Post-exercise ingestion of a unique, high molecular weight glucose polymer solution improves performance during a subsequent bout of cycling exercise

The aim of the present study was to determine the effect of post-exercise ingestion of a unique, high molecular weight glucose polymer solution, known to augment gastric emptying and post-exercise muscle glycogen re-synthesis, on performance during a subsequent bout of intense exercise. On three randomized visits, eight healthy men cycled to exhaustion at 73.0% (s = 1.3) maximal oxygen uptake (90 min, s = 15). Immediately after this, participants consumed a one-litre solution containing sugar-free flavoured water (control), 100 g of a low molecular weight glucose polymer or 100 g of a very high molecular weight glucose polymer, and rested on a bed for 2 h. After recovery, a 15-min time-trial was performed on a cycle ergometer, during which work output was determined. Post-exercise ingestion of the very high molecular weight glucose polymer solution resulted in faster and greater increases in blood glucose (P < 0.001) and serum insulin (P < 0.01) concentrations than the low molecular weight glucose polymer solution, and greater work output during the 15-min time-trial (164.1 kJ, s = 21.1) than both the sugar-free flavoured water (137.5 kJ, s = 24.2; P < 0.05) and the low molecular weight glucose polymer (149.4 kJ, s = 21.8; P < 0.05) solutions. These findings could be of practical importance for athletes wishing to optimize performance by facilitating rapid re-synthesis of the muscle glycogen store during recovery following prolonged sub-maximal exercise.     

Longitudinal changes in submaximal oxygen uptake in 11- to 13-year-olds

The aim of this study was to monitor longitudinal changes in young people's submaximal oxygen uptake (VO2) responses during horizontal treadmill running at 8 km x h(-1). The 236 participants (118 boys, 118 girls) were aged 11.2+/-0.4 years (mean +/- s) at the onset of the study. Submaximal VO2, peak VO2 and anthropometry were recorded annually for three consecutive years. The data were analysed using multi-level regression modelling within a multiplicative, allometric framework. The initial model examined sex, age and maturity-related changes in submaximal VO2 relative to body mass as the sole anthropometric covariate. Our results demonstrate that the conventional ratio standard ml x kg(-1) x min(-1) does not adequately describe the true relationship between body mass and submaximal VO2 during this period of growth. The effects of maturity and age were non-significant, but girls consumed significantly less VO2 than boys running at 8 km x h(-1). In subsequent models, stature was shown to be a significant explanatory variable, but this effect became non-significant when the sum of two skinfolds was added. Thus, within this population, submaximal VO2 responses were explained predominantly by changes in body mass and skinfold thicknesses, with no additional maturity-related increments. When differences in body mass and skinfolds were controlled for, there was still a difference between the sexes in submaximal VO2, with girls becoming increasingly more economical with age.     

Contextual and individual-level predictors of abused children's reentry into out-of-home care: a multilevel mixture survival analysis

Objectives

This study examined the effects of individual and contextual factors on reentry into out-of-home care among children who were discharged from child protective services in fiscal year 2004-2005. The objectives were to: (1) examine individual and contextual factors associated with reentry, (2) explore whether there are meaningful groups of youth who differ in terms of risk for reentry, and (3) determine whether relatively homogeneous clusters of child welfare agencies, based on contextual characteristics, differ significantly in terms of the reentry rates of the children whom they serve.

Method

The study design involved a multilevel longitudinal analysis of administrative data based on an exit cohort. Two Cox proportional hazards multilevel mixture models were tested. The first model included multiple individual level predictors and no agency level predictors. The second model included both levels of predictors.

Results

The results of multilevel Cox regression mixture modeling indicated that at the individual level, younger age, being placed in out-of-home care because of neglect and having physical, health problems corresponded to a decreased likelihood for reentry. At the agency level, lower average expenditures per child and contracting out case management services were associated with faster reentry into out-of-home care.

Conclusions

This study demonstrates that children who reenter out-of-home care appear to be a homogeneous population and that reentry is associated with both contextual factors and individual characteristics.

Practice implications

The most important implication that can be drawn from the study findings is that reentry may be most effectively prevented by focusing on such factors at the organizational level as contracting out case management services and funding allocation. Child welfare agencies that are responsible for an array of services and decide to contract out case management should consider the use of performance-based contracts and emphasize and strengthen quality assurance approaches for contracted services. In addition, to compensate for lower funding allocated for children served in out-of-home care, child welfare workers should become more familiar with community resources and help connect families to these supports.     

Physical Disability,Stigma, and Physical Activity in Children

Using the stereotype content model as a guiding framework, this study explored whether the stigma that able‐bodied adults have towards children with a physical disability is reduced when the child is portrayed as being active. In a 2 (physical activity status) x 2 (ability status) study design, 178 university students rated a child described in one of four vignettes on 12 dimensions of perceived warmth and competence. Results revealed a main effect of ability status on warmth (p < 0.001) such that children with a physical disability were rated significantly higher in perceived warmth than able‐bodied children, regardless of activity status (d = 0.86). Also, there was a significant interaction (p = 0.02) of ability and activity status on perceived competence, indicating that ratings of perceived competence were significantly higher for active children with a physical disability than for all other children (d = 0.54–0.64). Results suggest that physical activity should be explored as a way to mitigate the stigmatisation of children with a physical disability.     

Home birth matters-for all women

Although it remains rare in the United States, planned home birth has drawn increasing attention and criticism in the mainstream media and has come under attack from organized medicine. Yet, recent peer-reviewed studies contribute to the evidence base supporting home birth as a safe option for low-risk women attended by skilled midwives. The author of this editorial argues that home birth is an important cultural touchstone in the landscape of American maternity care.     

Changes in short-term power output in 10- to 12-year-olds

In this study, we used multi-level regression modelling to assess the influence of age, sex, body size, skinfold thicknesses, maturity, thigh muscle volume and isokinetic leg strength on the development of load- and inertia-adjusted peak (1 s) and mean power (30 s) determined using the Wingate anaerobic test. Fifteen males and 19 females were measured twice, first aged 10.0 +/- 0.3 years and then aged 11.8 +/- 0.3 years. Initial models identified body mass and height as significant explanatory variables (P < 0.05) for peak power and mean power, with an additional age effect for the former. No significant differences between the sexes or maturity effects were observed for either peak or mean power (P > 0.05). The introduction of sum of skinfolds improved the fit of the model and rendered the height term non-significant for both peak and mean power (P> 0.05). An age effect became apparent for mean power. When isokinetic leg strength and thigh muscle volume were entered into the model, the latter exerted a significant effect on both peak and mean power (P< 0.05), whereas isokinetic leg strength was not a significant explanatory variable for either (P> 0.05). In conclusion, thigh muscle volume exerts a positive influence on young people's short-term power output, which is additional to the effects of body mass, sum of skinfolds and age.     

Nutritional strategies for football: counteracting heat, cold, high altitude, and jet lag

Environmental factors often influence the physical and mental performance of football players. Heat, cold, high altitude, and travel across time zones (i.e. leading to jet lag) act as stressors that alter normal physiological function, homeostasis, metabolism, and whole-body nutrient balance. Rather than accepting performance decrements as inevitable, well-informed coaches and players should plan strategies for training and competition that offset environmental challenges. Considering the strength of scientific evidence, this paper reviews recommendations regarding nutritional interventions that purportedly counterbalance dehydration, hyperthermia, hypothermia, hypoxia, acute or chronic substrate deficiencies, sleep loss, and desynchronization of internal biological clocks.