When and what you eat before and after you run is a personal thing, it can be influenced by things such as your schedule or how your digestive system copes with food and exercise. However there are some tips and guidelines that can help you to perform at your best.
In this blog post we will look at how your body fuels exercise, and top tips for fueling and hydrating before, during and after your run.
The body converts the food you consume into energy in order to function, keep the body alive and for you to undertake activities such as exercise. The energy in food comes from carbohydrates, fats and protein which are broken down during digestion in the body and used and stored in different ways.
Carbohydrates are the body’s main source of energy. When eaten carbohydrates are converted to glucose to be used straight away, or converted to glycogen to be stored in the body. Carbohydrates deliver energy to muscles faster than fats but are stored in much smaller amounts, approximately 500 grams, so need topping up during longer high intensity exercise such as longer runs.
Fats are vital in small amounts for the body’s functions, and are a major source of energy for the body during low intensity workouts.
Protein is converted into amino acids and used in the body for repair and growth. Amino Acids are in every cell and are vital to the body’s functions. Protein is used as energy when glycogen (from carbs) stores are low, when this occurs the amino acids in muscles are used to be converted into energy.
Before you head out the door it is a good idea to have a meal which includes some slow release carbohydrates approximately 2 hrs before running, the aim is to top-up carbs to ensure your liver glycogen stores are full before the start.
If you have a full marathon or ultra coming up, it can be a good idea to top up the body’s glycogen stores gradually over the days running up to the event, often referred to as carb-loading. However it is important to not overload the digestive system as this may cause issues while running on the day. It is also important to make sure your body is fully hydrated, so a good way to top up both the fuel and water in the body is with a carb based sports drink, as this wont overload the digestive system as much.
It is not always possible to eat something before a run, if you prefer running early in the morning or straight after, or just your stomach might not fancy it. In this situation it can be handy to have a small snack of around 20-30 grams of carbs with a bit of water about 15-30 mins you start.
How you fuel during your run is a very personal thing, and should be practised in advance of race day. It also depends on the distance/ time you are planning on running for. Sports Nutritionist Anita Bean offers the following advice:
Exercise < 45 minutes
If you’re exercising for less than 45 minutes, there is no performance advantage to be gained by consuming additional carbohydrates.
Exercise > 60 minutes
For exercise lasting longer than about 60 minutes, consuming carbohydrates will help maintain your blood glucose level, delay fatigue and enhance your performance. The general recommendation is an intake of 30–60 g carbohydrate/hour, depending on the exercise intensity and duration.
Exercise > 2 ½ hours
Research suggests that it is possible for the body to absorb up to 90g carbohydrate per hour if it comes from multiple carbohydrates sources, for example a mix of glucose and fructose.
Most energy gels or supplements which can be added to water, provide a mix of carbohydrates such as glucose, maltodextrin or sucrose.
Long runs and marathon distance
Start fuelling 45 – 60 minutes into your run, aiming for 30g carbs / hour if you’re anticipating a finish time > 4 hours; 60g/ h for a < 4-hour finish time or 90g/ h for a < 3 hour finish time.
Source: Anita Bean website
Post run it is important to help your body recover and repair, so it can adapt to the exercise stresses you’ve put on it and grow stronger. Protein is the building blocks of the muscles in our body and helps with growth and repair, so try to include some in your post run drink or snack.
If you plan to run or train again within the next 8 to 12 hrs it is also important to top up those glycogen stores with some good quality carbohydrates.
When we exercise the body loses water and electrolytes through sweat, if these are not replaced we can experience mild to serious symptoms which can impact running performance, such as:
It is therefore really important to have a hydration strategy that is appropriate to the distance being covered, the weather conditions of the day and also your individual needs.
How much you sweat during exercise is very individual and can range from between 0.3 to 3 litres per hour. One way to find out how much you sweat is to weigh yourself before and after a run, with a loss of 1kg of body weight equalling approximately a litre of sweat loss.
Try and drink around 500ml of water approx 2 hours before your run to make sure you are fully hydrated.
If you are running for less than an hour it is fine to top up your hydration after your run, however if you are running for an hour or longer it might be beneficial to drink while you are running. There are no hard rules around how much to consume, however it is a good idea to aim for between 0.5-1 litres per hour. Taking on small amounts often is a better approach than downing a bottle at the water station as this can lead to the stomach feeling bloated and the water sloshing around while you are running.
When we sweat we also lose electrolytes which are found in the body and play an important role in maintaining fluid balance, activating muscle function and preventing cramp.
Electrolytes include potassium, magnesium, chloride and sodium, the latter being the most important as it enables the body to absorb and retain fluid. You can top up electrolytes either using supplements in your water, in energy gels or tablets.
After running, drinking extra liquids will help with muscle recovery and prevent dehydration. Try to stick to the daily recommended fluid intake 6 to 8 cups on rest days, and have extra on run days.
Just a note on over-hydrating, this can be a problem on longer runs such as marathon distances and longer. Drinking too much can lead to hyponatremia, when the levels of sodium in the blood become too diluted, and can lead to serious consequences. The key is to drink small amounts often over the duration and to include electrolytes in your fluids.
Overall supporting your physical activity with a nutritional balanced diet will help your body recover and grow stronger, making it easier for you to see progress in your running and feel overall wellness.
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