Attitudes toward sport psychology consulting of adult athletes from the United States, United Kingdom, and Germany

The purpose of this study was to explore attitudes about sport psychology consulting of athletes living in the United States, United Kingdom and Germany. The Sport Psychology Attitudes - Revised form (SPA-R; Martin, Kellmann, Lavallee, & Page, 2002) was administered to 404 athletes from the United States, 147 athletes from the United Kingdom, and 260 athletes from Germany. A 2 (Gender) x 3 (Nationality: American, British and German) x 2 (Type of Sport: physical contact and physical non-contact) MANCOVA was conducted with past sport psychology conducting experience as a covariant and attitudes about sport psychology as dependent variables. Follow-up univariate and discriminant function analyses were then performed to identify the attitiudes that maximized differences related to gender, nationality, and type of sport. Results revealed that attitudes about sport psychology services might be influenced by gender, nationality, and type of sport. Sport psychology practitioners must be sensitive to how personal characteristics and past experiences influence athletes' expectations and attitudes toward sport psychology consulting to improve the services they offer

Conformation-regulated mechanosensory control via titin domains in cardiac muscle

The giant filamentous protein titin is ideally positioned in the muscle sarcomere to sense mechanical stimuli and transform them into biochemical signals, such as those triggering cardiac hypertrophy. In this review, we ponder the evidence for signaling hotspots along the titin filament involved in mechanosensory control mechanisms. On the way, we distinguish between stress and strain as triggers of mechanical signaling events at the cardiac sarcomere. Whereas the Z-disk and M-band regions of titin may be prominently involved in sensing mechanical stress, signaling hotspots within the elastic I-band titin segment may respond primarily to mechanical strain. Common to both stress and strain sensor elements is their regulation by conformational changes in protein domains

Characterization of Hypercontracted Fibers in Skeletal Muscle of Domestic Turkey (Meleagris Gallopavo)

Several different muscles from a population of thirty Large White male turkeys were studied by histological and histochemical methods, and a high incidence of hypercontracted fibers was noted . The fibers were characterized in cross-section by an apparent swelling, a rounded rather than polygonal shape and a homogenous appearance. They were eosinophilic, positive to Gomori-trichrome and appeared to have an elevated lipid content. An unusual histochemical profile was noted. It was postulated that the hypercontracted fibers were real , not artifnctual, and resulted from some change occurring in the muscle

Altered kinetics of contraction in skeletal muscle fibers containing a mutant myosin regulatory light chain with reduced divalent cation binding.

We examined the kinetic properties of rabbit skinned skeletal muscle fibers in which the endogenous myosin regulatory light chain (RLC) was partially replaced with a mutant RLC (D47A) containing a point mutation within the Ca2+/Mg2+ binding site that severely reduced its affinity for divalent cations. We found that when approximately 50% of the endogenous RLC was replaced by the mutant, maximum tension declined to approximately 60% of control and the rate constant of active tension redevelopment (ktr) after mechanical disruption of cross-bridges was reduced to approximately 70% of control. This reduction in ktr was not an indirect effect on kinetics due to a reduced number of strongly bound myosin heads, because when the strongly binding cross-bridge analog N-ethylmaleimide-modified myosin subfragment1 (NEM-S1) was added to the fibers, there was no effect upon maximum ktr. Fiber stiffness declined after D47A exchange in a manner indicative of a decrease in the number of strongly bound cross-bridges, suggesting that the force per cross-bridge was not significantly affected by the presence of D47A RLC. In contrast to the effects on ktr, the rate of tension relaxation in steadily activated fibers after flash photolysis of the Ca2+ chelator diazo-2 increased by nearly twofold after D47A exchange. We conclude that the incorporation of the nondivalent cation-binding mutant of myosin RLC decreases the proportion of cycling cross-bridges in a force-generating state by decreasing the rate of formation of force-generating bridges and increasing the rate of detachment. These results suggest that divalent cation binding to myosin RLC plays an important role in modulating the kinetics of cross-bridge attachment and detachment