Effects of a 12-week resistance exercise program on physical self-perceptions in college students

There is an increase in literature suggesting exercise can promote positive changes in physical self-perceptions that can manifest as an increase in global self-esteem. In the present study, we assessed self-esteem using the hierarchical framework of the Exercise and Self-Esteem Model (EXSEM) along with cognitive facets at the subdomain level (e.g., competence, certainty, importance, and ideal self-discrepancy). This allowed for an analysis of cognitive facets as possible contributors to changes in physical self-perceptions. We addressed these aims with a sample of 120 college-age adults who completed a 12-week resistance exercise program. Results indicated significant improvements in self-perception constructs at all levels of the EXSEM. The hierarchical structure of the EXSEM was partially supported, as we observed successively smaller improvements at each level of the model (e.g., self-esteem showed lesser improvements than physical self-worth). In addition, a path model developed to explain the impact of strength changes on self-esteem proved a good fit for the data. Results are discussed in terms of contemporary models of self-perception, potential mediators of exercise on self-esteem, and the need to consider cognitive facets of self-perception.     

Kinematic analysis of shot-putting performed by wheelchair athletes of different medical classes

The aim of this study was to identify those kinematic characteristics that are most closely related to an athlete's medical classification and measured distance of a put. Two S-VHS camcorders (60 fields per second) were used to record the performance of 17 males of different classes. Each participant performed six trials and the best trial for each was selected for analysis. Three-dimensional kinematics of the shot and upper body segments at the instant of release and during the forward thrust (delivery) were determined. The average speeds and angles of the shot at release for different classes (5.3-7.8 m x s(-1) and 21.2 to 34.4 degrees, respectively) were smaller than those exhibited by elite male able-bodied throwers. The height of the shot at release, the angular speed of the upper arm at release, the range of motion of the shoulder girdle during the delivery, and the average angular speeds of the trunk, shoulder girdle and upper arm during the delivery, were all significantly correlated with both the classification and measured distance (P < 0.05). The results indicate the importance of achieving a high average angular speed for each upper body segment during the delivery.     

圣乔治山的化石

在二亿多年前，在世界的一角，即在现今的瑞士和意大利边境，曾经有一个小的海。虽然这个水体最终干涸和消失掉，但其中栖居的动物的残体——多种多样的鱼类和爬行动物集群——在其死亡后保存在盆地底部的泥质沉积物内。经过几百万年的漫长岁月，沉积物变硬了，并因构造活动而抬升，最终变成一座山，称为圣乔治山。     

In vivo lumbo-sacral forces and moments during constant speed running at different stride lengths

The aim of this study was to introduce a Newton-Euler inverse dynamics model that included reaction force and moment estimation at the lumbo-sacral (L5-S1) and thoraco-lumbar (T12-L1) joints. Data were collected while participants ran over ground at 3.8 m x s(-1) at three different stride lengths: preferred stride length, 20% greater than preferred, and 20% less than preferred. Inputs to the model were ground reaction forces, bilateral lower extremity and pelvis kinematics and inertial parameters, kinematics of the lumbar spine and thorax and inertial parameters of the lumbar segment. Repeated measures ANOVA were performed on the lower extremity sagittal kinematics and kinetics, including L5-S1 and T12-L1 three-dimensional joint angles, reaction forces and moments at touchdown and peak values during impact phase across the three stride conditions. Results indicated that L5-S1 and T12-L1 vertical reaction forces at touchdown and during the impact portion of the support phase increased significantly as stride length increased (P < 0.001), as did peak sagittal L5-S1 moments during impact (P = 0.018). Additionally, the transverse T12-L1 joint moment increased as running speed increased (P = 0.006). We concluded from our findings that our model was sensitive to our perturbations in healthy runners, and may prove useful in future mechanistic studies of L5-S1 mechanics.     

Lectin-functionalized microchannels for characterizing pluripotent cells and early differentiation

Embryonic stem (ES) cells are capable of proliferating and differentiating to form cells of the three embryonic germ layers, namely, endoderm, mesoderm, and ectoderm. The utilization of human ES cell derivatives requires the ability to direct differentiation to specific lineages in defined, efficient, and scalable systems. Better markers are needed to identify early differentiation. Lectins have been reported as an attractive alternative to the common stem cell markers. They have been used to identify, characterize, and isolate various cell subpopulations on the basis of the presentation of specific carbohydrate groups on the cell surface. This article demonstrates how simple adhesion assays in lectin-coated microfluidic channels can provide key information on the interaction of lectins with ES and definitive endoderm cells and thereby track early differentiation. The microfluidic approach incorporates both binding strength and cell surface receptor density, whereas traditional flow cytometry only incorporates the latter. Both approaches are examined and shown to be complementary with the microfluidic approach providing more biologically relevant information.