Effects of series elasticity and activation conditions on muscle power output and efficiency

Lichtwark, Glen A.; Wilson, Alan M.

doi:10.1242/jeb.01710

Cited by 63 publications

(71 citation statements)

References 22 publications

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“…2003) and changed tendon mechanical properties (Karamanidis and Arampatzis. 2005;Kubo et al 2003;Morse et al 2005) favor different kinds of muscle activation for optimal efficiency and power output in these two age groups (Lichtwark and Wilson. 2005b).…”

Section: Discussionmentioning

confidence: 99%

Neuromuscular mechanics and hopping training in elderly

et al. 2014

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Phone +358-40-8053384 merja.hoffren@jyu.fi 2 ABSTRACT Purpose: The present study examined the effects of repetitive hopping training on muscle activation profiles and fascicletendon interaction in the elderly.Methods: 20 physically active elderly men were randomly assigned for training (TG) and control groups (CG). TG performed supervised bilateral short contact hopping training with progressively increasing training volume. Measurements were performed before the training period (BEF) as well as after 2 weeks (2W) and 11 weeks (11W) of training. During measurements the gastrocnemius medialis -muscle (GaM) fascicle and its outer Achilles tendon length changes during hopping were examined by ultrasonography together with electromyographic (EMG) activities of calf muscles, kinematics, and kinetics.Results: At 2W the ankle joint stiffness was increased by 21.0 ± 19.3 % and contact time decreased by 9.4 ± 7.8 % in TG.Thereafter, from 2-11W the jumping height increased 56.2 ± 18.1 % in TG. Simultaneously tendon forces increased 24.3 ± 19.0 % but tendon stiffness did not change. GaM fascicles shifted to shorter operating lengths after training without any changes in their length modifications during the contact phase of hopping. Normalized EMG amplitudes during hopping did not change with training.Conclusions: The present study shows that 11 weeks of hopping training improves the performance of physically active elderly men. This improvement is achieved with shorter GaM operating lengths and therefore increased fascicle stiffness and improved tendon utilization after training. Based on these results hopping training could be recommended for healthy fit elderly to retain and improve rapid force production capacity.

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Section: Discussionmentioning

confidence: 99%

Neuromuscular mechanics and hopping training in elderly

et al. 2014

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“…Translated to gibbon tendons, this would mean that the gibbon Achilles tendon, with a relative compliance (i.e. RC=1/S×MVC/FL) of 10%, would achieve a muscle efficiency of ~32%, while the patellar tendon, with an RC of 3%, would have an efficiency of ~26% [by comparison, the RC of 'stiff' rat Achilles tendon is 5%, while the 'compliant' wallaby Achilles tendon has a RC of 35% (Litchwark and Barclay, 2010;Lichtwark and Wilson, 2005a)]. Compliant tendons are particularly important to improve the power output of short-fibred muscles, which have a restricted shortening range, such as the triceps surae in gibbons and humans.…”

Section: Discussion Gibbon Achilles and Patellar Tendon: Elastic Enermentioning

confidence: 99%

“…In addition, it has been shown that tendons also have an important role in reducing the cost of locomotion by: (1) reducing the amount and rate of shortening of muscle fibres, allowing near-isometric force production and contraction in their optimal fibre length range (Biewener and Roberts, 2000;Lichtwark and Wilson, 2005a;Lichtwark and Barclay, 2010); and (2) acting as elastic springs, storing and releasing elastic strain energy during locomotion (Alexander, 1984;Alexander, 2002). Such an energy-saving function has been demonstrated for different tendons in a wide range of species, such as the hind limb tendons in hopping kangaroos and wallabies (Dawson and Taylor, 1973;Alexander and Vernon, 1975;Biewener and Baudinette, 1995;Ker et al, 2000) and the Achilles tendon in humans (Lichtwark and Wilson, 2005b;.…”

Section: Introduction Tendons As Elastic Energy Storesmentioning

confidence: 99%

The role of hind limb tendons in gibbon locomotion: springs or strings?

Vereecke

Channon

2013

Journal of Experimental Biology

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SUMMARYTendon properties have an important effect on the mechanical behaviour of muscles, with compliant tendons allowing nearisometric muscle contraction and facilitating elastic energy storage and recoil. Stiff tendons, in contrast, facilitate rapid force transfer and precise positional control. In humans, the long Achilles tendon contributes to the mechanical efficiency of running via elastic energy storage and recovery, and its presence has been linked to the evolution of habitual bipedalism. Gibbons also possess relatively long hind limb tendons; however, their role is as yet unknown. Based on their large dimensions, and inferring from the situation in humans, we hypothesize that the tendons in the gibbon hind limb will facilitate elastic energy storage and recoil during hind-limb-powered locomotion. To investigate this, we determined the material properties of the gibbon Achilles and patellar tendon in vitro and linked this with available kinematic and kinetic data to evaluate their role in leaping and bipedalism. Tensile tests were conducted on tendon samples using a material testing machine and the load-displacement data were used to calculate stiffness, Young's modulus and hysteresis. In addition, the average stress-in-life and energy absorption capacity of both tendons were estimated. We found a functional difference between the gibbon Achilles and patellar tendon, with the Achilles tendon being more suitable for elastic energy storage and release. The patellar tendon, in contrast, has a relatively high hysteresis, making it less suitable to act as elastic spring. This suggests that the gibbon Achilles tendon might fulfil a similar function as in humans, contributing to reducing the locomotor cost of bipedalism by acting as elastic spring, while the high stiffness of the patellar tendon might favour fast force transfer upon recoil and, possibly, enhance leaping performance.

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“…It appears that increasing relative shortening duration above 50% offsets the potentially efficiency-reducing effect of increasing stimulation duty factor (Table2) (Curtin and Woledge, 1996;Lichtwark and Wilson, 2005). This is not surprising as the detrimental effect of increasing stimulus duty factor is thought to be due to the continuation of energy turnover into lengthening (Curtin and Woledge, 1996).…”

Section: Initial Mechanical Efficiency and Length Trajectorymentioning

confidence: 99%

The effects of asymmetric length trajectories on the initial mechanical efficiency of mouse soleus muscles

Holt

Askew

2012

Journal of Experimental Biology

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SUMMARYAsymmetric cycles with more than half of the cycle spent shortening enhance the mechanical power output of muscle during flight and vocalisation. However, strategies that enhance muscle mechanical power output often compromise efficiency. In order to establish whether a trade-off necessarily exists between power and efficiency, we investigated the effects of asymmetric muscle length trajectories on the maximal mechanical cycle-average power output and initial mechanical efficiency (E i ). Work and heat were measured in vitro in a mouse soleus muscle undergoing contraction cycles with 25% (Saw25%), 50% (Saw50%) and 75% (Saw75%) of the cycles spent shortening. Cycle-average power output tended to increase with the proportion of the cycle spent shortening at a given frequency. Maximum cycle-average power output was 102.9±7.6Wkg -1 for Saw75% cycles at 5Hz. E i was very similar for Saw50% and Saw75% cycles at all frequencies (approximately 0.27 at 5Hz). Saw25% cycles had E i values similar to those of Saw50% and Saw75% cycles at 1Hz (approximately 0.20), but were much less efficient at 5Hz (0.08±0.03). The lower initial mechanical efficiency of Saw25% cycles at higher frequencies suggests that initial mechanical efficiency is reduced if the time available for force generation and relaxation during shortening is insufficient. The similar initial mechanical efficiency of Saw50% and Saw75% cycles at all frequencies shows that increasing the proportion of the contraction cycle spent shortening is a strategy that allows an animal to increase muscle mechanical power output without compromising initial mechanical efficiency.

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Effects of series elasticity and activation conditions on muscle power output and efficiency

Cited by 63 publications

References 22 publications

Neuromuscular mechanics and hopping training in elderly

Neuromuscular mechanics and hopping training in elderly

The role of hind limb tendons in gibbon locomotion: springs or strings?

The effects of asymmetric length trajectories on the initial mechanical efficiency of mouse soleus muscles

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