The influence of carbohydrate and protein ingestion during recovery from prolonged exercise on subsequent endurance performance

Abstract

Ingesting carbohydrate plus protein following prolonged exercise may restore exercise capacity more effectively than ingestion of carbohydrate alone. The objective of the present study was to determine whether this potential benefit is a consequence of the protein fraction per se or simply due to the additional energy it provides. Six active males participated in three trials, each involving a 90-min treadmill run at 70% maximal oxygen uptake (run 1) followed by a 4-h recovery. At 30-min intervals during recovery, participants ingested solutions containing: (1) 0.8 g carbohydrate · kg body mass (BM)^?1 · h^?1 plus 0.3 g · kg^?1 · h^?1 of whey protein isolate (CHO-PRO); (2) 0.8 g carbohydrate · kg BM^?1 · h^?1 (CHO); or (3) 1.1 g carbohydrate · kg BM^?1 · h^?1 (CHO-CHO). The latter two solutions matched the CHO-PRO solution for carbohydrate and for energy, respectively. Following recovery, participants ran to exhaustion at 70% maximal oxygen uptake (run 2). Exercise capacity during run 2 was greater following ingestion of CHO-PRO and CHO-CHO than following ingestion of CHO (P ≤ 0.05) with no significant difference between the CHO-PRO and CHO-CHO treatments. In conclusion, increasing the energy content of these recovery solutions extended run time to exhaustion, irrespective of whether the additional energy originated from sucrose or whey protein isolate.     

Movement Pattern and Parameter Learning in Children

Reduced feedback during practice has been shown to be detrimental to movement accuracy in children but not in young adults. We hypothesized that the reduced accuracy is attributable to reduced movement parameter learning, but not pattern learning, in children. A rapid arm movement task that required the acquisition of a motor pattern scaled to specific spatial and temporal parameters was used to investigate the effects of feedback (FB) frequency (100% vs. 62% faded) on motor learning differences between 19 school-age children and 19 young adults. Adults and children practiced the task for 200 trials under the 100% or faded FB condition on Day 1 and returned on Day 2 for a no-FB retention test. On the retention test, children who practiced with reduced feedback performed with greater temporal parameter errors, but not pattern error, than children who received frequent feedback. Motor skill learning in children is influenced by feedback frequency during practice that affects parameter learning but not pattern learning.     

Not quite normal: Consequences of violating the assumption of normality in regression mixture models

Regression mixture models are a new approach for finding differential effects which have only recently begun to be used in applied research. This approach comes at the cost of the assumption that error terms are normally distributed within classes. The current study uses Monte Carlo simulations to explore the effects of relatively minor violations of this assumption, the use of an ordered polytomous outcome is then examined as an alternative which makes somewhat weaker assumptions, and finally both approaches are demonstrated with an applied example looking at differences in the effects of family management on the highly skewed outcome of drug use. Results show that violating the assumption of normal errors results in systematic bias in both latent class enumeration and parameter estimates. Additional classes which reflect violations of distributional assumptions are found. Under some conditions it is possible to come to conclusions that are consistent with the effects in the population, but when errors are skewed in both classes the results typically no longer reflect even the pattern of effects in the population. The polytomous regression model performs better under all scenarios examined and comes to reasonable results with the highly skewed outcome in the applied example. We recommend that careful evaluation of model sensitivity to distributional assumptions be the norm when conducting regression mixture models.     

24 Hours in the Children’s Section: An Observational Study at the Public Library

The purpose of this study was to explore patronage and usage of the children’s section of a public library. Patrons of the children’s section of a public library in a small Northern Arizona city were observed for a total of 24 h over 12 sessions. Analytic induction was used to formulate categories based on field notes made during these observations. An observation of a story time session was also conducted. Data from an interview with a librarian was triangulated with observational data. In terms of patronage, the clear majority of parents/adult caregivers accompanying a child or children to the children’s section were observed to be female and speaking English. In terms of usage, the following three categories of early learning were identified from the data: early literacy learning; learning how to use a library; and other developmentally appropriate learning. Study results offer insight into both the role of females in the intergenerational transmission of literacy and the rich learning young children experience at the library. At a time of library cutbacks and closures across the United States, this study speaks to the continued relevance of the children’s section of the public library in providing free early learning experiences during the pivotal birth to five age range.     

Droplet dispensing in digital microfluidic devices: Assessment of long-term reproducibility

We report an in-depth study of the long-term reproducibility and reliability of droplet dispensing in digital microfluidic devices (DMF). This involved dispensing droplets from a reservoir, measuring the volume of both the droplet and the reservoir droplet and then returning the daughter droplet to the original reservoir. The repetition of this process over the course of several hundred iterations offers, for the first time, a long-term view of droplet dispensing in DMF devices. Results indicate that the ratio between the spacer thickness and the electrode size influences the reliability of droplet dispensing. In addition, when the separation between the plates is large, the volume of the reservoir greatly affects the reproducibility in the volume of the dispensed droplets, creating "reliability regimes." We conclude that droplet dispensing exhibits superior reliability as inter-plate device spacing is decreased, and the daughter droplet volume is most consistent when the reservoir volume matches that of the reservoir electrode.     

Mission matters: The cost of small high schools revisited

With the financial support of several large foundations and the federal government, creating small schools has become a prominent high school reform strategy in many large American cities. While some research supports this strategy, little research assesses the relative costs of these smaller schools. We use data on over 200 New York City high schools, from 1996 through 2003, to estimate school cost functions relating per pupil expenditures to school size, controlling for school output and quality, student characteristics, and school organization.We find that the structure of costs differs across schools depending upon mission—comprehensive or themed. At their current levels of outputs, themed schools minimize per pupil costs at smaller enrollments than comprehensive schools, but these optimally sized themed schools also cost more per pupil than optimally sized comprehensive schools. We also find that both themed and comprehensive high schools at actual sizes are smaller than their optimal sizes.     

Working conditions in urban schools

The recent wave of reform reports in education promulgated a wide variety of recommendations to address identified concerns. This research explores an issue mostly ignored by the reform reports, the working conditions teachers face. Utilizing ethnographic techniques and multisite analyses of in-depth case studies of six schools in two large urban areas, the authors identify five broad categories of stressors in the work environment, including governance/leadership, budget cuts, security, staff relations, and student issues. In addition, two major themes characterizing working conditions for teachers are specified, the no respect syndrome and barriers to teaching. The need to address these issues before attempting to implement the major reforms in the national reports is highlighted.     

Information-seeking behavior changes in community-based teaching practices.

A National Library of Medicine information access grant allowed for a collaborative project to provide computer resources in fourteen clinical practice sites that enabled health care professionals to access medical information via PubMed and the Internet. Health care professionals were taught how to access quality, cost-effective information that was user friendly and would result in improved patient care. Selected sites were located in medically underserved areas and received a computer, a printer, and, during year one, a fax machine. Participants were provided dial-up Internet service or were connected to the affiliated hospital's network. Clinicians were trained in how to search PubMed as a tool for practicing evidence-based medicine and to support clinical decision making. Health care providers were also taught how to find patient-education materials and continuing education programs and how to network with other professionals. Prior to the training, participants completed a questionnaire to assess their computer skills and familiarity with searching the Internet, MEDLINE, and other health-related databases. Responses indicated favorable changes in information-seeking behavior, including an increased frequency in conducting MEDLINE searches and Internet searches for work-related information.