Megan E. Holmes

Sleep duration and overweight among Australian children and adolescents

Aim: To examine the association between sleep and overweight and waist circumference (WC) in children and adolescents. Methods: Data were from a nationally representative sample of 6324 7–15‐y‐old males and females from the Australian Health and Fitness Survey. Associations between sleep duration and body mass index (BMI) and WC were examined by analysis of covariance, linear regression, and logistic regression. Results: In the total sample, there was a significant main effect across sleep‐duration categories (≤8 h, 8–9 h, 9–10 h, and ≥10 h) for BMI. Linear regression showed significant age, sex, age‐sleep, and age‐sex‐sleep interactions in the total sample. There was an inverse graded relationship between sleep and BMI and WC in boys. In boys, there was a 1.6–1.8 times greater odds of overweight for those who reported 8–9 h or 9–10 h of sleep compared to those reporting ≥10 h of sleep. For boys reporting ≤8 h of sleep, there was about 3.1 times greater odds of overweight compared to those reporting ≥10 h of sleep. In contrast, no significant associations between sleep and overweight were found in girls.

The physical activity, stress and metabolic syndrome triangle: a guide to unfamiliar territory for the obesity researcher

Research aimed at deciphering the aetiology of obesity and the metabolic syndrome remains focused on two behavioural factors, namely diet and physical activity, even though epidemiologic research suggests that these two cornerstones of treatment and prevention account for only a small‐to‐moderate portion of the variance in these phenotypes. In recent years, this observation has prompted the intensified investigation of the pathogenic potential of factors that extend beyond the traditional concept of energy imbalance and examine the putative causes of this imbalance. Psychosocial stress has emerged as one such factor, raising the need for researchers to be informed about this expansive and complex literature. The purpose of this review is twofold (i) To introduce obesity researchers to fundamental concepts and historically important theoretical developments in the stress field and (ii) To outline the dyadic and triadic interactions between stress, physical activity and the metabolic syndrome. Although the expansion of the research focus to multiple, diverse and interacting putative causal agents will certainly increase the complexity of the research enterprise, this step seems essential for the comprehension and effective response to the continuing rise in the prevalence of obesity and the metabolic syndrome.

The association between morning cortisol and adiposity in children varies by weight status.

Abstract Objective: To examine the associations between morning cortisol and adiposity in children at baseline and 9-month follow-up. Methods: Participants included 649 (301 males, 348 females) children (9.6±0.9 years) for the cross-sectional analysis and 316 (153 males, 163 females) for the longitudinal analysis. Body mass index (BMI, kg/m2) was calculated from measured height and weight and waist circumference (WC, cm) was measured at the superior border of the iliac crest. Cortisol was assessed via saliva samples collected on a single morning. Cross-sectional and longitudinal analyses were conducted to examine the relationships between cortisol and adiposity. Results: Approximately 31% were overweight (17.7%) or obese (12.8%). The mean cortisol level was 9.36±5.64 nmol/L (0.34±0.20 μg/dL). At baseline, no significant correlations were found between cortisol and BMI or WC (r<0.07). Baseline cortisol did not correlate with change in BMI z-score (r=–0.03) or WC (r<–0.01) over the follow-up period. When examined by weight status, baseline cortisol was significantly related to changes in WC (r=0.32) and BMI z-score (r=0.28) among overweight subjects. Conclusions: A positive relationship was found between morning cortisol and change in WC over 9 months in overweight children. Future studies should examine the association between 24-h cortisol patterns and direct measures of trunk fat.

Morning cortisol is not associated with truncal fatness or resting blood pressure in children: cross-sectional and 1-2 year follow-up analyses.

ABSTRACT Objective: To evaluate the cross-sectional and longitudinal relationships of morning cortisol with trunk fat and resting blood pressure (BP) in children. Methods: Participants included 72 children aged 4-10 years (mean 7.4 yrs) for the cross-sectional analysis and 58 for the longitudinal analysis. Height, weight, waist circumference, body fat by dual x-ray absorptiometry, and resting BP measures were obtained during a laboratory visit. Saliva samples were collected at home on a single morning and assayed for cortisol. Results: Approximately 21% were overweight (15.3%) or obese (5.6%). Mean morning cortisol was 0.25 ± 0.12 μg/dL (6.99 ± 3.46 nmol/L). There were no significant correlations between morning cortisol and any of the measures of fatness (r<-0.17) or BP (r<-0.10) at baseline. Cortisol at baseline was not associated with changes in body size parameters after the 1- and 2- year follow-up period. Conclusion: Morning cortisol was not associated with body fatness or BP. Future studies should examine the associations between the diurnal cortisol patterns, trunk fat, and BP by collecting samples throughout an entire day.

Nutritional Considerations for Performance in Young Athletes.

Nutrition is an integral component to any athletes training and performance program. In adults the balance between energy intake and energy demands is crucial in training, recovery, and performance. In young athletes the demands for training and performance remain but should be a secondary focus behind the demands associated with maintaining the proper growth and maturation. Research interventions imposing significant physiological loads and diet manipulation are limited in youth due to the ethical considerations related to potential negative impacts on the growth and maturation processes associated with younger individuals. This necessary limitation results in practitioners providing nutritional guidance to young athletes to rely on exercise nutrition recommendations intended for adults. While many of the recommendations can appropriately be repurposed for the younger athlete attention needs to be taken towards the differences in metabolic needs and physiological differences.

Physical Activity, Stress, and Obesity

In its most basic sense, obesity is considered a pathological excess of adiposity that is the result of energy intake chronically exceeding energy expenditure (Blundell 2001). Indeed, diet and physical activity are considered the cornerstones of obesity prevention and treatment strategies. However, data supporting a hypothesis that suggests people are eating more and moving less is limited in developed nations such as the United States (Eisenmann 2003). However, national survey data for the United States does suggest that there has been an increase in fast-food consumption (Ebbeling et al. 2004) as well as snacking (Zizza et al. 2001). Likewise, with regard to energy expenditure, research suggests that leisure time physical activity has decreased (Cole 2003). Given the high prevalence of obesity and the potential implications for so many other facets of life, the obesity epidemic is viewed as a critical public health concern worldwide. A basic understanding of thermodynamics makes disregarding the contribution of diet and physical activity impossible. Nonetheless, researchers have begun examining the condition as a result of many antecedents that influence either side of the energy balance equation (Eisenmann 2006; Keith et al. 2006). One particularly intriguing line of research examines the putative role of chronically dysregulated stress responses on the development of obesity and metabolic syndrome. This relationship is well established in the adult literature (Björntorp 1993, 2001; Brunner et al. 2002; Rosmond 2005) and is receiving increased attention in pediatric work (Cheek et al. 1981; Dimitriou et al. 2003; Goldbacher et al. 2005; Mellbin and Vuille 1989a). Additionally, researchers have begun to examine the relationship between physical activity and stress (Forcier et al. 2006; Hamer et al. 2006; Jackson and Dishman 2006; Strong et al. 2005) and moderating potential of physical activity on the stress-obesity M.E. Holmes (*) Department of Kinesiology, Mississippi State University, Mississippi State, MS, USA E-Mail: mholmes@colled.msstate.edu # Springer-Verlag GmbH Deutschland 2016 R. Fuchs, M. Gerber (Hrsg.), Handbuch Stressregulation und Sport, Springer Reference Psychologie, DOI 10.1007/978-3-662-49411-0_13-1 1 relationship (Holmes et al. 2008; Yin et al. 2005). This chapter will first examine the basic epidemiology of obesity and related conditions to help aid the illustration of the magnitude of the problem. This chapter will also examine the current literature regarding the relationship between stress and obesity, with a keen focus on the potential moderation of the relationship by physical activity.

Assessment of balance among adolescent track and field athletes.

Abstract Track and field events place different demands on athletes and may have an effect on balance. This study investigated the effects of event specialty, gender, and leg dominance on balance among adolescent track and field athletes. Forty healthy adolescent track and field athletes (male = 23, female = 17) categorised into three different groups (sprinter = 20, distance runners = 13, throwers = 7) had their single leg static balance measured with the eyes open and the eyes closed using an AMTI force platform. Dependent variables included average displacement (cm) of the centre of pressure (COP) in the anterior/posterior direction and medial/lateral directions, the average velocity of the COP (cm/s) and the 95% ellipse area (cm2). Variables were analysed using a 3 (event specialty) × 2 (gender) × 2 (leg) ANOVA with repeated measures on the leg variable (p < 0.05). There was a significant difference (p < 0.05) in the average displacement of the COP in the medial/lateral direction for both the eyes open and closed condition, with the non-dominant leg demonstrating greater displacement than the dominant leg. This might increase the risk of injury for the non-dominant leg, but additional data should be collected and analysed on both dynamic balance and performance.

Efficacy of Carbohydrate Ingestion on CrossFit Exercise Performance

The efficacy of carbohydrate (CHO) ingestion during high-intensity strength and conditioning type exercise has yield mixed results. However, little is known about shorter duration high-intensity exercise such as CrossFit. The purpose of this study was to investigate the performance impact of CHO ingestion during high-intensity exercise sessions lasting approximately 30 min. Eight healthy males participated in a total of four trials; two familiarizations, a CHO trial, and a similarly flavored, non-caloric placebo (PLA) trial. CrossFit’s “Fight Gone Bad Five” (FGBF) workout of the day was the exercise model which incorporated five rounds of maximal repetition exercises, wall throw, box jump, sumo deadlift high pull, push press, and rowing, followed by one minute of rest. Total repetitions and calories expended were summated from each round to quantify total work (FGBF score). No difference was found for the total work between CHO (321 ± 51) or PLA (314 ± 52) trials (p = 0.38). There were also no main effects (p > 0.05) for treatment comparing exercise performance across rounds. Based on the findings of this study, it does not appear that ingestion of CHO during short duration, high-intensity CrossFit exercise will provide a beneficial performance effect.

Erratum to “Nutritional Considerations for Performance in Young Athletes”

[This corrects the article DOI: 10.1155/2015/734649.].