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Restricted sugar and ketogenic diets can alter energy balance/metabolism, but decreased energy intake may be compensated by reduced expenditure. In healthy adults, randomization to restricting free sugars or overall carbohydrates (ketogenic diet) for 12 weeks reduces fat mass without changing energy expenditure versus control. Free-sugar restriction minimally affects metabolism or gut microbiome but decreases low-density lipoprotein cholesterol (LDL-C). In contrast, a ketogenic diet decreases glucose tolerance, increases skeletal muscle PDK4, and reduces AMPK and GLUT4 levels. By week 4, the ketogenic diet reduces fasting glucose and increases apolipoprotein B, C-reactive protein, and postprandial glycerol concentrations. However, despite sustained ketosis, these effects are no longer apparent by week 12, when gut microbial beta diversity is altered, possibly reflective of longer-term adjustments to the ketogenic diet and/or energy balance. These data demonstrate that restricting free sugars or overall carbohydrates reduces energy intake without altering physical activity, but with divergent effects on glucose tolerance, lipoprotein profiles, and gut microbiome., Competing Interests: Declaration of interests P.D.C. is a co-founder and CTO of SeqBiome Ltd. J.T.G. has received research funding from BBSRC, MRC, Cancer Research UK, the British Heart Foundation, Clasado Biosciences, Lucozade Ribena Suntory, Arla Foods Ingredients, the Cosun Nutrition Center, and the Fruit Juice Science Center; is a scientific advisory board member to ZOE; and has completed paid consultancy for 6d Sports Nutrition, The Dairy Council, PepsiCo, Violicom Medical, Tour Racing Ltd., and SVGC. J.A.B. is an investigator on research grants funded by BBSRC, MRC, the British Heart Foundation, Rare Disease Foundation, EU Hydration Institute, GlaxoSmithKline, Nestlé, Lucozade Ribena Suntory, Arla Foods, Cosun Nutrition Center, American Academy of Sleep Medicine Foundation, and Salus Optima (L3M Technologies Ltd.); has completed paid consultancy for PepsiCo, Kellogg’s, SVGC, and Salus Optima (L3M Technologies Ltd.); is Company Director of Metabolic Solutions Ltd.; receives an annual honorarium as a member of the academic advisory board for the International Olympic Committee Diploma in Sports Nutrition; and receives an annual stipend as Editor-in-Chief of International Journal of Sport Nutrition & Exercise Metabolism., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Context: Skeletal muscle plays a central role in the storage, synthesis, and breakdown of nutrients, yet little research has explored temporal responses of this human tissue, especially with concurrent measures of systemic biomarkers of metabolism., Objective: To characterise temporal profiles in skeletal muscle expression of genes involved in carbohydrate metabolism, lipid metabolism, circadian clocks, and autophagy and descriptively relate them to systemic metabolites and hormones during a controlled laboratory protocol., Methods: Ten healthy adults (9M/1F, mean ± SD: age: 30 ± 10 y; BMI: 24.1 ± 2.7 kg·m-2) rested in the laboratory for 37 hours with all data collected during the final 24 hours of this period (i.e., 0800-0800 h). Participants ingested hourly isocaloric liquid meal replacements alongside appetite assessments during waking before a sleep opportunity from 2200-0700 h. Blood samples were collected hourly for endocrine and metabolite analyses, with muscle biopsies occurring every 4 h from 1200 h to 0800 h the following day to quantify gene expression., Results: Plasma insulin displayed diurnal rhythmicity peaking at 1804 h. Expression of skeletal muscle genes involved in carbohydrate metabolism (Name - Acrophase; GLUT4 - 1440 h; PPARGC1A -1613 h; HK2 - 1824 h) and lipid metabolism (FABP3 - 1237 h; PDK4 - 0530 h; CPT1B - 1258 h) displayed 24 h rhythmicity that reflected the temporal rhythm of insulin. Equally, circulating glucose (0019 h), NEFA (0456 h), glycerol (0432 h), triglyceride (2314 h), urea (0046 h), CTX (0507 h) and cortisol concentrations (2250 h) also all displayed diurnal rhythmicity., Conclusion: Diurnal rhythms were present in human skeletal muscle gene expression as well systemic metabolites and hormones under controlled diurnal conditions. The temporal patterns of genes relating to carbohydrate and lipid metabolism alongside circulating insulin are consistent with diurnal rhythms being driven in part by the diurnal influence of cyclic feeding and fasting., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.)

Objectives: A systematic review with meta-analysis was completed to study the effects of dietary inorganic nitrate (NO 3 - ) oral ingestion from vegetables and salts on blood pressure responses during and following exercise., Background: NO 3 - is a hypotensive agent with the potential to reduce blood pressure peaks during exercise and amplify exercise-induced hypotensive effects. Several randomized and controlled trials have investigated the effects of NO 3 - on hemodynamic responses to physical exercise, however this still has yet to be studied systematically., Methods: The searches were conducted on EMBASE, Medline, and SPORTSDiscus databases. The study included masked randomized controlled trials (RCTs) with participants ≥18 years old. The NO 3 - intervention group received at least 50 mg NO 3 - /day with similar sources amid NO 3 - and placebo conditions. Included studies reported systolic blood pressure (SBP) or diastolic blood pressure (DBP) values during or following exercise performance., Results: 1903 studies were identified, and twenty-six achieved the inclusion criteria. NO 3 - daily dosages ranged from 90 to 800 mg/day. Throughout exercise, SBP had smaller increases in the NO 3 - group (-2.81 mmHg (95%CI: -5.20 to -0.41), p=0.02. DBP demonstrated lower values in the NO 3 - group (-2.41 mmHg (95%CI: -4.02 to -0.79), p=0.003. In the post-exercise group, the NO 3 - group presented lower SBP values (-3.53 mmHg (95%CI: -5.65 to 1.41), p=0.001, while no changes were identified in DBP values between NO 3 - and placebo groups (p=0.31). Subgroup meta-analysis revealed that SBP baseline values, exercise type, duration of NO 3 - ingestion, and its dosages mediated blood pressure responses during and following exercise., Conclusions: NO 3 - ingestion prior to exercise attenuated the increases in SBP and DBP during exercise, and increased the decline in SBP after exercise. These results are dependent on factors that moderate the blood pressure responses (e.g., health status, type of exercise, resting blood pressure values)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Typical breakfast foods are rich in carbohydrate, so they not only elevate blood glucose during the morning, but also elicit a second-meal effect that can attenuate blood glucose responses in the afternoon., Objectives: To determine whether a reduced-carbohydrate protein-enriched breakfast can elicit similar effects on glucose control later in the day but without hyperglycemia in the morning., Methods: In a randomized crossover design, 12 healthy men and women (age 22 ± 2 y, BMI 24.1 ± 3.6 kg·m -2 ; Mean ± SD) completed 3 experimental conditions. In all conditions, participants consumed an ad libitum lunch at 1200 ± 1 h but differed in terms of whether they had fasted all morning (control) or had consumed a standardized porridge breakfast at 0900 ± 1 h (320 ± 50 kcal; prescribed relative to resting metabolic rate) that was either carbohydrate-rich (50 ± 10 g CHO) or protein-enriched (that is, isoenergetic substitution of carbohydrate for 15 g whey protein isolate)., Results: The protein-enriched breakfast reduced the morning glycemic response (iAUC 87 ± 36 mmol·L -1 ·180 min) relative to the carbohydrate-rich breakfast (119 ± 37 mmol·L -1 ·180 min; P = 0.03). Despite similar energy intake at lunch in all 3 conditions (protein-enriched 769 ± 278 kcal; carbohydrate-rich 753 ± 223 kcal; fasting 790 ± 227 kcal), postlunch insulinemic responses were markedly attenuated when breakfasts had been consumed that were either protein-enriched (18.0 ± 8.0 nmol·L -1 ·120 min; P = 0.05) or carbohydrate-rich (16.0 ± 7.7 nmol·L -1 ·120 min; P = 0.005), relative to when lunch was consumed in an overnight fasted state (26.9 ± 13.5 nmol·L -1 ·120 min)., Conclusions: Breakfast consumption attenuates insulinemic responses to a subsequent meal, achieved with consumption of energy-matched breakfasts typically high in carbohydrates or enriched with whey protein isolate relative to extended morning fasting., Trial Registration Number: NCT03866720 (clinicaltrials.gov)., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Background & Aims: It is unclear if dietary adjustments to maintain energy balance during reduced physical activity can offset inactivity-induced reductions in insulin sensitivity and glucose disposal to produce normal daily glucose concentrations and meal responses. Therefore, the aim of the present study was to examine the impact of long-term physical inactivity (60 days of bed rest) on daily glycemia when in energy balance., Methods: Interstitial glucose concentrations were measured using Continuous Glucose Monitoring Systems (CGMS) for 5 days before and towards the end of bed rest in 20 healthy, young males (Age: 34 ± 8 years; BMI: 23.5 ± 1.8 kg/m 2 ). Energy intake was reduced during bed rest to match energy expenditure, but the types of foods and timing of meals was maintained. Fasting venous glucose and insulin concentrations were determined, as well as the change in whole-body glucose disposal using a hyperinsulinemic-euglycemic clamp (HIEC)., Results: Following long-term bed rest, fasting plasma insulin concentration increased 40% (p = 0.004) and glucose disposal during the HIEC decreased 24% (p < 0.001). Interstitial daily glucose total area under the curve (tAUC) from pre-to post-bed rest increased on average by 6% (p = 0.041), despite a 20 and 25% reduction in total caloric and carbohydrate intake, respectively. The nocturnal period (00:00-06:00) showed the greatest change to glycemia with glucose tAUC for this period increasing by 9% (p = 0.005). CGMS measures of daily glycemic variability (SD, J-Index, M-value and MAG) were not changed during bed rest., Conclusions: Reduced physical activity (bed rest) increases glycemia even when daily energy intake is reduced to maintain energy balance. However, the disturbance to daily glucose homeostasis was much more modest than the reduced capacity to dispose of glucose, and glycemic variability was not negatively affected by bed rest, likely due to positive mitigating effects from the contemporaneous reduction in dietary energy and carbohydrate intake., Clinical Trials Record: NCT03594799 (registered July 20, 2018) (https://clinicaltrials.gov/ct2/show/NCT03594799)., Competing Interests: Conflicts of interest I.A.M. was a member of the Mars Scientific Advisory Council, member of the Mars Europe Nutrition Advisory Board, and Scientific Adviser to the Waltham Centre for Pet Nutrition, and was also a member of the Nestle Research Scientific Advisory Board, and of the Novozymes Scientific Advisory Board. He withdrew from all of these roles in 2020 and on 1 August 2020 became Professor Emeritus at the University of Nottingham and took up the post of Scientific Director of the Nestle Institute of Health Sciences in Lausanne, Switzerland, which terminated in August 2022. D. T is an investigator on research grants funded by BBSRC, British Heart Foundation, Diabetes UK, Evolution Education Trust, GlaxoSmithKline R&D, MRC, NIHR, Nutricia Research Foundation, UK Sport, Unilever, and Versus Arthritis; and has completed paid consultancy for Gemina Labs, International Consumer Research & Testing (ICRT), Unilever, and Sugar Nutrition UK. The remaining authors have no conflicts of interest to declare., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: The prevalence of intra-articular knee injuries and reparative surgeries is increasing in many countries. Alarmingly, there is a risk of developing post-traumatic osteoarthritis (PTOA) after sustaining a serious intra-articular knee injury. Although physical inactivity is suggested as a risk factor contributing to the high prevalence of the condition, there is a paucity of research characterising the association between physical activity and joint health. Consequently, the primary aim of this review will be to identify and present available empirical evidence regarding the association between physical activity and joint degeneration after intra-articular knee injury and summarise the evidence using an adapted Grading of Recommendations Assessment, Development and Evaluations. The secondary aim will be to identify potential mechanistic pathways through which physical activity could influence PTOA pathogenesis. The tertiary aim will be to highlight gaps in current understanding of the association between physical activity and joint degeneration following joint injury., Methods: A scoping review will be conducted using the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews checklist and best-practice recommendations. The review will be guided by the following research question: what is the role of physical activity in the trajectory from intra-articular knee injury to PTOA in young men and women? We will identify primary research studies and grey literature by searching the electronic databases Scopus, Embase: Elsevier, PubMed, Web of Science: all databases, and Google Scholar. Reviewing pairs will screen abstracts, full texts and will extract data. Data will be presented descriptively using charts, graphs, plots and tables., Ethics and Dissemination: This research does not require ethical approval due to the data being published and publicly available. This review will be submitted for publication in a peer-reviewed sports medicine journal irrespective of discoveries and disseminated through scientific conference presentations and social media., Trial Registration Number: https://osf.io/84pnh/., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY. Published by BMJ.)

Purpose: To determine the effects of dietary sugar or carbohydrate restriction on physical activity energy expenditure, energy intake, and physiological outcomes across 24 h., Methods: In a randomized, open-label crossover design, twenty-five healthy men (n = 10) and women (n = 15) consumed three diets over a 24-h period: moderate carbohydrate and sugar content (MODSUG = 50% carbohydrate [20% sugars], 15% protein, 35% fat); low sugar content (LOWSUG = 50% carbohydrate [< 5% sugars], 15% protein, 35% fat); and low carbohydrate content (LOWCHO = 8% carbohydrate [< 5% sugars], 15% protein, 77% fat). Postprandial metabolic responses to a prescribed breakfast (20% EI) were monitored under laboratory conditions before an ad libitum test lunch, with subsequent diet and physical activity monitoring under free-living conditions until blood sample collection the following morning., Results: The MODSUG, LOWSUG and LOWCHO diets resulted in similar mean [95%CI] rates of both physical activity energy expenditure (771 [624, 919] vs. 677 [565, 789] vs. 802 [614, 991] kcal·d -1 ; p = 0.29] and energy intake (2071 [1794, 2347] vs. 2195 [1918, 2473] vs. 2194 [1890, 2498] kcal·d -1 ; P = 0.34), respectively. The LOWCHO condition elicited the lowest glycaemic and insulinaemic responses to breakfast (P < 0.01) but the highest 24-h increase in LDL-cholesterol concentrations (P < 0.001), with no differences between the MODSUG and LOWSUG treatments. Leptin concentrations decreased over 24-h of consuming LOWCHO relative to LOWSUG (p < 0.01)., Conclusion: When energy density is controlled for, restricting either sugar or total dietary carbohydrate does not modulate physical activity level or energy intake over a 24-h period (~ 19-h free-living) despite substantial metabolic changes., Clinical Trials Registration Id: NCT03509610, https://clinicaltrials.gov/show/NCT03509610., (© 2022. The Author(s).)

Intravenous ketone body infusion can increase erythropoietin (EPO) concentrations, but responses to ketone monoester ingestion postexercise are currently unknown. The purpose of this study was to assess the effect of ketone monoester ingestion on postexercise erythropoietin (EPO) concentrations. Nine healthy men completed two trials in a randomized, crossover design (1-wk washout). During trials, participants performed 1 h of cycling (initially alternating between 50% and 90% of maximal aerobic capacity for 2 min each interval, and then 50% and 80%, and 50% and 70% when the higher intensity was unsustainable). Participants ingested 0.8 g·kg -1 sucrose with 0.4 g·kg -1 protein immediately after exercise, and at 1, 2, and 3 h postexercise. During the control trial (CONTROL), no further nutrition was provided, whereas on the ketone monoester trial (KETONE), participants also ingested 0.29 g·kg -1 of the ketone monoester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate immediately postexercise and at 1 and 2 h postexercise. Blood was sampled immediately postexercise, every 15 min in the first hour and hourly thereafter for 4 h. Serum EPO concentrations increased to a greater extent in KETONE than in CONTROL (time × condition interaction: P = 0.046). Peak serum EPO concentrations were higher with KETONE (means ± SD: 9.0 ± 2.3 IU·L -1 ) compared with CONTROL (7.5 ± 1.5 IU·L -1 , P < 0.01). Serum β-hydroxybutyrate concentrations were also higher, and glucose concentrations lower, with KETONE versus CONTROL (both P < 0.01). In conclusion, ketone monoester ingestion increases postexercise erythropoietin concentrations, revealing a new avenue for orally ingestible ketone monoesters to potentially alter hemoglobin mass. NEW & NOTEWORTHY To our knowledge, this study was the first to assess the effects of ketone monoester ingestion on erythropoietin concentrations after exercise. We demonstrated that ingestion of a ketone monoester postexercise increased serum erythropoietin concentrations and reduced serum glucose concentrations in healthy men. These data reveal the possibility for ketone monoesters to alter hemoglobin mass.

Introduction: Continuous exercise can increase postprandial gut hormone such as glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) responses, but it is unknown whether interrupting prolonged sitting with intermittent walking elicits this effect., Method: Ten participants with central overweight/obesity (7 men and 3 postmenopausal women, 51 ± 5 yr; mean ± SD) completed a randomized crossover study in which they consumed breakfast and lunch in the laboratory while either sitting continuously for the entire 5.5-h period (SIT) or the prolonged sitting interrupted every 20 min by walking briskly (6.4 km·h-1) for 2 min (BREAKS). Blood samples were collected at regular intervals to examine postprandial plasma GLP-1, PYY, and glucose-dependent insulinotropic polypeptide concentrations. Adipose tissue samples were collected at baseline and at the end of the trials to examine changes in net dipeptidyl peptidase 4 secretion from primary explants., Results: Mean (95% confidence interval) postprandial GLP-1 and PYY incremental area under curve values were elevated by 26% and 31% in the BREAKS trial versus SIT (8.4 [0.7, 16.1] vs 6.7 [-0.8, 14.2], P = 0.001, and 26.9 [8.1, 45.6] vs 20.4 [5.1, 35.8] nmol·330 min·L-1, P = 0.024, respectively) but without any such effect on glucose-dependent insulinotropic polypeptide (P = 0.076) or net adipose tissue dipeptidyl peptidase 4 secretion (P > 0.05)., Conclusions: Interrupting prolonged sitting with regular short bouts of brisk walking increases postprandial GLP-1 and PYY concentrations in healthy middle-age men and women with central adiposity., (Copyright © 2022 by the American College of Sports Medicine.)

Key Points: Ageing is associated with increased systemic inflammation and metabolic dysfunction that contributes to the development of age-associated diseases. The role of adipose tissue in immunometabolic alterations that take place with ageing is unknown in humans. We show, in healthy, active and lean older adults, that adipose tissue, but not skeletal muscle, displays considerable pro-inflammatory transcriptomic, cellular and secretory changes, as well as a reduction in insulin signalling proteins compared to younger adults. These findings indicate that adipose tissue undergoes substantial immunometabolic alterations with ageing, and that these changes are tissue-specific and more profound than those observed in skeletal muscle or in the circulation. These results identify adipose tissue as an important tissue in the biological ageing process in humans, which may exhibit signs of immunometabolic dysfunction prior to systemic manifestation., Abstract: Ageing and obesity are both characterized by inflammation and a deterioration in metabolic health. It is now clear that adipose tissue plays a major role in inflammation and metabolic control in obesity, although little is known about the role of adipose tissue in human ageing. To understand how ageing impacts adipose tissue, we characterized subcutaneous adipose tissue and skeletal muscle samples from twelve younger (27 ± 4 years [Young]) and twelve older (66 ± 5 years [Old]) active/non-obese males. We performed a wide-range of whole-body and tissue measures, including RNA-sequencing and multicolour flow cytometry. We also measured a range of inflammatory and metabolic proteins in the circulation and their release by adipose tissue, ex vivo. Both adipose tissue and muscle had ∼2-fold more immune cells per gram of tissue with ageing. In adipose tissue, this immune cell infiltration was driven by increased memory/effector T-cells, whereas, in muscle, the accumulation was driven by memory/effector T-cells and macrophages. Transcriptomic analysis revealed that, with ageing, adipose tissue, but not muscle, was enriched for inflammatory transcripts/pathways related to acquired and innate immunity. Ageing also increased the adipose tissue pro-inflammatory secretory profile. Insulin signalling protein content was reduced in adipose tissue, but not muscle. Our findings indicate that adipose tissue undergoes substantial immunometabolic changes with ageing in humans, and that these changes are tissue-specific and more profound than those observed in the circulation and skeletal muscle., (© 2021 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Context: Adipose tissue and physical inactivity both influence metabolic health and systemic inflammation, but how adipose tissue responds to chronic physical inactivity is unknown., Objective: This work aimed to characterize the impact of chronic physical inactivity on adipose tissue in healthy, young males., Methods: We collected subcutaneous adipose tissue from 20 healthy, young men before and after 60 days of complete bed rest with energy intake reduced to maintain energy balance and fat mass. We used RNA sequencing, flow cytometry, ex vivo tissue culture, and targeted protein analyses to examine adipose tissue phenotype., Results: Our results indicate that the adipose tissue transcriptome, stromal cellular compartment, and insulin signaling protein abundance are largely unaffected by bed rest when fat mass is kept stable. However, there was an increase in the circulating concentration of several adipokines, including plasma leptin, which was associated with inactivity-induced increases in plasma insulin and absent from adipose tissue cultured ex vivo under standardized culture conditions., Conclusion: Physical inactivity-induced disturbances to adipokine concentrations such as leptin, without changes to fat mass, could have profound metabolic implications outside a clinical facility when energy intake is not tightly controlled., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society.)

This study investigated whether carbohydrate-energy replacement immediately after prolonged endurance exercise attenuates insulin sensitivity the following morning, and whether exercise improves insulin sensitivity the following morning independent of an exercise-induced carbohydrate deficit. Oral glucose tolerance and whole-body insulin sensitivity were compared the morning after 3 evening conditions, involving (1) treadmill exercise followed by a carbohydrate replacement drink (200 or 150 g maltodextrin for males and females, respectively; CHO-replace ); (2) treadmill exercise followed by a non-caloric, taste-matched placebo ( CHO-deficit ); or (3) seated rest with no drink provided ( Rest ). Treadmill exercise involved 90 minutes at ∼80% age-predicted maximum heart rate. Seven males and 2 females (aged 23 ± 1 years; body mass index 24.0 ± 2.7 kg·m -2 ) completed all conditions in a randomised order. Matsuda index improved by 22% (2.2 [0.3, 4.0] au, p  = 0.03) and HOMA2-IR improved by 10% (-0.04 [-0.08, 0.00] au, p  = 0.04) in CHO-deficit versus CHO-replace , without corresponding changes in postprandial glycaemia. Outcomes were similar between Rest and other conditions. These data suggest that improvements to insulin sensitivity in healthy populations following acute moderate/vigorous intensity endurance exercise may be dependent on the presence of a carbohydrate-energy deficit. Novelty: Restoration of carbohydrate balance following acute endurance exercise attenuated whole-body insulin sensitivity. Exercise per se failed to enhance whole-body insulin sensitivity. Maximising or prolonging the post-exercise carbohydrate deficit may enhance acute benefits to insulin sensitivity.

Purpose of Review: To consider emerging research into the physiological effects of excessive dietary carbohydrate intake, with a particular focus on interactions with physical activity., Recent Findings: A single episode of massive carbohydrate overload initiates physiological responses to stimulate additional peptide hormone secretion by the gut and the conversion of carbohydrate into lipid by the intestine, liver and adipose tissue. These acute responses maintain glycaemic control both via increased oxidation of carbohydrate (rather than lipid) and via nonoxidative disposal of surplus carbohydrate into endogenous glycogen and lipid storage depots. Sustained carbohydrate overfeeding therefore results in a chronic accumulation of lipid in the liver, skeletal muscle and adipose tissue, which can impair insulin sensitivity and cardiometabolic health in general. Beyond any direct effect of such lipid deposition on body mass/composition, there is not yet clear evidence of physiologically meaningful metabolic or behavioural adaptations to carbohydrate overfeeding in terms of other components of energy balance. However, regular physical exercise can mitigate the negative health effects of carbohydrate overfeeding, independent of any effect on the net carbohydrate surplus., Summary: Research in this area has advanced understanding regarding the mechanisms of weight gain and associated health outcomes within the modern context of an abundant supply of dietary carbohydrate., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Intermittent fasting may impart metabolic benefits independent of energy balance by initiating fasting-mediated mechanisms. This randomized controlled trial examined 24-hour fasting with 150% energy intake on alternate days for 3 weeks in lean, healthy individuals (0:150; n = 12). Control groups involved a matched degree of energy restriction applied continuously without fasting (75% energy intake daily; 75:75; n = 12) or a matched pattern of fasting without net energy restriction (200% energy intake on alternate days; 0:200; n = 12). Primary outcomes were body composition, components of energy balance, and postprandial metabolism. Daily energy restriction (75:75) reduced body mass (-1.91 ± 0.99 kilograms) almost entirely due to fat loss (-1.75 ± 0.79 kilograms). Restricting energy intake via fasting (0:150) also decreased body mass (-1.60 ± 1.06 kilograms; P = 0.46 versus 75:75) but with attenuated reductions in body fat (-0.74 ± 1.32 kilograms; P = 0.01 versus 75:75), whereas fasting without energy restriction (0:200) did not significantly reduce either body mass (-0.52 ± 1.09 kilograms; P ≤ 0.04 versus 75:75 and 0:150) or fat mass (-0.12 ± 0.68 kilograms; P ≤ 0.05 versus 75:75 and 0:150). Postprandial indices of cardiometabolic health and gut hormones, along with the expression of key genes in subcutaneous adipose tissue, were not statistically different between groups ( P > 0.05). Alternate-day fasting less effectively reduces body fat mass than a matched degree of daily energy restriction and without evidence of fasting-specific effects on metabolic regulation or cardiovascular health., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Constant routine and forced desynchrony protocols typically remove the effects of behavioral/environmental cues to examine endogenous circadian rhythms, yet this may not reflect rhythms of appetite regulation in the real world. It is therefore important to understand these rhythms within the same subjects under controlled diurnal conditions of light, sleep, and feeding. Ten healthy adults (9 M/1 F, means ±SD: age, 30 ± 10 yr; body mass index, 24.1 ± 2.7 kg·m -2 ) rested supine in the laboratory for 37 h. All data were collected during the final 24 h of this period (i.e., 0800-0800 h). Participants were fed hourly isocaloric liquid meal replacements alongside appetite assessments during waking before a sleep opportunity from 2200 to 0700 h. Hourly blood samples were collected throughout the 24-h period. Dim light melatonin onset occurred at 2318 ± 46 min. A diurnal rhythm in mean plasma unacylated ghrelin concentration was identified ( P = 0.04), with the acrophase occurring shortly after waking (0819), falling to a nadir in the evening with a relative amplitude of 9%. Plasma leptin concentration also exhibited a diurnal rhythm ( P < 0.01), with the acrophase occurring shortly after lights-out (0032 h) and the lowest concentrations at midday. The amplitude for this rhythm was 25%. Diurnal rhythms were established in all dimensions of appetite except for sweet preference ( P = 0.29), with both hunger (2103 h) and prospective food consumption (1955 h) reaching their peak in the evening before falling to their nadir shortly after waking. Under controlled diurnal conditions, simultaneous measurement of leptin, unacylated ghrelin, and subjective appetite over a 24-h period revealed rhythmicity in appetite regulation in lean, healthy humans. NEW & NOTEWORTHY Simultaneous assessment of subjective appetite, unacylated ghrelin, and leptin was carried out over a continuous 37-h protocol for the first time under conditions of controlled light, sleep, and feeding in healthy, lean adults. Rhythms were observed in unacylated ghrelin, leptin, and components of subjective appetite, such as hunger, prospective consumption, and fullness. Concurrent measurement of rhythms in these variables is important to fully understand the temporal relationships between components of appetite as well as the influence of diurnal factors such as sleep, light, and feeding.

New Findings: What is the central question of this study? What is the relationship between proteins in skeletal muscle and adipose tissue determined at rest and at peak rates of fat oxidation in men and women? What is the main finding and its importance? The resting contents of proteins in skeletal muscle involved in triglyceride hydrolysis and mitochondrial lipid transport were more strongly associated with peak fat oxidation rates than proteins related to lipid transport or hydrolysis in adipose tissue. Although females displayed higher relative rates of fat oxidation than males, this was not explained by the proteins measured in this study, suggesting that other factors determine sex differences in fat metabolism., Abstract: We explored key proteins involved in fat metabolism that might be associated with peak fat oxidation (PFO) and account for sexual dimorphism in fuel metabolism during exercise. Thirty-six healthy adults [15 women; 40 ± 11 years of age; peak oxygen consumption 42.5 ± 9.5 ml (kg body mass) -1  min -1 ; mean ± SD] completed two exercise tests to determine PFO via indirect calorimetry. Resting adipose tissue and/or skeletal muscle biopsies were obtained to determine the adipose tissue protein content of PLIN1, ABHD5 (CGI-58), LIPE (HSL), PNPLA2 (ATGL), ACSL1, CPT1B and oestrogen receptor α (ERα) and the skeletal muscle protein content of FABP 3 (FABPpm), PNPLA2 (ATGL), ACSL1, CTP1B and ESR1 (ERα). Moderate strength correlations were found between PFO [in milligrams per kilogram of fat-free mass (FFM) per minute] and the protein content of PNPLA2 (ATGL) [r s  = 0.41 (0.03-0.68), P < 0.05] and CPT1B [r s  = 0.45 (0.09-0.71), P < 0.05] in skeletal muscle. No other statistically significant bivariate correlations were found consistently. Females had a greater relative PFO than males [7.1 ± 1.9 vs. 4.5 ± 1.3 and 7.3 ± 1.7 vs. 4.8 ± 1.2 mg (kg FFM) -1  min -1 in the adipose tissue (n = 14) and skeletal muscle (n = 12) subgroups, respectively (P < 0.05)]. No statistically significant sex differences were found in the content of these proteins. The regulation of PFO might involve processes relating to intramyocellular triglyceride hydrolysis and mitochondrial fatty acid transport, and adipose tissue is likely to play a more minor role than muscle. Sex differences in fat metabolism are likely to be attributable to factors other than the resting content of proteins in skeletal muscle and adipose tissue relating to triglyceride hydrolysis and fatty acid transport., (© 2021 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Purpose: Ingested ethanol (EtOH) is metabolized gastrically and hepatically, which may influence resting and exercise metabolism. Previous exercise studies have provided EtOH intravenously rather than orally, altering the metabolic effects of EtOH. No studies to date have investigated the effects of EtOH ingestion on systemic and peripheral (e.g., skeletal muscle) exercise metabolism., Methods: Eight men (mean ± SD; age = 24 ± 5 yr, body mass = 76.7 ± 5.6 kg, height = 1.80 ± 0.04 m, V˙O2peak = 4.1 ± 0.2 L·min) performed two bouts of fasted cycling exercise at 55% V˙O2peak for 2 h, with (EtOH) and without (control) prior ingestion of EtOH 1 h and immediately before exercise (total dose = 0.1 g·kg lean body mass·h; 30.2 ± 1.1 g 40% ABV Vodka; fed in two equal boluses) in a randomized order, separated by 7-10 d., Results: Muscle glycogen use during exercise was not different between conditions (mean [normalized 95% confidence interval]; EtOH, 229 [156-302] mmol·kg dm, vs control, 258 [185-331] mmol·kg dm; P = 0.67). Mean plasma glucose concentrations during exercise were similar (control, 5.26 [5.22-5.30], vs EtOH, 5.34 [5.30-5.38]; P = 0.06). EtOH ingestion resulted in similar plasma nonesterified fatty acid concentrations compared with rest (control, 0.43 [0.31-0.55] mmol·L, vs EtOH, 0.30 [0.21-0.40] mmol·L) and during exercise. Plasma lactate concentration was higher during the first 30 min of rest after EtOH consumption (mean concentration; control, 0.83 [0.77-0.90] mmol·L, vs EtOH, 1.00 [0.93-1.07] mmol·L), but the response during exercise was similar between conditions., Conclusions: Muscle glycogen utilization was similar during exercise with or without prior EtOH ingestion, reflected in similar total whole-body carbohydrate oxidation rates observed.

Morning coffee is a common remedy following disrupted sleep, yet each factor can independently impair glucose tolerance and insulin sensitivity in healthy adults. Remarkably, the combined effects of sleep fragmentation and coffee on glucose control upon waking per se have never been investigated. In a randomised crossover design, twenty-nine adults (mean age: 21 (sd 1) years, BMI: 24·4 (sd 3·3) kg/m2) underwent three oral glucose tolerance tests (OGTT). One following a habitual night of sleep (Control; in bed, lights-off trying to sleep approximately 23.00-07.00 hours), the others following a night of sleep fragmentation (as Control but waking hourly for 5 min), with and without morning coffee approximately 1 h after waking (approximately 300 mg caffeine as black coffee 30 min prior to OGTT). Individualised peak plasma glucose and insulin concentrations were unaffected by sleep quality but were higher following coffee consumption (mean (normalised CI) for Control, Fragmented and Fragmented + Coffee, respectively; glucose: 8·20 (normalised CI 7·93, 8·47) mmol/l v. 8·23 (normalised CI 7·96, 8·50) mmol/l v. 8·96 (normalised CI 8·70, 9·22) mmol/l; insulin: 265 (normalised CI 247, 283) pmol/l; and 235 (normalised CI 218, 253) pmol/l; and 310 (normalised CI 284, 337) pmol/l). Likewise, incremental AUC for plasma glucose was higher in the Fragmented + Coffee trial compared with Fragmented. Whilst sleep fragmentation did not alter glycaemic or insulinaemic responses to morning glucose ingestion, if a strong caffeinated coffee is consumed, then a reduction in glucose tolerance can be expected.

This study investigated metabolic, endocrine, appetite and mood responses to a maximal eating occasion in fourteen men (mean: age 28 (sd 5) years, body mass 77·2 (sd 6·6) kg and BMI 24·2 (sd 2·2) kg/m2) who completed two trials in a randomised crossover design. On each occasion, participants ate a homogenous mixed-macronutrient meal (pizza). On one occasion, they ate until 'comfortably full' (ad libitum) and on the other, until they 'could not eat another bite' (maximal). Mean energy intake was double in the maximal (13 024 (95 % CI 10 964, 15 084) kJ; 3113 (95 % CI 2620, 3605) kcal) compared with the ad libitum trial (6627 (95 % CI 5708, 7547) kJ; 1584 (95 % CI 1364, 1804) kcal). Serum insulin incremental AUC (iAUC) increased approximately 1·5-fold in the maximal compared with ad libitum trial (mean: ad libitum 43·8 (95 % CI 28·3, 59·3) nmol/l × 240 min and maximal 67·7 (95 % CI 47·0, 88·5) nmol/l × 240 min, P < 0·01), but glucose iAUC did not differ between trials (ad libitum 94·3 (95 % CI 30·3, 158·2) mmol/l × 240 min and maximal 126·5 (95 % CI 76·9, 176·0) mmol/l × 240 min, P = 0·19). TAG iAUC was approximately 1·5-fold greater in the maximal v. ad libitum trial (ad libitum 98·6 (95 % CI 69·9, 127·2) mmol/l × 240 min and maximal 146·4 (95 % CI 88·6, 204·1) mmol/l × 240 min, P < 0·01). Total glucagon-like peptide-1, glucose-dependent insulinotropic peptide and peptide tyrosine-tyrosine iAUC were greater in the maximal compared with ad libitum trial (P < 0·05). Total ghrelin concentrations decreased to a similar extent, but AUC was slightly lower in the maximal v. ad libitum trial (P = 0·02). There were marked differences on appetite and mood between trials, most notably maximal eating caused a prolonged increase in lethargy. Healthy men have the capacity to eat twice the energy content required to achieve comfortable fullness at a single meal. Postprandial glycaemia is well regulated following initial overeating, with elevated postprandial insulinaemia probably contributing.

The timing of carbohydrate ingestion and how this influences net muscle glycogen utilization and fatigue has only been investigated in prolonged cycling. Past findings may not translate to running because each exercise mode is distinct both in the metabolic response to carbohydrate ingestion and in the practicalities of carbohydrate ingestion. To this end, a randomized, cross-over design was employed to contrast ingestion of the same sucrose dose either at frequent intervals (15 × 5 g every 5 min) or at a late bolus (1 × 75 g after 75 min) during prolonged treadmill running to exhaustion in six well-trained runners (V˙O2max 61 ± 4 ml·kg-1·min-1). The muscle glycogen utilization rate was lower in every participant over the first 75 min of running (Δ 0.51 mmol·kg dm-1·min-1; 95% confidence interval [-0.02, 1.04] mmol·kg dm-1·min-1) and, subsequently, all were able to run for longer when carbohydrate had been ingested frequently from the start of exercise compared with when carbohydrate was ingested as a single bolus toward the end of exercise (105.6 ± 3.0 vs. 96.4 ± 5.0 min, respectively; Δ 9.3 min, 95% confidence interval [2.8, 15.8] min). A moderate positive correlation was apparent between the magnitude of glycogen sparing over the first 75 min and the improvement in running capacity (r = .58), with no significant difference in muscle glycogen concentrations at the point of exhaustion. This study indicates that failure to ingest carbohydrates from the outset of prolonged running increases reliance on limited endogenous muscle glycogen stores-the ergolytic effects of which cannot be rectified by subsequent carbohydrate ingestion late in exercise.

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., (© Endocrine Society 2019.)

Background: At rest, omission of breakfast lowers daily energy intake, but also lowers energy expenditure, attenuating any effect on energy balance. The effect of breakfast omission on energy balance when exercise is prescribed is unclear., Objectives: The aim of this study was to assess the effect on 24-h energy balance of omitting compared with consuming breakfast prior to exercise., Methods: Twelve healthy physically active young men (age 23 ± 3 y, body mass index 23.6 ± 2.0 kg/m2) completed 3 trials in a randomized order (separated by >1 week): a breakfast of oats and milk (431 kcal; 65 g carbohydrate, 11 g fat, 19 g protein) followed by rest (BR); breakfast before exercise (BE; 60 min cycling at 50 % peak power output); and overnight fasting before exercise (FE). The 24-h energy intake was calculated based on the food consumed for breakfast, followed by an ad libitum lunch, snacks, and dinner. Indirect calorimetry with heart-rate accelerometry was used to measure substrate utilization and 24-h energy expenditure. A [6,6-2H2]glucose infusion was used to investigate tissue-specific carbohydrate utilization., Results: The 24-h energy balance was -400 kcal (normalized 95% CI: -230, -571 kcal) for the FE trial; this was significantly lower than both the BR trial (492 kcal; normalized 95% CI: 332, 652 kcal) and the BE trial (7 kcal; normalized 95% CI: -153, 177 kcal; both P < 0.01 compared with FE). Plasma glucose utilization in FE (mainly representing liver glucose utilization) was positively correlated with energy intake compensation at lunch (r = 0.62, P = 0.03), suggesting liver carbohydrate plays a role in postexercise energy-balance regulation., Conclusions: Neither exercise energy expenditure nor restricted energy intake via breakfast omission were completely compensated for postexercise. In healthy men, pre-exercise breakfast omission creates a more negative daily energy balance and could therefore be a useful strategy to induce a short-term energy deficit. This trial was registered at clinicaltrials.gov as NCT02258399., (Copyright © American Society for Nutrition 2019.)

Objective: To examine (i) the associations between physical activity dimensions, cardiorespiratory fitness and body composition and, (ii) the associations between physical activity dimensions, cardiorespiratory fitness, body composition and biomarkers of cardiometabolic health in persons with spinal cord injury (SCI)., Methods: A cross-sectional prospective cohort study with 7-day follow-up was conducted. Body composition, cardiorespiratory fitness and biomarkers of cardiometabolic health were measured in thirty-three participants with SCI (> 1 year post injury). Physical activity dimensions were objectively assessed over 7-days., Results: Activity energy expenditure (r =.43), physical activity level (r =.39), and moderate-to-vigorous physical activity (MVPA) (r =.48) were significantly (P < 0.001) associated with absolute (L/min) peak oxygen uptake (⩒O 2 peak). ⩒O 2 peak was significantly higher in persons performing ≥150 MVPA minutes/week compared to <40 minutes/week (P = 0.003). Individual physical activity dimensions were not significantly associated with biomarkers of cardiometabolic health. However, body composition characteristics (BMI, waist and hip circumference) showed significant (P < 0.04), moderate (r >.30) associations with parameters of metabolic regulation, lipid profiles and inflammatory biomarkers. Relative ⩒O 2 peak (ml/kg/min) was moderately associated with only insulin sensitivity (r = 0.37, P = 0.03)., Conclusions: Physical activity dimensions are associated with cardiorespiratory fitness; however, stronger and more consistent associations suggest that poor cardiometabolic health is associated with higher body fat content. Given these findings, the regulation of energy balance should be an important consideration for researchers and clinicians looking to improve cardiometabolic health in persons with SCI.

The aim of this study was to characterize postprandial glucose flux after exercise in the fed versus overnight fasted state and to investigate the potential underlying mechanisms. In a randomized order, twelve men underwent breakfast-rest [(BR) 3 h semirecumbent], breakfast-exercise [(BE) 2 h semirecumbent before 60 min of cycling (50% peak power output)], and overnight fasted exercise [(FE) as per BE omitting breakfast] trials. An oral glucose tolerance test (OGTT) was completed after exercise (after rest on BR). Dual stable isotope tracers ([U- 13 C] glucose ingestion and [6,6- 2 H 2 ] glucose infusion) and muscle biopsies were combined to assess postprandial plasma glucose kinetics and intramuscular signaling, respectively. Plasma intestinal fatty acid binding (I-FABP) concentrations were determined as a marker of intestinal damage. Breakfast before exercise increased postexercise plasma glucose disposal rates during the OGTT, from 44 g/120 min in FE {35 to 53 g/120 min [mean (normalized 95% confidence interval)] to 73 g/120 min in BE [55 to 90 g/120 min; P = 0.01]}. This higher plasma glucose disposal rate was, however, offset by increased plasma glucose appearance rates (principally OGTT-derived), resulting in a glycemic response that did not differ between BE and FE ( P = 0.11). Plasma I-FABP concentrations during exercise were 264 pg/ml (196 to 332 pg/ml) lower in BE versus FE ( P = 0.01). Breakfast before exercise increases postexercise postprandial plasma glucose disposal, which is offset (primarily) by increased appearance rates of orally ingested glucose. Therefore, metabolic responses to fed-state exercise cannot be readily inferred from studies conducted in a fasted state.

Objective: To assess the influence of a home-based exercise intervention on indices of health-related quality of life (HRQOL) in persons with spinal cord injury (SCI)., Design: This was a randomized controlled trial (HOMEX-SCI; ISRCTN57096451). After baseline laboratory testing and a week of free-living physical activity monitoring, eligible participants were randomly assigned (2:1 allocation ratio) to a home-based moderate-intensity upper-body exercise intervention group (INT, n=13), or a lifestyle maintenance control group (CON, n=8), for 6 weeks., Setting: Home-based with short laboratory visits immediately before and after the intervention/control period., Participants: Inactive participants (N=21) with chronic (>1yr) SCI (injury level

Purpose: Breaking prolonged sitting reduces postprandial glucose and insulin concentrations and influences skeletal muscle molecular signaling pathways, but it is unknown whether breaking sitting also affects adipose tissue., Methods: Eleven central overweight participants (seven men and four postmenopausal women) 50 ± 5 yr old (mean ± SD) completed two mixed-meal feeding trials (prolonged sitting vs breaking sitting) in a randomized, counterbalanced design. The breaking sitting intervention comprised walking for 2 min every 20 min over 5.5 h. Blood samples were collected at regular intervals to examine metabolic biomarkers and adipokine concentrations. Adipose tissue samples were collected at baseline and at 5.5 h to examine changes in mRNA expression and secretion of selected adipokines ex vivo., Results: Postprandial glycemia and insulinemia were attenuated by approximately 50% and 40% in breaking sitting compared with prolonged sitting (iAUC: 359 ± 117 vs 697 ± 218 mmol per 330 min·L, P = 0.001, and 202 ± 71 vs 346 ± 150 nmol per 330 min·L, P = 0.001, respectively). Despite these pronounced and sustained differences in postprandial glucose and insulin concentrations, adipose tissue mRNA expression for various genes (interleukin 6, leptin, adiponectin, pyruvate dehydrogenase kinase isozyme 4, insulin receptor substrates 1 and 2, phosphoinositide 3-kinase, and RAC-alpha serine/threonine-protein kinase) and ex vivo adipose tissue secretion of interleukin 6, leptin, and adiponectin were not different between trials., Conclusions: This study demonstrates that breaking sitting with short bouts of physical activity has very pronounced effects on systemic postprandial glucose and insulin concentrations, but this does not translate into corresponding effects within adipose tissue.

New Findings: What is the central question of this study? Glucagon-like peptide-1 (GLP-1) is an important obesity/diabetes target, with effects dependent on circulating GLP-1 concentrations. Peripheral tissues extract GLP-1; therefore, sampling venous versus arterialized blood might provide different GLP-1 concentrations. This study examined whether arterialization alters GLP-1 concentrations during fasting and feeding. What is the main finding and its importance? This study demonstrates that venous blood provides lower postprandial but not fasting GLP-1 concentrations versus arterialized blood. Therefore, when accurate assessment of postprandial peripheral availability of GLP-1 is required, blood sampling methods should be considered carefully, reported clearly, and arterialization is recommended., Abstract: Glucagon-like peptide-1 (GLP-1) displays concentration-dependent effects on metabolism, appetite and angiogenesis; therefore, accurate determination of circulating GLP-1 concentrations is important. In this study, we compared GLP-1 concentrations in venous versus arterialized blood in both fasted and fed conditions. Venous and arterialized blood samples were obtained simultaneously from 10 young, healthy men before and 30, 60 and 120 min after ingestion of 75 g glucose. Plasma GLP-1 concentrations increased in response to glucose ingestion (time effect, P < 0.01) and to a lesser extent in venous versus arterialized plasma (time × arterialization interaction, P < 0.01). Accordingly, the plasma incremental area under the curve was lower in venous versus arterialized plasma (974 ± 88 versus 1214 ± 115 pmol l (120 min) -1 , respectively, P = 0.049). In the postprandial state, there was a positive relationship between arterialized GLP-1 concentrations and the venous-arterialized difference in GLP-1 concentrations (r 2  = 0.51; P < 0.01). Both arterialized and venous peak GLP-1 concentrations showed positive relationships with peak arterialized insulin concentrations (both r 2  > 0.6, P < 0.01). Venous sampling results in lower concentrations of GLP-1 in the postprandial but not the fasted state compared with arterialized blood. This absolute difference is biologically meaningful and is magnified when GLP-1 availability is high. Therefore, sampling from arterialized blood may provide a better chance of detecting small differences in postprandial GLP-1 availability with interventions. If absolute GLP-1 concentrations are of interest, the blood sampling method should be considered carefully and reported clearly., (© 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.)

Circadian regulation of transcriptional processes has a broad impact on cell metabolism. Here, we compared the diurnal transcriptome of human skeletal muscle conducted on serial muscle biopsies in vivo with profiles of human skeletal myotubes synchronized in vitro. More extensive rhythmic transcription was observed in human skeletal muscle compared to in vitro cell culture as a large part of the in vivo mRNA rhythmicity was lost in vitro. siRNA-mediated clock disruption in primary myotubes significantly affected the expression of ~8% of all genes, with impact on glucose homeostasis and lipid metabolism. Genes involved in GLUT4 expression, translocation and recycling were negatively affected, whereas lipid metabolic genes were altered to promote activation of lipid utilization. Moreover, basal and insulin-stimulated glucose uptake were significantly reduced upon CLOCK depletion. Our findings suggest an essential role for the circadian coordination of skeletal muscle glucose homeostasis and lipid metabolism in humans., Competing Interests: LP, UL, SC, NH, LI, JW, IT, KS, DT, KT, MR, CH, HR, JJ, ED, FG, EL, CD No competing interests declared, CG Is a full-time employee of the Nestlé Institute of Health Sciences SA. BW Benjamin D Weger: Is a full-time employee of the Nestlé Institute of Health Sciences SA. EM Eugenia Migliavacca: Is a full-time employee of the Nestlé Institute of Health Sciences SA. AC Aline Charpagne: Is a full-time employee of the Nestlé Institute of Health Sciences SA. JB Has been a consultant for PepsiCo (Quaker) and Kellogg's. JF Jerome N Feige: Is a full-time employee of the Nestlé Institute of Health Sciences SA. LK Is an employee of Nestec Ltd., (© 2018, Perrin et al.)

Background: Short-term overfeeding combined with reduced physical activity impairs metabolic function and alters the expression of key genes within adipose tissue. We have shown that daily vigorous-intensity running can prevent these changes independent of any net effect on energy imbalance. However, which type, intensity and/or duration of exercise best achieves these benefits remains to be ascertained., Methods/design: Forty-eight healthy young men will be recruited and randomly allocated to one of four experimental conditions for 1 week: (1) to ingest 50% more energy than normal by over-consuming their habitual diet whilst simultaneously restricting their physical activity below 4000 steps day -1 (i.e. energy surplus; SUR group); (2) the same regimen but with a daily 45-min bout of vigorous-intensity arm crank ergometry at 70% of maximum oxygen uptake (SUR + ARM group); (3) the same regimen but with a daily 45-min bout of moderate-intensity treadmill walking at 50% of maximum oxygen uptake (SUR + MOD group); (4) the same regimen but with the addition of intermittent short bouts of walking during waking hours (SUR + BREAKS group). Critically, all exercise groups will receive additional dietary energy intake to account for the energy expended by exercise, thus maintaining a matched energy surplus. At baseline and follow-up, fasted blood samples, abdominal subcutaneous adipose tissue and skeletal muscle biopsies will be obtained and oral glucose tolerance tests conducted., Discussion: This study will establish the impact of different forms of daily exercise on metabolic function at the whole-body level as well as within adipose tissue and skeletal muscle in the context of a standardised energy surplus., Trial Registration: ISRCTN, ISRCTN18311163 . Registered on 24 June 2015.

Background: Prior studies have shown that intermittent fasting is capable of producing improvements in body weight and fasted health markers. However, the extent to which intermittent fasting incurs compensatory changes in the components of energy balance and its impact on postprandial metabolism are yet to be ascertained., Methods: A total of 30-36 lean participants and 30-36 overweight/obese participants will be recruited to provide two separate study groups who will undergo the same protocol. Following an initial assessment of basic anthropometry and key health markers, measurements of habitual energy intake (weighed food and fluid intake) and physical activity energy expenditure (combined heart rate and accelerometry) will be obtained over 4 weeks under conditions of energy balance. Participants will then be randomly allocated to one of three experimental conditions for 20 days, namely (1) daily calorie restriction (reduce habitual daily energy intake by 25%), (2) intermittent fasting with calorie restriction (alternate between 24-hour periods of fasting and feeding to 150% of habitual daily energy intake), (3) intermittent fasting without calorie restriction (alternate between 24-hour periods of fasting and feeding to 200% of habitual daily energy intake). In addition to continued monitoring of energy intake and physical activity during the intervention, participants will report for laboratory-based assessments of various metabolic parameters both before and after the intervention. Specifically, fasting and postprandial measurements of resting metabolic rate, substrate oxidation, appetite, food preference, and plasma concentrations of key metabolites and hormones will be made, in addition to subcutaneous abdominal adipose tissue biopsies in the fasted state and an assessment of body composition via dual-energy x-ray absorptiometry., Discussion: Comparing observed changes in these measures across the three intervention arms in each group will establish the impact of intermittent fasting on postprandial metabolism and the components of energy balance in both lean and overweight/obese populations. Furthermore, this will be benchmarked against current nutritional interventions for weight management and the relative contributions of negative energy balance and fasting-dependent mechanisms in inducing any observed effects will be elucidated., Trial Registration: Trial retrospectively registered at clinicaltrials.gov under reference number NCT02498002 (version: IMF-02, date: July 6, 2015).

Purpose: Spinal cord injury (SCI) creates a complex pathology, characterized by low levels of habitual physical activity and an increased risk of cardiometabolic disease. This study aimed to assess the effect of a moderate-intensity upper-body exercise training intervention on biomarkers of cardiometabolic component risks, adipose tissue metabolism, and cardiorespiratory fitness in persons with SCI., Methods: Twenty-one inactive men and women with chronic (>1 yr) SCI (all paraplegic injuries) 47 ± 8 yr of age (mean ± SD) were randomly allocated to either a 6-wk prescribed home-based exercise intervention (INT; n = 13) or control group (CON; n = 8). Participants assigned to the exercise group completed 4 × 45-min moderate-intensity (60%-65% peak oxygen uptake (V˙O2peak)) arm-crank exercise sessions per week. At baseline and follow-up, fasted and postload blood samples (collected during oral glucose tolerance tests) were obtained to measure metabolic regulation and biomarkers of cardiovascular disease. Abdominal subcutaneous adipose tissue biopsies were also obtained, and cardiorespiratory fitness was assessed., Results: Compared with CON, INT significantly decreased (P = 0.04) serum fasting insulin (Δ, 3.1 ± 10.7 pmol·L for CON and -12.7 ± 18.7 pmol·L for INT) and homeostasis model assessment of insulin resistance (HOMA2-IR; Δ, 0.06 ± 0.20 for CON and -0.23 ± 0.36 for INT). The exercise group also increased V˙O2peak (Δ, 3.4 mL·kg·min; P ≤ 0.001). Adipose tissue metabolism, composite insulin sensitivity index (C-ISIMatsuda), and other cardiovascular disease risk biomarkers were not different between groups., Conclusions: Moderate-intensity upper-body exercise improved aspects of metabolic regulation and cardiorespiratory fitness. Changes in fasting insulin and HOMA2-IR, but not C-ISIMatsuda, suggest improved hepatic but not peripheral insulin sensitivity after 6 wk of exercise training in persons with chronic paraplegia.

Circadian clocks play an important role in lipid homeostasis, with impact on various metabolic diseases. Due to the central role of skeletal muscle in whole-body metabolism, we aimed at studying muscle lipid profiles in a temporal manner. Moreover, it has not been shown whether lipid oscillations in peripheral tissues are driven by diurnal cycles of rest-activity and food intake or are able to persist in vitro in a cell-autonomous manner. To address this, we investigated lipid profiles over 24 h in human skeletal muscle in vivo and in primary human myotubes cultured in vitro. Glycerolipids, glycerophospholipids, and sphingolipids exhibited diurnal oscillations, suggesting a widespread circadian impact on muscle lipid metabolism. Notably, peak levels of lipid accumulation were in phase coherence with core clock gene expression in vivo and in vitro. The percentage of oscillating lipid metabolites was comparable between muscle tissue and cultured myotubes, and temporal lipid profiles correlated with transcript profiles of genes implicated in their biosynthesis. Lipids enriched in the outer leaflet of the plasma membrane oscillated in a highly coordinated manner in vivo and in vitro. Lipid metabolite oscillations were strongly attenuated upon siRNA-mediated clock disruption in human primary myotubes. Taken together, our data suggest an essential role for endogenous cell-autonomous human skeletal muscle oscillators in regulating lipid metabolism independent of external synchronizers, such as physical activity or food intake., Competing Interests: Conflict of interest statement: B.D.W. and F.G. are employees of Nestlé Institute of Health Sciences SA; L.G.K. is an employee of Nestec Ltd. J.A.B. has been a consultant for PepsiCo (Quaker) and Kellogg’s. The other authors have no conflict of interest to declare.

Feeding profoundly affects metabolic responses to exercise in various tissues, but the effect of feeding status on human adipose tissue responses to exercise has never been studied. Ten healthy overweight men aged 26 ± 5 yr (mean ± SD) with a waist circumference of 105 ± 10 cm walked at 60% of maximum oxygen uptake under either fasted or fed conditions in a randomized, counterbalanced design. Feeding comprised 648 ± 115 kcal 2 h before exercise. Blood samples were collected at regular intervals to examine changes in metabolic parameters and adipokine concentrations. Adipose tissue samples were obtained at baseline and 1 h after exercise to examine changes in adipose tissue mRNA expression and secretion of selected adipokines ex vivo. Adipose tissue mRNA expression of pyruvate dehydrogenase kinase isozyme 4 ( PDK4 ), adipose triglyceride lipase, hormone-sensitive lipase ( HSL ), fatty acid translocase/CD36, glucose transporter type 4 ( GLUT4 ), and insulin receptor substrate 2 ( IRS2 ) in response to exercise were lower in fed compared with fasted conditions (all P ≤ 0.05). Postexercise adipose IRS2 protein was affected by feeding ( P ≤ 0.05), but Akt2, AMPK, IRS1, GLUT4, PDK4, and HSL protein levels were not different. Feeding status did not impact serum and ex vivo adipose secretion of IL-6, leptin, or adiponectin in response to exercise. This is the first study to show that feeding before acute exercise affects postexercise adipose tissue gene expression, and we propose that feeding is likely to blunt long-term adipose tissue adaptation to regular exercise., (Copyright © 2017 the American Physiological Society.)

Oral glucose tolerance and insulin sensitivity are common measures, but are determined using various blood sampling methods, employed under many different experimental conditions. This study established whether measures of oral glucose tolerance and oral glucose-derived insulin sensitivity (insulin sensitivity indices; ISI) differ when calculated from venous v. arterialised blood. Critically, we also established whether any differences between sampling methods are consistent across distinct metabolic conditions (after rest v. after exercise). A total of ten healthy men completed two trials in a randomised order, each consisting of a 120-min oral glucose tolerance test (OGTT), either at rest or post-exercise. Blood was sampled simultaneously from a heated hand (arterialised) and an antecubital vein of the contralateral arm (venous). Under both conditions, glucose time-averaged AUC was greater from arterialised compared with venous plasma but importantly, this difference was larger after rest relative to after exercise (0·99 (sd 0·46) v. 0·56 (sd 0·24) mmol/l, respectively; P<0·01). OGTT-derived ISIMatsuda and ISICederholm were lower when calculated from arterialised relative to venous plasma and the arterialised-venous difference was greater after rest v. after exercise (ISIMatsuda: 1·97 (sd 0·81) v. 1·35 (sd 0·57) arbitrary units (au), respectively; ISICederholm : 14·76 (sd 7·83) v. 8·70 (sd 3·95) au, respectively; both P<0·01). Venous blood provides lower postprandial glucose concentrations and higher estimates of insulin sensitivity, compared with arterialised blood. Most importantly, these differences between blood sampling methods are not consistent after rest v. post-exercise, preventing standardised venous-to-arterialised corrections from being readily applied.

This study aimed to establish whether vigorous-intensity exercise offers additional adipose-related health benefits and metabolic improvements compared to energy-matched moderate-intensity exercise. Thirty-eight sedentary overweight men (n = 24) and postmenopausal women (n = 14) aged 52 ± 5 years (mean ± standard deviations [SD]) were prescribed a 3-week energy deficit (29302 kJ∙week -1 ) achieved by increased isocaloric moderate or vigorous-intensity exercise (+8372 kJ∙week -1 ) and simultaneous restricted energy intake (-20930 kJ∙week -1 ). Participants were randomly assigned to either an energy-matched vigorous (VIG; n = 18) or moderate (MOD; n = 20) intensity exercise group (five times per week at 70% or 50% maximal oxygen uptake, respectively). At baseline and follow-up, fasted blood samples and abdominal subcutaneous adipose tissue biopsies were obtained and oral glucose tolerance tests conducted. Body mass was reduced similarly in both groups (∆ 2.4 ± 1.1 kg and ∆ 2.4 ± 1.4 kg, respectively, P < 0.05). Insulinemic responses to a standard glucose load decreased similarly at follow-up relative to baseline in VIG (∆ 8.6 ± 15.4 nmol.120 min.l -1 ) and MOD (∆ 5.4 ± 8.5 nmol.120 min.l -1 ; P < 0.05). Expression of SREBP-1c and FAS in adipose tissue was significantly down-regulated, whereas expression of PDK4 and hormone-sensitive lipase (HSL) was significantly up-regulated in both groups (P < 0.05). Thus, when energy expenditure and energy deficit are matched, vigorous or moderate-intensity exercise combined with energy restriction provide broadly similar (positive) changes in metabolic control and adipose tissue gene expression., (© 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Background: Spinal cord injury (SCI) creates a complex pathology that can lead to an increase in sedentary behaviours and deleterious changes in body composition. Consequently, individuals with SCI are at increased risk of developing cardiovascular disease and type-2 diabetes mellitus. While the role of physical activity on the reduction of chronic disease risk is well documented in non-disabled individuals the evidence is less conclusive for persons with SCI. The aim of this methodological paper is to outline the design of a study that will assess the role of a home-based exercise intervention on biomarkers of metabolic and cardiovascular health in persons with SCI: the HOMEX-SCI study., Methods/design: Eligible participants will be inactive (physical activity level ≤1.60) individuals, with a chronic (more than 1 year) spinal cord lesion between the second thoracic and the fifth lumbar vertebrae, and aged between 18 and 65 years. Following baseline laboratory testing and lifestyle monitoring, participants will be randomly allocated to a control (CON) group or a 6-week home-based exercise intervention (INT) group. The INT consists of 45 minutes of moderate-intensity (60-65 % peak oxygen uptake) arm-crank exercise four times per week. Participants assigned to the CON group will be asked to maintain their normal lifestyle. The main outcomes of this study (biomarkers of metabolic and cardiovascular health) are obtained from venous blood samples, collected in the fasted and postprandial state. Eight other measurement categories will be assessed: (1) body composition, (2) physical activity, (3) energy intake, (4) measures of health and wellbeing, (5) resting metabolic rate, heart rate and blood pressure, (6) aerobic capacity, (7) immune function, and (8) adipose tissue gene expression., Discussion: This study will explore the feasibility of home-based moderate-intensity exercise and ascertain its impact on metabolic and cardiovascular health in comparison to a lifestyle maintenance CON group. Findings from this study may help to inform new evidence-based physical activity guidelines and also help to elucidate the physiological mechanisms whereby exercise might exert beneficial effects in persons with chronic SCI. The results will also act as a scientific platform for further intervention studies in other diverse and at-risk populations., Trial Registration: International Standard Randomised Controlled Trial Number: ISRCTN57096451 . Registered on 11 July 2014.

Aim: To assess the error in predicting physical activity energy expenditure (PAEE), using a multisensor device in wheelchair users, and to examine the efficacy of using an individual heart rate calibration (IC) method., Methods: 15 manual wheelchair users (36±10 years, 72±11 kg) completed 10 activities: resting, folding clothes, wheelchair propulsion on a 1% gradient (3456 and 7 km/h) and propulsion at 4 km/h (with an additional 8% of body mass, 2% and 3% gradient) on a motorised wheelchair treadmill. Criterion PAEE was measured using a computerised indirect calorimetry system. Participants wore a combined accelerometer and heart rate monitor (Actiheart). They also performed an incremental arm crank ergometry test to exhaustion which permitted retrospective individual calibration of the Actiheart for the activity protocol. Linear regression analysis was conducted between criterion (indirect calorimetry) and estimated PAEE from the Actiheart using the manufacturer's proprietary algorithms (group calibration, GC) or IC. Bland-Altman plots were used and mean absolute error was calculated to assess the agreement between criterion values and estimated PAEE., Results: Predicted PAEE was significantly (p<0.01) correlated with criterion PAEE (GC, r=0.76 and IC, r=0.95). The absolute bias ±95% limits of agreement were 0.51±3.75 and -0.22±0.96 kcal/min for GC and IC, respectively. Mean absolute errors across the activity protocol were 51.4±38.9% using GC and 16.8±15.8% using IC., Summary: PAEE can be accurately and precisely estimated using a combined accelerometer and heart rate monitor device, with integration of an IC. Interindividual variance in cardiovascular function and response to exercise is high in this population. Therefore, in manual wheelchair users, we advocate the use of an IC when using the Actiheart to predict PAEE.

Purpose: To assess the validity of two accelerometer devices, at two different anatomical locations, for the prediction of physical activity energy expenditure (PAEE) in manual wheelchair users (MWUs)., Methods: Seventeen MWUs (36 ± 10 yrs, 72 ± 11 kg) completed ten activities; resting, folding clothes, propulsion on a 1% gradient (3,4,5,6 and 7 km·hr-1) and propulsion at 4km·hr-1 (with an additional 8% body mass, 2% and 3% gradient) on a motorised wheelchair treadmill. GT3X+ and GENEActiv accelerometers were worn on the right wrist (W) and upper arm (UA). Linear regression analysis was conducted between outputs from each accelerometer and criterion PAEE, measured using indirect calorimetry. Subsequent error statistics were calculated for the derived regression equations for all four device/location combinations, using a leave-one-out cross-validation analysis., Results: Accelerometer outputs at each anatomical location were significantly (p < .01) associated with PAEE (GT3X+-UA; r = 0.68 and GT3X+-W; r = 0.82. GENEActiv-UA; r = 0.87 and GENEActiv-W; r = 0.88). Mean ± SD PAEE estimation errors for all activities combined were 15 ± 45%, 14 ± 50%, 3 ± 25% and 4 ± 26% for GT3X+-UA, GT3X+-W, GENEActiv-UA and GENEActiv-W, respectively. Absolute PAEE estimation errors for devices varied, 19 to 66% for GT3X+-UA, 17 to 122% for GT3X+-W, 15 to 26% for GENEActiv-UA and from 17.0 to 32% for the GENEActiv-W., Conclusion: The results indicate that the GENEActiv device worn on either the upper arm or wrist provides the most valid prediction of PAEE in MWUs. Variation in error statistics between the two devices is a result of inherent differences in internal components, on-board filtering processes and outputs of each device.

Background and Aims: We investigated whether objectively measured sedentary time was associated with markers of inflammation in adults with newly diagnosed type 2 diabetes., Methods and Results: We studied 285 adults (184 men, 101 women, mean age 59.0 ± 9.7) who had been recruited to the Early ACTivity in Diabetes (Early ACTID) randomised controlled trial. C-reactive protein (CRP), adiponectin, soluble intracellular adhesion molecule-1 (sICAM-1), interleukin-6 (IL-6), and accelerometer-determined sedentary time and moderate-vigorous physical activity (MVPA) were measured at baseline and after six-months. Linear regression analysis was used to investigate the independent cross-sectional and longitudinal associations of sedentary time with markers of inflammation. At baseline, associations between sedentary time and IL-6 were observed in men and women, an association that was attenuated following adjustment for waist circumference. After 6 months of follow-up, sedentary time was reduced by 0.4 ± 1.2 h per day in women, with the change in sedentary time predicting CRP at follow-up. Every hour decrease in sedentary time between baseline and six-months was associated with 24% (1, 48) lower CRP. No changes in sedentary time between baseline and 6 months were seen in men., Conclusions: Higher sedentary time is associated with IL-6 in men and women with type 2 diabetes, and reducing sedentary time is associated with improved levels of CRP in women. Interventions to reduce sedentary time may help to reduce inflammation in women with type 2 diabetes., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Inflammation plays a major role in diabetes-associated cardiovascular disease (CVD). There is uncertainty whether diet and physical activity interventions can be successfully integrated into healthcare settings and reduce markers of inflammation and risk of CVD in patients with type 2 diabetes (T2D)., Methods and Results: Systemic markers of inflammation were determined in a 12-month, real-world, multicenter, randomized, controlled trial that investigated the effect of diet, diet plus physical activity, and usual care in 593 individuals with newly diagnosed T2D. During the first 6 months, serum C-reactive protein (CRP) improved by -21 (-36 to -1.4)% and -22 (-38 to -3.1)% in diet and diet plus physical activity arms versus usual care. There were also improvements in adiponectin and soluble intercellular adhesion molecule-1 (sICAM-1). Though medication-adjusted CRP was improved between 6 and 12 months for usual care, both interventions were more successful in reducing the relative risk of a high-risk CRP level of >3 mg/L (risk ratios of 0.72 [0.55 to 0.95] for diet versus usual care and 0.67 [0.50 to 0.90] for diet plus activity versus usual care). Furthermore, sICAM-1 (a marker of vascular risk), remained substantially lower than usual care in both intervention arms at 12 months., Conclusions: Motivational, unsupervised diet and/or diet plus physical activity interventions given soon after diagnosis in real-world healthcare settings improve markers of inflammation and cardiovascular risk in patients with T2D, even after accounting for the effect of adjustments to medication to try and control blood pressure, glycated hemoglobin, and lipids., Clinical Trial Registration Url: http://www.controlled-trials.com/. Unique identifier: ISRCTN92162869.

Physical activity can affect many aspects of metabolism but it is unclear to what extent this relies on manipulation of energy balance. Twenty-six active men age 25 ± 7 years (mean ± SD) were randomly assigned either to consume 50% more energy than normal by over-consuming their habitual diet for 7 days whilst simultaneously restricting their physical activity below 4000 steps day(-1) to induce an energy surplus (SUR group; n = 14) or to the same regimen but with 45 min of daily treadmill running at 70% of maximum oxygen uptake (SUR+EX group; n = 12). Critically, the SUR+EX group received additional dietary energy intake to account for the energy expended by exercise, thus maintaining a matched energy surplus. At baseline and follow-up, fasted blood samples and abdominal subcutaneous adipose tissue biopsies were obtained and oral glucose tolerance tests conducted. Insulinaemic responses to a standard glucose load increased 2-fold from baseline to follow-up in the SUR group (17 ± 16 nmol (120 min) l(-1); P = 0.002) whereas there was no change in the SUR+EX group (1 ± 6 nmol (120 min) l(-1)). Seven of 17 genes within adipose tissue were differentially expressed in the SUR group; expression of SREBP-1c, FAS and GLUT4 was significantly up-regulated and expression of PDK4, IRS2, HSL and visfatin was significantly down-regulated (P ≤ 0.05). The pAMPK/AMPK protein ratio in adipose tissue was significantly down-regulated in the SUR group (P = 0.005). Vigorous-intensity exercise counteracted most of the effects of short-term overfeeding and under-activity at the whole-body level and in adipose tissue, even in the face of a standardised energy surplus.

Proteins of the CLCA gene family including the human ClCa1 (hClCa1) have been suggested to constitute a new family of chloride channels mediating Ca(2+)-dependent Cl- currents. The present study examines the relationship between the hClCa1 protein and Ca(2+)-dependent Cl- currents using heterologous expression of hClCa1 in HEK293 and NCIH522 cell lines and whole cell recordings. By contrast to previous reports claiming the absence of Cl- currents in HEK293 cells, we find that HEK293 and NCIH522 cell lines express constitutive Ca(2+)-dependent Cl- currents and show that hClCa1 increases the amplitude of Ca(2+)-dependent Cl- currents in those cells. We further show that hClCa1 does not modify the permeability sequence but increases the Cl- conductance while decreasing the G(SCN-)/G(Cl-) conductance ratio from approximately 2-3 to approximately 1. We use an Eyring rate theory (two barriers, one site channel) model and show that the effect of hClCa1 on the anionic channel can be simulated by its action on lowering the first and the second energy barriers. We conclude that hClCa1 does not form Ca(2+)-dependent Cl- channels per se or enhance the trafficking/insertion of constitutive channels in the HEK293 and NCIH522 expression systems. Rather, hClCa1 elevates the single channel conductance of endogenous Ca(2+)-dependent Cl- channels by lowering the energy barriers for ion translocation through the pore.

Background: Physical activity (including exercise) is prescribed for health and there are various recommendations that can be used to gauge physical activity status. The objective of the current study was to determine whether twelve commonly-used physical activity recommendations similarly classified middle-aged men as sufficiently active for general health., Methods and Findings: We examined the commonality in the classification of physical activity status between twelve variations of physical activity recommendations for general health in ninety men aged 45-64 years. Physical activity was assessed using synchronised accelerometry and heart rate. Using different guidelines but the same raw data, the proportion of men defined as active ranged from to 11% to 98% for individual recommendations (median 73%, IQR 30% to 87%). There was very poor absolute agreement between the recommendations, with an intraclass correlation coefficient (A,1) of 0.24 (95% CI, 0.15 to 0.34). Only 8% of men met all 12 recommendations and would therefore be unanimously classified as active and only one man failed to meet every recommendation and would therefore be unanimously classified as not sufficiently active. The wide variability in physical activity classification was explained by ostensibly subtle differences between the 12 recommendations for thresholds related to activity volume (time or energy), distribution (e.g., number of days of the week), moderate intensity cut-point (e.g., 3 vs. 4 metabolic equivalents or METs), and duration (including bout length)., Conclusions: Physical activity status varies enormously depending on the physical activity recommendation that is applied and even ostensibly small differences have a major impact. Approximately nine out of every ten men in the present study could be variably described as either active or not sufficiently active. Either the effective dose or prescription that underlies each physical activity recommendation is different or each recommendation is seeking the same prescriptive outcome but with variable success.

The aryl hydrocarbon receptor nuclear translocator (ARNT) and cathepsin K (CTSK) genes lie in a tandem head-to-tail arrangement on human chromosome 1. The two genes are in extremely close proximity; the usual CTSK transcription start site is less than 1.4 kb downstream of the end of the longest reported ARNT transcript. By generating an RT-PCR product that overlaps both the 3' end of ARNT and the 5' end of CTSK, we show that ARNT transcripts may extend through the ARNT-CTSK intergenic region and progress into the CTSK gene. Furthermore, by using quantitative RT-PCR from several tissues to detect the ARNT expression signature in CTSK introns, we show that ARNT transcripts can read through into CTSK as far as CTSK intron 3, extending approximately 3.7 kb downstream of the end of the longest previously described ARNT mRNA. Given that ARNT and CTSK are expressed in an overlapping range of tissues, ARNT read-through may have a negative impact on CTSK transcript levels by interfering with CTSK expression. We also present evidence for novel CTSK transcripts following sequence analysis of CTSK-derived ESTs and RT-PCR products. These transcripts show alternate 5' splicing and or 5' extension and are sometimes initiated from a cryptic alternative promoter which is upstream of the known CTSK promoter and possibly in the 3' UTR of ARNT.

The human tissue distribution of the nineteen known human regulators of G-protein signaling (RGS) is described. Measurement of RGS mRNA levels in human brain and in nine peripheral tissues revealed striking tissue preferences in gene expression. Five RGS members were identified with enriched expression in brain. RGS4, RGS7, RGS8, RGS11 and RGS17 were all significantly expressed in striatal regions including the nucleus accumbens and putamen. RGS4 had the highest measured levels of mRNA expression and was highly enriched in the gyrus of the cortex and in the parahippocampus. RGS7 and RGS17 had overlapping distribution profiles and were both noticeably enriched in the cerebellum. Several RGS family members showed high expression in peripheral tissues. RGS5 was preferentially expressed in heart, and RGS1, RGS13, RGS18 and GAIP were predominately expressed in lymphocytes. RGS1 was also highly enriched in the lung, as was RGS2 and RGS16. Five family members, RGS3, RGS9, RGS10, RGS 12 and RGS14 had a broad and overlapping mRNA distribution. These results suggest roles of the individual RGS members in a diversity of functions in humans and support a role of several RGS members in the regulation of central nervous system function via modulation of signaling by G-protein coupled receptors.

Vanilloid receptor-1 (VR1, also known as TRPV1) is a thermosensitive, nonselective cation channel that is expressed by capsaicin-sensitive sensory afferents and is activated by noxious heat, acidic pH and the alkaloid irritant capsaicin. Although VR1 gene disruption results in a loss of capsaicin responses, it has minimal effects on thermal nociception. This and other experiments--such as those showing the existence of capsaicin-insensitive heat sensors in sensory neurons--suggest the existence of thermosensitive receptors distinct from VR1. Here we identify a member of the vanilloid receptor/TRP gene family, vanilloid receptor-like protein 3 (VRL3, also known as TRPV3), which is heat-sensitive but capsaicin-insensitive. VRL3 is coded for by a 2,370-base-pair open reading frame, transcribed from a gene adjacent to VR1, and is structurally homologous to VR1. VRL3 responds to noxious heat with a threshold of about 39 degrees C and is co-expressed in dorsal root ganglion neurons with VR1. Furthermore, when heterologously expressed, VRL3 is able to associate with VR1 and may modulate its responses. Hence, not only is VRL3 a thermosensitive ion channel but it may represent an additional vanilloid receptor subunit involved in the formation of heteromeric vanilloid receptor channels.