Reallocating desk workers' sitting time to standing or stepping: associations with work performance.

BACKGROUND: Studies have suggested that sitting time at work may lead to underperformance but they may underestimate the benefits to desk workers' performance of reducing occupational sitting time without considering the relative effects of the specific activities replaced. AIMS: To estimate differences in work performance (presenteeism, absenteeism and engagement) when occupational sitting time is reallocated to standing/stepping in desk workers. METHODS: Data for middle-aged desk workers were from a Japan-wide online survey (n = 2228). Self-report proportion of occupational sitting and standing/stepping, work hours and work performance indicators, including absolute (ratings relating only to self) and relative (ratings of self, compared to others) presenteeism and absenteeism, and dimensions of work engagement, were collected. Partition and isotemporal substitution models were used to investigate the associations of occupational sitting and standing/stepping time with work performance, including their reallocation effects. RESULTS: In partition models, longer occupational sitting time was associated with a lower absolute presenteeism score (i.e. less productivity), lower absolute absenteeism (i.e. longer-than-expected work hours), and lower engagement. Longer occupational standing/stepping time was associated with lower absolute absenteeism and more engagement. Isotemporal substitution models showed that each hour of occupational sitting reallocated to standing/stepping was favourably associated with overall work engagement (B = 0.087; 95% confidence interval 0.051, 0.122) and its dimensions (B ranged from 0.078 to 0.092), but was not associated with presenteeism or absenteeism. CONCLUSIONS: These findings suggest that management support and practical initiatives to encourage desk workers to replace portions of their sitting time with standing/stepping may contribute to enhanced work engagement.

Sedentary behaviour and bone health in older adults: a systematic review.

Older adults spend more than 8 h/day in sedentary behaviours. Detrimental effects of sedentary behaviour (SB) on health are established, yet little is known about SB and bone health (bone mineral density; BMD) in older adults. The purpose of this review is to examine associations of SB with BMD in older adults. Five electronic databases were searched: Web of Science (Core Collection); PubMed; EMBASE; Sports Medicine and Education and PsycInfo. Inclusion criteria were healthy older adults mean age ≥ 65 years; measured SB and measured BMD using dual-energy X-ray absorptiometry. Quality was assessed using National Institute of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. After excluding duplicates 17813 papers were assessed; 17757 were excluded on title/abstract, 49 at full text, resulting in two prospective and five cross-sectional observational studies reviewed. Four were rated 'good' and three were rated 'fair' using the quality assessment criteria. Findings varied across the studies and differed by gender. In women, four studies reported significant positive associations of SB with BMD at different sites, and two found significant negative associations. Five studies which examined both men and women, men reported negative or no associations of SB with femoral neck, pelvic, whole body, spine or leg BMD. Whilst these findings suggest differences between men and women in the associations of SB with BMD, they may be due to the varying anatomical sections examined for BMD, the different methods used to measure SB, the varied quality of the studies included and the limited number of published findings.

Prospective relationships of adolescents' screen-based sedentary behaviour with depressive symptoms: the Millennium Cohort Study.

BACKGROUND: Frequent use of screen-based devices could be a modifiable risk factor for adolescent depression, but findings have been inconsistent and mostly from cross-sectional studies. We examined prospective associations of video gaming, social media, and internet use with depressive symptoms in adolescents. METHODS: A total of 11 341 adolescents from the Millennium Cohort Study, a representative, UK population-based. The main outcome was depressive symptoms from a Moods and Feelings Questionnaire (age 14). Exposures were frequency of video game, social media, and internet use (age 11). Physical activity (effect modifier) was measured by self-report. RESULTS: The fully adjusted models indicated that boys playing video games most days, at least once a week, and at least once a month at age 11 had lower depression scores at age 14 by 24.2% (IRR = 0.77, 95% CI 0.66-0.91), 25.1% (IRR = 0.75, 95% CI 0.62-0.90), and 31.2% (IRR = 0.69, 95% CI 0.57-0.83), compared with playing less than once a month/never. In girls, compared with less than once a month/never, using social media most days at age 11 was associated with 13% higher depression scores at age 14 (IRR = 1.13, 95% CI 1.05-1.22). We found some evidence of associations between using the internet most days and depressive symptoms compared with less than once a month/never in boys (IRR = 0.86, 95% CI 0.75-1.00). More frequent video game use was consistently associated with fewer depressive symptoms in boys with low physical activity, but not in those with high physical activity. CONCLUSIONS: Different types of screen-time may have contrasting associations with depressive symptoms during adolescence. Initiatives to address adolescents' screen-time may require targeted approaches.

The effect of breaking up prolonged sitting on paired associative stimulation-induced plasticity.

Paired associative stimulation (PAS) can induce plasticity in the motor cortex, as measured by changes in corticospinal excitability (CSE). This effect is attenuated in older and less active individuals. Although a single bout of exercise enhances PAS-induced plasticity in young, physically inactive adults, it is not yet known if physical activity interventions affect PAS-induced neuroplasticity in middle-aged inactive individuals. Sixteen inactive middle-aged office workers participated in a randomized cross-over design investigating how CSE and short-interval intracortical inhibition (SICI) were affected by PAS preceded by 3 h of sitting (SIT), 3 h of sitting interrupted every 30 min by 3 min of frequent short bouts of physical activity (FPA) and 2.5 h of sitting followed by 25 min of moderate-intensity exercise (EXE). Transcranial magnetic stimulation was applied over the primary motor cortex (M1) of the dominant abductor pollicis brevis to induce recruitment curves before and 5 min and 30 min post-PAS. Linear mixed models were used to compare changes in CSE using time and condition as fixed effects and subjects as random effects. There was a main effect of time on CSE and planned within-condition comparisons showed that CSE was significantly increased from baseline to 5 min and 30 min post-PAS, in the FPA condition, with no significant changes in the SIT or EXE conditions. SICI decreased from baseline to 5 min post-PAS, but this was not related to changes in CSE. Our findings suggest that in middle-aged inactive adults, FPAs may promote corticospinal neuroplasticity. Possible mechanisms are discussed.

Regular brief interruptions to sitting after a high-energy evening meal attenuate glycemic excursions in overweight/obese adults.

BACKGROUND AND AIMS: Modern Western lifestyles are characterized by consumption of approximately 45% of total daily energy intake at the evening meal, followed by prolonged sitting while watching television (TV), which may deleteriously impact glycemic control. After a high-energy evening meal (dinner), we examined whether regular, brief activity bouts during TV commercial breaks could acutely lower postprandial glucose and insulin responses in overweight/obese adults, compared to prolonged uninterrupted sitting. METHODS AND RESULTS: Nine overweight/obese adults (29.7 ± 4.06 kg m-2; aged 32 ± 3 years; 5 male) completed two laboratory-based conditions of three and a half hours: prolonged sitting during TV viewing (SIT); and, prolonged sitting interrupted every 20 min with 3 min of light-intensity body-weight resistance activities (active commercial breaks; ACBs). Venous postprandial glucose and insulin responses to dinner were calculated as positive incremental area under the curve (iAUC) from baseline. Interstitial glucose was measured using a continuous glucose monitor and quantified as total AUC (tAUC). Compared to SIT, plasma glucose iAUC was reduced by 33% [3.4 ± 1.0 vs 5.1 ± 1.0 (mean ± SEM) mmol h·L-1, p = 0.019] and plasma insulin iAUC by 41% (813 ± 224 vs 1373 ± 224, p = 0.033 pmol h·L-1) for the ACB condition. During the ACB condition there was a significant reduction in interstitial glucose tAUC (24.4 ± 5.2 vs 26.9 ± 5.2 mmol h·L-1, p < 0.001), but this did not persist beyond the laboratory observation period. CONCLUSIONS: Regular brief light-intensity activity bouts can attenuate glycemic responses during television viewing time following a high-energy evening meal in overweight/obese adults.

Evaluating the effectiveness of organisational-level strategies with or without an activity tracker to reduce office workers' sitting time: a cluster-randomised trial.

BACKGROUND: Office workers engage in high levels of sitting time. Effective, context-specific, and scalable strategies are needed to support widespread sitting reduction. This study aimed to evaluate organisational-support strategies alone or in combination with an activity tracker to reduce sitting in office workers. METHODS: From one organisation, 153 desk-based office workers were cluster-randomised (by team) to organisational support only (e.g., manager support, emails; 'Group ORG', 9 teams, 87 participants), or organisational support plus LUMOback activity tracker ('Group ORG + Tracker', 9 teams, 66 participants). The waist-worn tracker provided real-time feedback and prompts on sitting and posture. ActivPAL3 monitors were used to ascertain primary outcomes (sitting time during work- and overall hours) and other activity outcomes: prolonged sitting time (≥30 min bouts), time between sitting bouts, standing time, stepping time, and number of steps. Health and work outcomes were assessed by questionnaire. Changes within each group (three- and 12 months) and differences between groups were analysed by linear mixed models. Missing data were multiply imputed. RESULTS: At baseline, participants (46 % women, 23-58 years) spent (mean ± SD) 74.3 ± 9.7 % of their workday sitting, 17.5 ± 8.3 % standing and 8.1 ± 2.7 % stepping. Significant (p < 0.05) reductions in sitting time (both work and overall) were observed within both groups, but only at 12 months. For secondary activity outcomes, Group ORG significantly improved in work prolonged sitting, time between sitting bouts and standing time, and overall prolonged sitting time (12 months), and in overall standing time (three- and 12 months); while Group ORG + Tracker, significantly improved in work prolonged sitting, standing, stepping and overall standing time (12 months). Adjusted for confounders, the only significant between-group differences were a greater stepping time and step count for Group ORG + Tracker relative to Group ORG (+20.6 min/16 h day, 95 % CI: 3.1, 38.1, p = 0.021; +846.5steps/16 h day, 95 % CI: 67.8, 1625.2, p = 0.033) at 12 months. Observed changes in health and work outcomes were small and not statistically significant. CONCLUSIONS: Organisational-support strategies with or without an activity tracker resulted in improvements in sitting, prolonged sitting and standing; adding a tracker enhanced stepping changes. Improvements were most evident at 12 months, suggesting the organisational-support strategies may have taken time to embed within the organisation. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry: ACTRN12614000252617 . Registered 10 March 2014.

Breaking up prolonged sitting reduces resting blood pressure in overweight/obese adults.

AIM: To compare the effect of 7 h of prolonged sitting on resting blood pressure with a similar duration of sitting combined with intermittent brief bouts of light-intensity or moderate-intensity physical activity. METHODS AND RESULTS: Overweight/obese adults (n = 19; aged 45-65 years) were recruited for a randomized three-treatment crossover trial with a one-week washout between treatments: 1) uninterrupted sitting; 2) sitting with 2 min bouts of light-intensity walking at 3.2 km/h every 20 min; and, 3) sitting with 2 min bouts of moderate-intensity walking at between 5.8 and 6.4 km/h every 20 min. After an initial 2 h period seated, participants consumed a test meal (75 g carbohydrate, 50 g fat) and completed each condition over the next 5 h. Resting blood pressure was assessed oscillometrically every hour as a single measurement, 5 min prior to each activity bout. GEE models were adjusted for sex, age, BMI, fasting blood pressure and treatment order. After adjustment for potential confounding variables, breaking up prolonged sitting with light and moderate-intensity activity breaks was associated with lower systolic blood pressure [light: 120 ± 1 mmHg (estimated marginal mean ± SEM), P = 0.002; moderate: 121 ± 1 mmHg, P = 0.02], compared to uninterrupted sitting (123 ± 1 mmHg). Diastolic blood pressure was also significantly lower during both of the activity conditions (light: 76 ± 1 mmHg, P = 0.006; moderate: 77 ± 1 mmHg, P = 0.03) compared to uninterrupted sitting (79 ± 1 mmHg). No significant between-condition differences were observed in mean arterial pressure or heart rate. CONCLUSION: Regularly breaking up prolonged sitting may reduce systolic and diastolic blood pressure. TRIAL REGISTRATION NUMBER: ACTRN12609000656235 (http://www.anzctr.org.au) TRIAL REGISTRATION DATE: August 4th 2009.

Six-month outcomes from living well with diabetes: A randomized trial of a telephone-delivered weight loss and physical activity intervention to improve glycemic control.

BACKGROUND: Intensive lifestyle intervention trials in type 2 diabetes contribute evidence on what can be achieved under optimal conditions, but are less informative for translation in applied settings. PURPOSE: Living Well with Diabetes is a telephone-delivered weight loss intervention designed for real-world delivery. METHODS: This study is a randomized controlled trial of telephone counseling (n = 151) versus usual care (n = 151); 6-month primary outcomes of weight, physical activity, HbA1c; secondary diet outcomes; analysis was by adjusted generalized linear models. RESULTS: Relative to usual care, telephone counseling participants had small but significantly better weight loss [-1.12 % of initial body weight; 95 % confidence interval (CI) -1.92, -0.33 %]; physical activity [relative rate (RR) = 1.30; 95 % CI, 1.08, 1.57]; energy intake reduction (-0.63 MJ/day; 95 % CI, -1.01, -0.25); and diet quality (3.72 points; 95 % CI, 1.77, 5.68), with no intervention effect for HbA1c (RR = 0.99; 95 % CI, 0.96, 1.01). CONCLUSIONS: Results are discussed in light of challenges to intervention delivery.

A bi-directional relationship between obesity and health-related quality of life: evidence from the longitudinal AusDiab study.

OBJECTIVE: To assess the prospective relationship between obesity and health-related quality of life, including a novel assessment of the impact of health-related quality of life on weight gain. DESIGN AND SETTING: Longitudinal, national, population-based Australian Diabetes, Obesity and Lifestyle (AusDiab) study, with surveys conducted in 1999/2000 and 2004/2005. PARTICIPANTS: A total of 5985 men and women aged ≥ 25 years at study entry. MAIN OUTCOME MEASURE(S): At both time points, height, weight and waist circumference were measured and self-report data on health-related quality of life from the SF-36 questionnaire were obtained. Cross-sectional and bi-directional, prospective associations between obesity categories and health-related quality of life were assessed. RESULTS: Higher body mass index (BMI) at baseline was associated with deterioration in health-related quality of life over 5 years for seven of the eight health-related quality of life domains in women (all P ≤ 0.01, with the exception of mental health, P>0.05), and six out of eight in men (all P<0.05, with the exception of role-emotional, P=0.055, and mental health, P>0.05). Each of the quality-of-life domains related to mental health as well as the mental component summary were inversely associated with BMI change (all P<0.0001 for women and P ≤ 0.01 for men), with the exception of vitality, which was significant in women only (P=0.008). For the physical domains, change in BMI was inversely associated with baseline general health in women only (P=0.023). CONCLUSIONS: Obesity was associated with a deterioration in health-related quality of life (including both physical and mental health domains) in this cohort of Australian adults followed over 5 years. Health-related quality of life was also a predictor of weight gain over 5 years, indicating a bi-directional association between obesity and health-related quality of life. The identification of those with poor health-related quality of life may be important in assessing the risk of future weight gain, and a focus on health-related quality of life may be beneficial in weight management strategies.

Physical activity, family history of diabetes and risk of developing hyperglycaemia and diabetes among adults in Mainland China.

AIMS: To investigate the joint influence of physical activity and family history of diabetes on the subsequent risk of developing hyperglycaemia and Type 2 diabetes among Chinese adults. METHODS: A prospective community-based cohort study was conducted among adults aged 35 years and older during 2004-2007 in Nanjing, China. Four communities (three urban and one rural) were randomly selected from 11 urban districts and two rural counties. Hyperglycaemia and Type 2 diabetes were defined using World Health Organization criteria based on fasting blood glucose concentration and physicians' diagnosis, respectively. Physical activity, parental diabetes history, and other important covariates were assessed at baseline and in the third-year follow-up survey. RESULTS: At study conclusion data were collected from 3031 participants (follow-up rate 81.3%). The 3-year cumulative incidence of hyperglycaemia and Type 2 diabetes was 6.2% and 2.4%, respectively. After adjustment for potential confounding variables, compared with those with positive family history and insufficient physical activity, the adjusted relative risk ratio (95% CI) of developing hyperglycaemia was 0.19 (0.02, 1.51) for participants with sufficient physical activity and a positive family history; 0.55 (0.31, 0.97) for participants with insufficient physical activity and a negative family history; and 0.36 (0.19, 0.70) for participants with sufficient physical activity but a negative family history. Participants who had a negative family history and insufficient physical activity were also less likely to develop Type 2 diabetes (RRR = 0.28; 0.14, 0.54), and participants with a negative family history and sufficient physical activity were the least likely to develop Type 2 diabetes (0.23; 0.10, 0.56). CONCLUSIONS: Sufficient physical activity and negative family history of diabetes may jointly reduce the risk of developing hyperglycaemia and Type 2 diabetes in Chinese adults.

Adverse associations of increases in television viewing time with 5-year changes in glucose homoeostasis markers: the AusDiab study.

BACKGROUND: Television viewing time is associated cross-sectionally with abnormal glucose tolerance and diabetes risk; however, the impact of changes in television viewing time on glycaemic measures is less understood. We examined relationships of 5-year change in television viewing time with 5-year change in glucose homeostasis markers. METHODS: Participants in the Australian Diabetes, Obesity and Lifestyle study with data available at the 1999-2000 baseline and the 2004-2005 follow-up were included (4870; 45% men). Television viewing time (h/week) was assessed by questionnaire. Fasting plasma glucose, serum insulin and 2-h plasma glucose were obtained from an oral glucose tolerance test. Beta-cell function and insulin resistance were ascertained using the homeostasis model assessment 2-calculator. Associations of change in television viewing time with changes in glucose homeostasis markers were examined using linear regression models [ß-coefficients (95% CI)]. Adjustments included baseline measures of age, television viewing time and glycaemic marker, and baseline and 5-year change in diet quality, energy intake, physical activity and waist circumference. RESULTS: For every 5-h per week increase in television viewing time from baseline to 5-year follow-up, changes in glucose homeostasis markers were observed: among women there was a significant increase in fasting plasma glucose [0.01 (0.00-0.02) mmol/l] insulin resistance [0.03 (0.01-0.05)] and insulin secretion [1.07 (0.02-2.12) %]; insulin levels increased [men: 1.20 (0.30-2.09); women: 1.06 (0.32-1.80) pmol/l]; in men, 2-h plasma glucose levels increased [0.06 (0.01-0.1) mmol/l]. CONCLUSION: Five-year increases in television viewing time were associated adversely with changes in glucose homeostasis markers. These findings add to earlier cross-sectional evidence that television viewing time can be associated with biomarkers of diabetes risk.

Television viewing time and mortality: the Australian Diabetes, Obesity and Lifestyle Study (AusDiab).

BACKGROUND: Television viewing time, the predominant leisure-time sedentary behavior, is associated with biomarkers of cardiometabolic risk, but its relationship with mortality has not been studied. We examined the associations of prolonged television viewing time with all-cause, cardiovascular disease (CVD), cancer, and non-CVD/noncancer mortality in Australian adults. METHODS AND RESULTS: Television viewing time in relation to subsequent all-cause, CVD, and cancer mortality (median follow-up, 6.6 years) was examined among 8800 adults > or =25 years of age in the Australian Diabetes, Obesity and Lifestyle Study (AusDiab). During 58 087 person-years of follow-up, there were 284 deaths (87 CVD deaths, 125 cancer deaths). After adjustment for age, sex, waist circumference, and exercise, the hazard ratios for each 1-hour increment in television viewing time per day were 1.11 (95% confidence interval [CI], 1.03 to 1.20) for all-cause mortality, 1.18 (95% CI, 1.03 to 1.35) for CVD mortality, and 1.09 (95% CI, 0.96 to 1.23) for cancer mortality. Compared with a television viewing time of <2 h/d, the fully adjusted hazard ratios for all-cause mortality were 1.13 (95% CI, 0.87 to 1.36) for > or =2 to <4 h/d and 1.46 (95% CI, 1.04 to 2.05) for > or =4 h/d. For CVD mortality, corresponding hazard ratios were 1.19 (95% CI, 0.72 to 1.99) and 1.80 (95% CI, 1.00 to 3.25). The associations with both cancer mortality and non-CVD/noncancer mortality were not significant. CONCLUSIONS: Television viewing time was associated with increased risk of all-cause and CVD mortality. In addition to the promotion of exercise, chronic disease prevention strategies could focus on reducing sitting time, particularly prolonged television viewing.

Objectively assessed physical activity, sedentary time and waist circumference among prostate cancer survivors: findings from the National Health and Nutrition Examination Survey (2003-2006).

Physical activity is well-established on the cancer survivorship research agenda, but prostate cancer survivors remain an understudied population. Additionally, the unique relationships between sedentary time and health outcomes have not yet been considered in this group. We examined the associations of accelerometer-assessed physical activity and sedentary time with waist circumference in 103 prostate cancer survivors from the National Health and Nutrition Examination Survey 2003-2004 and 2005-2006. Participants wore an Actigraph accelerometer for 7 days, and activity levels were summarised as moderate-to-vigorous intensity activity (accelerometer counts/minute ≥ 1952), light-intensity activity (counts/minute 100-1951) and sedentary time (counts/minute < 100). Moderate-to-vigorous intensity physical activity was inversely associated with waist circumference (ß=-6.728, 95% CI: -12.267, -1.190, P= 0.020), equating to a top versus bottom quartile difference of 13.7 cm. No discernable relationship existed between light-intensity activity or sedentary time and adiposity. This is the first study to objectively measure the activity levels of prostate cancer survivors. Increasing moderate-to-vigorous activity may assist this population with weight management. More research into the relationships of light-intensity physical activity and sedentary behaviour with health outcomes among prostate cancer survivors is warranted, given the strong relationships seen in the broader population.

Association between hyperglycaemia and fracture risk in non-diabetic middle-aged and older Australians: a national, population-based prospective study (AusDiab).

SUMMARY: The association between pre-diabetes and fracture risk remains unclear. In this large cohort of middle-aged and older Australian men and women without diabetes, elevated 2-h plasma glucose and pre-diabetes were associated with a reduced 5-year risk of low trauma and all fractures in women, independently of BMI, fasting insulin and other lifestyle factors. INTRODUCTION: We aimed to (1) examine associations between fasting and 2-h plasma glucose (FPG and 2-h PG), fasting insulin and risk of low trauma and all fractures in non-diabetic adults and (2) compare fracture risk between adults with pre-diabetes (impaired glucose tolerance or impaired fasting glucose) and those with normal glucose tolerance (NGT). METHODS: Six thousand two hundred fifty-five non-diabetic men and women aged ≥40 years with NGT (n = 4,855) and pre-diabetes (n = 1,400) were followed for 5 years in the AusDiab Study. Fractures were self-reported. RESULTS: Five hundred thirty-nine participants suffered at least one fracture (368 women, 171 men), of which the majority (318) occurred after a low-energy trauma (258 women, 60 men). In women, a 2-h PG ≥ 7.2 mmol/L (highest quartile) was associated with a decreased risk of low trauma and all fractures independent of age and BMI [OR (95% CI) for low trauma fractures, 0.59 (0.40-0.88)], but also fasting insulin, smoking, physical activity, history of fracture, dietary calcium and alcohol intake or menopausal status. There was no effect of 2-h PG on fracture risk in men [OR (95% CI), 1.39 (0.60-3.26)] or any relationship between fracture risk and quartiles of FPG or insulin in either sex. Compared to women with NGT, those with pre-diabetes had a reduced risk of fracture [OR (95% CI) for all fractures, 0.70 (0.52-0.95); for low trauma fractures, 0.75 (0.53-1.05)]. CONCLUSION: Elevated 2-h PG levels and pre-diabetes were inversely associated with low trauma and/or all fractures in non-diabetic women, independent of BMI and fasting insulin levels.

Differences in height explain gender differences in the response to the oral glucose tolerance test- the AusDiab study.

AIM: To determine the extent of gender-related differences in the prevalence of glucose intolerance for the Australian population and whether body size may explain such differences. METHODS: Cross-sectional data were collected from a national cohort of 11 247 Australians aged > or = 25 years. Glucose tolerance status was assessed according to both fasting plasma glucose (FPG) and 2-h plasma glucose (2hPG) levels following a 75-g oral glucose tolerance test (OGTT). Anthropometric and glycated haemoglobin measurements were also made. RESULTS: Undiagnosed diabetes and non-diabetic glucose abnormalities were more prevalent among men than women when based only on the FPG results (diabetes: men 2.2%, women 1.6%, P = 0.02; impaired fasting glycaemia: men 12.3%, women 6.6%, P < 0.001). In contrast 16.0% of women and 13.0% of men had a 2hPG abnormality (either diabetes or impaired glucose tolerance, P = 0.14). Women had a mean FPG 0.3 mmol/l lower than men (P < 0.001), but 2hPG 0.3 mmol/l higher (P = 0.002) and FPG-2hPG increment 0.5 mmol/l greater (P < 0.001). The gender difference in mean 2hPG and FPG-2hPG increment disappeared following adjustment for height. For both genders, those in the shortest height quartile had 2hPG levels 0.5 mmol/l higher than the tallest quartile, but height showed almost no relationship with the FPG. CONCLUSIONS: Men and women had different glycaemic profiles; women had higher mean 2hPG levels, despite lower fasting levels. It appeared that the higher 2hPG levels for women related to lesser height and may be a consequence of using a fixed glucose load in the OGTT, irrespective of body size.

Mediating effects of dietary intake on associations of TV viewing, body mass index and metabolic syndrome in adolescents.

OBJECTIVE: Evidence suggests that TV viewing is associated with body mass index (BMI) and metabolic syndrome (MetS) in adolescents. However, it is unclear whether dietary intake mediates these relationships. METHODS: A cross-sectional analysis was conducted in adolescents (12-19 years) participating in the 2003-2006 United States National Health and Nutrition Examination Survey. BMI z scores (zBMI) (n = 3,161) and MetS (n = 1,379) were calculated using age- and sex-specific criteria for adolescents. TV viewing (h/day) was measured via a self-reported questionnaire, and dietary intake was assessed using two 24-h recalls. Using the MacKinnon method, a series of mediation analyses were conducted examining five dietary mediators (total energy intake, fruit and vegetable intake, discretionary snacks, sugar-sweetened beverages and diet quality) of the relationships between TV viewing and zBMI and MetS. RESULTS: Small positive relationships were observed between TV viewing and zBMI (ß = 0.99, p < 0.001) and TV viewing and MetS (OR = 1.18, p = 0.046). No dietary element appeared to mediate the relationship between TV viewing and zBMI. However, sugar-sweetened beverage consumption and fruit and vegetable intake partially mediated the relationship between TV viewing and MetS, explaining 8.7% and 4.1% of the relationship, respectively. CONCLUSIONS: These findings highlight the complexity of the relationships between TV viewing, dietary intake and cardiometabolic health outcomes, and that TV viewing should remain a target for interventions.

Associations of sedentary time patterns and TV viewing time with inflammatory and endothelial function biomarkers in children.

OBJECTIVE: Investigate associations of TV viewing time and accelerometry-derived sedentary time with inflammatory and endothelial function biomarkers in children. METHODS: Cross-sectional analysis of 164 7-10-year-old children. TV viewing time was assessed by parental proxy report and total and patterns of sedentary time accumulation (e.g. prolonged bouts) were assessed by accelerometry. C-reactive protein (CRP), homeostasis model assessment of insulin resistance, interleukin-2, -6, -8, -10, tumour necrosis factor alpha, adiponectin, resistin, brain-derived neurotrophic factor, soluble intercellular and vascular adhesion molecule 1, plasminogen activator inhibitor 1 and soluble E-selectin were assessed. Generalised linear models assessed the associations of TV viewing and sedentary time with biomarkers, adjusting for sex, waist circumference, moderate- to vigorous-intensity physical activity and diet density. RESULTS: Each additional h week(-1) of TV viewing was associated with 4.4% (95% CI: 2.1, 6.7) greater CRP and 0.6% (0.2, 1.0) greater sVCAM-1 in the fully adjusted model. The association between frequency and duration of 5-10 min bouts of sedentary time and CRP was positive after adjustment for sex and waist circumference but attenuated after adjustment for diet density. CONCLUSIONS: This study suggests that TV viewing was unfavourably associated with several markers of inflammation and endothelial dysfunction. The detrimental association between 5 and 10 min bouts of sedentary time and CRP approached significance, suggesting that further research with a stronger study design (longitudinal and/or experimental) is needed to better understand how the accumulation of sedentary time early in life may influence short and longer term health.

The independent and combined effects of aerobic exercise and dietary fish intake on serum lipids and glycemic control in NIDDM. A randomized controlled study.

OBJECTIVE: The triglyceride-lowering effects of omega-3 fats and HDL cholesterol-raising effects of exercise may be appropriate management for dyslipidemia in NIDDM. However, fish oil may impair glycemic control in NIDDM. The present study examined the effects of moderate aerobic exercise and the incorporation of fish into a low-fat (30% total energy) diet on serum lipids and glycemic control in dyslipidemic NIDDM patients. RESEARCH DESIGN AND METHODS: In a controlled, 8-week intervention, 55 sedentary NIDDM subjects with serum triglycerides > 1.8 mmol/l and/or HDL cholesterol < 1.0 mmol/l were randomly assigned to a low-fat diet (30% daily energy intake) with or without one fish meal daily (3.6 g omega-3/day) and further randomized to a moderate (55-65% VO2max) or light (heart rate < 100 bpm) exercise program. An oral glucose tolerance test (75 g), fasting serum glucose, insulin, lipids, and GHb were measured before and after intervention. Self-monitoring of blood glucose was performed throughout. RESULTS: In the 49 subjects who completed the study, moderate exercise improved aerobic fitness (VO2max) by 12% (from 1.87 to 2.07 l/min, P = 0.0001). Fish consumption reduced triglycerides (0.80 mmol/l, P = 0.03) and HDL3 cholesterol (0.05 mmol/l, P = 0.02) and increased HDL2 cholesterol (0.06 mmol/l, P = 0.01). After adjustment for age, sex, and changes in body weight, fish diets were associated with increases in GHb (0.50%, P = 0.05) and self-monitored glucose (0.57 mmol/l, P = 0.0002), which were prevented by moderate exercise. CONCLUSIONS: A reduced fat diet incorporating one daily fish meal reduces serum triglycerides and increases HDL2 cholesterol in dyslipidemic NIDDM patients. Associated deterioration in glycemic control can be prevented by a concomitant program of moderate exercise.

Is the relationship between sedentary behaviour and cardiometabolic health in adolescents independent of dietary intake? A systematic review.

Screen time, but not overall sedentary behaviour, is consistently related to cardiometabolic health in adolescents. Because of the associations screen time has with dietary intake, diet may be an important factor in the screen time and health relationship; however, evidence has not previously been synthesized. Thus, the aim of this systematic review was to explore whether the associations between various sedentary behaviours and cardiometabolic risk markers are independent of dietary intake in adolescents. Online databases and personal libraries were searched for peer-reviewed original research articles published in English before March 2014. Included studies assessed associations between sedentary behaviour and cardiometabolic markers in 12- to 18-year-olds and adjusted for dietary intake. Twenty-five studies met the inclusion criteria. From the 21 studies examining sedentary behaviour and adiposity, the majority found significant positive associations between television viewing, screen time and self-reported overall sedentary behaviour with markers of adiposity, independent of dietary intake. No significant associations between screen time with blood pressure and cholesterol were reported. Sedentary behaviour appears to be associated with adiposity in adolescents, irrespective of dietary intake. However, the variability of dietary variables between studies suggests further work is needed to understand the role of dietary intake when examining these associations in youth.

A randomised, controlled study of the effects of aerobic exercise and dietary fish on coagulation and fibrinolytic factors in type 2 diabetics.

Type 2 diabetes is associated with disturbances in coagulation and fibrinolysis. Prospective studies show that increased tissue plasminogen activator (tPA) antigen increases the risk of cardiovascular mortality. The present study examined the hypothesis that combining a regime of moderate aerobic exercise with one daily fish meal as part of a low-fat diet (30% total energy) would improve coagulation and fibrinolytic factors in dyslipidaemic type 2 diabetic patients. In a randomised. controlled, 8-week trial, 55 sedentary type 2 diabetic subjects with serum triglycerides >1.8 mmol/l and/or HDL-C <1.0 mmol/l were randomly assigned to a low-fat diet (30% daily energy intake) with or without one fish meal daily (3.6 g omega3 fatty acids/day) and further randomized to a moderate (55-65% VO2max) or light (heart rate <100 bpm) exercise program. Plasma levels of fibrinogen, coagulation factor VIIc, tPA and plasminogen activator inhibitor (PAI-1) antigen were measured before and after intervention. In the 49 subjects who completed the study, the fish diet alone, moderate exercise alone and the combination of fish and moderate exercise all led to significant reductions in tPA antigen concentrations (-2.1 ng/ml, p = 0.02. -1.9 ng/ml, p = 0.03, -2.0 ng/ml, p = 0.01, respectively) compared to controls. In multivariate regression, changes in fasting blood glucose (positively) and erythrocyte omega3 fatty acid composition (inversely) were independent predictors of the change in tPA antigen. The fish diet alone contributed to a significant rise in coagulation factor VIIc compared to controls (4.9%, p = 0.02), which was prevented by moderate exercise. No significant effects on PAI-1 antigen and fibrinogen were seen. In view of recent epidemiological findings, the reduction in tPA antigen with both fish and moderate exercise in these dyslipidaemic type 2 diabetic patients could reflect a reduced thrombotic potential and decreased cardiovascular risk. Furthermore, a small, albeit significant, increase in coagulation factor VIIc associated with fish can be prevented by a concomitant programme of moderate exercise.