:Rotation; D013314:Stress, Mechanical; D013710:Tendons / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D055815:Young Adult
keywords: Connective tissue; Isometric contraction; Skeletal muscles; Tendons; Ultrasonography