Viscoelastic creep in the human skeletal muscle–tendon unit

• Published in: European journal of applied physiology 2010-01, Vol.108 (1), p.207-211
• Main Authors: Ryan, Eric D., Herda, Trent J., Costa, Pablo B., Walter, Ashley A., Hoge, Katherine M., Stout, Jeffery R., Cramer, Joel T.
• Format: Article
• Language: English
• Subjects: Age Factors; Aging - physiology; Ankle Joint - physiology; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Electromyography; Fundamental and applied biological sciences. Psychology; Human Physiology; Humans; Laboratories; Leg - physiology; Muscle Contraction - physiology; Muscle Strength - physiology; Muscle Stretching Exercises - methods; Muscle, Skeletal; Neuromuscular diseases; Occupational Medicine/Industrial Medicine; Posture - physiology; Proprioception; Range of motion; Range of Motion, Articular - physiology; Short Communication; Signal processing; Sports Medicine; Tendon Injuries - physiopathology; Tendons; Torque; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Viscoelastic Substances; Viscoelasticity
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-009-1284-2

The purposes of the present study were to (1) characterize viscoelastic creep in vivo in the human skeletal muscle–tendon unit and (2) to examine the consistency of these responses during a single 30-s stretch. Twelve volunteers (mean ± SD = 22 ± 3 years; height = 169 ± 11 cm; mass = 70 ± 17 kg) participated in two separate experimental trials. Each trial consisted of a 30-s constant-torque stretch of the plantar flexor muscles. Position (°) values were quantified at every 5-s period (0, 5, 10, 15, 20, 25, and 30 s) and the percent change in position was quantified for each 5-s epoch (0–5, 5–10, 10–15, 15–20, 20–25, and 25–30 s) relative to the total increase in the range of motion. In addition, the intraclass correlation coefficient (ICC) and standard errors of the measurement (SEM) were calculated for test–retest reliability. These results indicated that position increased over the entire 30-s stretch ( P   0.994 and SEM values (expressed as percentage of the mean) were < 1.54%. In conclusion, these results demonstrate viscoelastic creep in vivo in the human skeletal muscle–tendon unit and suggest that these responses may be reliable for future studies.