Sedentary Time Is Independently Related to Adipose Tissue Insulin Resistance in Adults With or at Risk of Type 2 Diabetes.

INTRODUCTION: This cross-sectional study examined associations of device-measured sedentary time and moderate-to-vigorous physical activity (MVPA) with adipose tissue insulin resistance in people with or at high risk of type 2 diabetes (T2DM). METHOD: Data were combined from six previous experimental studies (within our group) involving patients with T2DM or primary risk factors (median (interquartile range) age, 66.2 (66.0-70.8) yr; body mass index (BMI), 31.1 (28.0-34.4) kg·m -2 ; 62% male; n = 179). Adipose tissue insulin resistance was calculated as the product of fasted circulating insulin and nonesterified fatty acids (ADIPO-IR), whereas sedentary time and MVPA were determined from wrist-worn accelerometery. Generalized linear models examined associations of sedentary time and MVPA with ADIPO-IR with interaction terms added to explore the moderating influence of ethnicity (White European vs South Asian), BMI, age, and sex. RESULTS: In finally adjusted models, sedentary time was positively associated with ADIPO-IR, with every 30 min of sedentary time associated with a 1.80-unit (95% confidence interval, 0.51-3.06; P = 0.006) higher ADIPO-IR. This relationship strengthened as BMI increased ( ß = 3.48 (95% confidence interval, 1.50-5.46), P = 0.005 in the upper BMI tertile (≥33.2 kg·m -2 )). MVPA was unrelated to ADIPO-IR. These results were consistent in sensitivity analyses that excluded participants taking statins and/or metformin ( n = 126) and when separated into the participants with T2DM ( n = 32) and those at high risk ( n = 147). CONCLUSIONS: Sedentary time is positively related to adipose tissue insulin sensitivity in people with or at high risk of T2DM. This relationship strengthens as BMI increases and may help explain established relationships between greater sedentary time, ectopic lipid, and hyperglycemia.

Improvements in Glycemic Control After Acute Moderate-Intensity Continuous or High-Intensity Interval Exercise Are Greater in South Asians Than White Europeans With Nondiabetic Hyperglycemia: A Randomized Crossover Study.

OBJECTIVE: To examine whether circulating metabolic responses to low-volume high-intensity interval exercise (LV-HIIE) or continuous moderate-intensity aerobic exercise (CME) differ between white Europeans and South Asians with nondiabetic hyperglycemia (NDH). RESEARCH DESIGN AND METHODS: Thirteen white Europeans and 10 South Asians (combined median [interquartile range] age 67 [60-68] years, HbA1c 5.9% [5.8-6.1%] [41.0 (39.9-43.2) mmol ⋅ mol-1]) completed three 6-h conditions (sedentary control [CON], LV-HIIE, and CME) in a randomized order. Exercise conditions contained a single bout of LV-HIIE and CME, respectively (each ending at 2 h), with meals provided at 0 and 3 h. Circulating glucose (primary outcome), insulin, insulin resistance index (IRI), triglycerides, and nonesterified fatty acids were measured at 0, 0.5, 1, 2, 3, 3.5, 4, 5, and 6 h. Data were analyzed as postexercise time-averaged area under the curve (AUC) adjusted for age, sex, and preexercise AUC. RESULTS: Glucose was similar in each condition and with ethnicity, with no condition-by-ethnicity interaction (P ≥ 0.28). However, insulin was lower in LV-HIIE (mean [95% CI] -44.4 [-23.7, -65.1] mU ⋅ L-1) and CME (-33.8 [-13.7, -53.9] mU ⋅ L-1) compared with CON. Insulin responses were greater in South Asians (interaction P = 0.03) such that values were similar in each ethnicity during exercise conditions, despite being 33% higher in South Asians during CON. IRI followed a similar pattern to insulin. Lipids were unaffected by exercise. CONCLUSIONS: Reductions in insulin and insulin resistance after acute LV-HIIE and CME are greater in South Asians than in white Europeans with NDH. Further trials are required to examine the longer-term impact of LV-HIIE and CME on cardiometabolic health.

A Cross-Sectional Description of Parental Perceptions and Practices Related to Risky Play and Independent Mobility in Children: The New Zealand State of Play Survey.

The potential for risky play and independent mobility to increase children's physical activity, and enhance cognitive development and emotional wellbeing has been recognised for some time. The aim of this study was to describe the attitudes of New Zealand parents towards such risky play practices and independent mobility, the barriers preventing them from allowing their children to participate, and how often their children engaged in risky play activities. An online survey comprised mostly of validated scales and standardised questions was completed by a nationally representative sample of 2003 parents. We found that parents had neutral feelings about the risk of injury to their child through play, rather they were concerned about road safety and "stranger danger". There was strong agreement that there are multiple benefits to be gained from exposure to risk and challenge, and that health and safety rules are too strict. However, 73% of respondents stated that their 5⁻12 year old child seldom or never engaged in four or more risky activities, and only 14.3% engaged in four or more often or always. While parents agree that their child is likely to benefit from risky play, they do not have the confidence to allow their children to engage in such activities. Future research should address barriers and fears when implementing strategies to facilitate risky play.

Exercise training and weight loss, not always a happy marriage: single blind exercise trials in females with diverse BMI.

Individuals show high variability in body weight responses to exercise training. Expectations and motivation towards effects of exercise on body weight might influence eating behaviour and could conceal regulatory mechanisms. We conducted 2 single-blind exercise trials (4 weeks (study 1) and 8 weeks (study 2)) with concealed objectives and exclusion of individuals with weight loss intention. Circuit exercise training programs (3 times a week (45-90 min), intensity 50%-90% peak oxygen uptake for 4 and 8 weeks) were conducted. Thirty-four females finished the 4-week intervention and 36 females the 8-week intervention. Overweight/obese (OV/OB) and lean female participants' weight/body composition responses were assessed and fasting and postprandial appetite hormone levels (PYY, insulin, amylin, leptin, ghrelin) were measured before and after the intervention for understanding potential contribution to individuals' body weight response to exercise training (study 2). Exercise training in both studies did not lead to a significant reduction of weight/body mass index (BMI) in the participants' groups; however, lean participants gained muscle mass. Appetite hormones levels were significantly (p < 0.05) altered in the OV/OB group, affecting fasting (-24%) and postprandial amylin (-14%) levels. Investigation of individuals' BMI responses using multiple regression analysis revealed that levels of fasting leptin, postprandial amylin increase, and BMI were significant predictors of BMI change, explaining about 43% of the variance. In conclusion, tested exercise training did not lead to weight loss in female participants, while a considerable proportion of variance in body weight response to training could be explained by individuals' appetite hormone levels and BMI.

Associations of Physical Activity Intensities with Markers of Insulin Sensitivity.

BACKGROUND: Objectively measured physical activity (PA) intensity has traditionally been categorized as light, moderate, and vigorous using laboratory calibrated cut points. The relative contribution of time spent across a spectrum of accelerometer-determined intensities on health outcomes is less clear. PURPOSE: This study aimed to assess the relationship between objectively measured PA intensity on a continuous scale and markers of insulin sensitivity (IS). METHODS: Participants at high risk of type 2 diabetes mellitus were recruited from primary care (Leicestershire, UK). PA was measured using an ActiGraph accelerometer. Fasting and postchallenge glucose and insulin levels were assessed using an oral glucose tolerance test. IS was calculated using the Matsuda-IS and the HOMA-IS indices. Log-linear regression modeling was used to assess the relationship between PA intensity, in increments of 500 counts per minute, with markers of IS. Models were controlled for known confounders. RESULTS: Complete data were available for 569 participants. PA intensity was favorably associated with fasting and 2 h of insulin and IS, with the association increasing in magnitude with each increment of 500 counts per minute. Differences in HOMA-IS per 10 min of PA ranged from 12.4% (95% confidence interval = 3.7%-21.8%) to 26.8% (11.0%-44.7%) within the moderate-intensity PA category (from 2000-2499 to 3500-3999 counts per minute). For Matsuda-IS, these differences were 22.0% (10.3%-34.9%) and 34.7% (13.9%-59.3%), respectively. Significant associations for fasting insulin were no longer observed after controlling for body mass index, whereas differences associated with 2-h insulin and IS were attenuated but still significant. CONCLUSION: PA of any intensity may positively influence glucose regulation and insulin sensitivity in individuals at high risk of type 2 diabetes mellitus in a dose-response manner. Further research is required to identify the intensity thresholds at which clinically relevant benefits occur in this population.

Optic nerve sheath diameter is not related to high altitude headache: a randomized controlled trial.

The mechanism of high altitude headache (HAH) remains unknown. The aim of this study was to determine experimentally whether optic nerve sheath diameter (ONSD), as an indicator of intracranial pressure, is related to HAH. Following sea level measurements at 3 and 12 hours (SL), 23 subjects were passively transported to high altitude (3777 m, HA) via cable car. HAH, ONSD, arterial oxygen saturation (Spo(2)), and fluid balance were determined at 3, 12, 24, and 36 hours. After 12 hours exposure to HA, subjects were classified by visual analogue scale (VAS) as either HAH positive (HAH+) or HAH negative (HAH-). Acetazolamide (250 mg) or placebo was then randomly prescribed at 15, 20, and 28 hours. Outcome means were compared via analysis of variance, and relationships between variables were analyzed by longitudinal regression. Acetazolamide had no statistically significant effect on HAH (p=0.63) or ONSD (p=0.98), but produced a negative fluid balance (p<0.01) (and also increased Spo(2) in exploratory analyses). Spo(2) was lower in HAH+ than HAH- [85 (3)% versus 88 (2)%, p=0.03). Nevertheless, ONSD increased similarly in HAH+ and HAH- (interaction p=0.90). ONSD also remained significantly elevated above SL values for the entire HA period [SL, 5.2 (0.5) versus HA, 5.6 (0.5) mm, p<0.01], despite headache resolving with acclimatization [VAS: SL, 1/100 (3) mm versus HA 3 h, 9/100 (13); 12 h, 10/100 (14); 24 h, 8/100 (12); 36 h, 1/100 (4) mm, p<0.01]. Furthermore, HAH was significantly correlated with Spo(2) (ß=-1.39, p<0.01) but not with ONSD (ß=0.59, p=0.57). These data do not support that intracranial pressure is associated with the development or amelioration of mild HAH. Clinical trial registration NCT01288781.