...Nicole Rice; Caitlin M. Bemis; Monica A. Daley; Kiisa Nishikawa ABSTRACT The work loop technique has provided key insights into in vivo muscle work and power during steady locomotion. However, for many animals and muscles, ex vivo experiments are not feasible. In addition, purely sinusoidal strain...

...Sharn P. Shelley; Rob S. James; Steven J. Eustace; Emma Eyre; Jason Tallis ABSTRACT This study examined the effect of stimulation frequency (140, 200, 230 and 260 Hz) on isometric force, work loop (WL) power and the fatigue resistance of extensor digitorum longus (EDL) muscle ( n =32), isolated...

... muscle. Four-week-old female CD-1 mice were randomly selected to consume either a standard laboratory diet or a standard laboratory diet in conjunction with a HFD for 20 weeks. Peripheral soleus and core diaphragm were isolated from each animal and maximal isometric force and work loop power were...

... amplitude over frequency may instead derive from limitations of muscle physiology at high frequency. We tested this hypothesis by developing a novel in situ work loop approach to measure muscle force and power output from the whole pectoralis major of zebra finches. This method allowed for multiple...

... strain perturbations is history dependent, but is captured by a viscoelastic model with memory; the data and model show that the muscle perturbation response depends on locomotor frequency. Muscle Work loop Force Running Cockroach Viscoelastic Muscle produces, dissipates, stores...

... of the humerotriceps, we developed an in situ work loop approach to measure how activation duration and contractile cycle frequency affected muscle work and power across the full range of activation onset times. The humerotriceps produced predominantly net negative power, likely due to relatively long stimulus...

... served as controls or underwent 8 weeks of voluntary wheel running. Following the treatment intervention, whole soleus (SOL) or a section of the costal diaphragm (DIA) was isolated from each mouse and tested to determine the effect of 70 µmol l −1 caffeine on work loop power output. Although caffeine...

... in vivo . Robert Josephson incorporated lengthening contractions into a work loop analysis that shifted the focus to dynamic muscle function, varying force, length and work done both by and on muscle during a single muscle work cycle. It became apparent that muscle is both a force generator and a spring...

... (force per muscle cross-sectional area) and maximal work loop power output (normalised to muscle mass) all significantly increased with greater SVL. In contrast, fatigue resistance during repeated work loops significantly decreased with SVL and there was no effect of size on tetanus activation time. When...

... elements (CEs) within a compliant muscle–tendon unit (MTU), we used a novel work loop approach that included implanted sonomicrometry crystals along muscle fascicles. This enabled us to decouple CE and SEE length trajectories when cyclic strain patterns were applied to an isolated plantaris MTU from...

... lasting more than a week, during which the animals are largely immobile. Previous hibernation studies have demonstrated that such natural models of skeletal muscle disuse cause limited or no change in either skeletal muscle size or contractile performance. However, work loop analysis of skeletal muscle...

... of temperature on sustained skeletal muscle performance. The iliotibialis muscle was isolated from eight male Xenopus tropicalis individuals and subjected to in vitro isometric and work-loop studies at test temperatures of 15, 24, 30 and 32°C. Work-loop power output (average power per cycle) was maximised...

... (C,D) and heat (E,F) traces and work loops (G,H) for mouse soleus muscles subjected to Saw25% (A,C,E,G) and Saw50% (B,D,F,H) cycles at 5 Hz. The dashed lines highlight the end of shortening. Fig. 4. Example strain (A,B), stress (C,D) and heat (E,F) traces and work loops (G,H) for mouse soleus...

... and power production were measured in isolated bundles of red fibres from 0.5 L by the work loop technique. Power was maximal at 3–4 Hz and fell to less than 50% of maximum after 6 Hz. Based on the timing of activation, muscle strain, tail beat frequencies and forces in the caudal tendon while swimming, we...

... resting length. We subjected in vitro VIL preparations to strain cycling and stimulus phase and duration similar to that of natural crawling. The resulting work loops were figure-eight shaped, with the muscle performing work during the shortest 45–65% of the strain cycle but dissipating work during...

... and activation. A simulated work loop method was used to understand prior observations of sub-maximal power output in the dominant flight musculature of the hawkmoth Manduca sexta L. Here we show that mechanical work output and energy consumption ( via ATP) vary with the phase of activation, although they do so...

...Jeanine M. Donley; Robert E. Shadwick; Chugey A. Sepulveda; Douglas A. Syme The work loop technique was used to examine contractile properties of the red aerobic locomotor muscle (RM) in the ectothermic leopard shark Triakis semifasciata and endothermic shortfin mako shark Isurus oxyrinchus...

... months of aestivation (time to peak twitch increased by 25%, time from peak twitch to half relaxation increased by 34% and time from last stimulus to half tetanus relation increased by 20%). However, the results of the work-loop analysis clearly demonstrate that, despite changes to muscle morphology...

...: Movement Science Group, Department of Health Sciences,University Maastricht, PO Box 616, 6200 MD, Maastricht, The Netherlands 18 6 2006 © The Company of Biologists Limited 2006 2006 muscle work loop motor control The nervous system generates electrical signals that activate...

...-mail: rjs360@psu.edu ) 25 11 2003 © The Company of Biologists Limited 2004 2004 force work power scaling allometry dynamic force output dragonfly flight motor lever arm basalar muscle work loop load lifting Table 1. Species used in this study and their body mass...