Gastric Emptying Characteristics of Glucose and Glucose Polymer Solutions

Abstract

In an effort to evaluate various carbohydrate (CHO) molecules for inclusion in an athletic drink, the gastric emptying characteristics of 5, 10, 20, and 40% solutions of glucose and a glucose polymer were compared. The volume of gastric residue remaining 30 minutes after ingestion of 400 ml of each of the solutions was determined in 15 healthy individuals. The volume of gastric residue recovered increased progressively with increasing solute concentration. At the lowest CHO concentration the glucose polymer yielded a significantly smaller gastric residue than glucose. The smaller residue appeared to be attributable both to a greater rate of exit of the polymer from the stomach as well as to a lower rate of gastric secretion induced by the polymer. The calculated delivery of CHO to the intestine increased with solute concentration. At the lowest CHO concentration the more rapid gastric emptying of the polymer allowed significantly greater calculated CHO delivery. We conclude that at low CHO concentrations (≤5 g/100 ml), such as used in drinks designed for athletics participants, the glucose polymer might be an advantageous alternative to glucose as a source of CHO.     

Lower extremity muscle function of front row rugby union scrummaging

A rugby scrum’s front row must act uniformly to transfer maximal horizontal force and improve performance. This study investigated the muscle activation patterns of lower extremity muscles in front row forwards during live and machine scrums at professional and amateur levels. Electromyography was collected bilaterally on vastus lateralis, rectus femoris and gastrocnemius muscles of 75 male rugby prop players during live and machine scrums. ANOVAs compared muscle reaction time, rate of change in muscle amplitude and muscle amplitude between groups and conditions. Cross-correlation analysis explored muscle synchronicity. There were significantly greater rates of change in each muscle amplitude in professional players than amateur players. Additionally, there was significantly quicker muscle reaction time in all muscles, and greater amplitude in vastus lateralis and gastrocnemius, during the live scrum vs. machine condition. The professional props produced more synchronised muscle activation than amateur players and all players produced more synchronised muscle activation against the scrum machine vs. live scrummage. The results indicate a higher skill proficiency and muscle synchronicity in professional players. While scrum machine training is ideally suited for functional muscle strengthening during practice, to truly simulate the requirements of the scrum, training should incorporate the live situation as much as possible.     

Child Care Quality and Cognitive Development: Trajectories Leading to Better Preacademic Skills

The associations between trajectories of child care quality from ages 2 to 4 years and children's cognitive performance at 4 years (n = 250) were tested. Distinct quality trajectories were identified: low and high ascending Teaching and Interactions trajectory; low and high Provision for Learning trajectory. Membership in the high ascending Teaching and Interactions trajectory was associated with better numeracy (effect size [ES] = .39, confidence interval [CI] = .21–.66), receptive vocabulary (ES = .41, CI = .14–.68), and school readiness (ES = .32, CI = .06–.58). The results suggest that a pattern of increasing quality of teacher–child interactions during the preschool years, particularly with regard to supporting the development of language, has a moderate impact on children's cognitive development.     

Quantification of brake data acquired with a brake power meter during simulated cross-country mountain bike racing

There is currently a dearth of information describing cycling performance outside of propulsive and physiological variables. The aim of the present study was to utilise a brake power meter to quantify braking during a multi-lap cross-country mountain bike time trial and to determine how braking affects performance. A significant negative association was determined between lap time and brake power (800.8 ± 216.4 W, mean ± SD; r = ?0.446; p < 0.05), while the time spent braking (28.0 ± 6.4 s) was positively associated with lap time (314.3 ± 37.9 s; r = 0.477; p < 0.05). Despite propulsive power decreasing after the first lap (p < 0.05), lap time remained unchanged (p > 0.05) which was attributed to decreased brake work (p < 0.05) and brake time (p < 0.05) in both the front and rear brakes by the final lap. A multiple regression model incorporating braking and propulsion was able to explain more of the variance in lap time (r² = 0.935) than propulsion alone (r² = 0.826). The present study highlights that riders’ braking contributes to mountain bike performance. As riders repeat a cross-country mountain bike track, they are able to change braking, which in turn can counterbalance a reduction in power output. Further research is required to understand braking better.     

Botany and environmental education in elementary school in Brazil: articulating knowledge,values, and procedures

Abstract

The increasing urbanization and alienation from nature reduce children’s opportunities to interact with plants and challenge teachers to devise educational practices that contribute to learning botany. This study presents the results of activities developed in a Brazilian school through explorations, drawings, dried and pressed specimens, and semi-structured interviews. The data were evaluated using mixed methods analysis. Leaves were the structure that was most frequently drawn by 1st- and 2nd-year students, followed by stems. Among students in their 3rd, 4th, and 5th years, more emphasis was on flowers and their detailed morphological structures. The 1st- and 2nd-year students included non-living elements and the surrounding environment in their drawings, whereas the older students focused on the plant itself. These particularities point to methods of teaching botany in context and link students’ specific knowledge to values and practices that contribute to an environmental education that aims to minimize the utilitarian view of nature and move towards a view of human beings as integrated and interdependent with other living and non-living elements.     

Leg preference and interlateral asymmetry of balance stability in soccer players

To examine the effect of long lasting practice on pedal behavior in sport, we compared experienced adult soccer players and nonsoccer players on leg preference in motor tasks requiring general mobilization, soccer related mobilization, and body balance stabilization. We also evaluated performance asymmetry between the right and left legs in static and dynamic unipedal body balance, based on center of pressure displacement, and correlated that with leg preference in balance stabilization tasks. Results revealed (a) a distinct leg preference between mobilization and stabilization tasks, which were significantly different between players and nonplayers, (b) similar balance stability between the right and left legs, (c) greater stability of experienced players compared with nonplayers in static and dynamic balance, and (d) absence of a significant leg preference correlation with interlateral balance asymmetry. These results suggest an effect of extensive soccer skill practice on establishing leg preference for specific mobilization tasks and overall balance control.