R. J. Maughan

A simple, rapid method for the determination of glucose, lactate, pyruvate, alanine, 3-hydroxybutyrate and acetoacetate on a single 20-μl blood sample

Abstract Existing methods for the estimation of glucose, lactate, pyruvate, alanine, 3-hydroxybutyrate and acetoacetate normally require relatively large volumes of blood. In addition spectrophotometric methods are tedious and time-consuming. A series of simple methods for the measurement of these metabolites whereby all can be measured on a single 20-μ1 blood sample is described here. All methods, with the exception of that for glucose, which is measured spectrophotometrically, depend on the use of fluorimetry to determine the concentration of the reduced co-enzyme NADH. As far as is possible, the methods have been standardised for the sake of simplicity and convenience. In routine use they have proved to be both rapid and reliable.

Comparison of the effects of pre-exercise feeding of glucose, glycerol and placebo on endurance and fuel homeostasis in man

SummarySix men were studied during exercise to exhaustion on a cycle ergometer at 73% of

Effects of ibuprofen on exercise-induced muscle soreness and indices of muscle damage.

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Role of micronutrients in sport and physical activity

following ingestion of glycerol, glucose or placebo. Five of the subjects exercised for longer on the glucose trial compared to the placebo trial (p<0.1; 108.8 vs 95.9 min). Exercise time to exhaustion on the glucose trial was longer (p<0.01) than on the glycerol trial (86.0 min). No difference in performance was found between the glycerol and placebo trials. The ingestion of glucose (lg · kg−1 body weight) 45 min before exercise produced a 50% rise in blood glucose and a 3-fold rise in plasma insulin at zero min of exercise. Total carbohydrate oxidation was increased by 26% compared to placebo and none of the subjects exhibited a fall in blood glucose below 4 mmol · l−1 during the exercise. The ingestion of glycerol (lg · kg−1 body weight) 45 min before exercise produced a 340-fold increase in blood glycerol concentration at zero min of exercise, but did not affect resting blood glucose or plasma insulin levels; blood glucose levels were up to 14% higher (p<0.05) in the later stages of exercise and at exhaustion compared to the placebo or glucose trials. Both glycerol and glucose feedings lowered the magnitude of the rise in plasma FFA during exercise compared to placebo. Levels of blood lactate and alanine during exercise were not different on the 3 dietary treatments. These data contrast with previous reports that have indicated glucose feeding pre-exercise produces hypoglycaemia during strenuous submaximal exercise and reduces endurance performance. It appears that man cannot use glycerol as a gluconeogenic substrate rapidly enough to serve as a major energy source during this type of exercise.

Diet composition and the performance of high-intensity exercise

SummaryThe availability of carbohydrate (CHO) as a substrate for the exercising muscles is known to be a limiting factor in the performance of prolonged cycle exercise, and provision of exogenous CHO in the form of glucose can increase endurance capacity. The present study examined the effects of ingestion of fluids and of CHO in different forms on exercise performance. Six male volunteers exercised to exhaustion on a cycle ergometer at a workload which required approximately 70% of

The effects of exercise and diet manipulation on the capacity to perform prolonged exercise in the heat and in the cold in trained humans

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