A5041530560- Muscle activation and electromyography studies
- Sports Performance and Training
- Cardiomyopathy and Myosin Studies
- Muscle Physiology and Disorders
- Sports injuries and prevention
- Motor Control and Adaptation
- Physiological and biochemical adaptations
- Animal Behavior and Reproduction
- Genetics and Physical Performance
- Robotic Locomotion and Control
- Orthopedic Infections and Treatments
- Advanced Sensor and Energy Harvesting Materials
- Force Microscopy Techniques and Applications
- Distributed Control Multi-Agent Systems
- Nutrition and Health in Aging
- Children's Physical and Motor Development
- Endodontics and Root Canal Treatments
- Botulinum Toxin and Related Neurological Disorders
- Innovative Energy Harvesting Technologies
- Tendon Structure and Treatment
- Insect and Arachnid Ecology and Behavior
- Connective tissue disorders research
- Cardiovascular Effects of Exercise
- Surgical Sutures and Adhesives
- Amphibian and Reptile Biology
University of California, Riverside
2019-2024
Northern Arizona University
2018-2019
Royal Liverpool University Hospital
2014-2018
University of Liverpool
2014-2018
University of California, Irvine
2014-2017
Google (United States)
2016
Simon Fraser University
2014
University of Leeds
2009-2014
Skeletal muscles power a broad diversity of animal movements, despite only being able to produce high forces over limited range velocities. Pennate use gear ratios, the ratio muscle shortening velocity fiber velocity, partially circumvent these force-velocity constraints. Muscles operate with at low forces; fibers rotate greater angles pennation, enhancing but compromising force. At higher forces, lower ratio; little so limiting helping preserve This ability shift gears is thought be due...
Abstract The distal muscle-tendon units of cursorial species are commonly composed short muscle fibres and long, compliant tendons. It is assumed that the ability these tendons to store return mechanical energy over course a stride, thus avoiding cyclic absorption regeneration by active muscle, offers some metabolic savings during running. However, this assumption has not been tested directly. We used ergometry myothermic measurements determine cost force production in muscles acting...
The output of skeletal muscle can be varied by selectively recruiting different motor units. However, our knowledge function is largely derived from in which all units are activated. This discrepancy may limit understanding vivo function. Hence, this study aimed to characterize the mechanical properties with unit activation. We determined isometric and isotonic force-velocity relationship rat plantaris muscles situ active, 30% containing predominately slower active or 20% faster active....
Skeletal muscles are rarely recruited maximally during movement. However, much of our understanding muscle properties is based on studies using maximal activation. The effect activation level skeletal remains poorly understood. Muscle optimum length increases with decreased activation; however, the mechanism responsible unclear. Here, we attempted to determine whether length-dependent calcium effects, or absolute force underpin this shift. Fixed-end contractions were performed in frog...
Skeletal muscle exhibits broad functional diversity, despite its inherent length and velocity constraints. The observed variation in morphology physiology is assumed to have evolved allow operate at optimal during locomotion. Here, we used the optimum lengths velocities that occurs with activation level experimentally test this assumption. Muscle ergometry sonomicrometry were characterize force–length power–velocity relationships, vivo operating velocities, a range of levels. Operating...
Muscle is the universal agent of animal movement, and limits to muscle performance are therefore an integral aspect behaviour, ecology, evolution. A mechanical perspective on movement makes it amenable analysis from first principles, so brings seeming certitude simple physical laws challenging comparative study complex biological systems. Early contributions biomechanics considered energy output be limited by work capacity, W max ; triggered seminal in late 1960s, now held broadly that a...
Skeletal muscle force is generated by cross-bridge interactions between the overlapping contractile proteins, actin and myosin. The geometry of this overlap gives us force-length relationship in which maximum isometric at an intermediate, optimum, length. However, not constant; optimum length increases with decreasing activation. This effect predicted from actin-myosin overlap. Here we present evidence that activation-dependent shift may be due to a series compliance within muscles. As...
SUMMARY The metabolic cost of the negotiation obstacles, and influence that this has on route selection, are important determinants an animal's locomotor behaviour. We determined gross locomotion slopes different gradients, ranging from –90 to +90 deg, in leaf-cutter ants (Acromyrmex octospinosus) a closed-circuit respirometry system. Ants were able select their preferred speed for each gradient. energy expenditure per unit distance travelled slope (Cpath) was calculated rate CO2 production...
Efficient muscle-tendon performance during cyclical tasks is dependent on both active and passive mechanical tissue properties. Here we examine whether age-related changes in the properties of units (MTUs) compromise their ability to do work utilize elastic energy storage. We empirically quantified medial gastrocnemius muscle material Achilles tendon young (∼6 mo) old (∼32 rats. then used these computer simulations a Hill-type model operating series with Hookean spring. The modeled MTU was...
Fibrillins 1 (FBN1) and 2 (FBN2) are components of microfibrils, microfilaments that present in many connective tissues, either alone or association with elastin. Marfan's syndrome congenital contractural arachnodactyly (CCA) result from dominant mutations the genes FBN1 FBN2 respectively. Patients both conditions often specific muscle atrophy weakness, yet this has not been reported mouse models. In case Fbn1, is due to perinatal lethality homozygous null mice making measurements strength...
AbstractMuscle-tendon unit (MTU) morphology and physiology are likely major determinants of locomotor performance therefore Darwinian fitness. However, the relationships between underlying traits, performance, fitness complicated by phenomena such as coadaptation, multiple solutions, trade-offs. Here, we leverage a long-running artificial selection experiment in which mice have been bred for high levels voluntary running to explore MTU adaptation, well role trade-offs, evolution endurance...
Skeletal muscle powers animal movement through interactions between the contractile proteins, actin and myosin. Structural variation contributes greatly to in mechanical performance observed across muscles. In vertebrates, gross structural occurs form of changes cross-sectional area : fibre length ratio. This results a trade-off force displacement capacity, leaving work capacity unaltered. Consequently, maximum per unit volume—the density—is considered constant. Invertebrate also varies...
SUMMARY Asymmetric cycles with more than half of the cycle spent shortening enhance mechanical power output muscle during flight and vocalisation. However, strategies that often compromise efficiency. In order to establish whether a trade-off necessarily exists between efficiency, we investigated effects asymmetric length trajectories on maximal cycle-average initial efficiency (Ei). Work heat were measured in vitro mouse soleus undergoing contraction 25% (Saw25%), 50% (Saw50%) 75% (Saw75%)...
A trade-off between locomotor speed and endurance occurs in various taxa, is thought to be underpinned by a muscle-level trade-off. Among four replicate high runner (HR) lines of mice, selectively bred for voluntary wheel-running behavior, negative correlation average running time spent has evolved. We hypothesize that this due changes muscle physiology. studied the HR at generation 90, which one line (L3) fixed mini-muscle phenotype, another polymorphic (L6) others (L7, L8) lack...
Biological movement is an inherently dynamic process, characterized by large spatiotemporal variations in force and mechanical energy. Molecular level interactions between the contractile proteins actin myosin do work, generating forces transmitting them to environment via muscle's supporting tissues' complex structures. Most existing theories of muscle contraction are derived from observations performance under simple, tightly controlled, vitro or situ conditions. These provide predictive...
The ways locomotor abilities may interact with life history traits are complicated and involve shifts in resource allocation. For example, individuals that have large litters reduced energy available to support the organ systems required for high performance abilities. Alternatively, spent on excess physical activity might subtract from somatic maintenance, thus be negatively related lifespan or other fitness components contribute lifetime reproductive success (LRS). We studied successes,...