Moderate-intensity endurance exercise prevents short-term starvation-induced intramyocellular lipid accumulation but not insulin resistance.

Exercise has the potential to alleviate the resistance to insulin-mediated glucose uptake precipitated by elevated circulating free fatty acids (FFAs) in conditions such as obesity, lipid infusion, and starvation. In this study, 6 lean healthy men underwent two 3-day periods of starvation with either no exercise or daily endurance exercise (80 min d(-1) at 50% maximal rate of oxygen consumption) and a 3-day mixed diet without exercise. Insulin sensitivity was determined by intravenous glucose tolerance test, and intramyocellular lipid (IMCL) concentration was measured by (1)H magnetic resonance spectroscopy.

Effects of eccentric exercise-induced muscle damage on intramyocellular lipid concentration and high energy phosphates.

Eccentric exercise is known to cause changes to the ultrastructure of skeletal muscle and, in turn, may alter the ability of the muscle to store and utilise intracellular substrates such as intramyocellular lipid (IMCL). The purpose of this study was to test the hypothesis that exercise-induced muscle damage (EIMD) results in IMCL accumulation. Six males (31 ± 6 years; mean ± SD, and 72.

Low-carbohydrate diet does not affect intramyocellular lipid concentration or insulin sensitivity in lean, physically fit men when protein intake is elevated.

It has been speculated that dietary carbohydrate restriction is solely responsibly for mobilization of endogenous lipid stores, elevation of plasma free fatty acid (FFA) concentration, and an associated reduction in insulin sensitivity seen in starvation and low-carbohydrate diets. In 6 healthy men, dietary carbohydrate was eliminated but gluconeogenic substrate supply was maintained by 3 days of very low-carbohydrate/high-protein (HPLC) diet. Results were compared with 3-day starvation and 3-day mixed-carbohydrate diet.

Aerobic exercise training reduces hepatic and visceral lipids in obese individuals without weight loss.

Unlabelled: Weight loss remains the most common therapy advocated for reducing hepatic lipid in obesity and nonalcoholic fatty liver disease. Yet, reduction of body weight by lifestyle intervention is often modest, and thus, therapies which effectively modulate the burden of fatty liver but are not contingent upon weight loss are of the highest practical significance. However, the effect of aerobic exercise on liver fat independent of weight loss has not been clarified.

Dynamic changes in brain bioenergetics during obstructive sleep apnea.

Repetitive collapse of the upper airway during obstructive sleep apnea/hypopnea (OSA) exposes the brain of sufferers to frequent, transient, hypoxic episodes. The loss of cerebrovascular reactivity in sleep, and particularly in OSA, means that physiologic compensatory mechanisms may not ensure adequate brain oxygen levels. This (31)P magnetic resonance spectroscopy study, of 13 males with severe, untreated OSA undertaken after overnight sleep deprivation, represents the first, seconds time-scale analysis of human brain bioenergetics during transient hypoxia and demonstrates that a moderate degree of oxygen desaturation during sleep has significant effects on brain bioenergetic status.

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.

Effect of short-term starvation versus high-fat diet on intramyocellular triglyceride accumulation and insulin resistance in physically fit men.

It is currently believed that intramyocellular triglyceride (IMTG) accumulation and insulin resistance are a consequence of dietary fat ingestion and/or the elevated circulating lipid levels associated with chronic fat surplus. The purpose of this study was to compare the effect of short-term starvation versus low-carbohydrate (CHO)/high-fat diet on IMTG accumulation and the development of insulin resistance in physically fit men. Intramyocellular triglyceride content, measured as intramyocellular lipid (IMCL) by proton magnetic resonance spectroscopy (1H-MRS), and glucose tolerance/insulin sensitivity, assessed by frequently sampled intravenous glucose tolerance test (IVGTT), were determined after 67 h of: (a) water-only starvation (S); and (b) very low-CHO/high-fat diet (LC).

Exercise capacity and quadriceps muscle metabolism following training in subjects with COPD.

The aim of the study was to determine whether 16 sessions of exercise training, completed twice weekly, alters exercise capacity, quadriceps muscle metabolism, cross-sectional area (CSA) and strength in subjects with chronic obstructive pulmonary disease (COPD). We studied (a) 10 COPD subjects (mean age+/-sem = 71+/-2 years; FEV1 = 0.99+/-0.

Aerobic exercise and muscle metabolism in patients with mitochondrial myopathy.

Exercise therapy improves mitochondrial function in patients with mitochondrial myopathy (MM). We undertook this study to determine the metabolic abnormalities that are improved by exercise therapy. This study identified metabolic pathology using (31)P-magnetic resonance spectroscopy and magnetic resonance imaging (MRI) in a group of patients with MM compared to a control group matched for age, gender, and physical activity.

Muscle function and resting energy expenditure in female athletes with cystic fibrosis.

The pathophysiology of impaired exercise tolerance in patients with cystic fibrosis (CF) is not completely understood. The objective of this study was to compare exercise ability (at clinical and cellular levels) and resting energy expenditure in female athletes with CF compared with matched control subjects. Sixteen subjects and matched control subjects participated in the study.

Cervical ependymoma presenting with brainstem and cerebellar signs: case report.

This case report demonstrates cervical spinal cord pathology which presented with brainstem and cerebellar signs consequent to the peritumoural oedema that extended rostrally to the pontomedullary junction. A Medline search of the literature back to 1960 failed to produce any previous report of a cervical ependymoma presenting with brainstem and cerebellar signs purely consequent to oedema. This case highlights the need to look further afield when presented with the scenario of clinical features of a brainstem lesion with only oedema apparent on cranial imaging.