Event Nutrition Series- 50km Nutrition
Over the next few months there will be a host of us challenging our limits in very different events. I will put together some information in the lead up to each event to develop nutrition strategies for both pre, during and post. The most important strategy is practice, like training you need to condition the body to what ever nutrition you plan on being apart of your race strategy. Our first event will be held in two weeks, the 50km time trial.
Before we go into the what to eat and when you need to understand some limitations in the body. Refer back to an older blog if you would like more information on how exercise can be limited, however specifically for the 50km time trial a key factor here is glycogen. Specifically the supply of glycogen to the muscle during prolonged endurance events, Prolonged cycling at moderate intensity has been reported to deplete muscle glycogen stores and thus becomes a limitation whereby the exercise intensity must reduce or the exercise is ceased (exhaustion). Strategies that promote glycogen availability during exercise (available to the muscle) have a performance enhancing affect. The 50km time trial will take between 90-120 minutes, meaning we need to adopt some nutritional strategies to complete the event and maintain pace towards the end.
To perform at your best for the event it is important to understand glycogen availability, this is how readily available glycogen is to the working muscle. We store glycogen in the muscle and in the liver. Fuelling pre-event becomes important to optimise glycogen stores. 2-3 days before an event we want to maximise glycogen storage as the event will last longer then 90 minutes and the pace will be relatively moderate. Carbohydrate loading is reported to be around 8-12 g/kg of Body Mass (BM). That means for an 80kg individual you want about 640g-960g of carbohydrates. I think for this event being indoors and on a fixed cycling you can get away with less. 5-7g/kg of BM of carbohydrate should be sufficient. If we add in a during event strategy you should have enough to get you through without limitation.
- Carbohydrate loading takes 3 days, the target for the 50km time trial should be 5-7g/kg of Body mass
- Eat quality carbohydrate sources brown rices, wholegrain, pasta, sweet potato, potato, fruits
Endurance events like the 50km time trial will have an affect on muscle glycogen and without proper nutrition support hypoglycaemia is a real threat. This is where blood glucose drops below the required level to maintain active transport into the tissue. So it is important to maintain blood glucose by supplementing during exercise at durations greater then 60 minutes. Depending on your food preferences different solutions will suit. Sports drinks are an easily available option and provide hydration and glucose. Aim for a sports drink with 4-8% carbohydrate content 600-1000ml. If you have used them before sports gels are a good option, however trial them first as they can give you stomach upset and you may be running for a toilet not finishing the 50km ride. 1 gel should be fine for the 50km, I would take it around 45-60 minute mark to get you through. If you prefer more natural products bananas are a great carbohydrate source, however you will need to eat 2-3 medium bananas.
- During event consumption of carbohydrates is necessary to maintain blood glucose and maintain exercise intensity.
- Sports drinks provide by hydration and carbohydrate supplementation, aim for 4-8% carbohydrate solutions
- Gels are a good option, make sure you practice using them to avoid gastrointestinal discomfort
- Natural options can be used (fruits), however greater quantities need to be consumed.
Lastly, hydration is very important for exercise performance. It is important in maintain blood pressure, nutrient concentration and also cooling. So hydrating before an event and during an event is important. Try and come up with a fluid plan, pre event you should consume a fluid bolus (large quantity) to promote fluid intake during the event, during the event keep sipping water to maintain fluid intake. Avoid excessively drinking as it can be detrimental.
Following the event resume normal eating practices and make sure you are rehydrating. A good rule is aim to replace 150% of fluid loss. If you weigh yourself before the event and after that will be a good indication. For example if your pre-event weight is 60kg and you loose 1kg, then you should aim to replace 1.5L (1.5kg) of fluid. Other strategies help here, consume water with food sources, adding or consuming higher salt dishes, and avoiding alcohol.