Influence of nutrition on muscle metabolism and performance during prolonged intermittent high intensity shuttle running in man

The purpose of this thesis was to study the effects of I) carbohydrate intake, either during or in the recovery from exhaustive intermittent exercise, and 2) oral creatine supplementation for 5 days, on metabolism, performance and endurance capacity during a prolonged intermittent high intensity shuttle run test (PIHSRT). Prolonged intermittent high intensity running is an activity pattern which is typical of the multiple sprint sports such as soccer, hockey and rugby. Understanding the physiological and metabolic responses to this type of activity can improve our understanding of the aetiology of fatigue and how training and nutritional intervention can improve performance during prolonged intermittent high intensity running. The aims of the first and second studies were to investigate the effect of increased carbohydrate availability, by ingesting additional carbohydrate in the recovery from (Chapter 4) and by drinking a carbohydrate-electrolyte solution immediately prior to, and during (Chapter 5), prolonged intermittent high intensity running. In the first study (Chapter 4), six games players performed two prolonged intermittent high intensity shuttle run tests (PIHSRT) consisting of a fixed 70 min period of intermittent exercise (Part A) followed by high intensity intermittent running to fatigue (Part B), separated by 22 h recovery, on two occasions, separated by one week. During the 22 h recovery, subjects were prescribed their normal dietary intake of carbohydrate plus the additional energy needed to consume the equivalent of 10 g.kg·1bm.day·l. This extra energy was consumed either in the form of carbohydrate (the CHO trial) or as fat and protein (the CON trial). No differences in sprint performance were observed 22 h following either recovery diet. High intensity running capacity was improved after 22 h in the CHO trial (T2) by 16% (