This summary is from the IAAF 2nd International Consensus Conference on “Nutrition for Athletics“ held in Monaco from April 18-20, 2007. Copies of the CD and booklet are available from the IAAF website www.iaaf.org
Nutrition for Middle-Distance Running
Presenter: Trent Stellingwerff (SUI)
Middle-distance running is at the cross roads of training stimuli used for running events. After nearly matching the mileage of marathon runners in the base phase, middle-distance runners proceed to almost the intensity used by sprinters during the racing season. The different phases of the training programme require different amounts of energy and different macronutrient content. Towards the racing season, the total energy needs are not as high as during base training. However, because of the intensity of training, the relative reliance on CHO use is higher. Protein needs also differ between seasons. The recommended fat intake is based on estimated total energy needs minus CHO and protein needs.
Buffering agents are effective for maintaining blood and intracellular pH. Much research has been done on bicarbonate. Many studies have shown positive effects in events ranging from one to 15 minutes duration. A “chronic” supplementation of bicarbonate can be applied and has been proven successful in keeping blood bicarbonate elevated for several days. This protocol might be especially useful in persons prone to GI distress after acute bicarbonate loading. Recently there have been studies on alanine. Alanine combines with histidine to form carnosine. This is one of the few dipeptides in the muscle with the right dissociation curve to buffer the intramuscular fluid. Administration of alanine has been shown to improve the amount present in the cells. Similar small, but significant, performance benefits have been reported compared to bicarbonate.
Middle-distance runners and other athletes should be warned against the use of pseudoephedrine. Although the substance itself is not on the WADA-list, use may lead to a positive test for one of the metabolites, which are banned.
As much of the training of a middle-distance runner is intense, above 75% V02max, carbohydrate should be the primary fuel. Moreover, the weight training that is often done alongside the running relies heavily on anaerobic ATP production, with declines in muscle glycogen reported of 25-40% after a multiple set resistance exercise bout. Future studies should answer the present questions about optimal timing of different training stimuli and concurrent nutritional status.
The endurance training typically used in the base period relies more on fat metabolism and usually energy expenditure is higher than in the other training phases. The absolute and relative contributions of fat can be highest in this period but should probably only still be around 2g/kg/day or around 30% of total energy. Carbohydrate intake can remain around 7-10g/kg/day. Lower total energy expenditure towards racing season makes the relative contribution of carbohydrate higher in this phase. Protein intake needs to increase with increased mileage and resistance training. However, protein needs will never be more than 1.7g/kg/day. Most athletes consume this amount of protein in their normal diet, so there is no need for extra protein.
Strategies to maximise glycogen recovery between sessions include taking 1.2 to 1.5g/kg/hour in the first two hours after training. There is still debate over whether inclusion of protein can benefit recovery. Data show either no difference or enhanced protein balance as well as subsequent performance and muscle protein degradation markers. No negative effects of protein in a recovery meal have been reported. Inclusion of protein seems prudent at a dose of about 0.1g of essential amino acids per kg body mass. This would translate to about 14g of whole protein from milk. No difference has been shown between protein from foods or from supplements.
The above summary was written by Peter Res
If you wish to download this handy Grams and Calorie Calculator for Carbohydrate, Protein, and Fat, click here for the Excel spreadsheet.
This is part 3 of 14 in a series from the 2007 2nd IAAF International Consensus Conference “Nutrition for Athletics”