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The effect of morning vs evening exercise training on glycaemic control and serum metabolites in overweight/obese men: a randomised trial.
Moholdt, T, Parr, EB, Devlin, BL, Debik, J, Giskeødegård, G, Hawley, JA
Diabetologia. 2021;64(9):2061-2076
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Timing of exercise, whether morning or evening, may have differing effects on blood sugar control. However, it is unclear as to the exact effects with some previous research reporting that morning exercise is more beneficial to blood sugar levels and others reporting that evening exercise is. This 12-week randomised control trial of 25 overweight/obese men aimed to determine the effect of a 6-day high fat diet followed by 5 days of either morning or evening exercise on several health measures, including blood sugar. The results showed that improvements to heart and lung fitness were similar regardless of the timing of exercise, however improvements to blood sugar and reversal of several indicators of poor heart health were only observed when participants engaged in evening exercise. It was concluded that late afternoon/evening exercise may be of greater benefit to health. This study could be used by healthcare professionals to recommend evening as an optimal time to exercise for people who are overweight/obese and who are wanting to confer the greatest benefits to their health.
Abstract
AIMS/HYPOTHESIS We determined whether the time of day of exercise training (morning vs evening) would modulate the effects of consumption of a high-fat diet (HFD) on glycaemic control, whole-body health markers and serum metabolomics. METHODS In this three-armed parallel-group randomised trial undertaken at a university in Melbourne, Australia, overweight/obese men consumed an HFD (65% of energy from fat) for 11 consecutive days. Participants were recruited via social media and community advertisements. Eligibility criteria for participation were male sex, age 30-45 years, BMI 27.0-35.0 kg/m2 and sedentary lifestyle. The main exclusion criteria were known CVD or type 2 diabetes, taking prescription medications, and shift-work. After 5 days, participants were allocated using a computer random generator to either exercise in the morning (06:30 hours), exercise in the evening (18:30 hours) or no exercise for the subsequent 5 days. Participants and researchers were not blinded to group assignment. Changes in serum metabolites, circulating lipids, cardiorespiratory fitness, BP, and glycaemic control (from continuous glucose monitoring) were compared between groups. RESULTS Twenty-five participants were randomised (morning exercise n = 9; evening exercise n = 8; no exercise n = 8) and 24 participants completed the study and were included in analyses (n = 8 per group). Five days of HFD induced marked perturbations in serum metabolites related to lipid and amino acid metabolism. Exercise training had a smaller impact than the HFD on changes in circulating metabolites, and only exercise undertaken in the evening was able to partly reverse some of the HFD-induced changes in metabolomic profiles. Twenty-four-hour glucose concentrations were lower after 5 days of HFD compared with the participants' habitual diet (5.3 ± 0.4 vs 5.6 ± 0.4 mmol/l, p = 0.001). There were no significant changes in 24 h glucose concentrations for either exercise group but lower nocturnal glucose levels were observed in participants who trained in the evening, compared with when they consumed the HFD alone (4.9 ± 0.4 vs 5.3 ± 0.3 mmol/l, p = 0.04). Compared with the no-exercise group, peak oxygen uptake improved after both morning (estimated effect 1.3 ml min-1 kg-1 [95% CI 0.5, 2.0], p = 0.003) and evening exercise (estimated effect 1.4 ml min-1 kg-1 [95% CI 0.6, 2.2], p = 0.001). Fasting blood glucose, insulin, cholesterol, triacylglycerol and LDL-cholesterol concentrations decreased only in participants allocated to evening exercise training. There were no unintended or adverse effects. CONCLUSIONS/INTERPRETATION A short-term HFD in overweight/obese men induced substantial alterations in lipid- and amino acid-related serum metabolites. Improvements in cardiorespiratory fitness were similar regardless of the time of day of exercise training. However, improvements in glycaemic control and partial reversal of HFD-induced changes in metabolic profiles were only observed when participants exercise trained in the evening. TRIAL REGISTRATION anzctr.org.au registration no. ACTRN12617000304336. FUNDING This study was funded by the Novo Nordisk Foundation (NNF14OC0011493).
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The Effect of Kefir Supplementation on Improving Human Endurance Exercise Performance and Antifatigue.
Lee, MC, Jhang, WL, Lee, CC, Kan, NW, Hsu, YJ, Ho, CS, Chang, CH, Cheng, YC, Lin, JS, Huang, CC
Metabolites. 2021;11(3)
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Compared to sedentary people, athletes exhibit a much more abundant and diverse composition of gut bacteria. Hence the relationship between gut microbes and energy usage and exercise performance has attracted much attention in recent years. Probiotics and prebiotic-related products have demonstrated the potential to enhance metabolic pathways and influence energy levels, energy consumption and exercise performance. And previous studies demonstrated positive effects on exercise endurance associated with the consumption of kefir, a fermented dairy product containing Lactobacilli species as part of the microbial symbiosis. This study investigated whether kefir can promote changes in the gut microbiota, improve exercise endurance performance, and influences fatigue during and after exercise. The study enrolled sixteen, untrained 20–30-year-old for a double-blind crossover design study, supplementing with SYNKEFIR™ for 28 days whilst observing changes in metabolic markers, body composition, exercise endurance and faecal gut bacteria. In summary, supplementation with SYNKEFIR™ significantly improved exercise performance and reduced the production of lactic acid after exercise. In addition, kefir supplementation seemed to reduce fatigue and accelerated the recovery from fatigue after exercise, with a marked reduction in lactic acid production after exercise. Though kefir supplementation had no significant effect on other post-exercise fatigue biochemical indicators nor did it induce notable changes in gut bacteria composition. As SYNKEFIR™ is a starter culture isolated from traditional kefir it could be expected that other traditional kefir products would have similar effects. Kefir as a food product is suited to a wide range of people, and it could be considered part of a healthy diet plan for untrained individuals wishing to support their exercise performance.
Abstract
Kefir is an acidic, carbonated, and fermented dairy product produced by fermenting milk with kefir grains. The Lactobacillus species constitutes an important part of kefir grains. In a previous animal study, kefir effectively improved exercise performance and had anti-fatigue effects. The purpose of this research was to explore the benefits of applying kefir to improve exercise performance, reduce fatigue, and improve physiological adaptability in humans. The test used a double-blind crossover design and supplementation for 28 days. Sixteen 20-30 year-old subjects were divided into two groups in a balanced order according to each individual's initial maximal oxygen uptake and were assigned to receive a placebo (equal flavor, equal calories, 20 g/day) or SYNKEFIR™ (20 g/day) every morning. After the intervention, there were 28 days of wash-out, during which time the subjects did not receive further interventions. After supplementation with SYNKEFIR™, the exercise time to exhaustion was significantly greater than that before ingestion (p = 0.0001) and higher than that in the Placebo group by 1.29-fold (p = 0.0004). In addition, compared with the Placebo group, the SYNKEFIR™ administration group had significantly lower lactate levels in the exercise and recovery (p < 0.05). However, no significant difference was observed in the changes in the gut microbiota. Although no significant changes in body composition were found, SYNKEFIR™ did not cause adverse reactions or harm to the participants' bodies. In summary, 28 days of supplementation with SYNKEFIR™ significantly improved exercise performance, reduced the production of lactic acid after exercise, and accelerated recovery while also not causing any adverse reactions.
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High-Intensity Interval Circuit Training Versus Moderate-Intensity Continuous Training on Cardiorespiratory Fitness in Middle-Aged and Older Women: A Randomized Controlled Trial.
Ballesta-García, I, Martínez-González-Moro, I, Ramos-Campo, DJ, Carrasco-Poyatos, M
International journal of environmental research and public health. 2020;17(5)
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Ageing populations have increased in recent years increasing the prevalence of chronic diseases. Chronic diseases can impact the elderly in many ways and see them unable to perform day to day activities. Maintaining fitness may prevent chronic diseases such as heart disease from developing and ensure that these individuals maintain their independence. This randomised control trial of fifty-four middle-aged and older women aimed to compare the effects of high-intensity interval circuit training (HIICT) versus moderate-intensity continuous training (MICT) on measures of fitness over 18 weeks. The results showed that measures of aerobic fitness were improved with both HIICT and MICT, however HIICT showed slightly greater improvements than MICT. Blood pressure was improved in both exercise groups compared to control. It was concluded that both types of exercise can increase aerobic fitness, although HIICT may have a slightly greater benefit. This study could be used by practitioners to recommend the use of either HIICT or MICT to increase fitness, prevent chronic diseases and ensure that independence is maintained in middle-aged and older female patients.
Abstract
High-intensity interval training (HIIT) has similar or better effects than moderate-intensity continuous training (MICT) in increasing peak oxygen consumption (VO2max), however, it has not been studied when HIIT is applied in a circuit (HIICT). The aim of this study was to compare the effects of a HIICT versus MICT on VO2max estimated (VO2max-ES), heart rate (HR) and blood pressure (BP) of middle-aged and older women. A quasi-experimental randomized controlled trial was used. Fifty-four women (67.8 ± 6.2 years) were randomized to either HIICT (n = 18), MICT (n = 18) or non-exercise control group (CG; n = 18) for 18 weeks. Participants in HIICT and MICT trained two days/week (one hour/session). Forty-one participants were assessed (HIICT; n = 17, MICT; n = 12, CG; n = 12). Five adverse events were reported. Cardiorespiratory fitness, HR and BP were measured. The tests were performed before and after the exercise intervention programs. VO2max-ES showed significant training x group interaction, in which HIICT and MICT were statistically superior to CG. Moreover, HIICT and MICT were statistically better than CG in the diastolic blood pressure after exercise (DBPex) interaction. For the systolic blood pressure after exercise (SBPex), HIICT was statistically better than CG. In conclusion, both HIICT and MICT generated adaptations in VO2max-ES and DBPex. Furthermore, only HIICT generated positive effects on the SBPex. Therefore, both training methods can be considered for use in exercise programs involving middle-aged and older women.
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The Weight Optimization Revamping Lifestyle using the Dietary Guidelines (WORLD) Study: Sustained Weight Loss Over 12 Months.
Psota, TL, Tindall, AM, Lohse, B, Miller, PE, Petersen, KS, Kris-Etherton, PM
Obesity (Silver Spring, Md.). 2020;28(7):1235-1244
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Effective long-term weight loss strategies to reduce the risk of death and diseases associated with being obese or overweight are required, as restrictive programmes are difficult to sustain, and weight loss may be heavily influenced by behavioural factors. This randomised control trial of 101 premenopausal women with obesity or overweight aimed to compare a lower-fat and moderate-fat diets, both with nutrition education for 12 months. The results showed that both treatment groups lost weight. Both groups consumed the same amount of fat but increased their diet quality. Diet quality and greater attendance at nutritional education sessions were associated with greater weight loss. Cholesterol was significantly lower in both groups, but blood pressure remained unchanged. Interestingly there were a large number of women who did not complete the trial. It was concluded that irrespective of the amount of fat consumed, nutrition education can help to achieve sustained weight loss, improve diet quality and decrease heart disease risk for at least 12 months. This study could be used by healthcare professionals to understand that recommending fat-based targets for weight loss may be ineffective and the importance of emotional and behavioural support for individuals on a weight loss regime to improve their risk for heart disease.
Abstract
OBJECTIVE This study aimed to compare two energy-restricted, nutrient-dense diets at the upper or lower ends of the dietary fat recommendation range (lower fat [20% energy from fat] versus moderate fat [35%]) on weight loss using behavioral theory-based nutrition education. METHODS A total of 101 premenopausal women with overweight or obesity were randomized to an energy-restricted lower-fat or moderate-fat diet for 1 year. Interventions included 28 behavioral theory-based nutrition education sessions plus weekly exercise sessions. RESULTS Both treatment groups experienced weight loss (-5.0 kg for lower fat and -4.3 kg for moderate fat; P < 0.0001), but there was no difference in weight loss or fat intake between groups. Total and low-density lipoprotein cholesterol decreased (-3. 4 mg/dL and -3.8 mg/dL; P < 0.05), and high-density lipoprotein cholesterol increased (1.9 mg/dL; P < 0.05) in both groups at 12 months. Diet quality, assessed by the Healthy Eating Index, increased significantly at 4 months versus baseline (70.8 [0.9] vs. 77.8 [1.0]) and was maintained through 12 months. Higher Healthy Eating Index scores were associated with greater weight loss at 4 months (r = -0.2; P < 0.05). CONCLUSIONS In the context of a well-resourced, free-living weight-loss intervention, total fat intake did not change; however, theory-based nutrition education underpinned by food-based recommendations resulted in caloric deficits, improvements in diet quality, and weight loss that was sustained for 1 year.
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Lipid Metabolism Links Nutrient-Exercise Timing to Insulin Sensitivity in Men Classified as Overweight or Obese.
Edinburgh, RM, Bradley, HE, Abdullah, NF, Robinson, SL, Chrzanowski-Smith, OJ, Walhin, JP, Joanisse, S, Manolopoulos, KN, Philp, A, Hengist, A, et al
The Journal of clinical endocrinology and metabolism. 2020;105(3)
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Following exercise, various metabolic changes occur which may be of benefit in fighting diseases such as type 2 diabetes and obesity. However, the degree of change may vary depending on whether the exercise has been performed pre or post meal consumption. This 6-week randomised crossover trial of 30 overweight or obese men aimed to determine the effect of exercising before or after breakfast on the use of fats and sugars by the body. The results showed that exercise before breakfast increased fat and sugar use in the body and also resulted in the alteration of eight genes associated with metabolism. Exercise before carbohydrate consumption also increased lipid use and improved insulin sensitivity, however body composition was similar regardless of when exercise was performed. It was concluded that exercising in the fasted state can optimise the body’s response without having to change intensity or effort. This study could be used by health care professionals to advise patients with obesity or overweight that exercising whilst in the fasted state could optimise their outcomes without having to increase exercise intensity or frequency.
Abstract
CONTEXT Pre-exercise nutrient availability alters acute metabolic responses to exercise, which could modulate training responsiveness. OBJECTIVE To assess acute and chronic effects of exercise performed before versus after nutrient ingestion on whole-body and intramuscular lipid utilization and postprandial glucose metabolism. DESIGN (1) Acute, randomized, crossover design (Acute Study); (2) 6-week, randomized, controlled design (Training Study). SETTING General community. PARTICIPANTS Men with overweight/obesity (mean ± standard deviation, body mass index: 30.2 ± 3.5 kg⋅m-2 for Acute Study, 30.9 ± 4.5 kg⋅m-2 for Training Study). INTERVENTIONS Moderate-intensity cycling performed before versus after mixed-macronutrient breakfast (Acute Study) or carbohydrate (Training Study) ingestion. RESULTS Acute Study-exercise before versus after breakfast consumption increased net intramuscular lipid utilization in type I (net change: -3.44 ± 2.63% versus 1.44 ± 4.18% area lipid staining, P < 0.01) and type II fibers (-1.89 ± 2.48% versus 1.83 ± 1.92% area lipid staining, P < 0.05). Training Study-postprandial glycemia was not differentially affected by 6 weeks of exercise training performed before versus after carbohydrate intake (P > 0.05). However, postprandial insulinemia was reduced with exercise training performed before but not after carbohydrate ingestion (P = 0.03). This resulted in increased oral glucose insulin sensitivity (25 ± 38 vs -21 ± 32 mL⋅min-1⋅m-2; P = 0.01), associated with increased lipid utilization during exercise (r = 0.50, P = 0.02). Regular exercise before nutrient provision also augmented remodeling of skeletal muscle phospholipids and protein content of the glucose transport protein GLUT4 (P < 0.05). CONCLUSIONS Experiments investigating exercise training and metabolic health should consider nutrient-exercise timing, and exercise performed before versus after nutrient intake (ie, in the fasted state) may exert beneficial effects on lipid utilization and reduce postprandial insulinemia.
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Effect of an interdisciplinary intervention with motivational approach on exercise capacity in obese adolescents: a randomized controlled clinical trial.
Zanatta, LB, Heinzmann-Filho, JP, Vendrusculo, FM, Campos, NE, Oliveira, MDS, Feoli, AMP, Gustavo, ADS, Donadio, MVF
Einstein (Sao Paulo, Brazil). 2020;18:eAO5268
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Obesity is becoming a growing concern in adolescents with the growing use of technology and subsequent reduction in physical activity. Exercise and lifestyle modifications may help combat obesity in adolescents, however lack of motivation may be hindering treatments. This randomised control trial of 37 overweight and obese adolescents aimed to assess the effect of methods aimed at motivating individuals to exercise on daily physical activity over 3 months. The results showed that exercise recommendations focusing on motivation did not affect the amount of daily exercise or the amount of exertion an individual could sustain. It was concluded that motivational based recommendations did not modify exercise behaviour in overweight and obese adolescents. This could be due to the short study time and the relatively infrequent meetings when motivational exercise recommendations were delivered. This study could be used by health professionals to understand the increasing incidence of obesity in adolescents and the need for lifestyle interventions such as diet and exercise.
Abstract
Objective To evaluate the effect of an interdisciplinary intervention with a motivational approach on exercise capacity and usual physical activity levels in overweight and obese adolescents. Methods This is a randomized, controlled clinical trial with single blinding of subjects. Adolescents aged 15 to 18 years with overweight and obesity (body mass index ≥ 85 percentile) were included. The adolescents were randomized into two groups: interdisciplinary intervention or control - traditional approach aiming at lifestyle modifications. The initial evaluations were carried out, including the cardiopulmonary exercise test and the physical activity level measurement by using the International Physical Activity Questionnaire and a pedometer. The evaluations were performed in two moments: time zero (time of inclusion in the study) and after 3 months (end of intervention). There were 12 sessions with weekly meetings. Results A total of 37 participants were included, 19 in the Intervention Group. There were no significant differences in the baseline demographic, anthropometric and physical activity characteristics between groups, with mean age of 17.3±1.0 years in the Control Group, and 16.8±0.9 years in the Intervention Group (p=0.14). The motivational intervention did not cause significant differences (p>0.05) in the comparison of the variables of exercise capacity and usual physical activity (questionnaire and pedometer) between groups. Conclusion The intervention with a motivational approach did not alter exercise capacity and levels of usual physical activity in overweight and obese adolescents. Clinical Trial Registry: NCT02455973 and REBEC RBR-234nb5.
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The effects of bovine colostrum supplementation on in vivo immunity following prolonged exercise: a randomised controlled trial.
Jones, AW, March, DS, Thatcher, R, Diment, B, Walsh, NP, Davison, G
European journal of nutrition. 2019;58(1):335-344
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Upper respiratory tract symptoms (URS) are the most common ailment reported by athletes to medicine clinics at major sporting events. The main aim of this study was to investigate the effects of bovine colostrum (COL) supplementation on the induction of invivo immune responses to a novel antigen, diphenylcyclopropenone (DPCP) [a topically administered experimental drug], following prolonged exercise. The study is a double-blind randomised placebo-controlled trial which recruited 34 healthy male participants aged between 18 and 45 years. The participants were randomly assigned to one of the two groups: COL group (n = 17) or placebo group (n = 17). Results indicate that COL did not significantly affect the overall response to the novel antigen, DPCP, but COL supplementation induced greater sensitivity of antigen-specific memory recalled 4 weeks following the initial sensitisation. Authors conclude that their findings may suggest a nutritional strategy to counter exercise-induced immunodepression assessed via an established, clinically relevant in vivo marker of immunity.
Abstract
BACKGROUND Bovine colostrum (COL) has been advocated as a nutritional countermeasure to exercise-induced immune dysfunction, but there is a lack of research with clinically relevant in vivo measures. AIM: To investigate the effects of COL supplementation on in vivo immunity following prolonged exercise using experimental contact hypersensitivity (CHS) with the novel antigen diphenylcyclopropenone (DPCP). METHODS In a double-blind design, 31 men were randomly assigned to COL (20 g/day) or placebo (PLA) for 58 days. Participants ran for 2 h at 60% maximal aerobic capacity on day 28 and received a primary DPCP exposure (sensitisation) 20 min after. On day 56, participants received a low-dose-series DPCP challenge to elicit recall of in vivo immune-specific memory (quantified by skinfold thickness 24 and 48 h later). Analysis of the dose-response curves allowed determination of the minimum dose required to elicit a positive response (i.e., sensitivity). RESULTS There was no difference in summed skinfold thickness responses between COL and PLA at 24 h (p = 0.124) and 48 h (p = 0.405). However, sensitivity of in vivo immune responsiveness was greater with COL at 24 h (p < 0.001) and 48 h (p = 0.023) with doses ~ twofold greater required to elicit a positive response in PLA. CONCLUSIONS COL blunts the prolonged exercise-induced decrease in clinically relevant in vivo immune responsiveness to a novel antigen, which may be a mechanism for reduced illness reports observed in the previous studies. These findings also suggest that CHS sensitivity is highly relevant to host defence.
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Effects of Mediterranean Diet and Physical Activity on Pulmonary Function: A Cross-Sectional Analysis in the ILERVAS Project.
Gutiérrez-Carrasquilla, L, Sánchez, E, Hernández, M, Polanco, D, Salas-Salvadó, J, Betriu, À, Gaeta, AM, Carmona, P, Purroy, F, Pamplona, R, et al
Nutrients. 2019;11(2)
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The Mediterranean diet is characterised by an abundant consumption of extra-virgin olive oil, fruits, vegetables, nuts, and legumes, a moderate consumption of fish and seafood, poultry, fermented dairy products, and red wine with meals, and low intakes of sweetened beverages, red meat and ready meals. The aim of the study was to evaluate the association between adherence to a Mediterranean diet and physical activity on pulmonary function in a large middle-aged population at low-to-moderate cardiovascular risk. The study is an ongoing study that between 2015 and 2017 enrolled a total of 3020 subjects – women aged between 50 to 70 years and men aged between 45 to 65 years – with the presence of at least one cardiovascular risk factor. Results indicate that a low adherence to the Mediterranean diet was linked with impaired breathing patterns and higher prevalence of abnormal lung function when compared to participants with a higher adherence to this dietary pattern. Additionally, vigorous physical activity was accompanied by better results in lung function than that observed in inactive subjects. The study provides initial clinical evidence about the independent and deleterious effect of both low adherence to the Mediterranean diet and low physical activity practice on lung function in participants without known pulmonary disease.
Abstract
A few studies showed that both adherence to Mediterranean diet (MedDiet) and physical activity practice have a positive impact on pulmonary function in subjects with lung disease. These associations are not well studied in subjects free from lung disease. In a cross-sectional study conducted in 3020 middle-aged subjects free of lung disease, adherence to the MedDiet using the Mediterranean Diet Adherence Screener, and physical activity practice using the International Physical Activity Questionnaire short form were recorded. Respiratory function was assessed using forced spirometry and the results were evaluated according to the Global initiative for Chronic Obstructive Lung Disease. Logistic regression models were used to analyze the associations between adherence to the MedDiet and physical activity practice with the presence of ventilatory defects. Participants with a high adherence to MedDiet, in comparison to those with low adherence, had both higher forced vital capacity (FVC; 100 (87⁻109) vs. 94 (82⁻105) % of predicted, p = 0.003) and forced expired volume in the first second (FEV1; 100 (89⁻112) vs. 93 (80⁻107) % of predicted, p < 0.001). According to their degree of physical activity, those subjects with a high adherence also had both higher FVC (100 (88⁻107) vs. 94 (83⁻105) % of predicted, p = 0.027) and FEV1 (100 (89⁻110) vs. 95 (84⁻108) % of predicted, p = 0.047) in comparison with those with low adherence. The multivariable logistic regression models showed a significant and independent association between both low adherence to MedDiet and low physical activity practice, and the presence of altered pulmonary patterns, with differences between men and women. However, no joint effect between adherence to MedDiet and physical activity practice on respiratory function values was observed. Low adherence to MedDiet and low physical activity practice were independently associated with pulmonary impairment. Therefore, the lung mechanics seem to benefit from heart-healthy lifestyle behaviors.
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Swimming pool exposure is associated with autonomic changes and increased airway reactivity to a beta-2 agonist in school aged children: A cross-sectional survey.
Cavaleiro Rufo, J, Paciência, I, Silva, D, Martins, C, Madureira, J, Oliveira Fernandes, E, Padrão, P, Moreira, P, Delgado, L, Moreira, A
PloS one. 2018;13(3):e0193848
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Studies have shown an association between swimming in chemically-treated pools and a higher risk of asthma in children, although the mechanism is not fully understood. This study aimed to investigate how swimming pool attendance influences lung and nervous system function in school-aged children. Around 800 children were classified as current swimmers (CS), past swimmers (PS) or non-swimmers (NS). The children underwent several tests to determine their lung function and allergic response to common allergens. Parasympathetic nervous system function was tested by measuring the speed at which their pupils constricted in response to light. The current swimmers group had significantly lower pupil constriction speeds compared to PS and NS, suggesting a poorer functioning of the autonomic nervous system, possibly due to inflammation resulting from swimming pool chemical exposure. CS experienced greater constriction of the airways compared to NS. A non-significant trend for a higher risk of asthma, atopic eczema and rhinitis, was observed in swimmers. The authors concluded that swimming pool attendance appears to be associated with autonomic nervous system changes and increased baseline airway smooth muscle constriction even in children without asthma.
Abstract
BACKGROUND Endurance swimming exercises coupled to disinfection by-products exposure has been associated with increased airways dysfunction and neurogenic inflammation in elite swimmers. However, the impact of swimming pool exposure at a recreational level on autonomic activity has never been explored. Therefore, this study aimed to investigate how swimming pool attendance is influencing lung and autonomic function in school-aged children. METHODS A total of 858 children enrolled a cross sectional survey. Spirometry and airway reversibility to beta-2 agonist, skin-prick-tests and exhaled nitric oxide measurements were performed. Pupillometry was used to evaluate autonomic nervous function. Children were classified as current swimmers (CS), past swimmers (PS) and non-swimmers (NS), according to the amount of swimming practice. RESULTS Current swimmers group had significantly lower maximum and average pupil constriction velocities when compared to both PS and NS groups (3.8 and 5.1 vs 3.9 and 5.3 vs 4.0 and 5.4 mm/s, p = 0.03 and p = 0.01, respectively). Moreover, affinity to the beta-2 agonist and levels of exhaled nitric oxide were significantly higher in CS when compared to NS (70 vs 60 mL and 12 vs 10 ppb, p<0.01 and p = 0.03, respectively). A non-significant trend for a higher risk of asthma, atopic eczema and allergic rhinitis was found with more years of swimming practice, particularly in atopic individuals (β = 1.12, 1.40 and 1.31, respectively). After case-case analysis, it was possible to observe that results were not influenced by the inclusion of individuals with asthma. CONCLUSIONS Concluding, swimming pool attendance appears to be associated with autonomic changes and increased baseline airway smooth muscle constriction even in children without asthma.
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Effects of Providing High-Fat versus High-Carbohydrate Meals on Daily and Postprandial Physical Activity and Glucose Patterns: a Randomised Controlled Trial.
Parr, EB, Devlin, BL, Callahan, MJ, Radford, BE, Blankenship, JM, Dunstan, DW, Hawley, JA
Nutrients. 2018;10(5)
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The timing of habitual meal consumption and composition is known to be an important factor in health status, particularly for blood glucose regulation. The aim of this randomised crossover study was to assess the effects of altering meal timing and diet composition on postprandial glucose and physical activity levels. Eight overweight or obese men with a sedentary lifestyle completed two 12-day measurement periods including a 7-day habitual period followed by a 5-day experimental period, with an 8-day washout period. The two conditions tested were a high-fat, low carbohydrate diet (HFD) and a high-carbohydrate, low-fat diet (HCD) and participants were instructed to consume meals at standardised times throughout both conditions. Body composition, oxygen consumption and blood glucose were measured at baseline and between each experimental condition. This trial found the provision of meals did not alter overall activity patterns or postprandial activity patterns. The authors observed increased sedentary activity across the day, and identify evening time as an important target for sedentary time to be minimised. Based on these results, the authors suggest that future dietary interventions consider habitual meal consumption and composition to best replicate real-world behaviours.
Abstract
We determined the effects of altering meal timing and diet composition on temporal glucose homeostasis and physical activity measures. Eight sedentary, overweight/obese men (mean ± SD, age: 36 ± 4 years; BMI: 29.8 ± 1.8 kg/m²) completed two × 12-day (12-d) measurement periods, including a 7-d habitual period, and then 5 d of each diet (high-fat diet [HFD]: 67:15:18% fat:carbohydrate:protein versus high-carbohydrate diet [HCD]: 67:15:18% carbohydrate:fat:protein) of three meals/d at ±30 min of 0800 h, 1230 h, and 1800 h, in a randomised order with an 8-d washout. Energy intake (EI), the timing of meal consumption, blood glucose regulation (continuous glucose monitor system (CGMS)), and activity patterns (accelerometer and inclinometer) were assessed across each 12-d period. Meal provision did not alter the patterns of reduced physical activity, and increased sedentary behaviour following dinner, compared with following breakfast and lunch. The HCD increased peak (+1.6 mmol/L, p < 0.001), mean (+0.5 mmol/L, p = 0.001), and total area under the curve (+670 mmol/L/min, p = 0.001), as well as 3-h postprandial meal glucose concentrations (all p < 0.001) compared with the HFD. In overweight/obese males, the provision of meals did not alter physical activity patterns, but did affect glycaemic control. Greater emphasis on meal timing and composition is required in diet and/or behaviour intervention studies to ensure relevance to real-world behaviours.