Evening regular activity breaks extend subsequent free-living sleep time in healthy adults: a randomised crossover trial.

Objective: To determine if performing regular 3-min bouts of resistance exercise spread over 4 hours in an evening will impact subsequent sleep quantity and quality, sedentary time and physical activity compared with prolonged uninterrupted sitting. Methods: In this randomised crossover trial, participants each completed two 4-hour interventions commencing at approximately 17:00 hours: (1) prolonged sitting and (2) sitting interrupted with 3 min of bodyweight resistance exercise activity breaks every 30 min. On completion, participants returned to a free-living setting. This paper reports secondary outcomes relating to sleep quality and quantity, physical activity and sedentary time which were assessed using wrist-worn ActiGraph GT3+ accelerometers paired with a sleep and wear time diary. Results: A total of 28 participants (women, n=20), age 25.6±5.6 years, body mass index 29.5±6.7 kg/m2 (mean±SD) provided data for this analysis. Compared with prolonged sitting, regular activity breaks increased mean sleep period time and time spent asleep by 29.3 min (95% CI: 1.3 to 57.2, p=0.040) and 27.7 min (95% CI: 2.3 to 52.4, p=0.033), respectively, on the night of the intervention. There was no significant effect on mean sleep efficiency (mean: 0.2%, 95% CI: -2.0 to 2.4, p=0.857), wake after sleep onset (1.0 min, 95% CI: -9.6 to 11.7, p=0.849) and number of awakenings (0.8, 95% CI: -1.8 to 3.3, p=0.550). Subsequent 24-hour and 48-hour physical activity patterns were not significantly different. Conclusions: Performing bodyweight resistance exercise activity breaks in the evening has the potential to improve sleep period and total sleep time and does not disrupt other aspects of sleep quality or subsequent 24-hour physical activity. Future research should explore the longer-term impact of evening activity breaks on sleep. Trial registration number: Australian New Zealand Clinical Trials Registry (ACTRN12621000250831).

Improved glycaemic control induced by evening activity breaks does not persist overnight amongst healthy adults: A randomized crossover trial.

AIMS: To compare the effects of 4 hours of laboratory-based regular activity breaks (RABs) and prolonged sitting (SIT) on subsequent 48-h free-living interstitial glucose levels in a group of healthy adults. MATERIALS AND METHODS: In this randomized crossover trial, participants completed two 4-h laboratory-based interventions commencing at ~5:00 pm: (1) SIT and (2) SIT interrupted with 3 min of body weight resistance exercise activity breaks every 30 min (RABs). Continuous glucose monitoring was performed during the intervention and for 48-h after, during which time participants returned to a free-living setting. RESULTS: Twenty-eight adults (female n = 20, mean ± SD age 25.5 ± 5.6 years, body mass index 29.2 ± 6.9 kg/m2) provided data for this analysis. During the intervention period, RABs lowered mean interstitial glucose by 8.3% (-0.47 mmol/L/4 h, 95% confidence interval [CI] -0.74 to -0.20; p = 0.001) and area under the curve (AUC) by 8.9% (-2.01 mmol/L/4 h, 95% CI -3.05 to -0.97; p < 0.001) compared to SIT. Measures of glycaemic variability were not significantly different during the intervention. There were no significant differences in mean glucose and AUC between conditions during the first nocturnal period and 24-h post intervention. When compared to SIT, RABs increased continuous overall net action of glucose at 1 h and SD glucose by 22% (0.18 mmol/L, 95% CI 0.03 to 0.29; p = 0.018) and 26% (95% CI 4.9 to 42.7; p = 0.019) in the first nocturnal period and by 10% (0.09 mmol/L, 95% CI 0.01, 0.17; p = 0.025) and 15% (95% CI 6.6 to 22.4; p = 0.001) in the 24-h post intervention period, respectively. CONCLUSION: Performing activity breaks in the evening results in acute reductions in interstitial glucose concentrations; however, the magnitude of these changes is not maintained overnight or into the following 48 hours.

Micronutrient status of New Zealand adolescent women consuming vegetarian and non-vegetarian diets.

BACKGROUND AND OBJECTIVES: Globally, there appears to be an ever-increasing interest in adopting a vegetarian diet. However, there are concerns that avoiding meat may increase the risk of anaemia and micronutrient deficiencies, especially for vulnerable populations, such as adolescent women. The objective of this study was to compare the micronutrient status of vegetarian and non-vegetarian adolescent women in New Zealand. METHODS AND STUDY DESIGN: Adolescent women aged 15-18 y were recruited from eight locations across New Zealand. Blood samples were analysed for: haemoglobin, serum ferritin, soluble transferrin receptor, zinc, selenium, retinol binding protein, folate, vitamin B-12, vitamin D and parathyroid hormone. RESULTS: Of the 182 participants who provided a blood sample, 15% self-identified as vegetarian (n=27). On average, vegetarians had 3.1% (95% CI -5.8 to -0.4, p=0.025) lower haemoglobin, and 8.3% (95%CI -14.1 to -2.1, p=0.004) lower selenium. In contrast, serum folate was 80.5% (95% CI 45.7 to 123.7, p<0.001) higher. The prevalence of zinc and selenium deficiency was higher among vegetarians (50% and 12%, respectively) than non-vegetarians (21%, and 2%, respectively). CONCLUSIONS: Adolescent vegetarian women may be at increased risk of deficiency of micronutrients commonly found in animal products, including zinc and selenium, and may benefit from following dietary practices that enhance micronutrient intake and absorption.

Breaking Up Evening Sitting with Resistance Activity Improves Postprandial Glycemic Response: A Randomized Crossover Study.

INTRODUCTION: Interrupting sedentary time during the day reduces postprandial glycemia (a risk factor for cardiometabolic disease). However, it is not known if benefits exist for postprandial glucose, insulin and triglyceride responses in the evening, and if these benefits differ by body mass index (BMI) category. METHODS: In a randomized crossover study, 30 participants (25.4 ± 5.4 yr old; BMI 18.5-24.9: n = 10, BMI 25-29.9: n = 10, BMI ≥30: n = 10) completed two intervention arms, beginning at ~1700 h: prolonged sitting for 4 h, and sitting with regular activity breaks of 3 min of resistance exercises every 30 min. Plasma glucose, insulin, and triglyceride concentrations were measured in response to two meals fed at baseline and 120 min. Four-hour incremental area under the curve was compared between interventions. Moderation by BMI status was explored. RESULTS: Overall, when compared with prolonged sitting, regular activity breaks lowered plasma glucose and insulin incremental area under the curve by 31.5% (95% confidence interval = -49.3% to -13.8%) and 26.6% (-39.6% to -9.9%), respectively. No significant differences were found for plasma triglyceride area under the curve. Interactions between BMI status and intervention was not statistically significant. CONCLUSIONS: Interventions that interrupt sedentary time in the evening may improve cardiometabolic health by some magnitude in all participants regardless of bodyweight.

The Impact of Organised Sport, Physical Education and Active Commuting on Physical Activity in a Sample of New Zealand Adolescent Females.

BACKGROUND: The majority of adolescents do less physical activity than is recommended by the World Health Organization. Active commuting and participation in organised sport and/or physical education individually have been shown to increase physical activity in adolescents. However, how these domains impact physical activity both individually and in combination has yet to be investigated in a sample of New Zealand female adolescents from around the country. METHODS: Adolescent females aged 15-18 y (n = 111) were recruited from 13 schools across eight locations throughout New Zealand to participate in this cross-sectional study. Participants completed questions about active commuting, and participation in organised sport and physical education, before wearing an Actigraph GT3X (Actigraph, Pensacola, FL, USA) +24 h a day for seven consecutive days to determine time spent in total, MVPA and light physical activity. RESULTS: Active commuters accumulated 17 min/d (95% CI 8 to 26 min/d) more MVPA compared to those who did not. Those who participated in sport accumulated 45 min/d (95% CI 20 to 71 min/d) more light physical activity and 14 min/d (95% CI 5 to 23 min/d) more MVPA compared to those who did not. Participation in physical education did not seem to have a large impact on any component of physical activity. Participation in multiple domains of activity, e.g., active commuting and organised sport, was associated with higher accumulation of MVPA but not light activity. Conclusion Active commuting and sport both contribute a meaningful amount of daily MVPA. Sport participation has the potential to increase overall activity and displace sedentary behaviour. A combination of physical activity domains may be an important consideration when targeting ways to increase physical activity in adolescent females.

Translating hunger training research to primary health: a qualitative study of nurse attitudes towards a novel weight management intervention.

INTRODUCTION Practice nurses in general practice are ideally placed to deliver weight management treatments. Teaching people to eat according to their appetite, based on measurements of blood glucose ('hunger training'), is known to lead to weight loss and improved eating behaviour. To effectively translate this research to primary care requires understanding of key stakeholder perspectives. AIM The aim of this study was to explore the perspectives of practice nurses on the suitability of using hunger training as a weight management intervention in general practice. METHODS Ten nurses trialled hunger training for 1 week, followed by a semi-structured interview where they were asked about their experience; perceived patient interest; enablers and barriers; and suggested changes to hunger training. RESULTS All nurses were positive about hunger training and wanted to use it with their patients. They thought it was a useful method for teaching patients about eating according to their appetite, and the impact of food choices on glucose. Motivation was seen to be both an important potential barrier and enabler for patients. Other anticipated patient enablers included the educational value of hunger training and ease of the programme. Other barriers included lack of time and cost of equipment and appointments. For most nurses, 1 week of following hunger training was sufficient training to deliver the intervention. Suggested refinements included adding nutrition advice to the booklet, incorporating other health goals and enabling social support. DISCUSSION These findings suggest that hunger training could be translated to primary care with minor modifications.

"It's almost expected": rural Australian Aboriginal women's reflections on smoking initiation and maintenance: a qualitative study.

BACKGROUND: Despite declining smoking rates among the general Australian population, rates among Indigenous Australians remain high, with 47% of the Indigenous population reporting daily smoking - twice that of other Australians. Among women, smoking rates are highest in younger age groups, with more than half of Aboriginal women smoking during pregnancy. A lack of research focused on understanding the social context of smoking by Aboriginal women in rural Australia limits our ability to reduce these rates. This study aimed to explore the factors contributing to smoking initiation among rural Aboriginal women and girls and the social context within which smoking behaviour occurs. METHODS: We conducted three focus groups with 14 Aboriginal women and service providers and 22 individual interviews with Aboriginal women from four rural communities to explore their perceptions of the factors contributing to smoking initiation among Aboriginal girls. RESULTS: Four inter-related factors were considered important to understanding the social context in which girls start smoking: colonisation and the introduction of tobacco; normalization of smoking within separate Aboriginal social networks; disadvantage and stressful lives; and the importance of maintaining relationships within extended family and community networks. Within this context, young girls use smoking to attain status and as a way of asserting Aboriginal identity and group membership, a way of belonging, not of rebelling. Family and social structures were seen as providing strong support, but limited the capacity of parents to influence children not to smoke. Marginalization was perceived to contribute to limited aspirations and opportunities, leading to pleasure-seeking in the present rather than having goals for the future. CONCLUSIONS: The results support the importance of addressing contextual factors in any strategies aimed at preventing smoking initiation or supporting cessation among Aboriginal girls and women. It is critical to acknowledge Aboriginal identity and culture as a source of empowerment; and to recognise the role of persistent marginalization in contributing to the high prevalence and initiation of smoking.