Skeletal muscle accumulates intramuscular fat through age and obesity. Muscle quality, a measure of strength per unit size, decreases in these conditions. It is not clear how influences this loss performance. Changes to structural parameters (e.g. fibre pennation connective tissue properties) affect the quality. This study investigated mechanisms that lead deterioration performance due changes fat, aponeurosis stiffness. A finite-element model human gastrocnemius was developed as...

The free flapping flight of the dragonfly Sympetrum sanguineum and damselfly Calopteryx splendens was filmed in a large enclosure at 3000 frames s-1. wingtip kinematics are described for these flights. Despite two species being similar size, flew with wingbeat frequencies half those dragonfly. could perform clap fling, proximity to which wings approached each other during this manoeuvre correlated total force produced wingstroke. beat its set inclination stroke planes respect londitudinal...

This study tested the hypotheses that when excitation frequency of mechanical stimuli to foot was close natural soft tissues lower extremity, muscle activity increases 1) and 2) damping minimize resonance. Soft tissue vibrations were measured with triaxial accelerometers, by using surface electromyography from quadriceps, hamstrings, tibialis anterior, triceps surae groups 20 subjects. Subjects presented while standing on a vibrating platform. Both continuous pulsed bursts presented, across...

The free gliding flight of the dragonfly Sympetrum sanguineum was filmed in a large enclosure. Reconstruction glide paths showed flights to involve accelerations. Where acceleration could be considered constant, lift and drag forces acting on were calculated. maximum coefficient (CL) recorded from these glides 0.93; however, this is not necessarily possible wings. Lift additionally measured isolated wings bodies S. damselfly Calopteryx splendens steady air flow at Reynolds numbers 700-2400...

A mean lift coefficient quasi-steady analysis has been applied to the free flight of dragonfly Sympetrum sanguineum and damselfly Calopteryx splendens. The accommodated yaw accelerations involved in flight. For any given velocity or resultant aerodynamic force (thrust), was higher than that for because its clap fling. both species, maximum L steady CL,max. Both species aligned their strokes planes be nearly normal thrust, a strategy reduces required which is different from previously...

Vibration characteristics were recorded for the soft tissues of triceps surae, tibialis anterior, and quadriceps muscles. The frequency damping free vibrations in these measured while isometric isotonic contractions leg performed. Soft tissue vibration increased with both force produced by shortening velocity underlying muscle. Both greater a direction normal to skin surface than parallel major axis each segment. further changed muscle length between individuals tested. range frequencies...

Hill-type models are ubiquitous in the field of biomechanics, providing estimates a muscle's force as function its activation state and assumed force-length force-velocity properties. However, despite their routine use, accuracy with which predict forces generated by muscles during submaximal, dynamic tasks remains largely unknown. This study compared human gastrocnemius predicted estimated from ultrasound-based measures tendon length changes stiffness cycling, over range loads cadences. We...

ABSTRACT Fast-starts associated with escape responses were filmed at the median habitat temperatures of six teleost fish: Notothenia coriiceps and rossii (Antarctica), Myoxocephalus scorpius (North Sea), Scorpaena notata Serranus cabrilla (Mediterranean) Paracirrhites forsteri (Indo-West-Pacific Ocean). Methods are presented for estimating spine positions silhouettes swimming fish. These methods used to validate techniques calculating kinematics muscle dynamics during fast-starts. The starts...

This study investigates the motor unit recruitment patterns between and within muscles of triceps surae during cycling on a stationary ergometer at range pedal speeds resistances. Muscle activity was measured from soleus (SOL), medial gastrocnemius (MG) lateral (LG) using surface electromyography (EMG) quantified wavelet principal component analysis. fascicle strain rates were ultrasonography, muscle–tendon lengths calculated segmental kinematics. The EMG intensities showed that body uses...

SUMMARY Motor units are the functional of muscle contraction in vertebrates. Each motor unit comprises fibres a particular fibre type and can be considered as fast or slow depending on its fibre-type composition. typically recruited set order, from to fast, response force requirements muscle. The anatomical separation fish permits direct recordings these two types. frequency spectra different myotomal muscles were measured rainbow trout Oncorhynchus mykiss. These types generated distinct low...

Muscle synergies have been proposed as building blocks that could simplify the construction of motor behaviors. However, muscles within synergistic groups may different architectures, mechanical linkages to skeleton, and biochemical properties, these put competing demands on most appropriate way activate them for tasks. This study identifies extent which patterns muscle activity vary when a limb were altered, additionally how consistent spectral profiles electromyographic (EMG) intensities...

During walking and running, the human body reacts to its external environment. One such response is impact forces that occur at heel strike. This study tested previous speculation levels of muscle activity in lower extremities are adjusted loading rate forces. A pendulum apparatus was used deliver repetitive impacts heels 20 subjects. Impact were similar magnitude those experienced during but varied by 13% using different materials subjects' shoes. Myoelectric patterns measured tibialis...

WAKELING, J.M, S.A. PASCUAL, and B.M. NIGG. Altering muscle activity in the lower extremities by running with different shoes. Med. Sci. Sports Exerc., Vol. 34, No. 9, pp. 1529–1532, 2002. Purpose To provide evidence that lower-extremity during is tuned response to loading rate of impact forces at heel-strike. Methods Six runners ran two 30-min trials per week for 4 wk. The tested shoes which differed only material hardness midsole. were a randomized sequence. Bipolar surface EMG was...

SUMMARY Myoelectric signals measured using intramuscular electromyograms (EMGs) in animals have shown that faster motor units generate higher frequencies their power spectra. However, evidence to relate myoelectric frequency and unit type from the surface typically man remained elusive. The purpose of this study was determine if spectral properties EMG could be related different muscles leg extensors man. Reflex experiments (both tendon tap electrically stimulated) graded isometric...