A longitudinal investigation of the development of weight and muscle concerns among preadolescent boys

The study examined the impact of body mass index (BMI), negative affect, self-esteem, and sociocultural influences in the development of weight and muscle concerns among preadolescent boys. Body dissatisfaction, importance placed on weight and muscles, weight loss strategies, and strategies to increase muscles were evaluated. Participants were 237 boys aged between 8 and 11 years who were tested at three assessment periods 8 months apart. The main predictor of boys’ body change strategies was their perceived pressures to modify weight and muscles from parents, peers, and the media. The other main predictor of boys’ body change strategies and the sole predictor of body dissatisfaction was BMI. Self-esteem and negative affect were found to be weak and generally nonsignificant predictors of boys’ body image concerns and body change strategies. Additional studies that examine the risk and protective factors associated with boys’ weight and muscle concerns are needed to assist in the development of prevention programs for preadolescent boys.

A prospective study of individual factors in the development of weight and muscle concerns among preadolescent children

The present study was designed to assess body mass index (BMI), self-esteem, parent and peer relations, negative affect, and perfectionism, as predictors of dieting, food preoccupation, and muscle preoccupation, in 326 preadolescent children (150 girls and 176 boys) aged between 8 and 10 years. Preadolescents were tested twice over a 10-month period. BMI was found to be the main predictor of girls' and boys' dieting, both cross-sectionally and longitudinally. Perfectionism was an important predictor of boys' dieting and muscle preoccupation, while self-esteem, peer relations and negative affect predicted girls' muscle preoccupation. The findings are discussed in relation to past research with both preadolescents and adolescents.

Preventing weight and muscle concerns among preadolescents

The high level of weight and shape concerns amongst preadolescent children has prompted interest in the development of prevention programs for this age group. In the 1990s weight and shape concerns were considered primarily an adolescent phenomenon. However, prevention programs which have been designed with adolescent and adult populations have been found to show limited success. Some researchers have argued that programs which target preadolescent children are more likely to be effective than programs that target adolescents, as by adolescence many attitudes and behaviours have become entrenched so they may be more difficult to modify. On the other hand, children's weight and shape concerns are believed to be more malleable and amenable to change. To date there have been limited controlled studies implementing prevention programs designed to reduce weight and shape concerns with preadolescent populations. The new study conducted as part of this thesis involves the development and implementation of the ‘Everybody’ s Different, Nobody Else Is Me’ preadolescent prevention program. The program was designed to address some of the methodological biases of past research and incorporate three risk factors, social comparisons, negative affect, and self-esteem, to reduce and/or prevent the development of weight and muscle concerns among children. These three risk factors have been found to be associated with weight and shape concerns of adolescents and adults, and there is also increasing evidence that they are important factors among children. Research also suggests that social comparisons, negative affect, and self-esteem are interrelated, which highlights the importance of targeting the variables in one program. The new five session prevention initiative was implemented with 156 grade four children. Both the treatment and control conditions consisted of 78 children. Preliminary evidence from the new prevention initiative indicated that the program reduced muscle bulk and exercise (ie. An over-emphasis on exercise to lose weight rather than health promotion), and negative affect in the long term as assessed by the six month follow-up. At the six month follow-up, children in both the treatment and control conditions reported reduced negative affect, dieting, and muscle bulk and exercise scores and increased positive affect. Consistent with short term follow-up results, boys reported greater muscle bulk and exercise scores than girls at the six month follow-up. Girls, in both conditions, were also found to report greater positive affect than boys. These findings are discussed in relation to past research, and suggestions for future prevention initiatives are highlighted.

Social comparisons and negative affect as indicators of problem eating and muscle preoccupation among children

The present study examined the utilization of social comparison practices and the role of negative affect in predicting body dissatisfaction, problem eating, and muscle preoccupation among young children. Participants were 236 children aged between 8 and 10 years. Children's eating, exercising, and muscle concerns were examined using a modified version of the Children's Eating Attitudes Test (ChEAT), which included additional items pertaining to muscle bulk and exercising. Consistent with past findings, body mass index (BMI) was found to be the sole unique indicator of body dissatisfaction for both boys and girls. Utilization of social comparison practices with adults was the main unique indicator of the modified ChEAT factors for boys, while BMI was the main unique indicator of the modified ChEAT factors for girls. In addition, negative affect was associated with binging, food preoccupation, and social pressure to eat for boys and dieting and muscle preoccupation for girls. Findings are discussed in relation to previous studies with adolescents and adults.

Weight concerns among elementary school children : a review of prevention programs

There is increasing evidence that children display high levels of weight and muscle concerns, which include body dissatisfaction and problem eating. In order to address these issues, researchers have designed and implemented prevention programs for this age group. Thirteen published studies were located and reviewed, with children aged 8–12 years from elementary schools, or equivalent. Overall, the programs were shown to be effective in improving children's knowledge at post-test and at follow-up assessments. However, there is limited evidence to show that the programs reduced or prevented body image concerns and/or problem eating. Too few studies have examined muscle concerns so no conclusions can yet be drawn about this domain. Limitations of the studies and suggestions for future prevention efforts are discussed.

A biopsychosocial model for understanding body image and body change strategies among children

The present study was designed to assess the role of biopsychosocial factors in understanding body image concerns and cognitions and behaviors related to losing weight or increasing muscles among 507 children (270 girls and 237 boys) aged between 8 and 11 years. Biological, psychological, and sociocultural factors have been found to be relevant in understanding the development of body image concerns and weight loss strategies among children. However, these factors have not been examined together in a single study; thus, the relative influence of each factors and how these factors may interact is not known. In the current study, body mass index (BMI) was found to be a good indicator of girls' and boys' body dissatisfaction, while the main indicator of children's body change strategies was perceived pressure from parents, peers, and the media. Overall, there were more similarities than differences between girls and boys. The age between 8 and 11 years is a significant period to commence studying body image concerns and body change strategies, as it can be used to help us understand the emergence of gender differences in children's weight and muscle concerns.

Where is all the pressure coming from? Messages from mothers and teachers about preschool children's appearance, diet and exercise

This study used interviews and qualitative analyses to investigate the nature of the messages that preschool children receive from mothers and teachers about their bodies, general appearance, exercise and eating practices. Participants were 10 female teachers and 53 mothers. The behaviours of the 53 children (24 boys, 29 girls) were also observed to determine the nature of their eating and exercise behaviours. The results demonstrated that both mothers and teachers expressed concerns about their own bodies. Mothers also communicated messages to their daughters about losing weight and messages to their sons about increasing their muscles. Both girls and boys were concerned about their appearance, particularly their clothes and hair. Girls also demonstrated some concerns about losing weight, and boys with increasing muscles. Implications of these results are discussed in terms of designing education programs for mothers, teachers and children to prevent the development of body image concerns and disordered eating among children. Copyright © 2006 John Wiley & Sons, Ltd and Eating Disorders Association.

Age- and activity-related differences in the abundance of Myosin essential and regulatory light chains in human muscle

Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry) are labor-intensive and ill-suited to multixplex analysis, i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM).We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageing per se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping.

Diffusion characteristics of ethylene glycol in skeletal muscle

Part of the optical clearing study in biological tissues concerns the determination of the diffusion characteristics of water and optical clearing agents in the subject tissue. Such information is sufficient to characterize the time dependence of the optical clearing mechanisms—tissue dehydration and refractive index (RI) matching. We have used a simple method based on collimated optical transmittance measurements made from muscle samples under treatment with aqueous solutions containing different concentrations of ethylene glycol (EG), to determine the diffusion time values of water and EG in skeletal muscle. By representing the estimated mean diffusion time values from each treatment as a function of agent concentration in solution, we could identify the real diffusion times for water and agent. These values allowed for the calculation of the correspondent diffusion coefficients for those fluids. With these results, we have demonstrated that the dehydration mechanism is the one that dominates optical clearing in the first minute of treatment, while the RI matching takes over the optical clearing operations after that and remains for a longer time of treatment up to about 10 min, as we could see for EG and thin tissue samples of 0.5 mm.

Longitudinal study of children's disordered eating and muscle preoccupation

This thesis examined the role of individual factors in the development of dieting and muscal preoccupation in children. The main factor associated with these weight and shape concerns was perfectionism. It is important to identify risk factors in order to design intervention programs to decrease these behaviours in children.

Brief report : maltreatment in childhood and body concerns in adulthood

Objective: We examined the relationship between maltreatment in childhood and body concerns in adulthood.

Method: A community sample of 156 women and 143 men completed measures of maltreatment – frequency of sexual abuse, physical abuse, physical neglect, emotional abuse and emotional neglect – in childhood. They also reported current dissatisfaction with body weight and shape and drive for thinness and drive for muscle.

Results and conclusions: Childhood maltreatment was associated with drive for muscle in women and body dissatisfaction and drive for thinness in men. The results provide some evidence that adverse conditions in childhood can be associated with gender-atypical body concerns in adulthood.

Analysis of localized muscle fatigue in elderly women with and without a history of falls using electromyographic signal frequency parameters

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Advances and challenges in skeletal muscle angiogenesis.

The role of capillaries is to serve as the interface for delivery of oxygen and removal of metabolites to/from tissues. During the past decade there has been a proliferation of studies that have advanced our understanding of angiogenesis demonstrating tissue capillary supply is under strict control during health, but poorly controlled in disease - resulting in either excessive capillary growth (pathological angiogenesis) or losses in capillarity (rarefaction). Given that skeletal muscle comprises nearly 40% of body mass in humans, skeletal muscle capillary density has a significant impact on metabolism, endocrine function, and locomotion, and is tightly regulated at many different levels. Skeletal muscle is also high adaptable, and thus one of the few organ systems which can be experimentally manipulated (e.g. by exercise) to study physiologic regulation of angiogenesis. This review will focus on 1) the methodological concerns that have arisen in determining skeletal muscle capillarity, and 2) highlight the concepts that are reshaping our understanding of the angio-adaptation process. We also summarize selected new findings (physical influences, molecular changes and ultrastructural rearrangement of capillaries) that identify areas of future research with the greatest potential to expand our understanding of how angiogenesis is normally regulated, and that may also help to better understand conditions of uncontrolled (pathologic) angiogenesis.

Analysis of Histone Deacetylase 7 (HDAC7) Alternative Splicing and Its Role in Embryonic Stem Cell Differentiation Toward Smooth Muscle Lineage

Histone deacetylases (HDACs) have a central role in the regulation of gene expression, which undergoes alternative splicing during embryonic stem cell (ES) cell differentiation. Alternative splicing gives rise to vast diversity over gene information, arousing public concerns in the last decade. In this chapter, we describe a strategy to detect HDAC7 alternative splicing and analyze its function on ES cell differentiation.