case, tendon loadings may affect muscle properties (eg, tendon thickness and viscoelastic characteristics of muscle belly). 5 , 6 During repetitive sport actions, fatigue induces modifications in muscle characteristics, such as stiffness and creep, and in synchronization of synergic muscle activity
Sebastian Klich, Bogdan Pietraszewski, Matteo Zago, Manuela Galli, Nicola Lovecchio and Adam Kawczyński
Kathryn E. Keenan, Saikat Pal, Derek P. Lindsey, Thor F. Besier and Gary S. Beaupre
Cartilage material properties provide important insights into joint health, and cartilage material models are used in whole-joint finite element models. Although the biphasic model representing experimental creep indentation tests is commonly used to characterize cartilage, cartilage short-term response to loading is generally not characterized using the biphasic model. The purpose of this study was to determine the short-term and equilibrium material properties of human patella cartilage using a viscoelastic model representation of creep indentation tests. We performed 24 experimental creep indentation tests from 14 human patellar specimens ranging in age from 20 to 90 years (median age 61 years). We used a finite element model to reproduce the experimental tests and determined cartilage material properties from viscoelastic and biphasic representations of cartilage. The viscoelastic model consistently provided excellent representation of the short-term and equilibrium creep displacements. We determined initial elastic modulus, equilibrium elastic modulus, and equilibrium Poisson’s ratio using the viscoelastic model. The viscoelastic model can represent the short-term and equilibrium response of cartilage and may easily be implemented in whole-joint finite element models.
Kimberly Pratt and Richard Bohannon
Stretching exercise regimens are routinely prescribed to increase range of motion (ROM) and diminish injuries.
To examine the effect of a 3-minute passive stretch on ankle-dorsiflexion ROM in a nonpathological population.
Prospective, randomized, controlled study.
24 apparently healthy volunteers.
Subjects stood with their heels suspended from the edge of a platform. The experimental subjects stretched for 3 minutes on 3 consecutive days.
Main Outcome Measures:
Passive ankle-dorsiflexion ROM.
Ankle-dorsiflexion ROM increased significantly (P < .0005) over the course of each day’s stretch. No significant gains in ankle-dorsiflexion ROM were realized over 3 days.
These findings suggest the need for further research to determine the stretching frequency and duration that will result in lasting increases in ankle-dorsiflexion ROM
Leou-Chyr Lin, Thomas P. Hedman, Shyu-Jye Wang, Michael Huoh and Shih-Youeng Chuang
The goal of this study was to develop a nondestructive radial compression technique and to investigate the viscoelastic behavior of the rat tail disc under repeated radial compression. Rat tail intervertebral disc underwent radial compression relaxation testing and creep testing using a custom-made gravitational creep machine. The axisymmetric viscoelasticity and time-dependent recovery were determined. Different levels of hydration (with or without normal saline spray) were supplied to evaluate the effect of changes in viscoelastic properties. Viscoelasticity was found to be axisymmetric in rat-tail intervertebral discs at four equidistant locations. Complete relaxation recovery was found to take 20 min, whereas creep recovery required 25 min. Hydration was required for obtaining viscoelastic axisymmetry and complete viscoelastic recovery.
L. Kristi Sayers, Jo E. Cowden, Maria Newton, Barbara Warren and Bobby Eason
The purpose of this study was to describe the developmental stepping movements of 5 infants with Down syndrome who participated in a pediatric strength intervention. Pretest and posttest data were collected with the Hawaii Early Learning Profile Strands, Battelle Developmental Inventory, and specially designed gait analysis. An 8-week individualized pediatric strength intervention was implemented according to theoretical principles of progressive interactive facilitation (Cowden, in press). Posttest data and the Snyder-McLean (1987) intervention developmental quotient suggested an increase in the subjects’ rates of motor development during intervention as compared to their lifetime rates prior to intervention. One subject showed increased rate and distance, 2 subjects acquired independent upright locomotion, and 1 subject established independent sitting movements and creeping patterns. One subject was unable to complete the study.
Shona L. Halson and Michele Lastella
our athletes to limit or stop Instagram and Netflix time creeping into sleep time? How do we get athletes to prioritize sleep over “the fun stuff.” Athletes can have knowledge and desire, but continue to miss out on what is good for them. We can know something and even believe that changing a
Jan Wilke, Philipp Niemeyer, Daniel Niederer, Robert Schleip and Winfried Banzer
-related and neuronal effects, the viscoelastic properties of the extramuscular connective tissue do also affect mechanical stiffness. First, facial tissues are prone to creep deformation if strong compression forces are applied. 14 , 20 Second, the reported decrease in tissue stiffness may also be related to
John Goetschius, Mark A. Feger, Jay Hertel and Joseph M. Hart
variable increased, the gap in measurement differences between devices also expanded. This creeping pattern in our results was most evident in the larger magnitude variables of distance and area. In the current study we performed 10-second balance trials to coincide with trial lengths from musculoskeletal
Laura C. Slane, Stijn Bogaerts, Darryl G. Thelen and Lennart Scheys
joint cooling change in vivo patellar tendon mechanical properties? Eur J Appl Physiol . 2016 ; 116 : 1921 – 1929 . PubMed doi:10.1007/s00421-016-3444-5 27473447 10.1007/s00421-016-3444-5 13. Pearson SJ , Burgess K , Onambele GN . Creep and the in vivo assessment of human patellar tendon
Emma C. Neupert, Stewart T. Cotterill and Simon A. Jobson
it’s quite useful. You can kind of, sometimes you can notice a pattern or there is like something creeping up then you would say oh actually this has happened before. Feedback and Act Athletes identified a broad range of feedback preferences, favoring visual feedback supported by formal or informal