Effect of increased fat availability on metabolism and exercise capacity.

Several procedures have been utilized to elevate plasma free fatty acid (FFA) concentration and increase fatty acid (FA) delivery to skeletal muscle during exercise. These include fasting, caffeine ingestion, L-carnitine supplementation, ingestion of medium-chain and long-chain triglyceride (LCT) solutions, and intravenous infusion of intralipid emulsions. Studies in which both untrained and well-trained subjects have ingested LCT solutions or received an infusion of intralipid (in combination with an injection of heparin) before exercise have reported significant reductions in whole-body carbohydrate oxidation and decreased muscle glycogen utilization during both moderate and intense dynamic exercise lasting 15-60 min.

Symposium: Limits to fat oxidation by skeletal muscle during exercise--introduction.

Lipids, in the form of adipose tissue triacylglycerol (TG), intramuscular triglyceride (IMTG), and dietary-derived fatty acids (FA) from plasma TG (chylomicrons), and very low-density lipoproteins (VLDL), represent the largest store of nutrient energy in humans. Yet despite the abundance of endogenous TG, there is limited capacity for FA oxidation during exercise: there are no mechanisms that match the availability and metabolism of FA to the rate of energy expenditure. Because of the body's limited carbohydrate (CHO) stores, and because depletion of muscle and liver glycogen reserves often coincide with exhaustion, there is interest in several nutritional interventions that increase FA availability and rates of fat oxidation during exercise: such strategies have the potential to slow the rate of glycogen utilization and delay the onset of fatigue.

Effect of different protocols of caffeine intake on metabolism and endurance performance.

Competitive athletes completed two studies of 2-h steady-state (SS) cycling at 70% peak O(2) uptake followed by 7 kJ/kg time trial (TT) with carbohydrate (CHO) intake before (2 g/kg) and during (6% CHO drink) exercise. In Study A, 12 subjects received either 6 mg/kg caffeine 1 h preexercise (Precaf), 6 x 1 mg/kg caffeine every 20 min throughout SS (Durcaf), 2 x 5 ml/kg Coca-Cola between 100 and 120 min SS and during TT (Coke), or placebo. Improvements in TT were as follows: Precaf, 3.

Effect of training on activation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase pathways in rat soleus muscle.

1. The effect of a chronic programme of either low- or moderate-to-high-intensity treadmill running on the activation of the extracellular-signal regulated protein kinase (ERK1/2) and the p38 mitogen-activated protein kinase (MAPK) pathways was determined in rat muscle. 2.

Interaction of exercise and diet on GLUT-4 protein and gene expression in Type I and Type II rat skeletal muscle.

We determined the interaction of exercise and diet on glucose transporter (GLUT-4) protein and mRNA expression in type I (soleus) and type II [extensor digitorum longus (EDL)] skeletal muscle. Forty-eight Sprague Dawley rats were randomly assigned to one of two dietary conditions: high-fat (FAT, n=24) or high-carbohydrate (CHO, n=24). Animals in each dietary condition were allocated to one of two groups: control (NT, n=8) or a group that performed 8 weeks of treadmill running (4 sessions week-1 of 1000 m @ 28 m min-1, RUN, n=16).

Adaptations of skeletal muscle to prolonged, intense endurance training.

1. Endurance exercise induces a variety of metabolic and morphological responses/adaptations in skeletal muscle that function to minimize cellular disturbances during subsequent training sessions. 2.

Adrenalectomy abrogates reduction of 12-O-tetradecanoylphorbol-13-acetate-induced extracellular signal-regulated protein kinase activity in the epidermis of dietary energy-restricted SENCAR mice: implications of glucocorticoid hormone.

Previous studies in this laboratory demonstrated that dietary energy restriction (DER), a potent inhibitor of skin carcinogenesis, markedly suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced extracellular signal-regulated protein kinase (ERK) activity in mouse epidermis. Intact adrenal glands have been reported to be important in the inhibition of skin tumor promotion by food restriction. We investigated the role of adrenal glands and corticosterone in the DER effect on ERK activity.

Effect of short-term fat adaptation on high-intensity training.

Purpose: To determine the effect of short-term (3-d) fat adaptation on high-intensity exercise training in seven competitive endurance athletes (maximal O2 uptake 5.0 +/- 0.5 L x min(-1), mean +/-SD).

Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability.

Purpose: Five days of a high-fat diet produce metabolic adaptations that increase the rate of fat oxidation during prolonged exercise. We investigated whether enhanced rates of fat oxidation during submaximal exercise after 5 d of a high-fat diet would persist in the face of increased carbohydrate (CHO) availability before and during exercise.

Methods: Eight well-trained subjects consumed either a high-CHO (9.

Effect of carbohydrate ingestion on metabolism during running and cycling.

The effects of carbohydrate or water ingestion on metabolism were investigated in seven male subjects during two running and two cycling trials lasting 60 min at individual lactate threshold using indirect calorimetry, U-14C-labeled tracer-derived measures of the rates of oxidation of plasma glucose, and direct determination of mixed muscle glycogen content from the vastus lateralis before and after exercise. Subjects ingested 8 ml/kg body mass of either a 6.4% carbohydrate-electrolyte solution (CHO) or water 10 min before exercise and an additional 2 ml/kg body mass of the same fluid after 20 and 40 min of exercise.

Short-term high-fat diet alters substrate utilization during exercise but not glucose tolerance in highly trained athletes.

We determined the effect of a high-fat diet and carbohydrate (CHO) restoration on substrate oxidation and glucose tolerance in 7 competitive ultra-endurance athletes (peak oxygen uptake [VO(2peak)] 68 +/- 1 ml x kg(-1) x min(-1); mean +/- SEM). For 6 days, subjects consumed a random order of a high-fat (69% fat; FAT-adapt) or a high-CHO (70% CHO; HCHO) diet, each followed by 1 day of a high-CHO diet. Treatments were separated by an 18-day wash out.

Postexercise muscle glycogen resynthesis in obese insulin-resistant Zucker rats.

We determined the effect of an acute bout of swimming (8 x 30 min) followed by either carbohydrate administration (0.5 mg/g glucose ip and ad libitum access to chow; CHO) or fasting (Fast) on postexercise glycogen resynthesis in soleus muscle and liver from female lean (ZL) and obese insulin-resistant (ZO) Zucker rats. Resting soleus muscle glycogen concentration ([glycogen]) was similar between genotypes and was reduced by 73 (ZL) and 63% (ZO) after exercise (P < 0.

Pacing strategy in simulated cycle time-trials is based on perceived rather than actual distance.

This study determined the pacing strategies and performance responses of six well-trained cyclists/triathletes (peak O2 uptake 66.4+/-3.7 ml x kg(-1) x min(-1), mean+/-SD) during seven simulated time-trials (TT) conducted on a wind-braked cycle ergometer.

Moderate levels of hypohydration impairs bowling accuracy but not bowling velocity in skilled cricket players.

The effects of exercise-induced hypohydration on the motor skill performance of cricket bowling was examined in seven medium-fast bowlers who performed a random order of two experimental trials. Trials consisted of a bowling test (36 deliveries; PREBOWL) in a thermoneutral (16+/-2 degrees C) environment followed by approximately 1 hr of intermittent exercise in a heated environment (28+/-2 degrees C) and a further thermoneutral bowling test (36 deliveries; POSTBOWL). During one trial fluid intake was restricted (HYPO) whereas in the other, subjects were forced to drink in an effort to maintain euhydration (EUH).

Interaction of diet and training on endurance performance in rats.

We determined the interaction of diet and training on metabolic adaptations in skeletal muscle and liver, and the consequences of these adaptations for endurance. Eighty rats performed a baseline treadmill run to exhaustion at 16 m min(-1) (RUN1) and were then divided into two groups and given one of two diets: high carbohydrate (CHO) or high fat (FAT). Each dietary group was then divided into one of four subgroups: sedentary control that performed no training (NT); low-intensity running (8 m min(-1); LOW) and two groups who trained at their maximal voluntary running speed without electrical stimulation (28 m min(-1); VMAX).

Effect of caffeine co-ingested with carbohydrate or fat on metabolism and performance in endurance-trained men.

We examined the effect of caffeine co-ingested with either carbohydrate or fat on metabolism and performance in eight endurance-trained subjects who performed a random order of four experimental trials consisting of 120 min of steady-state ergometer cycling at 70 % of maximal O(2) uptake (SS) followed by a time trial in which subjects completed a set amount of work (7 kJ kg-1) as quickly as possible. One hour before SS subjects ingested either 2.6 g kg-1 carbohydrate (CHO); 2.

Adaptations to training in endurance cyclists: implications for performance.

Our present scientific knowledge of the effects of specific training interventions undertaken by professional cyclists on selected adaptive responses in skeletal muscle and their consequences for improving endurance performance is limited: sport scientists have found it difficult to persuade elite cyclists to experiment with their training regimens and access to muscle and blood samples from these athletes is sparse. Owing to the lack of scientific study we present a theoretical model of some of the major training-induced adaptations in skeletal muscle that are likely to determine performance capacity in elite cyclists. The model includes, but is not limited to, skeletal muscle morphology, acid-base status and fuel supply.

Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise.

We determined the effect of fat adaptation on metabolism and performance during 5 h of cycling in seven competitive athletes who consumed a standard carbohydrate (CHO) diet for 1 day and then either a high-CHO diet (11 g. kg(-1)x day(-1) CHO, 1 g x kg(-1) x day(-1) fat; HCHO) or an isoenergetic high-fat diet (2.6 g x kg(-1) x day(-1) CHO, 4.

High-fat diet versus habitual diet prior to carbohydrate loading: effects of exercise metabolism and cycling performance.

We examined the effects of a high-fat diet (HFD-CHO) versus a habitual diet, prior to carbohydrate (CHO)-loading on fuel metabolism and cycling time-trial (TT) performance. Five endurance-trained cyclists participated in two 14-day randomized cross-over trials during which subjects consumed either a HFD (> 65% MJ from fat) or their habitual diet (CTL) (30 +/- 5% MJ from fat) for 10 day, before ingesting a high-CHO diet (CHO-loading, CHO > 70% MJ) for 3 days. Trials consisted of a 150-min cycle at 70% of peak oxygen uptake (VáO2peak), followed immediately by a 20-km TT.

Carbohydrate ingestion attenuates the increase in plasma interleukin-6, but not skeletal muscle interleukin-6 mRNA, during exercise in humans.

1. The present study was undertaken to examine the effects of exercise and carbohydrate (CHO) ingestion on interleukin-6 (IL-6) gene expression in skeletal muscle and plasma IL-6 concentration. 2.

Relation of irrational thinking and the Pessimistic Explanatory Style.

This study investigated the possible relationship between Ellis's construct of irrational thinking and Seligman's construct of explanatory style, with a view toward possibly strengthening the personality theory underlying Rational Emotive Behavior Therapy in particular and cognitive-behavior therapies more generally. In this investigation 180 college students were administered the Survey of Personal Beliefs and the Attributional Style Questionnaire to measure irrational thinking and explanatory style, respectively. Students who scored higher on Pessimistic Explanatory Style also scored higher on Overall Irrational Thinking and on Low Frustration Tolerance than did those who were categorized as having an Optimistic Explanatory Style.

Selective serotonin reuptake inhibitors for aggressive behavior in patients with dementia after head injury.

Head injury of any severity can result in acute and chronic neuropsychiatric symptoms. After head injury, aggressive behaviors can be disabling to victims and stressful to their families. When aggression is compounded by dementia, treatment can be more difficult.

Reliability of power in physical performance tests.

The reliability of power in tests of physical performance affects the precision of assessment of athletes, patients, clients and study participants. In this meta-analytic review we identify the most reliable measures of power and the factors affecting reliability. Our measures of reliability were the typical (standard) error of measurement expressed as a coefficient of variation (CV) and the percent change in the mean between trials.

The bioenergetics of World Class Cycling.

Professional cycle racing is one of the most demanding of all sports combining extremes of exercise duration, intensity and frequency. Riders are required to perform on a variety of surfaces (track, road, cross-country, mountain), terrains (level, uphill and downhill) and race situations (criterions, sprints, time trials, mass-start road races) in events ranging in duration from 10 s to 3 wk stage races covering 200 m to 4,000 km. Furthermore, professional road cyclists typically have approximately 100 race d/yr.

Metabolic demands of intense aerobic interval training in competitive cyclists.

Purpose: To investigate the metabolic demands of a single session of intense aerobic interval training in highly trained competitive endurance cyclists.

Methods: Seven cyclists (peak O2 uptake [VO2 peak] 5.14 +/- 0.