Determining the minimum number of passive stretches necessary to alter musculotendinous stiffness

Abstract

In this study, we examined the minimum number of constant-torque passive stretches necessary to reduce musculotendinous stiffness. Thirteen healthy individuals (mean age 22 years, s = 3; stature 1.67 m, s = 0.1; mass 66 kg, s = 13 kg) volunteered to participate in the investigation and underwent four 30-s constant-torque passive stretches of the plantar flexor muscles. Musculotendinous stiffness was examined from the angle–torque curves generated prior to the passive stretches, at the beginning of each 30-s stretch, and immediately following the four 30-s passive stretches. The results indicated that musculotendinous stiffness of the plantar flexors was reduced following two 30-s constant-torque passive stretches (P < 0.05) compared with the pre- musculotendinous stiffness assessment. Musculotendinous stiffness remained depressed following the third and fourth stretches, but did not decrease further. These findings suggest that two 30-s bouts of constant-torque passive stretching may be necessary to cause a significant decrease in musculotendinous stiffness of the plantar flexor muscles.     

Drunkorexia: An Exploratory Investigation of College Students With Alcohol‐Related Infractions

The construct of drunkorexia, caloric restriction prior to or during alcohol consumption, was examined in 411 college students who experienced alcohol‐related infractions. Analyses were conducted to examine differences in demographic prevalence distributions, alcohol‐related consequences, and alcohol consumption between a subsample of participants who reported drunkorexia behaviors and a subsample who did not.     

Intertrial unconditioned stimuli differentially impact trace conditioning

Three experiments assessed how appetitive conditioning in rats changes over the duration of a trace conditioned stimulus (CS) when unsignaled unconditioned stimuli (USs) are introduced into the intertrial interval. In Experiment 1, a target US occurred at a fixed time either shortly before (embedded), shortly after (trace), or at the same time (delay) as the offset of a 120-s CS. During the CS, responding was most suppressed by intertrial USs in the trace group, less so in the delay group, and least in the embedded group. Unreinforced probe trials revealed a bell-shaped curve centered on the normal US arrival time during the trace interval, suggesting that temporally specific learning occurred both with and without intertrial USs. Experiments 2a and 2b confirmed that the bulk of the trace CS became inhibitory when intertrial USs were scheduled, as measured by summation and retardation tests, even though CS offset evoked a temporally precise conditioned response. Thus, an inhibitory CS may give rise to new stimuli specifically linked to its termination, which are excitatory. A modification to the microstimulus temporal difference model is offered to account for the data.     

Force– and power–time curve comparison during jumping between strength-matched male and female basketball players

The purpose of this study was to compare force– and power–time curve variables during jumping between Division I strength-matched male and female basketball athletes. Males (n?=?8) and females (n?=?8) were strength matched by testing a one-repetition maximum (1RM) back squat. 1RM back squat values were normalised to body mass in order to demonstrate that strength differences were a function of body mass alone. Subjects performed three countermovement jumps (CMJ) at maximal effort. Absolute and relative force– and power–time curve variables from the CMJs were analysed between males and females. Average force– and power–time curves were generated for all subjects. Jump height was significantly greater (p?≤?.05) in males than females. Absolute force was higher in males during the concentric phase, but not significantly different (p?≥?.05) when normalised to body mass. Significance was found in absolute concentric impulse between sexes, but not when analysed relative to body mass. Rate of force development, rate of power development, relative peak force, and work were not significantly different between sexes. Males had significantly greater impulse during the eccentric phase as well as peak power (PP) during the concentric phase of the CMJ than did females in both absolute and relative terms. It is concluded that sex differences are not a determining factor in measured force during a CMJ when normalised to body mass between strength-matched subjects. However, eccentric phase impulse and concentric phase PP appear to be influenced by sex differences independent of matching strength levels.     

Mechanical solution of algebraic equations

The paper describes a machine for determining the real and complex roots of higher-degree algebraic equations. The principle of operation is found in the correspondence between sine wave quantities and complex numbers. The particular machine is designed for equations of the eighth degree, and finds all the roots with engineering accuracy in the space of a few minutes.Though designed primarily with a view to determining the indicial admittance of electric networks, the machine should find utility in other fields of applied mathematics as well.     

To be or not to be an excellent football referee: different experts’ viewpoints

Football is central to the lives of countless individuals around the globe. While most of the attention of those passionate about the sport is focused on the players, football referees are often just as important in shaping the outcome of the games. Therefore, research is increasingly examining the role of referees. Even so, our understanding of the factors that create an excellent football referee is still scarce.

Based on our analysis of the opinions of 24 football experts, we demonstrate the multidimensionality of excellence in the performance of football referees. From a Categorical Principal Components Analysis (CatPCA), we were able to pinpoint that football referee excellence is shaped by three distinct dimensions: individual preparation, game preparation and game management. Additionally, we were able to see if these perceptions were different from individuals “within” the game versus those “outside” the game. Namely, we used CatPCA to graphically display the main correlations between the latent dimensions of football refereeing performance and the “inside” and “outside” perspective of the game. The findings of our work contribute towards the knowledge of the factors that shape football referee excellence, while also highlighting areas in need of additional research attention.     

Curriculum Integration: Helping Career and Technical Education Students Truly Develop College and Career Readiness

All students need to learn how to read, write, solve mathematics problems, and understand and apply scientific principles to succeed in college and/or careers. The challenges posed by entry-level career fields are no less daunting than those posed by college-level study. Thus, career and technical education students must learn effective math, literacy, and scientific concepts and processes. The National Center for Career and Technical Education Research completed three separate experimental design studies about the integration of math, literacy, and science in CTE courses. Across the studies, integration of core academics in CTE courses improved students' academic achievement as measured by standardized assessments.     

Designing Communication Process for the Design of an Idea Zone at a Science Center

In this paper, we use the occasion of the design of a learning space (The Idea Zone) in a science center setting, the Museum of Science and Industry, to illustrate the importance of attending to communication issues in the design of a process to design the space. We explore communication processes in the conceptual design phase, with specific attention to bringing Needfinding to a participatory design framework. Use of the World Café is made to create a conversational space for the participatory design process. We reflect on the recursive nature of designing communication process for participatory design of the Idea Zone and offer seven principles that integrate the theories and practices of both communication and design, bringing particular attention to generative metaphors, reflective practice, and emergence of a “third language” for designing together with others.