Reproducibility of plasma glucose responses to moderate-intensity exercise in individuals with type 1 diabetes.

AIM: To examine the within-person variability in plasma glucose responses to moderate-intensity morning exercise in young individuals with type 1 diabetes after overnight fasting and under basal insulin conditions. METHODS: In this pilot study, eight participants completed 40 min of moderate-intensity exercise at 60% V̇O2 peak on three separate days. The within-person standard deviation (SDw) in plasma glucose response was analysed both during and 1 h after exercise using the two visits per participant most closely matched by pre-exercise plasma glucose level. RESULTS: When the two closest matched visits per individual were included for analysis, mean (±SD) change in plasma glucose level was -1.8 ± 1.1 mmoL/L during exercise and -0.6 ± 1.0 mmoL/L during recovery, with the SDw of these changes being 0.5 mmol (95% CI 0.2, 0.8) during exercise and 0.8 mmoL/L (95% CI 0.4, 1.3) during recovery. The median intra-individual difference in plasma glucose level change was 0.3 mmoL/L [IQR 0.1, 0.7] during exercise and 0.8 mmoL/L [IQR 0.4, 1.0] during recovery. CONCLUSION: Within-person plasma glucose responses to moderate-intensity exercise may be reproducible under fasting and basal insulin conditions and similar pre-exercise plasma glucose levels. This finding may assist the design of future studies investigating both the reproducibility of glycaemic responses to exercise and blood glucose management for individuals with type 1 diabetes.

Attenuation of Post-Exercise Energy Intake Following 12 Weeks of Sprint Interval Training in Men and Women with Overweight.

An acute bout of sprint interval training (SIT) performed with psychological need-support incorporating autonomy, competence, and relatedness has been shown to attenuate energy intake at the post-exercise meal, but the long-term effects are not known. The aim of this trial was to investigate the effects of 12 weeks of SIT combined with need-support on post-exercise food consumption. Thirty-six physically inactive participants with overweight and obesity (BMI: 29.6 ± 3.8 kg·m−2; V˙O2peak 20.8 ± 4.1 mL·kg−1·min−1) completed three sessions per week of SIT (alternating cycling for 15 s at 170% V˙O2peak and 60 s at 32% V˙O2peak) with need-support or traditional moderate-intensity continuous training (MICT) without need-support (continuous cycling at 60% V˙O2peak). Assessments of appetite, appetite-related hormones, and ad libitum energy intake in response to acute exercise were conducted pre- and post-intervention. Fasting appetite and blood concentrations of active ghrelin, leptin, and insulin did not significantly differ between groups or following the training. Post-exercise energy intake from snacks decreased significantly from pre- (807 ± 550 kJ) to post- SIT (422 ± 468 kJ; p < 0.05) but remained unaltered following MICT. SIT with psychological need-support appears well-tolerated in a physically inactive population with overweight and offers an alternative to traditional exercise prescription where dietary intake is of concern.

Effects of diurnal exercise timing on appetite, energy intake and body composition: A parallel randomized trial.

OBJECTIVE: To determine the effect of diurnal exercise timing on appetite, energy intake and body composition in individuals with overweight or obesity. METHODS: Forty sedentary, individuals with overweight or obesity (17 males, 23 females; age: 51 ± 13 years; BMI: 30.9 ± 4.2 kg/m2) were randomly allocated to complete a 12-week supervised multi-modal exercise training program performed either in the morning (amEX) or evening (pmEX). Outcome measures included appetite in response to a standardised test meal, daily energy intake (EI), body weight and body composition. Measures of dietary behaviour were assessed at baseline and post-intervention, along with habitual physical activity, sleep quality and sleep quantity. Significance was set at p ≤ .05 and Hedge's g effect sizes were calculated. RESULTS: Regardless of timing, exercise training increased perceived fullness (AUC; g = 0.82-1.67; both p < .01), decreased daily EI (g = 0.73-0.93; both p < .01) and body-fat (g = 0.29-0.32; both p <. 01). The timing of exercise did not change the daily EI or body-fat response to training (all p ≥ .27), however, perceived fullness increased in the amEX group (p ≤ .01). DISINHIBITION: (g = 0.35-1.95; p ≤ .01) and Hunger (g = 0.05-0.4; p = .02) behaviours decreased following exercise training, with Disinhibition demonstrating greater improvements in the pmEX group (p = .01). Objective and subjective sleep quantity increased with training (all p ≤ .01), but sleep quality was not reported to change. CONCLUSIONS: Multi-modal exercise training improved body composition and some appetite outcomes, although changes were inconsistent and largely independent of exercise-timing. In the absence of dietary manipulation, the effect of diurnal exercise timing on appetite and body composition appear trivial compared to the overall benefits of exercise participation.

Understanding the determinants of stress-induced eating - A qualitative study.

The relationship between stress and food consumption is complex and often characterised by substantial between- and within-person variation. From a theoretical and practical perspective, more research is needed to improve our understanding of the factors that influence this relationship. The aim of this study was to identify those factors, and to derive insight into the nature of their effects on the relationship between stress and food consumption. Using semi-structured interviews, 41 adult participants (M ± SD age = 26.7 ± 6.3 yr, BMI = 22.9 ± 3.0 kg/m2) were invited to reflect on their food consumption following stressor exposure, and to elaborate on the factors that influence stress-induced eating behaviour. Reflexive thematic analyses revealed insight into the different ways in which individuals respond to stress in terms of food quantity and choices, and more significantly, highlighted a range of factors that may influence stress-induced eating behaviours. These factors included the intensity and/or nature of the stressor, aspects of prioritisation, rewarding, knowledge of and perceptions about food, normative (e.g., family, friend) influences, automated or habituated behaviours, the availability of food, and selected coping mechanisms. These findings present important directions for researchers seeking to study the variation in stress-induced eating, and may hold substantial practical value by way of informing interventions designed to alleviate unhealthy dietary responses to stress.

Perceived daily tension and food cravings and consumption: A within- and between-person investigation.

Previous research examining the relationship between negative states such as tension/anxiety and food intake has typically overlooked the naturally occurring variability of day-to-day experiences and the subsequent consequences for eating behavior. In this study, the relationship of within- and between-person perceived daily tension with food cravings and consumption was assessed. One hundred and forty-two men and women (Mage=21.3, SDage=5.3) completed a survey daily for 7 consecutive days. Levels of perceived daily tension, food cravings, and consumption were assessed. Linear and logistic mixed effect regression models were used to examine associations between tension and food cravings and consumption variables, respectively. Individuals reported greater cravings (for sweets, OR 95% CI 1.05-1.26; carbohydrates/starches, OR 95% CI 1.02-1.26; and fast foods, OR 95% CI 1.01-1.19) and consuming more carbohydrates/starches (b 95% CI 0.05-0.79) on days when they felt more tension. Individuals with higher tension had more cravings (total OR 95% CI 1.09-1.71; and specifically for sweets, OR 95% CI 1.04-1.42; and fast foods, OR 95% CI 1.15-1.54) and reported consuming more sweet (b 95% CI 0.21-1.10) and fast foods (b 95% CI 0.55-1.66). These findings suggest that greater perceived tension (both within and between individuals) is associated with increased food cravings and consumption.

'They deserve a treat': the nature and antecedents of parental licensing surrounding children's physical activity.

OBJECTIVE: Little is known about parents' compensatory health beliefs (CHB) surrounding their children's engagement in physical activity (PA). Our aim was to provide evidence regarding the nature of, and factors underpinning, parents' PA-related compensatory beliefs for their children. DESIGN: A qualitative descriptive approach and thematic content analysis were employed. SETTING: Parents were recruited from community sport and PA programmes. PARTICIPANTS: Eighteen parents aged 32-52 years (mean age = 40·8 (sd 5·4) years; six males; twelve females). RESULTS: Analyses indicated that parents compensate through 'passive' or 'active' means. Among parents who compensated, most described their provision of 'treat' foods/drinks and a minority described allowing extended sedentary time to their children. Parents' reasons underpinning these beliefs related to their child's general physical/health status and psychological characteristics, and their own motivation and mood state. CONCLUSIONS: These findings provide the first evidence of unhealthy dietary and sedentary behaviour CHB that parents may hold regarding their children's involvement in PA.

The effect of antecedent exercise on the acute stress response and subsequent food consumption: a preliminary investigation.

Physical activity has been shown to be protective against many of the deleterious consequences of stress; however, the effects of exercise on stress-induced food consumption are unclear. This study examined the effect of an acute bout of exercise prior to exposure to an acute stressor on subsequent eating behavior, together with the physiological (e.g., heart rate, blood pressure, salivary cortisol) and psychological (e.g., mood, perceived stress) responses to stress. Twenty-three men and women completed four experimental conditions (control, exercise only, stress only, and exercise prior to stress) conducted in a counterbalanced order using a within-subjects repeated measures design. Ad libitum energy intake from a laboratory test meal was assessed at each trial, together with monitoring of physiological and psychological responses. No difference in total energy intake (p = 0.146) or energy intake from 'unhealthy' foods was noted between conditions (p = 0.783), despite lower circulating ghrelin when antecedent exercise was performed compared with stress alone (p < 0.05). Exposure to an acute stressor is not necessarily associated with alterations in subsequent food intake, nor does antecedent exercise prior to stress exposure affect food choices, despite transient alterations in the hunger hormone ghrelin.

A preliminary investigation of the effects of short-duration, vigorous exercise following sleep restriction, fragmentation and extension on appetite and mood in inactive, middle-aged men.

This preliminary study aimed to investigate the effect of exercise on appetite and mood following multiple days of sleep disruption (restriction [RES], fragmentation [FRAG]) or sleep extension (EXT), compared to normal sleep (CONT) in inactive, middle-aged men. Nine men completed four randomised trials initiated by 3 nights (day 1-3) of CONT (6.5-8 hr), RES (4 hr), FRAG (6.5-8 hr, interrupted at 2-hr intervals) or EXT (10 hr). On day 4 between 08:30 and 11:00 hours, perceived appetite, food cravings, appetite-related hormones (acylated ghrelin, leptin, peptide tyrosine-tyrosine [PYY]total ), glucose, mood states and wellness (stress, fatigue, soreness, and mood) were assessed before (post-sleep manipulation [SM]) and after (post-exercise [EX]) a 20-min vigorous cycling bout (rating of perceived exertion: 15). There was no effect of sleep manipulation or exercise on perceived appetite (p = .34-.62). Some aspects of food craving were altered after RES and EXT, with vigorous exercise attenuating the desire for sweet foods in RES (p = .12). PYYtotal was lower after RES compared to EXT and FRAG (p = .03), but was unaltered by exercise (p = .03). Ghrelin was higher for RES and EXT compared to CONT and FRAG after exercise (p = .001-.03). Total wellness was reduced and total mood disturbance (TMD) was higher after RES and FRAG compared to CONT and EXT (p ≤ .05). However, vigorous exercise countered these changes, with wellness and TMD remaining significantly impaired for FRAG compared to EXT only at this time (p = .02-.03). Vigorous exercise mitigates some aspects of food cravings and counters the impaired mood states that exist after multiple days of restricted and fragmented sleep.

Exercise-related factors that influence post-exercise energy intake: A psychological perspective.

OBJECTIVES: Exercise confers numerous health benefits; however, unhealthy, or excessive food and drink consumption post-exercise may counteract at least some of these benefits. There is emerging evidence that certain exercise-related factors, including the psychological experiences associated with different forms of exercise motivation, may influence post-exercise energy intake. Questions remain, though, about the optimal exercise characteristics that may reduce overconsumption of food/drink post-exercise. DESIGN: Narrative review. METHODS: In this narrative review, we overview the developing body of literature linking the psychological experiences in exercise with subsequent energy intake, focusing first on the relationship between exercise motivation and food consumption, and then on practical strategies which may be utilised to promote healthier post-exercise food choices. RESULTS: Preliminary evidence suggests that psychological experiences associated with high-quality autonomous motivation for exercise may reduce subsequent energy intake. Exercise factors (both psychological and physiological in nature) that have been shown to influence post-exercise energy consumption may interact, resulting in synergistic or antagonistic effects on subsequent food and drink consumption, through mechanisms which have not been considered previously. CONCLUSIONS: Exercise experiences may be shaped to promote healthier subsequent eating behaviours and future work is encouraged to enable researchers to identify combinations of exercise conditions and experiences that have the strongest influence on post-exercise food and drink consumption.

Interactions of sprint interval exercise and psychological need-support on subsequent food intake among physically inactive men and women.

The aim of this study was to investigate the effect of sprint interval training (SIT) and psychological need-support in exercise on postexercise appetite and energy intake. Forty physically inactive men and women (body mass index, 24.6 ± 4.8 kg·m-2; peak oxygen consumption, 26.6 ± 4.9 mL·kg-1·min-1) were randomised to either a need-support or no-support condition, with each participant completing 2 experimental trials involving 30 min of moderate-intensity continuous training (MICT; 60% peak oxygen consumption) and SIT (alternating 15 s at 170% peak oxygen consumption and 60 s at 32% peak oxygen consumption) matched for total work. Perceptions of appetite and appetite-related blood variables were assessed, together with ad libitum energy intake for 3 h following exercise using a laboratory test meal and available snacks. Greater enjoyment, perceived exertion, heart rate, and blood lactate were observed in SIT compared with MICT (all p ≤ 0.006). Ratings of perceived appetite were similar across conditions and trials (p > 0.05); however, active ghrelin was lower following SIT compared with MICT (p < 0.001), and there was a significant condition-by-type interaction for energy intake (p = 0.033), with participants in the support group consuming less energy from foods following SIT (1895 ± 1040 kJ) than MICT (2475 ± 1192 kJ). Findings from this work highlight the need to reconsider traditional exercise guidelines where dietary intake is a concern. Novelty Enjoyment was greater during SIT compared with MICT. Enjoyment and choice were higher among participants provided with psychological need-support. In a need-supportive environment, SIT reduced subsequent energy intake compared with MICT.

The Effect of Exercise Timing on Glycemic Control: A Randomized Clinical Trial.

Despite the acknowledgment of exercise as a cornerstone in the management of type 2 diabetes (T2D), the importance of exercise timing has only recently been considered. PURPOSE: This study sought to determine the effect of diurnal exercise timing on glycemic control in individuals enrolled in a 12-wk supervised multimodal exercise training program. A secondary aim was to determine the effect of diurnal exercise timing on the circadian rhythm of wrist skin temperature. METHODS: Forty sedentary, overweight adults (mean ± SD, age = 51 ± 13 yr; body mass index = 30.9 ± 4.2 kg·m; women, n = 23) with and without (n = 20) T2D diagnosis were randomly allocated to either a morning (amEX) or an evening (pmEX) exercise training group. The supervised 12-wk (3 d·wk) program, comprised 30 min of moderate-intensity walking and 4 resistance-based exercises (3 sets, 12-18 repetitions each). Glycemic outcomes (glycated hemoglobin, fasting glucose, postprandial glucose) and wrist skin temperature were assessed at baseline and postintervention. RESULTS: Exercise training improved (main effect of time, all P < 0.01) all glycemic outcomes; however, this was independent of allocation to either the amEX (Hedge's g, 0.23-0.90) or the pmEX (Hedge's g, 0.16-0.90) group. Accordingly, the adopted exercise training program did not alter the circadian rhythm of skin temperature. When only T2D individuals were compared, amEX demonstrated greater effects (all Hedge's g) on glycated hemoglobin (amEX, 0.57; pmEX, 0.32), fasting glucose (amEX, 0.91; pmEX, 0.53), and postprandial glucose (amEX, 1.12; pmEX, 0.71) but was not statistically different. CONCLUSIONS: Twelve weeks of multimodal exercise training improved glycemic control and postprandial glycemic responses in overweight non-T2D and T2D individuals. However, no distinct glycemic benefits or alterations in circadian rhythm were associated with morning versus evening exercise, when performed three times per week in this cohort.

An 8-Week Relaxation Program Consisting of Progressive Muscle Relaxation and Mindfulness Meditation to Reduce Stress and Attenuate Stress-Driven Eating.

BACKGROUND: Stress is often associated with the intake of energy-dense palatable foods. This trial examined the feasibility and preliminary efficacy of an 8-week worksite-based relaxation intervention to address psychological stress and unhealthy food intake. METHODS: Thirty-six men and women were exposed to an acute stressor, while physiological and psychological responses were assessed, prior to being offered a test meal. Participants were then randomised to a relaxation intervention (RELAX; face-to-face classes and daily home practice of progressive muscle relaxation and mindfulness meditation), or a wait-list control (CON). All measures were repeated after the intervention. RESULTS: Intervention compliance was high (80% ± 19% face-to-face; 79% ± 18% home practice), and each session acutely reduced perceived stress (p < .001) and increased relaxation (p < .001). After 8 weeks, trait mindfulness was increased (p = .025), along with reduced tension (p = .013) and increased relaxation (p < .05) post-acute stressor in the intervention group. There was no effect of the intervention on palatable eating, cravings, or energy intake at a laboratory test meal, with small associated effect sizes (d = 0.01-0.3). CONCLUSIONS: The program studied here is feasible and sessions transiently reduce perceived stress and improve mindfulness; however, the program may not influence the physiological response to an acute stressor or appetite and eating variables.

The effect of a single, brief practice of progressive muscle relaxation after exposure to an acute stressor on subsequent energy intake.

BACKGROUND: Given previous research suggests an association between stress and the intake of energy-dense foods, this study investigated whether poststressor relaxation practice can attenuate stress-induced eating. METHODS: Twenty-five men and women were exposed to four conditions on separate days: an acute laboratory stressor (S), acute stressor followed by 20 min of relaxation (SR) in the form of Abbreviated Progressive Muscle Relaxation (APMR), relaxation alone (R), and a control condition (C). Physiological and psychological responses to stress and relaxation were assessed, in addition to the subsequent energy intake of high-energy snacks. RESULTS: Salivary cortisol, blood pressure, heart rate, and perceived stress were transiently elevated postlaboratory stressor (S and SR compared with R and C; p < .05). Meanwhile, perceived relaxation was acutely enhanced after APMR alone (R) compared with S, SR, and C (p < .05) and in SR (immediately after the APMR) compared with S (p < .05). No difference in mean energy intake was observed between conditions (p > .05). Likewise, no differences in perceived appetite or the levels of ghrelin, leptin, and insulin were found between conditions (p > .05). CONCLUSIONS: Much variation exists in stress-induced dietary responses, and APMR either postacute stressor or in isolation does not appear to consistently alter the intake of commonly eaten snacks.

Impact of maternal education on response to lifestyle interventions to reduce gestational weight gain: individual participant data meta-analysis.

OBJECTIVES: To identify if maternal educational attainment is a prognostic factor for gestational weight gain (GWG), and to determine the differential effects of lifestyle interventions (diet based, physical activity based or mixed approach) on GWG, stratified by educational attainment. DESIGN: Individual participant data meta-analysis using the previously established International Weight Management in Pregnancy (i-WIP) Collaborative Group database (https://iwipgroup.wixsite.com/collaboration). Preferred Reporting Items for Systematic reviews and Meta-Analysis of Individual Participant Data Statement guidelines were followed. DATA SOURCES: Major electronic databases, from inception to February 2017. ELIGIBILITY CRITERIA: Randomised controlled trials on diet and physical activity-based interventions in pregnancy. Maternal educational attainment was required for inclusion and was categorised as higher education (≥tertiary) or lower education (≤secondary). RISK OF BIAS: Cochrane risk of bias tool was used. DATA SYNTHESIS: Principle measures of effect were OR and regression coefficient. RESULTS: Of the 36 randomised controlled trials in the i-WIP database, 21 trials and 5183 pregnant women were included. Women with lower educational attainment had an increased risk of excessive (OR 1.182; 95% CI 1.008 to 1.385, p =0.039) and inadequate weight gain (OR 1.284; 95% CI 1.045 to 1.577, p =0.017). Among women with lower education, diet basedinterventions reduced risk of excessive weight gain (OR 0.515; 95% CI 0.339 to 0.785, p = 0.002) and inadequate weight gain (OR 0.504; 95% CI 0.288 to 0.884, p=0.017), and reduced kg/week gain (B -0.055; 95% CI -0.098 to -0.012, p=0.012). Mixed interventions reduced risk of excessive weight gain for women with lower education (OR 0.735; 95% CI 0.561 to 0.963, p=0.026). Among women with high education, diet based interventions reduced risk of excessive weight gain (OR 0.609; 95% CI 0.437 to 0.849, p=0.003), and mixed interventions reduced kg/week gain (B -0.053; 95% CI -0.069 to -0.037,p<0.001). Physical activity based interventions did not impact GWG when stratified by education. CONCLUSIONS: Pregnant women with lower education are at an increased risk of excessive and inadequate GWG. Diet based interventions seem the most appropriate choice for these women, and additional support through mixed interventions may also be beneficial.

Evening high-intensity interval exercise does not disrupt sleep or alter energy intake despite changes in acylated ghrelin in middle-aged men.

NEW FINDINGS: What is the central question of this study? What are the interactions between sleep and appetite following early evening high-intensity interval exercise (HIIE)? What is the main finding and its importance? HIIE can be performed in the early evening without subsequent sleep disruptions and may favourably alter appetite-related hormone concentrations. Nonetheless, perceived appetite and energy intake do not change with acute HIIE regardless of time of day. ABSTRACT: Despite exercise benefits for sleep and appetite, due to increased time restraints, many adults remain inactive. Methods to improve exercise compliance include preferential time-of-day or engaging in short-duration, high-intensity interval exercise (HIIE). Hence, this study aimed to compare effects of HIIE time-of-day on sleep and appetite. Eleven inactive men undertook sleep monitoring to determine baseline (BASE) sleep stages and exclude sleep disorders. On separate days, participants completed 30 min HIIE (60 s work at 100% V̇O2peak , 240 s rest at 50% V̇O2peak ) in (1) the morning (MORN; 06.00-07.00 h), (2) the afternoon (AFT; 14.00-16.00 h) and (3) the early evening (EVEN: 19.00-20.00 h). Measures included appetite-related hormones (acylated ghrelin, leptin, peptide tyrosine tyrosine) and glucose pre-exercise, 30 min post-exercise and the next morning; overnight polysomnography (PSG; sleep stages); and actigraphy, self-reported sleep and food diaries for 48 h post-exercise. There were no between-trial differences for total sleep time (P = 0.46). Greater stage N3 sleep was recorded for MORN (23 ± 7%) compared to BASE (18 ± 7%; P = 0.02); however, no between-trial differences existed (P > 0.05). Rapid eye movement (REM) sleep was lower and non-REM sleep was higher for EVEN compared to BASE (P ≤ 0.05). At 30 min post-exercise, ghrelin was higher for AFT compared to MORN and EVEN (P = 0.01), while glucose was higher for MORN compared to AFT and EVEN (P ≤ 0.02). No between-trial differences were observed for perceived appetite (P ≥ 0.21) or energy intake (P = 0.57). Early evening HIIE can be performed without subsequent sleep disruptions and reduces acylated ghrelin. However, perceived appetite and energy intake appear to be unaffected by HIIE time of day.

High-intensity interval exercise induces greater acute changes in sleep, appetite-related hormones, and free-living energy intake than does moderate-intensity continuous exercise.

The aim of this study was to compare the effect of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on sleep characteristics, appetite-related hormones, and eating behaviour. Eleven overweight, inactive men completed 2 consecutive nights of sleep assessments to determine baseline (BASE) sleep stages and arousals recorded by polysomnography (PSG). On separate afternoons (1400-1600 h), participants completed a 30-min exercise bout: either (i) MICE (60% peak oxygen consumption) or (ii) HIIE (60 s of work at 100% peak oxygen consumption: 240 s of rest at 50% peak oxygen consumption), in a randomised order. Measures included appetite-related hormones (acylated ghrelin, leptin, and peptide tyrosine tyrosine) and glucose before exercise, 30 min after exercise, and the next morning after exercise; PSG sleep stages; and actigraphy (sleep quantity and quality); in addition, self-reported sleep and food diaries were recorded until 48 h after exercise. There were no between-trial differences for time in bed (p = 0.19) or total sleep time (p = 0.99). After HIIE, stage N3 sleep was greater (21% ± 7%) compared with BASE (18% ± 7%; p = 0.02). In addition, the number of arousals during rapid eye movement sleep were lower after HIIE (7 ± 5) compared with BASE (11 ± 7; p = 0.05). Wake after sleep onset was lower following MICE (41 min) compared with BASE (56 min; p = 0.02). Acylated ghrelin was lower and glucose was higher at 30 min after HIIE when compared with MICE (p ≤ 0.05). There were no significant differences between conditions in terms of total energy intake (p ≥ 0.05). HIIE appears to be more beneficial than MICE for improving sleep quality and inducing favourable transient changes in appetite-related hormones in overweight, inactive men. However, energy intake was not altered regardless of exercise intensity.

Stress, Depressive Symptoms, and Maternal Self-Efficacy in First-Time Mothers: Modelling and Predicting Change across the First Six Months of Motherhood.

BACKGROUND: First-time mothers commonly experience stress and depressive symptoms in the postpartum period. Maternal self-efficacy has been shown to be an important protective factor against these experiences; however, research on the dynamic nature of stress, depressive symptoms, and maternal self-efficacy is limited. The aim of this study was to document changes in these psychological factors among first-time mothers, and determine how early maternal self-efficacy perceptions may predict change in stress and depressive symptoms over the first 6 months postpartum. METHODS: Sixty first-time Australian mothers were recruited during their third trimester of pregnancy. Participants completed a baseline survey during the third trimester of pregnancy (M = 32.87 weeks, SD = 2.62 weeks), and subsequently reported stress, depressive symptoms, and maternal self-efficacy every 3 weeks postpartum for 6 months. Latent growth curve modelling was used to estimate participants' change over time for stress and depressive symptoms. RESULTS: First-time mothers' stress and depressive symptoms peaked, and maternal self-efficacy was weakest, at 3 weeks postpartum. Maternal self-efficacy at 3 weeks postpartum was a significant (negative) predictor of 3-week levels of, and also (positively) predicted later reductions in, stress. CONCLUSION: Future interventions aimed at bolstering early maternal self-efficacy may protect against postpartum stress for first-time mothers.

Preliminary Validation of the Exercise-Snacking Licensing Scale: Rewarding Exercise with Unhealthy Snack Foods and Drinks.

There is evidence that individuals' compensatory health beliefs may be an important psychological driver of health behavior. Only recently, however, have researchers begun to develop and seek to validate instruments that are suited to measuring specific pairings of the diverse compensatory health beliefs that exist. The aim of this study was to provide support for key aspects of validity associated with the Exercise-Snacking Licensing Scale (ESLS), an instrument that was designed to assess individuals' endorsement (or licensing) of unhealthy snacking behaviors around exercise. Participants (N = 1095) responded to a version of the ESLS that was designed to assess their licensing responses following either "light" or "tiring" physical activity, and completed additional instruments assessing dispositional, exercise-related, and diet-related constructs. Analyses indicated that scores derived from both versions of the ESLS ("light" and "tiring" physical activity) displayed a relatively consistent factor structure, favorable alpha coefficients, and meaningful correlations with variables that are theoretically aligned with licensing. Factor analytic procedures did, however, indicate that researchers may wish, in future, to consider the use (or not) of reverse-scored items within the ESLS. Together, these findings provide important insight into the structural, external, and generalizability aspects of validity for scores derived from the ESLS, and indicate that the ESLS may be a valuable instrument for the brief assessment of unhealthy licensing beliefs around exercise. Further use of the ESLS is encouraged to determine if and how these licensing beliefs actually influence subsequent snacking behaviors, and the potential downstream effects these beliefs may have in shaping health outcomes associated with exercise participation.

Exercise Timing in Type 2 Diabetes Mellitus: A Systematic Review.

PURPOSE: The timing of exercise relative to meal consumption has recently been identified as potentially moderating the effectiveness of exercise on glycemic responses in type 2 diabetes mellitus (T2DM). The aim of this study was to systematically review the literature related to exercise timing, relative to meal consumption, and glycemic control in individuals with T2DM. METHODS: Systematic searches in PubMed, EMBASE, CINAHL, Cochrane Library, and ClinicalTrials.gov Registry databases were performed to identify articles published in English from inception to October 2017. Two authors independently extracted data and evaluated the quality of studies using the Cochrane Collaboration Data Collection Form and the Cochrane Collaboration Risk of Bias Assessment Tool, respectively. A qualitative synthesis was performed on the included studies, and results summarized in tables. RESULTS: Nineteen randomized controlled trials with a total of 346 participants were included. Improvements in glycemia (glucose concentrations and glucose area under the curve) and insulin area under the curve appeared more consistent when exercise was performed during the postmeal period as compared with the premeal period; however, this observation was largely based on indirect comparisons between studies. CONCLUSIONS: There is some evidence from randomized controlled trials that exercise performed 30 min after meal consumption may convey greater improvements in glycemic control for individuals with T2DM. However, there are only two studies that have directly assessed the role of exercise timing on glycemic management, and adopted methodologies are heterogeneous. Future low-risk trials in this field are warranted.