We thank Dr. Ortega for the opportunity to debate the concept that aging affects exercise efficiency. From the outset we must acknowledge that, indeed, some studies report an age-related reduction task efficiency during walking and other rather complex tasks (2, 12, 20, 21). However, in contrast, our recent study of leg cycling in centenarians (28), as well as other work focused more specifical...

Cell competition is a phenomenon originally described as the competition between cell populations with different genetic backgrounds; losing cells with lower fitness are eliminated. With the progress in identification of related molecules, some reports described the relevance of cell mechanics during elimination. Furthermore, recent live imaging studies have shown that even in tissues composed ...

the phase transformation phenomenon due to the crystallographic change of shape memory alloys subjected to mechanical or thermal loading is very complicated. regarding the thermo-mechanical coupling effects in shape memory alloys, in case of high  loading rates, heat generation/absorption during the forward/reverse transformation, will lead in temperature-dependent variation and consequently af...

Force and heat production were measured during isovelocity shortening of tetanized white myotomal muscle fibres from the dogfish at 12 degrees C. For each fibre preparation a range of velocities was used. Mechanical power was calculated from force X velocity of shortening. The rate of total energy output during shortening was evaluated as the sum of mechanical power and the rate of heat product...

During a force-matched bilateral task, when pain is induced in one limb, a shift of load to the non-painful leg is classically observed. This study aimed to test the hypothesis that this adaptation to pain depends on the mechanical efficiency of the non-painful leg. We studied a bilateral plantarflexion task that allowed flexibility in the relative force produced with each leg, but constrained ...

Human movements are physical processes combining the classical mechanics of the human body moving in space and the biomechanics of the muscles generating the forces acting on the body under sophisticated sensory-motor control. The characterization of the performance of human movements is a problem with important applications in clinical and sports research. One way to characterize movement perf...

Human movements are physical processes combining the classical mechanics of the human body moving in space and the biomechanics of the muscles generating the forces acting on the body under sophisticated sensory-motor control. One way to characterize movement performance is through measures of energy efficiency that relate the mechanical energy of the body and metabolic energy expended by the m...

cycle between the cross-bridges on the thick filament and the thin filament coupled with ATP hydrolysis (A. F. Huxley, 1957; H. E. Huxley, 1960; Bagshaw, 1994). The mechanical efficiency with which chemical energy derived from ATP hydrolysis is converted into mechanical work in demembranated muscle fibres has been estimated recently by measuring the amount of ATP utilized for work production, u...

BACKGROUND In idiopathic pulmonary arterial hypertension (IPAH), increased right ventricular (RV) power is required to maintain cardiac output. For this, RV O2 consumption (MVO2) must increase by augmentation of O2 supply and/or improvement of mechanical efficiency-ratio of power output to MVO2. In IPAH with overt RV failure, however, there is evidence that O2 supply (perfusion) reserve is redu...