title: Viscoelastic creep in the human skeletal muscle-tendon unit.
abstract: 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 (degrees) 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 < 0.05), while the majority of the increases in position (73-85%) occurred during the first 15-20 s. ICC values were >or = 0.994 and SEM values (expressed as percentage of the mean) were <or= 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.
authors.affiliation: Department of Health and Human Performance, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Ryan
authors.forename: Trent J
authors.initials: TJ
authors.lastname: Herda
authors.forename: Pablo B
authors.initials: PB
authors.lastname: Costa
authors.forename: Ashley A
authors.initials: AA
authors.lastname: Walter
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Hoge
authors.forename: Jeffery R
authors.initials: JR
authors.lastname: Stout
authors.forename: Joel T
authors.initials: JT
authors.lastname: Cramer
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology; D000843:Ankle Joint / Q000502:physiology; D004576:Electromyography; D006801:Humans; D007866:Leg / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal; D011187:Posture / Q000502:physiology; D011434:Proprioception; D016059:Range of Motion, Articular / Q000502:physiology*; D013708:Tendon Injuries / Q000503:physiopathology*; D013710:Tendons; D019415:Torque; D055682:Viscoelastic Substances
chemical_list: D055682:Viscoelastic Substances