La actividad física en la gestión de la obesidad en adultos: una ponencia de Exercise and Sport Science Australia / Physical activity in the management of obesity in adults: A position statement from Exercise and Sport Science Australia / Atividade física no controle da obesidade em adultos: um documento da Exercise and Sport Science Australia

Resumen Esta ponencia examina las evidencias para la actividad física en la pérdida de peso y de adiposidad, la prevención del aumento de peso y la adiposidad, así como la recuperación de peso en adultos, y provee orientación sobre las implicaciones para los profesionales del ejercicio. La evidencia de la investigación indica que se requieren > 150 minutos, pero preferiblemente 300 minutos por semana de actividad aeróbica de intensidad al menos moderada para prevenir el aumento de peso y adiposidad, y al menos el extremo superior de esta gama de actividad para prevenir la recuperación de peso después de la pérdida de peso. Para que la pérdida de peso y adiposidad total sea significativa, se requiere un mínimo de 300 a 400 minutos por semana de actividad aeróbica de intensidad, al menos, moderada. La evidencia en torno al volumen de actividad física aeróbica requerida para reducir la adiposidad central está surgiendo, y las investigaciones apuntan a que puede ser sustancialmente menor que la que se requiere para la pérdida de peso. El impacto de la actividad física de alta intensidad y el ejercicio de resistencia para la gestión del peso es incierto. Durante las consultas para la gestión del peso, los profesionales en ejercicio deben aconsejar que se pueden lograr beneficios para la salud metabólica y cardiovascular por medio de la actividad física a cualquier peso, e independientemente del cambio de peso.

Abstract This Position Statement examines the evidence for physical activity in weight and adiposity loss, prevention of weight and adiposity gain, and in weight regain in adults, and provides guidance on implications for exercise practitioners. Research evidence indicates that >150 min but preferably 300 min per week of aerobic activity of at least moderate intensity is required to prevent weight and adiposity gain, and at least the upper end of this range of activity to prevent weight regain after weight loss. For meaningful weight and total adiposity loss, a minimum of 300-420 min per week of aerobic activity of at least moderate intensity is required. The evidence around the volume of aerobic physical activity required to reduce central adiposity is emerging, and research suggests that it may be substantially less than that required for weight loss. The impact of high-intensity physical activity and resistance exercise for weight management is uncertain. During consultations for weight management, exercise practitioners should advise that metabolic and cardiovascular health benefits can be achieved with physical activity at any weight, and irrespective of weight change.

Resumo Este documento examina as evidências da atividade física na perda de peso e adiposidade, na prevenção do ganho de peso e adiposidade e na recuperação de peso em adultos, e fornece orientações sobre as implicações para os profissionais do exercício físico. As evidências da pesquisa indicam que são necessários mais de 150 minutos, mas preferencialmente 300 minutos por semana de atividade aeróbica de intensidade moderada para evitar o ganho de peso e adiposidade, e pelo menos o extremo superior dessa gama de atividade para evitar o ganho de peso após a perda de peso. É necessário um mínimo de 300 a 400 minutos por semana de atividade aeróbica de intensidade moderada para uma perda significativa de peso e adiposidade total. Estão surgindo evidências sobre a quantidade de atividade física aeróbica necessária para reduzir a adiposidade central, e pesquisas sugerem que ela pode ser substancialmente menor do que a necessária para a perda de peso. O impacto da atividade física de alta intensidade e dos exercícios de resistência no controle de peso é incerto. Durante as consultas de controle de peso, os profissionais do exercício físico devem informar que os benefícios metabólicos e cardiovasculares à saúde podem ser obtidos por meio da atividade física em qualquer peso, independentemente da mudança de peso.

Adherence to a Mediterranean diet may improve serum adiponectin in adults with nonalcoholic fatty liver disease: The MEDINA randomized controlled trial.

Nonalcoholic fatty liver disease (NAFLD) affects approximately 30% of adults worldwide, with chronic low-grade inflammation being a key pathophysiological feature of progression. The Mediterranean diet (MedDiet) is recognized for improving metabolic and hepatic outcomes in people with diabetes and NAFLD, in part, via anti-inflammatory properties. The aim of this study was to determine the effect of an ad libitum MedDiet versus low-fat diet (LFD) on inflammatory markers in adults with NAFLD. It was hypothesized that the MedDiet, and its individual components, would improve inflammation. This multicenter, randomized controlled trial, randomized participants to a MedDiet or LFD intervention for 12 weeks. Primary outcomes included change from baseline to 12 weeks for serum high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-α, adiponectin, leptin, and resistin. Forty-two participants (60% female; age 52.3 ± 12.6 years; body mass index, 32.2 ± 6.2 kg/m²) were randomized to the MedDiet (n = 19) or low-fat diet (n = 23). At 12 weeks, the LFD showed a greater decrease in leptin compared with the MedDiet (-1.20 ± 3.9 ng/mL vs 0.64 ± 3.5 ng/mL, P = .010). Adiponectin significantly improved within the MedDiet (13.7 ± 9.2 µg/mL to 17.0 ± 12.5 µg/mL, P = .016), but not within the LFD group. No statistically significant changes were observed for other inflammatory markers following the MedDiet or LFD. Adherence to the MedDiet significantly improved in both study arms, although greater improvements were seen in the MedDiet group. Adiponectin significantly improved following a Mediterranean diet intervention, in the absence of weight loss. The low-fat diet did not elicit improvements in inflammatory markers. High-quality clinical trials appropriately powered to inflammatory markers are required in this population.

Exercise in the Management of Metabolic-Associated Fatty Liver Disease (MAFLD) in Adults: A Position Statement from Exercise and Sport Science Australia.

Metabolic-associated fatty liver disease (MAFLD) is the most prevalent chronic liver disease worldwide, affecting 25% of people globally and up to 80% of people with obesity. MAFLD is characterised by fat accumulation in the liver (hepatic steatosis) with varying degrees of inflammation and fibrosis. MAFLD is strongly linked with cardiometabolic disease and lifestyle-related cancers, in addition to heightened liver-related morbidity and mortality. This position statement examines evidence for exercise in the management of MAFLD and describes the role of the exercise professional in the context of the multi-disciplinary care team. The purpose of these guidelines is to equip the exercise professional with a broad understanding of the pathophysiological underpinnings of MAFLD, how it is diagnosed and managed in clinical practice, and to provide evidence- and consensus-based recommendations for exercise therapy in MAFLD management. The majority of research evidence indicates that 150-240 min per week of at least moderate-intensity aerobic exercise can reduce hepatic steatosis by ~ 2-4% (absolute reduction), but as little as 135 min/week has been shown to be effective. While emerging evidence shows that high-intensity interval training (HIIT) approaches may provide comparable benefit on hepatic steatosis, there does not appear to be an intensity-dependent benefit, as long as the recommended exercise volume is achieved. This dose of exercise is likely to also reduce central adiposity, increase cardiorespiratory fitness and improve cardiometabolic health, irrespective of weight loss. Resistance training should be considered in addition to, and not instead of, aerobic exercise targets. The information in this statement is relevant and appropriate for people living with the condition historically termed non-alcoholic fatty liver disease (NAFLD), regardless of terminology.

Effects of Cannabidiol on Exercise Physiology and Bioenergetics: A Randomised Controlled Pilot Trial.

BACKGROUND: Cannabidiol (CBD) has demonstrated anti-inflammatory, analgesic, anxiolytic and neuroprotective effects that have the potential to benefit athletes. This pilot study investigated the effects of acute, oral CBD treatment on physiological and psychological responses to aerobic exercise to determine its practical utility within the sporting context. METHODS: On two occasions, nine endurance-trained males (mean ± SD V̇O2max: 57.4 ± 4.0 mL·min-1·kg-1) ran for 60 min at a fixed intensity (70% V̇O2max) (RUN 1) before completing an incremental run to exhaustion (RUN 2). Participants received CBD (300 mg; oral) or placebo 1.5 h before exercise in a randomised, double-blind design. Respiratory gases (V̇O2), respiratory exchange ratio (RER), heart rate (HR), blood glucose (BG) and lactate (BL) concentrations, and ratings of perceived exertion (RPE) and pleasure-displeasure were measured at three timepoints (T1-3) during RUN 1. V̇O2max, RERmax, HRmax and time to exhaustion (TTE) were recorded during RUN 2. Venous blood was drawn at Baseline, Pre- and Post-RUN 1, Post-RUN 2 and 1 h Post-RUN 2. Data were synthesised using Cohen's dz effect sizes and 85% confidence intervals (CIs). Effects were considered worthy of further investigation if the 85% CI included ± 0.5 but not zero. RESULTS: CBD appeared to increase V̇O2 (T2: + 38 ± 48 mL·min-1, dz: 0.25-1.35), ratings of pleasure (T1: + 0.7 ± 0.9, dz: 0.22-1.32; T2: + 0.8 ± 1.1, dz: 0.17-1.25) and BL (T2: + 3.3 ± 6.4 mmol·L-1, dz: > 0.00-1.03) during RUN 1 compared to placebo. No differences in HR, RPE, BG or RER were observed between treatments. CBD appeared to increase V̇O2max (+ 119 ± 206 mL·min-1, dz: 0.06-1.10) and RERmax (+ 0.04 ± 0.05 dz: 0.24-1.34) during RUN 2 compared to placebo. No differences in TTE or HRmax were observed between treatments. Exercise increased serum interleukin (IL)-6, IL-1ß, tumour necrosis factor-α, lipopolysaccharide and myoglobin concentrations (i.e. Baseline vs. Post-RUN 1, Post-RUN 2 and/or 1-h Post-RUN 2, p's < 0.05). However, the changes were small, making it difficult to reliably evaluate the effect of CBD, where an effect appeared to be present. Plasma concentrations of the endogenous cannabinoid, anandamide (AEA), increased Post-RUN 1 and Post-RUN 2, relative to Baseline and Pre-RUN 1 (p's < 0.05). CBD appeared to reduce AEA concentrations Post-RUN 2, compared to placebo (- 0.95 ± 0.64 pmol·mL-1, dz: - 2.19, - 0.79). CONCLUSION: CBD appears to alter some key physiological and psychological responses to aerobic exercise without impairing performance. Larger studies are required to confirm and better understand these preliminary findings. Trial Registration This investigation was approved by the Sydney Local Health District's Human Research Ethics Committee (2020/ETH00226) and registered with the Australia and New Zealand Clinical Trials Registry (ACTRN12620000941965).

The Effect of Exercise on Cardiometabolic Risk Factors in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis.

BACKGROUND: Polycystic Ovary Syndrome (PCOS), a common endocrine disorder in women of reproductive age, increases the risk for cardiometabolic morbidity. While regular exercise is effective in reducing cardiometabolic risk, women with PCOS may experience condition-specific barriers to exercise thereby limiting its efficacy. AIM: To determine the effect of exercise on cardiometabolic risk factors in women with PCOS. METHODS: Five databases (Cochrane, EMBASE, Medline, Scopus and SPORTDiscus) were searched up to December of 2021. Eligible studies included: a randomised controlled design; participants with a diagnosis of PCOS; aerobic and/or resistance exercise intervention lasting ≥4 weeks; cardiometabolic outcomes. Meta-analyses were performed to determine the effect of exercise versus non-exercising control on cardiometabolic outcomes. RESULTS: Of the 4517 studies screened, 18 studies were analysed involving 593 participants. When compared with control, exercise significantly improved cardiorespiratory fitness (weighted mean difference {WMD} = 4.00 mL/kg/min, 95% CI: 2.61 to 5.40, p < 0.001) and waist circumference (WMD = -1.48 cm, 95% CI: -2.35 to -0.62, p = 0.001). Systolic blood pressure, fasting blood glucose, insulin resistance, and lipid profiles remained unchanged. CONCLUSIONS: Regular exercise may improve cardiorespiratory fitness and waist circumference in women with PCOS. Further large-scale studies are required to determine whether exercise interventions improve various biochemical and anthropometric parameters in women with PCOS and more severe cardiometabolic abnormalities.

Effect of Fish Oil Supplementation on Hepatic and Visceral Fat in Overweight Men: A Randomized Controlled Trial.

Being overweight increases the risk of the development of metabolic conditions such as non-alcoholic fatty liver disease (NAFLD), which is itself an independent predictor of cardiovascular disease. Omega-3 polyunsaturated fatty acid (PUFA) supplementation is recommended for prevention of chronic disease, and is thought to reduce raised liver fat, yet there have been few randomized controlled trials with accurate measurement of liver fat. We assessed the effect of 12 weeks of supplementation with omega-3 PUFA from fish oil versus placebo on quantified liver fat, liver tests, and body composition including visceral adipose tissue (VAT) in a double-blind randomized controlled trial. Fifty apparently healthy overweight men (BMI 25.0⁻29.9 kg/m²; waist > 94 cm) were randomly allocated to consume fish oil (total daily dose: 1728 mg marine triglycerides, of which 588 mg EPA and 412 mg DHA, combined with 200 mg antioxidant, coenzyme Q10) or placebo (olive oil capsules) daily for 12 weeks. Liver fat was assessed using proton magnetic resonance spectroscopy. All outcomes were assessed at baseline and following 6 and 12 weeks of supplementation. Baseline liver fat was 4.6 ± 0.5% (range: 0.6 to 18.2%); 16 (32%) participants met the criteria for NAFLD (>5.5% liver fat). Repeated measures ANOVA revealed no significant time or group × time effect for fish oil versus placebo for liver fat, liver enzymes, anthropometry, or body composition including VAT (p > 0.05 for all), with similar finding for sub-analysis of participants with NAFLD. Omega-3 PUFA did not appear to be an effective agent for reducing liver fat in overweight men. The factors determining the health benefits of omega-3 PUFA supplementation on an individual level need to be clarified.

Molecular and morphological data reveal non-monophyly and speciation in imperiled freshwater mussels (Anodontoides and Strophitus).

Accurate taxonomic placement is vital to conservation efforts considering many intrinsic biological characteristics of understudied species are inferred from closely related taxa. The rayed creekshell, Anodontoides radiatus (Conrad, 1834), exists in the Gulf of Mexico drainages from western Florida to Louisiana and has been petitioned for listing under the Endangered Species Act. We set out to resolve the evolutionary history of A. radiatus, primarily generic placement and species boundaries, using phylogenetic, morphometric, and geographic information. Our molecular matrix contained 3 loci: cytochrome c oxidase subunit I, NADH dehydrogenase subunit I, and the nuclear-encoded ribosomal internal transcribed spacer I. We employed maximum likelihood and Bayesian inference to estimate a phylogeny and test the monophyly of Anodontoides and Strophitus. We implemented two coalescent-based species delimitation models to test seven species models and evaluate species boundaries within A. radiatus. Concomitant to molecular data, we also employed linear morphometrics and geographic information to further evaluate species boundaries. Molecular and morphological evidence supports the inclusion of A. radiatus in the genus Strophitus, and we resurrect the binomial Strophitus radiatus to reflect their shared common ancestry. We also found strong support for polyphyly in Strophitus and advocate the resurrection of the genus Pseudodontoideus to represent 'Strophitus' connasaugaensis and 'Strophitus' subvexus. Strophitus radiatus exists in six well-supported clades that were distinguished as evolutionary independent lineages using Bayesian inference, maximum likelihood, and coalescent-based species delimitation models. Our integrative approach found evidence for as many as 4 evolutionary divergent clades within S. radiatus. Therefore, we formally describe two new species from the S. radiatus species complex (Strophitus williamsi and Strophitus pascagoulaensis) and recognize the potential for a third putative species (Strophitus sp. cf. pascagoulaensis). Our findings aid stakeholders in establishing conservation and management strategies for the members of Anodontoides, Strophitus, and Pseudodontoideus.

The Mediterranean diet improves hepatic steatosis and insulin sensitivity in individuals with non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) affects up to 30% of the population and signifies increased risk of liver fibrosis and cirrhosis, type 2 diabetes, and cardiovascular disease. Therapies are limited. Weight loss is of benefit but is difficult to maintain. We aimed at examining the effect of the Mediterranean diet (MD), a diet high in monounsaturated fatty acids, on steatosis and insulin sensitivity, using gold standard techniques. METHODS: Twelve non-diabetic subjects (6 Females/6 Males) with biopsy-proven NAFLD were recruited for a randomised, cross-over 6-week dietary intervention study. All subjects undertook both the MD and a control diet, a low fat-high carbohydrate diet (LF/HCD), in random order with a 6-week wash-out period in- between. Insulin sensitivity was determined with a 3-h hyperinsulinemic-euglycemic clamp study and hepatic steatosis was assessed with localized magnetic resonance (1)H spectroscopy ((1)H-MRS). RESULTS: At baseline, subjects were abdominally obese with elevated fasting concentrations of glucose, insulin, triglycerides, ALT, and GGT. Insulin sensitivity at baseline was low (M=2.7 ± 1.0 mg/kg/min(-1)). Mean weight loss was not different between the two diets (p=0.22). There was a significant relative reduction in hepatic steatosis after the MD compared with the LF/HCD: 39 ± 4% versus 7 ± 3%, as measured by (1)H-MRS (p=0.012). Insulin sensitivity improved with the MD, whereas after the LF/HCD there was no change (p=0.03 between diets). CONCLUSIONS: Even without weight loss, MD reduces liver steatosis and improves insulin sensitivity in an insulin-resistant population with NAFLD, compared to current dietary advice. This diet should be further investigated in subjects with NAFLD.

Imaging surveillance of differentiated thyroid cancer.

Intensive imaging surveillance has resulted in the ability to detect small-volume, often clinically occult, residual or recurrent disease. For most patients with differentiated thyroid cancer (DTC), such findings are unlikely to have an impact on disease-specific survival but our ability to predict which patients are at greatest risk and should receive the most aggressive therapies is surpassed by our ability to detect recurrence. Thus, the optimal treatment and surveillance regimens will surely continue to evolve as our ability to predict tumor behavior and aggressiveness improves. This article explains the rationale underlying current surveillance strategies and the utility and implications of imaging findings that are critical for the appropriate care of patients with DTC.

Parathyroid imaging.

Primary hyperparathyroidism is a common endocrine disorder caused by the overproduction of parathyroid hormone either by a single adenomatous gland or by multiple adenomatous or hyperplastic glands. Surgical resection of the abnormal parathyroid glands is the standard treatment, the goal of initial parathyroidectomy being durable biochemical cure. Surgeons have recently shifted to more minimally invasive and selective techniques for parathyroid exploration. More selective surgical approaches rely on accurate preoperative imaging techniques to localize abnormal parathyroid glands. It is imperative that radiologists are familiar with imaging features of parathyroid glands as well as the role of imaging in patient care.

Cystic parathyroid adenoma: sonographic features and correlation with 99mTc-sestamibi SPECT findings.

OBJECTIVE: The purpose of this study was to describe the typical ultrasound features of cystic parathyroid adenoma. MATERIALS AND METHODS: A review of a surgical database and electronic medical records from 2006 to 2009 identified the cases of 15 patients who underwent preoperative cervical sonography for primary hyperparathyroidism with subsequent resection of pathologically proven parathyroid adenoma with predominantly cystic components. Two radiologists retrospectively evaluated the preoperative ultrasound images and assessed for cyst complexity, size, location, and color Doppler vascularity. Technetium-99m-sestamibi SPECT findings, surgical and pathologic reports, and the results of parathyroid hormone assay of the cyst fluid also were reviewed. RESULTS: Most of the cystic adenomas (14/15, 93%) were deep or inferolateral to the adjacent thyroid. The same percentage were elongated and had peripheral nodular components. An echogenic border separating the adenoma from the overlying thyroid was identified in 9 of 15 patients (60%). Color Doppler examination of 14 patients showed feeding vessels with internal color flow to the solid components in 10 patients (71%). Six of 14 patients underwent preoperative or intraoperative sampling of cyst fluid, and the assay showed the parathyroid hormone levels ranged from 1,198 to greater than 5,000 pg/mL. Fourteen of 15 patients underwent preoperative sestamibi SPECT, and the adenoma was definitively localized in four patients (29%). The accuracy of preoperative localization improved to 79% (11/14) when sestamibi SPECT scans were interpreted in correlation with cervical ultrasound images. CONCLUSION: Awareness of typical sonographic features (location, color Doppler vascularity) may aid radiologists in preoperative localization of parathyroid adenomas, even when cystic degeneration occurs. In cases in which imaging or clinical features are equivocal, the results of cyst fluid sampling and parathyroid hormone assay are confirmatory.

Postoperative surveillance of differentiated thyroid carcinoma: rationale, techniques, and controversies.

Although differentiated thyroid cancer (DTC) is typically an indolent disease with a high rate of cure, recurrence is common (15%-30% of patients), even in early-stage disease. These high rates of recurrence have resulted in the widespread adoption of intensive posttherapy surveillance algorithms. Currently used strategies rely primarily on serial serum thyroglobulin measurements combined with cervical ultrasonography (US): US is utilized to search for recurrences within the thyroid bed or anterior cervical lymph nodes and as a guidance system for directed fine-needle aspiration biopsy of suspicious lesions. Positron emission tomography (PET) and coregistered computed tomography/fluorine 18 fluorodeoxyglucose PET are used primarily in the setting of non-iodine-avid tumors. Intensive surveillance has improved the ability to detect small-volume tumor recurrence with a sensitivity that surpasses current understanding of the clinical implications of detecting clinically occult residual or recurrent disease. Knowledge of currently used treatment and surveillance strategies is crucial for understanding the appropriate use of imaging studies, the clinical implications of imaging findings, and the appropriate use of US-guided tissue sampling in patients with DTC. Recent advances in the understanding of DTC tumor biology hold promise for improving the ability to predict tumor behavior and aggressiveness, thereby allowing more appropriate risk stratification, imaging surveillance, and treatment.

Noninvasive assessment of hepatic lipid composition: Advancing understanding and management of fatty liver disorders.

UNLABELLED: Nonalcoholic fatty liver is frequently observed in obese individuals, yet the factors that predict its development and progression to liver disease are poorly understood. We proposed that proton magnetic resonance spectroscopy ((1)H-MRS) might allow noninvasive assessment of hepatic lipid composition. Lipid saturation (SI) and polyunsaturation (PUI) indices measured by (1)H-MRS were in agreement with those expected in oils of known composition. Hepatic triglyceride concentration (HTGC) and composition were then measured in healthy lean (LEAN) men, obese men with normal HTGC (OB), and obese men with hepatic steatosis (OB+HS). The effect of marked changes in dietary fat consumption on hepatic lipids were also compared in lean men after 67 hours of a normal mixed (NM) diet versus a low-carbohydrate, high-saturated-fat (LCHF) diet. SI was significantly higher in OB+HS (0.970 +/- 0.004) and OB (0.944 +/- 0.008) versus LEAN (0.818 +/- 0.025) (P < 0.01 for both). PUI was significantly lower in OB+HS (0.003 +/- 0.001) and OB (0.022 +/- 0.005) versus LEAN (0.120 +/- 0.021) (P < 0.01), and significantly lower in OB+HS versus OB (P < 0.05). LCHF diet did not alter HTGC, SI, or PUI (P > 0.05). The (1)H-MRS method provides for rapid, qualitative assessment of lipid composition. Application of this technique in the liver produces results that are consistent with biopsy-based approaches demonstrating that relative hepatic lipid saturation increases and polyunsaturation decreases with obesity. Obesity-related hepatic steatosis is characterized by further depletion of polyunsaturated hepatic lipids. CONCLUSION: This readily available and noninvasive approach should promote further study into interactions between hepatic and whole-body lipid metabolism and help to elucidate the pathogenesis of disorders characterized by lipid accumulation within the liver.

Parathyroid imaging: technique and role in the preoperative evaluation of primary hyperparathyroidism.

OBJECTIVE: This article discusses the commonly used techniques for imaging the parathyroid glands and their role in the preoperative evaluation of patients with primary hyperparathyroidism. CONCLUSION: The importance of sonography and sestamibi scintigraphy in the preoperative evaluation of patients with primary hyperthyroidism has increased with the adoption of minimally invasive parathyroidectomy techniques at most medical centers. When the results of these studies are concordant, the cure rates of minimally invasive surgery equal those of traditional bilateral neck exploration.

Muscle triglyceride and glycogen in endurance exercise: implications for performance.

The importance of muscle glycogen as a metabolic substrate in sustaining prolonged exercise is well acknowledged. Being stored in proximity to the site of contraction and able to sustain high rates of adenosine diphosphate (ADP) phosphorylation, glycogen is viewed as the primary fuel for the maintenance of exercise of a moderate to intense nature. As such, to ensure optimal exercise performance, endurance athletes are encouraged to maximise the availability of muscle glycogen through the ingestion of a high carbohydrate (CHO) diet prior to competition. The skeletal muscle cell also contains significant quantities of triglyceride. Recent improvements in the ability to measure these intramyocellular triglyceride (IMTG) stores have confirmed that IMTG acts as a significant fuel substrate during prolonged exercise. While early research of the role of muscle glycogen in endurance exercise provided clear prescriptive information for the endurance-trained athlete, no such direction for optimising exercise performance is yet apparent from research concerning IMTG. In this article, we review the processes of muscle glycogen and triglyceride storage and metabolism. Attention is given to the effects of short-term alterations in diet on muscle substrate, particularly IMTG storage, and the implications of this to endurance exercise performance and competition preparation. We demonstrate that like glycogen, IMTG formation may be relatively rapid, and its storage predominates under conditions that promote minimal glycogen formation. This observation suggests that the role of IMTG is to maintain a readily available substrate to ensure that physical activity of a moderate nature can be performed when glycogen availability is not optimal. Under these conditions, IMTG may offer a similar availability of energy as glycogen in the endurance-trained athlete. Given the potential value of this substrate, the possibility of maximising IMTG storage without compromising glycogen availability prior to competition is considered.

Sodium butyrate inhibits angiogenesis of human intestinal microvascular endothelial cells through COX-2 inhibition.

We examined the effect of sodium butyrate on in vitro angiogenesis and cyclooxygenase (COX) expression using primary cultures of human intestinal microvascular endothelial cells (HIMEC). Butyrate inhibited VEGF-induced cellular proliferation, transmigration and tube formation of HIMEC. Butyrate also inhibited COX-2 expression as well as prostaglandin (PG)E2 and PGI2 production, and administration of PGI2 analog partially reversed the effect of butyrate on HIMEC angiogenesis. These results indicate that sodium butyrate inhibits HIMEC angiogenesis through down-regulation of COX-2 expression and PG production, and suggest that anti-angiogenic mechanisms may also be involved in the inhibitory effect of sodium butyrate on tumor growth.

Butyrate modulates gene and protein expression in human intestinal endothelial cells.

We hypothesized that sodium butyrate, a product of enteric bacterial fermentation, modulates gene expression in gut microvascular endothelium which plays a central role in mucosal immunity. We examined sodium butyrate's effect on LPS-induced gene and protein expression in primary cultures of human intestinal microvascular endothelial cells. cDNA array analysis revealed that sodium butyrate augmented ICAM-1 mRNA expression, while it inhibited IL-6 and COX-2 expression in response to LPS stimulation. These results were confirmed at the protein level. Prostaglandin E2 production by LPS was also strongly inhibited by butyrate. The pattern of altered gene expression by butyrate was reproduced by the histone deacetylase inhibitor tricostatin A, suggesting that the regulatory mechanism of butyrate on HIMEC gene expression involves histone deacetylase inhibition. IkappaBalpha degradation and NF-kappaB activation were unaffected by butyrate. In addition to effects on epithelium, sodium butyrate modulates the innate mucosal immune response towards LPS through effects on microvascular endothelial function.