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Tendon Stiffness (tendon + stiffness)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

Influence of time of day on tendon compliance and estimations of voluntary activation levels

MUSCLE AND NERVE, Issue 6 2006
Stephen J. Pearson PhD
Abstract We investigated the importance of tendon stiffness on estimations of central activation capacity (CAC). Patella tendon,force elongation relationship, quadriceps torque, and response to 50-,s, 100-HZ electrical twitch doublets were studied at ,8:00 A.M. and ,6:00 P.M. in 8 healthy young men. Results show that in the evening, as compared with the morning, tendon stiffness decreased by 20.2 ± 9.5% (P = 0.03) and time to twitch peak (Ttp) increased by 55% (P = 0.04). Tendon stiffness and Ttp correlated significantly (r = 0.28, P < 0.05). Whereas the CAC, calculated as the ratio of force preceding the interpolated twitch (IT) to the total force at the peak of the IT, showed no change with time of day, calculations that used twitch ratios suggested CAC decrements (,10.3%, P = 0.03, unpotentiated; ,10%, P = 0.02, potentiated ratio) in the evening. This study shows that CAC estimations are invalid when tendon properties are not taken into account, an error that would have important implications in a clinical setting. Muscle Nerve, 2006 [source]

Myotendinous plasticity to ageing and resistance exercise in humans

EXPERIMENTAL PHYSIOLOGY, Issue 3 2006
N. D. Reeves
The age-related loss of muscle mass known as senile sarcopenia is one of the main determinants of frailty in old age. Molecular, cellular, nutritional and hormonal mechanisms are at the basis of sarcopenia and are responsible for a progressive deterioration in skeletal muscle size and function. Both at single-fibre and at whole-muscle level, the loss of force exceeds that predicted by the decrease in muscle size. For single fibres, the loss of intrinsic force is mostly due to a loss in myofibrillar protein content. For whole muscle, in addition to changes in neural drive, alterations in muscle architecture and in tendon mechanical properties, exemplified by a reduction in tendon stiffness, have recently been shown to contribute to this phenomenon. Resistance training can, however, cause substantial gains in muscle mass and strength and provides a protective effect against several of the cellular and molecular changes associated with muscle wasting and weakness. In old age, not only muscles but also tendons are highly responsive to training, since an increase in tendon stiffness has been observed after a period of increased loading. Many of the myotendinous factors characterizing ageing can be at least partly reversed by resistance training. [source]

Tendon surface modification by chemically modified HA coating after flexor digitorum profundus tendon repair

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2004
Chao Yang
Abstract Carbodiimide derivatized HA (cd-HA) is less soluble in water than normal HA, and therefore has an increased tissue residence time. The purpose of this study was to study the effect of cd-HA gel on gliding and repair integrity during simulated repetitive motion of a repaired tendon in vitro. A total of 36 flexor digitorum profundus (FDP) tendons from six adult mongrel dogs were used and divided into three groups of control, simple HA, and cd-HA. The gliding resistance between the FDP and the proximal pulley, FDS, and bone was measured before laceration and after modified Kessler technique repair at 1, 5, 10, 50, 100, 200, 300, 400, and 500 cycles. After gliding testing, failure load, tendon stiffness, and resistance to gap formation were measured. The results showed from the first cycle to the 10th cycle, there were no significant differences in gliding resistance between the three testing groups (p > 0.05). From the 50th cycle onwards, the friction was significantly lower in the cd-HA gel group than in the control group (p < 0.05). Neither breaking strength, nor tendon stiffness, nor resistance to gap formation of the repairs were significantly different between the three groups (p > 0.05). © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 15,20, 2004 [source]

Effect of acute tensile loading on gender-specific tendon structural and mechanical properties

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2009
Katherine E. Burgess
Abstract Stretching is commonly used prior to exercise, as it is thought to reduce the risk of injury, and it is also used in the preconditioning of tendon grafts. As tendon properties have been shown to be different between genders, it is proposed that stretching will differentially affect the structure. Here we examine the effect of acute stretch on the mechanical properties of both male and female medial gastrocnemius tendon. Female [20 years,±,1 (SEM), n,=,17] and male (22 years,±,1, n,=,18) subjects underwent a 5-min passive dorsiflexion stretch. Prior to and post stretch medial gastrocnemius tendon stiffness (K), length (l) and cross-sectional area (csa) were measured using ultrasonography and dynamometry. Stiffness and Young's modulus (,) were significantly reduced with stretch for both genders (p,<,0.05). Females showed significantly (p,<,0.05) greater pre- to poststretch decreases in K (22.4 vs. 8.8%) and , (20.5 vs. 8.4%) in comparison to males. The present results show that stretching acutely reduces stiffness of the medial gastrocnemius tendon in females and males, with females showing significantly greater change. The observed disparity between genders may be due in part to variations in tendon moment arm and intrinsic differences in tendon composition. These differential changes in tendon mechanical properties have functional, motor control, and injury risk implications, as well as possible implications for preconditioning of tendon grafts. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 510,516, 2009 [source]