The Effect of Glucose Infusion on Glucose Kinetics during a 1-h Time Trial

Carter, James M.; Jeukendrup, Asker E.; Mann, Chris H.; Jones, David A.

doi:10.1249/01.mss.0000139892.69410.d8

Cited by 113 publications

(103 citation statements)

References 25 publications

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“…When taken together, it is currently thought that CHO feeding during exercise may therefore augment exercise performance via multiple mechanisms consisting of muscle glycogen sparing [39], liver glycogen sparing [40] and maintenance of plasma glucose and CHO oxidation rates [41]. It is noteworthy, however, that exogenous CHO feeding during exercise also improves performance when exercise duration is <60 minutes [42], an effect that is not apparent when glucose is directly infused to the bloodstream during exercise [43]. Such data suggest that CHO feeding may also improve exercise performance via non-metabolic effects but through direct effects on the central nervous system [44].…”

Section: Is Carbohydrate Still King?mentioning

confidence: 99%

New strategies in sport nutrition to increase exercise performance

Hamilton

Philp

et al. 2016

Free Radical Biology and Medicine

178

118

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Despite over 50 years of research, the field of sports nutrition continues to grow at a rapid rate. Whilst the traditional research focus was one that centred on strategies to maximize competition performance, emerging data in the last decade has demonstrated how both macronutrient and micronutrient availability can play a prominent role in regulating those cell signalling pathways that modulate skeletal muscle adaptations to endurance and resistance training. Nonetheless, in the context of exercise performance, it is clear that carbohydrate (but not fat) still remains king and that carefully chosen ergogenic aids (e.g. caffeine, creatine, sodium bicarbonate, beta-alanine, nitrates) can all promote performance in the correct exercise setting. In relation to exercise training, however, it is now thought that strategic periods of reduced carbohydrate and elevated dietary protein intake may enhance training adaptations whereas high carbohydrate availability and antioxidant supplementation may actually attenuate training adaptation. Emerging evidence also suggests that vitamin D may play a regulatory role in muscle regeneration and subsequent hypertrophy following damaging forms of exercise. Finally, novel compounds (albeit largely examined in rodent models) such as epicatechins, nicotinamide riboside, resveratrol, β-hydroxy β-methylbutyrate, phosphatidic acid and ursolic acid may also promote or attenuate skeletal muscle adaptations to endurance and strength training. When taken together, it is clear that sports nutrition is very much at the heart of the Olympic motto, Citius, Altius, Fortius (faster, higher, stronger).

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Section: Is Carbohydrate Still King?mentioning

confidence: 99%

New strategies in sport nutrition to increase exercise performance

Hamilton

Philp

et al. 2016

Free Radical Biology and Medicine

178

118

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“…Events of this duration are not limited by the depletion of muscle glycogen, and there may be little muscle oxidation of carbohydrate consumed during such a race (McConell et al, 2000). Nevertheless, there is consistent evidence that the performance of sustained high-intensity exercise of 45-75 min is enhanced when carbohydrates are ingested during exercise of this nature, with the benefits isolated to situations in which it is consumed orally at frequent intervals and absent when it is delivered by intravenous means (Carter et al, 2004a(Carter et al, , 2004b. Several studies that have used a protocol of rinsing the mouth with a carbohydrate solution have demonstrated that the performance benefit is achieved via the frequent exposure of the oral cavity to small amounts of carbohydrate (Jeukendrup & Chambers, 2010).…”

Section: Carbohydrate For Events Lasting Less Than 1 Hrmentioning

confidence: 99%

Nutrition Considerations for Open-Water Swimming

Shaw¹,

Koivisto²,

Gerrard³

et al. 2014

International Journal of Sport Nutrition and Exercise Metabolism

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Open-water swimming (OWS) is a rapidly developing discipline. Events of 5-25 km are featured at FINA World Championships, and the international circuit includes races of 5-88 km. The Olympic OWS event, introduced in 2008, is contested over 10 km. Differing venues present changing environmental conditions, including water and ambient temperatures, humidity, solar radiation, and unpredictable tides. Furthermore, the duration of most OWS events (1-6 hr) creates unique physiological challenges to thermoregulation, hydration status, and muscle fuel stores. Current nutrition recommendations for open-water training and competition are either an extension of recommendations from pool swimming or are extrapolated from other athletic populations with similar physiological requirements. Competition nutrition should focus on optimizing prerace hydration and glycogen stores. Although swimmers should rely on self-supplied fuel and fluid sources for shorter events, for races of 10 km or greater, fluid and fuel replacement can occur from feeding pontoons when tactically appropriate. Over the longer races, feeding pontoons should be used to achieve desirable targets of up to 90 g/ hr of carbohydrates from multitransportable sources. Exposure to variable water and ambient temperatures will play a significant role in determining race nutrition strategies. For example, in extreme environments, thermoregulation may be assisted by manipulating the temperature of the ingested fluids. Swimmers are encouraged to work with nutrition experts to develop effective and efficient strategies that enhance performance through appropriate in-competition nutrition.

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“…Therefore, evidence of enhanced performance when carbohydrate is consumed during a variety of such exercise protocols is perplexing (for a review, see Burke, Wood, Pyne, Telford, & Saunders, 2005). Findings of a lack of improvement of a 1-h cycling protocol with glucose infusion (Carter, Jeukendrup, Mann, & Jones, 2004b) but benefits from carbohydrate ingestion (Carter, Jeukendrup, & Jones, 2004a) created an intriguing hypothesis that the central nervous system might sense the presence of carbohydrate via receptors in the mouth and oral space, promoting an enhanced sense of well-being and improved pacing. This theory was subsequently confirmed by observations that simply rinsing the mouth with a carbohydrate solution can also enhance performance of the cycling bout (Carter et al, 2004a).…”

mentioning

confidence: 99%

Carbohydrates for training and competition

Burke

Hawley

Wong

et al. 2011

Journal of Sports Sciences

Self Cite

710

711

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An athlete's carbohydrate intake can be judged by whether total daily intake and the timing of consumption in relation to exercise maintain adequate carbohydrate substrate for the muscle and central nervous system (''high carbohydrate availability'') or whether carbohydrate fuel sources are limiting for the daily exercise programme (''low carbohydrate availability''). Carbohydrate availability is increased by consuming carbohydrate in the hours or days prior to the session, intake during exercise, and refuelling during recovery between sessions. This is important for the competition setting or for high-intensity training where optimal performance is desired. Carbohydrate intake during exercise should be scaled according to the characteristics of the event. During sustained high-intensity sports lasting *1 h, small amounts of carbohydrate, including even mouth-rinsing, enhance performance via central nervous system effects. While 30-60 g Á h 71 is an appropriate target for sports of longer duration, events 42.5 h may benefit from higher intakes of up to 90 g Á h 71 . Products containing special blends of different carbohydrates may maximize absorption of carbohydrate at such high rates. In real life, athletes undertake training sessions with varying carbohydrate availability. Whether implementing additional ''train-low'' strategies to increase the training adaptation leads to enhanced performance in well-trained individuals is unclear.

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The Effect of Glucose Infusion on Glucose Kinetics during a 1-h Time Trial

Abstract: The results demonstrate that glucose infusion had no effect on 1-h cycle time-trial performance, despite an increased availability of plasma glucose for oxidation and evidence of increased glucose uptake into the tissues.

Cited by 113 publications

References 25 publications

New strategies in sport nutrition to increase exercise performance

New strategies in sport nutrition to increase exercise performance

Nutrition Considerations for Open-Water Swimming

Carbohydrates for training and competition

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