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1.
BMJ Open ; 11(11): e052563, 2021 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-34836904

RESUMO

INTRODUCTION: Exercise and physical activity (PA) are fundamental to the treatment of type 2 diabetes. Current exercise and PA strategies for newly diagnosed individuals with type 2 diabetes are either clinically effective but unsuitable in routine practice (supervised exercise) or suitable in routine practice but clinically ineffective (PA advice). Mobile health (mHealth) technologies, offering biometric data to patients and healthcare professionals, may bridge the gap between supervised exercise and PA advice, enabling patients to engage in regular long-term physically active lifestyles. This feasibility randomised controlled trial (RCT) will evaluate the use of mHealth technology when incorporated into a structured home-based exercise and PA intervention, in those recently diagnosed with type 2 diabetes. METHODS AND ANALYSIS: This feasibility multicentre, parallel group RCT will recruit 120 individuals with type 2 diabetes (diagnosis within 5-24 months, aged 40-75 years) in the UK (n=60) and Canada (n=60). Participants will undertake a 6-month structured exercise and PA intervention and be supported by an exercise specialist (active control). The intervention group will receive additional support from a smartwatch and phone app, providing real-time feedback and enabling improved communication between the exercise specialist and participant. Primary outcomes are recruitment rate, adherence to exercise and loss to follow-up. Secondary outcomes include a qualitative process evaluation and piloting of potential clinical outcome measures for a future RCT. ETHICS AND DISSEMINATION: The trial was approved in the UK by the South East Scotland Research Ethics Committee 01 (20/SS/0101) and in Canada by the Clinical Research Ethics Board of the University of British Columbia (H20-01936), and is being conducted in accordance with the Declaration of Helsinki and Good Clinical Practice. Results will be published in peer-reviewed journals and presented at national and international scientific meetings. TRIAL REGISTRATION NUMBERS: ISRCTN14335124; ClinicalTrials.gov: NCT04653532.


Assuntos
Diabetes Mellitus Tipo 2 , Telemedicina , Biometria , Diabetes Mellitus Tipo 2/terapia , Exercício Físico , Estudos de Viabilidade , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto
2.
Pediatr Exerc Sci ; 31(3): 290-295, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-30832540

RESUMO

PURPOSE: To understand the extent different types of acute exercise influence cerebral blood flow during and following exercise in children. METHODS: Eight children (7-11 y; 4 girls) completed 2 conditions: high-intensity interval exercise (HIIE; 6 × 1-min sprints at 90% watt maximum) and moderate-intensity steady-state exercise (MISS; 15 min at 44% watt maximum). Blood velocity in the middle cerebral artery (MCAV) and heart rate were assessed continuously. The partial pressure of end-tidal carbon dioxide and mean arterial pressure were assessed at baseline and following exercise. RESULTS: Percentage of maximum heart rate during HIIE was 82% (4%), compared with 69% (4%) during MISS. MCAV was increased above baseline in MISS after 75 seconds (5.8% [3.9%], P × .004) but was unchanged during HIIE. MCAV was reduced below baseline (-10.7% [4.1%], P × .004) during the sixth sprint of HIIE. In both conditions, MCAV remained below baseline postexercise, but returned to baseline values 30-minute postexercise (P < .001). A postexercise increase in mean arterial pressure was apparent following HIIE and MISS, and persisted 30-minute postexercise. Partial pressure of end-tidal carbon dioxide declined post HIIE (-3.4 mm Hg, P < .05), but not following MISS. CONCLUSION: These preliminary findings show HIIE and MISS elicit differing intracranial vascular responses; however, research is needed to elucidate the implications and underlying regulatory mechanisms of these responses.


Assuntos
Velocidade do Fluxo Sanguíneo , Exercício Físico , Treinamento Intervalado de Alta Intensidade , Artéria Cerebral Média/fisiologia , Pressão Sanguínea , Criança , Estudos Cross-Over , Feminino , Frequência Cardíaca , Humanos , Masculino , Pressão Parcial
3.
Eur J Pediatr ; 175(1): 31-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26174104

RESUMO

This study investigated the mediating role of body mass index (BMI) in the relationship between physical activity and body esteem in adolescents. Nine hundred and five Hong Kong Chinese students aged 12-18 years participated in a cross-sectional study in 2007. Students' BMI was computed as an indicator of their body composition. Their physical activity level and body esteem were examined using the Physical Activity Rating for Children and Youth (PARCY) and Body Esteem Scale (BES), respectively. Structural equation modelling was used to investigate the mediating effects of BMI and physical activity in predicting body esteem, with stratification by sex. The overall fit of the hypothesized models was satisfactory in boys (NFI = 0.94; NNFI = 0.88; CFI = 0.95; RMSEA = 0.07) and girls (NFI = 0.89; NNFI = 0.77; CFI = 0.91; RMSEA = 0.11). When BMI was considered as a mediator, higher physical activity had a significant negative total effect on body esteem in boys, but not in girls. The indirect effect of higher physical activity on body esteem via BMI was positive in boys, but negative in girls. CONCLUSIONS: Regular physical activity may help overweight adolescents, especially boys, improve their body esteem. Kinesiologists and health professionals could explore the use of physical activity prescriptions for weight management, aiming at body esteem improvement in community health programs for adolescents. WHAT IS KNOWN: Among Western adolescents, negative body esteem is more pervasive in girls than in boys. There are consistent findings of the association between higher body mass index and lower body esteem in adolescents, but the association between physical activity and body esteem are equivocal. WHAT IS NEW: A negative association between body mass index and body esteem was found in both Hong Kong adolescent boys and girls. The indirect effect of physical activity on body esteem via body mass index was positive in Hong Kong adolescent boys, but negative in girls.


Assuntos
Composição Corporal/fisiologia , Imagem Corporal , Índice de Massa Corporal , Atividade Motora/fisiologia , Adolescente , Criança , Estudos Transversais , Feminino , Hong Kong , Humanos , Masculino , Modelos Estatísticos , Psicologia do Adolescente
4.
Br J Sports Med ; 49(13): 860-4, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25940635

RESUMO

AIM: To provide an evidence-based review of muscle metabolism changes with sex-, age- and maturation with reference to the development of youth sport performance. METHODS: A narrative review of data from both invasive and non-invasive studies, from 1970 to 2015, founded on personal databases supported with computer searches of PubMed and Google Scholar. RESULTS: Youth sport performance is underpinned by sex-, age- and maturation-related changes in muscle metabolism. Investigations of muscle size, structure and metabolism; substrate utilisation; pulmonary oxygen uptake kinetics; muscle phosphocreatine kinetics; peak anaerobic and aerobic performance; and fatigue resistance; determined using a range of conventional and emerging techniques present a consistent picture. Age-related changes have been consistently documented but specific and independent maturation-related effects on muscle metabolism during exercise have proved elusive to establish. Children are better equipped for exercise supported primarily by oxidative metabolism than by anaerobic metabolism. Sexual dimorphism is apparent in several physiological variables underpinning youth sport performance. As young people mature there is a progressive but asynchronous transition into an adult metabolic profile. CONCLUSIONS: The application of recent developments in technology to the laboratory study of the exercising child and adolescent has both supplemented existing knowledge and provided novel insights into developmental exercise physiology. A sound foundation of laboratory-based knowledge has been established but the lack of rigorously designed child-specific and sport-specific testing environments has clouded the interpretation of the data in real life situations. The primary challenge remains the translation of laboratory research into the optimisation of youth sports participation and performance.


Assuntos
Desenvolvimento do Adolescente/fisiologia , Desempenho Atlético/fisiologia , Desenvolvimento Infantil/fisiologia , Músculo Esquelético/metabolismo , Esportes Juvenis/fisiologia , Adolescente , Criança , Metabolismo Energético/fisiologia , Exercício Físico/fisiologia , Feminino , Humanos , Lactatos/metabolismo , Masculino , Consumo de Oxigênio/fisiologia , Fosfocreatina/metabolismo , Caracteres Sexuais
5.
Saf Health Work ; 6(3): 192-9, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26929827

RESUMO

BACKGROUND: Overweight, obesity, and cardiovascular disease risk factors are prevalent among firefighters in some developed countries. It is unclear whether physical activity and cardiopulmonary fitness reduce cardiovascular disease risk and the cardiovascular workload at work in firefighters. The present study investigated the relationship between leisure-time physical activity, cardiopulmonary fitness, cardiovascular disease risk factors, and cardiovascular workload at work in firefighters in Hong Kong. METHODS: Male firefighters (n = 387) were randomly selected from serving firefighters in Hong Kong (n = 5,370) for the assessment of cardiovascular disease risk factors (obesity, hypertension, diabetes mellitus, dyslipidemia, smoking, known cardiovascular diseases). One-third (Target Group) were randomly selected for the assessment of off-duty leisure-time physical activity using the short version of the International Physical Activity Questionnaire. Maximal oxygen uptake was assessed, as well as cardiovascular workload using heart rate monitoring for each firefighter for four "normal" 24-hour working shifts and during real-situation simulated scenarios. RESULTS: Overall, 33.9% of the firefighters had at least two cardiovascular disease risk factors. In the Target Group, firefighters who had higher leisure-time physical activity had a lower resting heart rate and a lower average working heart rate, and spent a smaller proportion of time working at a moderate-intensity cardiovascular workload. Firefighters who had moderate aerobic fitness and high leisure-time physical activity had a lower peak working heart rate during the mountain rescue scenario compared with firefighters who had low leisure-time physical activities. CONCLUSION: Leisure-time physical activity conferred significant benefits during job tasks of moderate cardiovascular workload in firefighters in Hong Kong.

6.
J Health Psychol ; 20(9): 1133-41, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24174432

RESUMO

This study examined the association between propensity for emotional rehearsal, body image self-perception and weight status in Chinese Hong Kong pre-adolescents. Children 8-12 years of age (n = 278) completed measurement of body mass index, body image and emotional rehearsal. Multinomial regression analyses revealed that body mass index was positively associated with body image dissatisfaction and a significant predictor of body size estimation. However, only body size underestimation was associated with lower rehearsal tendencies. The prevalence of body image dissatisfaction and body size estimation was also reported for this population. Future research is suggested for greater understanding of emotional coping in body image dissatisfaction in young children.


Assuntos
Adaptação Psicológica/fisiologia , Imagem Corporal/psicologia , Índice de Massa Corporal , Emoções/fisiologia , Criança , Feminino , Hong Kong , Humanos , Masculino
7.
Public Health Nutr ; 18(6): 1067-74, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24844379

RESUMO

OBJECTIVE: To determine the potential predictors of body size dissatisfaction in Chinese children. DESIGN: The Child's Body Image Scale was used to assess body size perception and dissatisfaction. BMI was calculated from objectively measured height and weight. Predictors of body size dissatisfaction were examined by logistic regression analysis. SETTING: Hong Kong, China. SUBJECTS: Six hundred and twenty children (53 % boys, aged 6·1-12·9 years) from a state-run primary school. RESULTS: Female sex (adjusted OR (AOR)=1·91; 95 % CI 1·32, 2·76), age (AOR=2·62; 95 % CI 1·65, 4·16 for 8-10 years; AOR=2·16; 95 % CI 1·38, 3·38 for >10 years), overweight (AOR=6·23; 95 % CI 3·66, 10·60) and obesity (AOR=19·04; 95 % CI 5·64, 64·32) were positively associated with desire to be thinner. Size misperception was a strong predictor of body size dissatisfaction, irrespective of actual weight status (AOR=1·90; 95 % CI 1·02, 3·54 for overestimation; AOR=0·43; 95 % CI 0·27, 0·67 for underestimation). CONCLUSIONS: Body size dissatisfaction is prevalent among Chinese children as young as 6 years. Female sex, age, overweight, obesity and overestimation of size were associated with increased desire to be thinner. These findings emphasise the importance of preventing body image issues from an early age.


Assuntos
Transtornos Dismórficos Corporais/epidemiologia , Desenvolvimento Infantil , Modelos Psicológicos , Sobrepeso/psicologia , Obesidade Infantil/psicologia , Transtornos Dismórficos Corporais/etiologia , Índice de Massa Corporal , Criança , Estudos de Coortes , Estudos Transversais , Feminino , Hong Kong/epidemiologia , Humanos , Modelos Logísticos , Masculino , Sobrepeso/fisiopatologia , Obesidade Infantil/fisiopatologia , Percepção , Prevalência , Escalas de Graduação Psiquiátrica , Fatores de Risco , Instituições Acadêmicas , Fatores Sexuais
8.
J Paediatr Child Health ; 49(11): 969-975, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23735004

RESUMO

AIM: To investigate the effect of orlistat on endothelial function in obese adolescents. METHODS: Single-blind 10-week controlled trial of 67 normolipidaemic obese adolescents randomised into three groups. Group 1 (diet alone), Group 2 (diet and orlistat), Group 3 (diet, orlistat and exercise). Endothelial function measured by flow-mediated dilatation (FMD) of the brachial artery, anthropometric parameters, blood pressure, fasting blood lipids, insulin and glucose levels were recorded at baseline and at 10 weeks. RESULTS: Sixty four subjects completed the study. Groups were comparable at baseline. FMD increased significantly with orlistat (Groups 2 and 3) but not in Group 1. Orlistat treatment resulted in significantly reduced bodyweight, body mass index (BMI), waist circumference, total and low-density lipoprotein (LDL) cholesterol levels. High-density lipoprotein cholesterol levels were unchanged. Triglyceride and insulin levels were significantly reduced in all three groups. The reduction in cholesterols did not correlate with reductions in weight and BMI. A slight reduction of body fat, both with and without orlistat treatment, correlated with reduction in BMI after adjustment for baseline values. Blood pressure was unaltered by orlistat. Calorie intake was reduced with orlistat, and the decrease noted in % fat and increase in % carbohydrate was significant only in those taking orlistat. The addition of exercise (Group 3 compared with Group 2) altered no parameter. CONCLUSIONS: Orlistat improves endothelial function and reduces bodyweight, BMI, fasting total and LDL-cholesterol in obese adolescents when combined with dietary control. Improvement in endothelial function if maintained could reflect long-term cardiovascular benefit.


Assuntos
Fármacos Antiobesidade/farmacologia , Células Endoteliais/efeitos dos fármacos , Lactonas/farmacologia , Obesidade/tratamento farmacológico , Adolescente , Antropometria , Determinação da Pressão Arterial , Criança , Ingestão de Energia , Jejum/sangue , Feminino , Hong Kong , Humanos , Masculino , Atividade Motora , Obesidade/dietoterapia , Orlistate
9.
Ann Hum Biol ; 40(3): 276-9, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23402218

RESUMO

BACKGROUND AND AIM: The relationships between self-estimated adiposity using Stunkard's body silhouette scale with general and central adiposity in adolescents are unclear. This study examines the criterion validity of Stunkard's body silhouette scale as a self-estimated rating of adiposity against anthropometric measures of adiposity and percentage body fat in Hong Kong adolescents. SUBJECTS AND METHODS: The body composition of 903 adolescents (55.7% boys) was assessed by measured waist circumference (WC), waist-to-stature ratio (WSR), body mass index (BMI) and percentage body fat (%BF). Self-estimated adiposity was subjectively assessed using Stunkard's body silhouette scale. The association between self-estimated adiposity and body composition was examined by Spearman correlation coefficients and hierarchical multiple regression analyses. RESULTS: Self-estimated adiposity correlated significantly and positively with BMI (boys: r = 0.65; girls: r = 0.59), WC (boys: r = 0.62; girls: r = 0.51), WSR (boys: r = 0.55; girls: r = 0.42) and %BF (boys: r = 0.47; girls: r = 0.55). CONCLUSION: Self-estimated adiposity using the Stunkard's body silhouette scale was positively associated with actual measures of adiposity; however, the association was modest at best. It is unlikely that the Stunkard's body silhouette scale provides a suitably accurate substitute for actual body composition measures in Chinese adolescents.


Assuntos
Adiposidade , Antropometria/métodos , Composição Corporal , Adolescente , Povo Asiático , Estatura , Índice de Massa Corporal , Feminino , Hong Kong , Humanos , Masculino , Autorrelato , Caracteres Sexuais , Estatísticas não Paramétricas , Circunferência da Cintura
10.
Res Sports Med ; 21(1): 90-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23286425

RESUMO

This study investigates the associations between percentage body fat (%BF) and anthropometric parameters in adolescents of mixed weight status. Anthropometric parameters including height, weight, and waist circumference (WC), and %BF were assessed in 903 Hong Kong Chinese students (mean age 14.7 years). The calculated body mass index (BMI) and waist-to-stature ratio (WSR) were used to classify students into different weight status groups and central obesity groups, respectively. The %BF/BMI and %BF/WC relationships were examined by partial correlation coefficients and linear regression models. The %BF correlated significantly with BMI, except in underweight boys. BMI predicted %BF better (adjusted R (2): 0.40 in boys; 0.85 in girls) than WC (adjusted R (2): 0.34 in boys; 0.63 in girls) or WSR (adjusted R (2): 0.33 in boys; 0.60 in girls). In general, BMI predicts %BF better than WC or WSR in Hong Kong adolescents, but these relationships are sex and weight status specific.


Assuntos
Adiposidade , Tamanho Corporal , Adiposidade/etnologia , Adolescente , Povo Asiático , Estatura , Índice de Massa Corporal , Tamanho Corporal/etnologia , Peso Corporal , Impedância Elétrica , Feminino , Hong Kong , Humanos , Modelos Lineares , Masculino , Fatores Sexuais , Circunferência da Cintura
11.
Games Health J ; 2(2): 70-4, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26192124

RESUMO

OBJECTIVE: Contingent active videogame systems have been shown to result in increases in physical activity and decreases in sedentary behavior. The feasibility of using contingent active gaming systems (e.g., the videogame freezes when physical exertion ceases) as an activity alternative and whether these systems will elicit activity of moderate to vigorous intensity is unknown. We aimed to determine whether Hong Kong Chinese girls (8.5±0.3 years old) would (1) easily habituate to stepping and playing videogames and (2) whether stepping and videogaming would result in cardiovascular responses beneficial to health. SUBJECTS AND METHODS: Basic anthropometric measures as well as peak oxygen uptake (VO2) were assessed on the first of two laboratory visits. The girls were also given playing instructions for three XBbox 360 (Nintendo, Kyoto, Japan) games: "The Bee Movie," "Surfs Up," and "Kung Fu Panda." On the second laboratory visit, the girls completed a habituation protocol and a 15-minute play session on the Gamercize(®) (Databridge Services Ltd., Southampton, United Kingdom) Stepper™, during which cardiovascular effort was assessed using heart rate monitoring. RESULTS: Direct observation of the girls showed that four girls needed 90 seconds and 12 of the girls only required 60 seconds to habituate to the Gamercize Stepper. There was no significant difference (t15=-1.944, P>0.05) between the heart rate at 55 percent of peak VO2 (144±9 beats/minute) and heart rate during Gamercize stepping (139±13 beats/minute), indicating that mean heart rates in both conditions were similar. Further analysis showed that 25 percent of the girls stepped and played videogames at a heart rate equivalent to moderate intensity. CONCLUSIONS: Although the girls easily habituated to the Gamercize Stepper, a majority of the girls did not step and videogame at moderate intensity levels, which are associated with body composition changes. Further investigations are warranted to determine mediators responsible for increasing physical activity levels to meet current recommendations.

12.
Respirology ; 17(3): 513-8, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22212464

RESUMO

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the aerobic capacity of children 3 years after they were diagnosed with severe acute respiratory syndrome (SARS). METHODS: Twenty-seven patients who completed both pulmonary function and maximal aerobic capacity tests at 6 and 15 months after the acute illness were invited to return for reassessment. RESULTS: Twenty-one patients (median age 18.2 years, interquartile range (IQR) 16.5-19.7) completed all investigations at 36 months. Pulmonary function was normal in all patients. Maximal aerobic capacity, peak oxygen pulse (peak VO(2) ) and ventilatory anaerobic threshold showed significant improvements compared with values measured at 6 months in both boys and girls. In girls, ventilatory efficiency (ventilatory equivalents for oxygen and carbon dioxide) and perfusion of the lungs (end-tidal partial carbon dioxide pressure) had not increased further compared with the values measured at 15 months. Although peak VO(2) improved further at 36 months in patients with or without persistent radiological abnormalities, the values were 68% (IQR 50-84) and 74% (IQR 60-99), respectively, of those for normal control subjects. CONCLUSIONS: There were improvements in aerobic capacity at 36 months in children affected by SARS; however, the measured values remained suboptimal.


Assuntos
Exercício Físico/fisiologia , Resistência Física/fisiologia , Síndrome Respiratória Aguda Grave/fisiopatologia , Adolescente , Limiar Anaeróbio/fisiologia , Feminino , Seguimentos , Frequência Cardíaca/fisiologia , Humanos , Pulmão/fisiopatologia , Masculino , Consumo de Oxigênio/fisiologia , Estudos Prospectivos , Testes de Função Respiratória , Adulto Jovem
13.
Diabetes Metab Syndr Obes ; 4: 225-8, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21760739

RESUMO

BACKGROUND: There is increasing evidence that continuous activation of the hypothalamic-pituitary adrenal axis and the central sympathetic nervous system contributes to the pathogenesis of central adiposity via increased psychological stress. The purpose of this study was to examine the link between central adiposity and the propensity for Chinese children to rehearse emotionally upsetting events, a dimension of psychological stress. Additionally, gender differences in this relationship were explored. METHODS: Waist circumference, which is a marker of central adiposity and associated risks of developing cardiovascular disease, was measured and the propensity for rehearsal was assessed twice over two consecutive years in Hong Kong Chinese children (n = 194, aged 7-9 years), using a psychometric tool. RESULTS: Children with waist circumference indicative of a risk of cardiovascular disease displayed higher rehearsal scores than children categorized as "not at risk", as did boys compared with girls. Our results suggest that central adiposity and the propensity for rehearsal of emotionally upsetting events may be linked in Chinese children. CONCLUSION: Future prospective studies examining the direction of causality between central adiposity and rehearsal can potentially have valuable clinical implications.

14.
J Obes ; 2011: 679328, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21274276

RESUMO

Physical activity and sedentary behavior are central components of lifetime weight control; however, our understanding of dimensions of these behaviors in childhood is limited. This study investigated free-living activity pattern characteristics and the individual variability of these characteristics in 84 lean and obese Chinese children (7-9 y) during the school day and over the weekend. Activity pattern characteristics were established from triaxial accelerometry (StayHealthy RT3). Results indicated that children's free-living activity is characterized by many short-duration, low-intensity bouts of movement. Obese children take longer rest intervals between bouts and engage in fewer activity bouts both at school and at home. Intraindividual variability in activity patterns was low during school days but high for the rest intervals between bouts and number of activity bouts per day at the weekend. Finding ways to reduce the rest time between bouts of movement and increase the number of movement bouts a child experiences each day is an important next step.

15.
Int J Behav Nutr Phys Act ; 8: 3, 2011 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-21251295

RESUMO

Non-exercise physical activity (NEPA) is an important part of energy expenditure. This study aimed to investigate the prevalence of exercise and NEPA among adolescents. In the HKSOS project 2006-2007, the proportions of Hong Kong Chinese adolescents (N=32,005) achieving 60-minute exercise and 60-minute NEPA per day were analyzed. Exercise was defined as structured and planned physical activities, and NEPA was defined as unstructured and unplanned physical activities including walking for transportation and climbing stairs. The prevalence of exercise was higher in boys than girls (after school: 63.8% vs 39.6%; holidays: 78.7% vs 60.0%), but the prevalence of NEPA in boys was similar to that in girls (after school: 72.2% vs 68.0%; holidays: 80.3% vs 79.4%). In general, the prevalence of both exercise and NEPA decreased with age in boys and girls, but was more marked for exercise than NEPA. In conclusion, the prevalence of exercise was lower in adolescent girls than boys, and decreased more rapidly with age than NEPA. NEPA seems to be easier to accumulate than exercise among adolescents regardless of sex and age.


Assuntos
Comportamento do Adolescente , Exercício Físico , Atividade Motora , Adolescente , Fatores Etários , Metabolismo Energético , Feminino , Hong Kong , Humanos , Masculino , Sobrepeso/prevenção & controle , Autorrelato , Caracteres Sexuais , Fatores de Tempo
16.
J Clin Psychol ; 67(3): 261-6, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21254054

RESUMO

The main purpose of this study was to investigate whether rehearsal, defined as the tendency to recurrently ruminate over upsetting aversive experiences, had an effect on pedometry reactivity. A total of 156 Hong Kong Chinese children aged 9-12 years were recruited. Participants completed the Rehearsal Scale for Children-Chinese (RSC-C; Ling, Maxwell, Masters, & McManus, 2010) and wore the pedometers for 3 consecutive weeks. The mean number of steps was significantly higher in Week 1 than in Week 3. High rehearsers showed a larger decrease in mean number of steps from Week 1 to Week 3 than low rehearsers. Future physical activity intervention studies should adjust for reactivity in their baseline measurements and should further examine the relationship between habitual PA and individual propensities for rehearsal.


Assuntos
Estresse Psicológico/psicologia , Caminhada/fisiologia , Caminhada/psicologia , Análise de Variância , Pesos e Medidas Corporais , Criança , Feminino , Hong Kong , Humanos , Masculino , Monitorização Fisiológica , Estresse Psicológico/fisiopatologia , Inquéritos e Questionários
17.
Med Sport Sci ; 56: 1-22, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21178364

RESUMO

Performance in sport takes place within a matrix of bio-cultural characteristics but boys' success in elite youth sport is underpinned by a range of age-and maturity-related physical and physiological variables which act in a sport-specific manner to influence performance. Stature, body mass, and muscle mass increase with growth and maturation and earlier maturing boys are generally taller, heavier, and more muscular than boys of the same chronological age who mature later. Earlier maturing boys also benefit from changes in body shape which are advantageous in many sports. Marked increases in muscle strength and muscle power are expressed during adolescence. The muscle enzyme profile needed to promote the anaerobic generation of energy is enhanced as children move through adolescence into young adulthood. Aerobic fitness benefits from age and/or maturation-related increases in stroke volume, haemoglobin concentration, and muscle mass. These individual differences are most pronounced at 12-15 years when participation in elite youth sport is at its peak. Many boys fulfil their potential, gain great pleasure from elite youth sport and become elite adult sportsmen. Other equally talented boys are denied access to elite youth sport through selection policies which are influenced by stage of maturation or age relative to the beginning of the selection year. Others drop-out prematurely through early specialisation in a sport inappropriate for their late adolescent or adult physique. Boys are not mini-men and coaches and parents should focus on providing opportunities for all boys and on nurturing talent irrespective of the ticking of individual biological clocks.


Assuntos
Desempenho Atlético/fisiologia , Exercício Físico/fisiologia , Adolescente , Composição Corporal , Tamanho Corporal , Criança , Metabolismo Energético/fisiologia , Humanos , Lactatos/sangue , Masculino , Fadiga Muscular/fisiologia , Força Muscular/fisiologia , Consumo de Oxigênio/fisiologia , Aptidão Física/fisiologia , Recuperação de Função Fisiológica
18.
Med Sport Sci ; 56: 23-46, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21178365

RESUMO

The participation of girls in elite sport has increased exponentially over the past 30 years. Despite these increases a tradition for recruiting boys for exercise studies persists and our knowledge of the physiologic response to exercise in girls remains limited. Girls' physiology varies with age and maturation and is underpinned by a divergent hormonal milieu which begins early in foetal life. Sexual dimorphism underlies much of the physiologic response to exercise, and becomes most acute during adolescence when boys become taller, heavier, less fat and are more muscular than girls. Young girl athletes are not simply smaller, less muscular boys. The widening sex disparity in responses to exercise during puberty cannot always be accounted for by size. The woeful number of studies on girls and our prior inability to non-invasively study the complexity of the cellular metabolic response to exercise means an integrative understanding of girls' physiological responses to exercise remains elusive. Success in elite sport requires intense training, which for a long time was thought to cause disruption to normal growth and maturation. It would appear that exercise training, without other predisposing factors, is unlikely to cause aberrations to either growth or maturation. Nevertheless, there is clear evidence of a boundary between healthy and unhealthy levels of exertion when coupled with caloric limitation. Sports in which intense training is combined with the need for leanness may predispose girls to increased risk of skeletal and reproductive health problems, and ensuring risk is minimised should be a priority.


Assuntos
Desempenho Atlético/fisiologia , Exercício Físico/fisiologia , Adolescente , Volume Sanguíneo , Composição Corporal , Tamanho Corporal , Criança , Metabolismo Energético/fisiologia , Feminino , Síndrome da Tríade da Mulher Atleta/fisiopatologia , Humanos , Lactatos/sangue , Fadiga Muscular/fisiologia , Força Muscular/fisiologia , Consumo de Oxigênio/fisiologia , Aptidão Física/fisiologia , Puberdade/fisiologia , Recuperação de Função Fisiológica
19.
Int J Pediatr Obes ; 5(5): 390-5, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20836723

RESUMO

OBJECTIVES: To examine the percentile distribution of waist-to-stature ratio (WSR) and derive WSR cut-offs for underweight, normal weight, and overweight based on the International Obesity Task Force (IOTF) and local weight-for-height standards in Hong Kong Chinese adolescents. METHODS: In the Hong Kong Student Obesity Surveillance project in 2006-2007, height, weight and waist circumference of 13 568 (40.3% boys) Chinese adolescents aged 12-18 were measured. Smoothed percentile distributions of WSR by age and sex were examined using Lambda-Mu-Sigma (LMS) regression. The sex- and age-specific WSR values corresponding to underweight and overweight, as defined by the IOTF and local weight-for-height standards, were determined using receiver operating characteristic curves. RESULTS: The percentile values of WSR were stable across age in both sexes. In general, WSR values of 0.40 and 0.46 corresponded to underweight and overweight, respectively, as defined by both IOTF and local weight-for-height standards. As a reference for normal weight status, the median weight-for-height values corresponded to a WSR value of 0.42 in most sex-age subgroups. CONCLUSION: Sex and age independent WSR cut-off values for underweight, median weight and overweight in Hong Kong adolescents were identified. WSR is potentially a practical indicator for adolescents to monitor their weight status.


Assuntos
Estatura , Sobrepeso/diagnóstico , Vigilância da População , Magreza/diagnóstico , Circunferência da Cintura , Adolescente , Fatores Etários , Criança , Diagnóstico Diferencial , Feminino , Hong Kong/epidemiologia , Humanos , Masculino , Sobrepeso/epidemiologia , Sobrepeso/etnologia , Prevalência , Análise de Regressão , Fatores Sexuais , Magreza/epidemiologia , Magreza/etnologia
20.
Appetite ; 55(2): 343-7, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20655345

RESUMO

The purpose of this study was to examine whether the addition of a motor component to video gaming alters energy consumption. To address this problem we used an experimental manipulation design with 9-13 year olds incorporating 'seated video game' and 'activity enhanced video game' conditions, whilst allowing snacks ad libitum. No difference in snacking between the two video gaming conditions was apparent. The children consumed 374 and 383kcalh(-1) during seated and activity enhanced video gaming, respectively. A secondary purpose was to examine consistency of energy intake during free choice video game play. We found no difference in energy intake between four 1h free choice video gaming sessions. Snacking energy intake whilst video gaming was 166% more than the calories required during resting conditions. This study has shown that the addition of a motor component to the video game environment does not alter snack energy intake. However, the high calorific consumption during both seated and activity enhanced video game play highlights the need for an active attempt to restrict snacking whilst playing video games.


Assuntos
Ingestão de Energia , Atividade Motora , Jogos de Vídeo , Adolescente , Índice de Massa Corporal , Criança , Metabolismo Energético , Feminino , Humanos , Masculino
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