Twenty subjects participated in four experiments designed to compare time to task failure and motor-unit recruitment threshold during contractions sustained at 15% of maximum as the elbow flexor muscles either supported an inertial load (position task) or exerted an equivalent constant torque against a rigid restraint (force task). Subcutaneous branched bipolar electrodes were used to record si...

Tensile tests have been performed at up to five different displacement rates, from about lmm/s to over 20,000mm/s, on braided glass-fibre tubes of both square and circular cross-section and the corresponding force-displacement curves have been derived. In general both the maximum tensile force and the displacement at failure increase with increasing loading rate, implying a greater energy absor...

T his article reflects on the impact of a classic paper identifying the effects of loss of sarcoplasmic reticu-lum Ca-ATPase activity in heart failure. Understanding the effects of heart failure on contraction and Ca signaling in the heart has long been a priority. By the late 1980s, many studies on animal models had shown that heart failure resulted in a slowing of the decay of the systolic Ca...

It is becoming clear that upregulated protein kinase C (PKC) signaling plays a role in reduced ventricular myofilament contractility observed in congestive heart failure. However, data are scant regarding which PKC isozymes are involved. There is evidence that PKCmay be of particular importance. Here, we examined PKCquantity, activity, and signaling to myofilaments in chronically remodeled myoc...

Extensive research has been performed examining eccentric contraction and related muscle injury. Only a few studies have examined muscle failure due to an imposed tissue strain. Those that have examined failure tend to investigate active muscle failure and define failure as complete tearing of the muscle. However, muscle damage is known to occur well before a tear is apparent, and failure may b...

BACKGROUND Compressive and quadriceps forces have been associated with noncontact anterior cruciate ligament (ACL) injury. The purpose of this study was to quantify the relative importance of each load component during noncontact ACL injury. HYPOTHESIS We hypothesized that the introduction of a quadriceps force lowers the axial compressive force threshold to produce ACL injury. STUDY DESIGN...

Habitually, capuchin monkeys access encased hard foods by using their canines and premolars and/or by pounding the food on hard surfaces. Instead, the wild bearded capuchins (Cebus libidinosus) of Boa Vista (Brazil) routinely crack palm fruits with tools. We measured size, weight, structure, and peak-force-at-failure of the four palm fruit species most frequently processed with tools by wild ca...