Early changes in Achilles tendon behaviour in vivo following downhill backwards walking
- Authors: Joseph, Corey , Bradshaw, Elizabeth , Furness, Trentham , Kemp, Justin , Clark, Ross
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of Sports Sciences Vol. 34, no. 13 (Jul 2016), p. 1215-1221
- Full Text: false
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- Description: Downhill backwards walking causes repeated, cyclical loading of the muscle-tendon unit. The effect this type of repeated loading has on the mechanical behaviour of the Achilles tendon is presently unknown. This study aimed to investigate the biomechanical response of the Achilles tendon aponeurosis complex following a downhill backwards walking protocol. Twenty active males (age: 22.3 +/- 3.0years; mass: 74.7 +/- 5.6kg; height: 1.8 +/- 0.7m) performed 60min of downhill (8.5 degrees), backwards walking on a treadmill at -0.67m center dot s(-1). Data were collected before, immediately post, and 24-, 48- and 168-h post-downhill backwards walking. Achilles tendon aponeurosis elongation, strain and stiffness were measured using ultrasonography. Muscle force decreased immediately post-downhill backward walking (P=0.019). There were increases in Achilles tendon aponeurosis stiffness at 24-h post-downhill backward walking (307 +/- 179.6N center dot mm(-1), P=0.004), and decreases in Achilles tendon aponeurosis strain during maximum voluntary contraction at 24 (3.8 +/- 1.7%, P=0.008) and 48h (3.9 +/- 1.8%, P=0.002) post. Repeated cyclical loading of downhill backwards walking affects the behaviour of the muscle-tendon unit, most likely by altering muscle compliance, and these changes result in tendon stiffness increases.
Musculoskeletal stiffness during hopping and running does not change following downhill backwards walking
- Authors: Joseph, Corey , Bradshaw, Elizabeth , Kemp, Justin , Clark, Ross
- Date: 2014
- Type: Text , Journal article
- Relation: Sports Biomechanics Vol. 13, no. 3 (2014), p. 241-258
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- Description: Eccentric contractions that provide spring energy can also cause muscle damage. The aim of this study was to explore leg and vertical stiffness following muscle damage induced by an eccentric exercise protocol. Twenty active males completed 60 minutes of backward-walking on a treadmill at 0.67 m/s and a gradient of − 8.5° to induce muscle damage. Tests were performed immediately before; immediately post; and 24, 48, and 168 hours post eccentric exercise. Tests included running at 3.35 m/s and hopping at 2.2 Hz using single- and double-legged actions. Leg and vertical stiffness were measured from kinetic and kinematic data, and electromyography (EMG) of five muscles of the preferred limb were recorded during hopping. Increases in pain scores (over 37%) occurred post-exercise and 24 and 48 hours later (p < 0.001). A 7% decrease in maximal voluntary contraction occurred immediately post-exercise (p = 0.019). Changes in knee kinematics during single-legged hopping were observed 168 hours post (p < 0.05). No significant changes were observed in EMG, creatine kinase activity, leg, or vertical stiffness. Results indicate that knee mechanics may be altered to maintain consistent levels of leg and vertical stiffness when eccentric exercise-induced muscle damage is present in the lower legs. © 2014 Taylor & Francis.