The nutritional requirements for an edurance athlete are pretty straight forward however ensuring calorie sufficiency is of utmost importance through adequete carbohydrate intake first and foremost due to the nature of the sport but that does not mean that protein and fat should be ignored.
Calorie needs will vary day to day but this doesnt necassarily mean that intake should.
Eating roughly the same amount of calories each day can make energy sufficiency easier to achieve and improve performance, recovery and the primary strategy for avoiding RED-S (Relative energy deficiency in sport) and its associated health complications.
The first method to work out you energy requirements is to track day to day activity (without training) using a sports watch. Then again with a training day, we can see the energy replacement needed after the expenditure of the activity. However this can vary from a simple run to an epic long endurance day so intake can vary as much as 4000kcals and some athletes may find it difficult to consume this amount in one day.
The second method is to average out your training week or month in terms of energy expenditure using a tracking device and spread the calorie intake more evenly over the whole week, either with the same daily intake or marginal differences on the higher and lower activity days.
The benefit here is that it is more manageable and consistent to portion sizes and appetite. Also considering that recovery doesn't end at midnight. Spreading the intake evenly over the week may improve energy levels and aid in recovery more.
*A note on tracking calories- only add the calories burnt by the activity not the calories you would have burnt anyway without the exercise. Some tracking devises do this for you but if not i have outlined the method below.
Heres any example of how to calculate-
BMR (basal metabolic rate, the amount needed just for your body to function)- 1800kcals -divide this number by 24 this is the amount of cals burnt per hour without exercise =75 cals per hour
Activity( general activity in the day)= 600kcals -divide this by 16 hours (the amount of time you would have without sleep
=37.5 per hour
75=37.5=112.5 kcal per hour befor training (lets say 115kcal)
Now if your watch tells you that you burnt 600kcals running the additional burn is only actually 485kcal.
BMR=1800kcal/24=75 per hour
Activity=600kcal/16=37.5 per hour
75+37.5=112.5kcal per hour before training (rounded off to 115)
Then a run burning a total of 600kcals minus 115 = actual extra calorie burn from exercise is 485kcals
Protein intake for the athlete-
Studies using endurance athletes have shown that they have similar requirements to those of strength athletes. This is because of the vast amount of microtrauma caused by repeated repetitions on the road or bike.
Athletes participating in at least 2-3 bouts of endurance training a week benefit from levels of 1.8-2g of protein per KG of bodyweight. The higher end of the scale preventing lean body mass loss during periods of calorie restriction.
Protein intake intraworkout however is quite contraversial as this takes energy to be broken down and sends blood flow to the stomach. Periodised protein throughout the course of the day however has shown to have significant muscle protein sythesis benefits and does not need to be consumed before or during training.Look to aim for 25-40g of protein per meal and aim to consume a protein and carbohydrate rich meal post training within 1-2 hours maximum.
Fat- is an essential macronutrient and should not be eliminated from your diet,it is responsible for hormonal health and coats every cell in our body. Aim for 20% minimum of your daily calories, this allows for a good amount of carbohydrates to be consumed as the prefered fuel source for an endurance athlete.
Carbohydrates- these should make up the rest of your calorie goal for the day. Aim for a varied range to include all the micronutrients and fibre needed to optimise your bodies function and performance.
Pre race and in-race fuelling- Start your day with an easy to digest breakfast thats aimed at topping up you glycogen stores and blood sugar ahead of the race assuming that you have carb loaded for the two days prior at 10-12g of carbs per KG of body weight (I will go into more detail in another post at the risk of making this too long)
Aim for foods that sit well with you and that you've tried and tested before.
Maybe consider a bowl of rice krispies, an energy bar or a banana with rice cakes and honey around 1-4 hours prior.
For longer races you may need mid-race fuelling in the form of a gel an isotonic drink or a flapjack but trial these beforehand. Fuelling stations may be dispersed throughout the course so its a good idea to find out what they will be supplying (usually down to the sponsor) and where they are located.
Here are the reccomendations for carbohydate intra-race fuelling
<45min Not Required
45-75min Small amounts including mouth rinse
2.5-3hr up to 90g/hr using multiple transportable carbohydrate
*This is extremely relavent to the athletes tolerance and intensity of the event.
The key point here is to make sure you are fuelling your body enough for the huge energy requirements of the endurance athletes weekly activities to acheive optimal performance and recovery as well avoiding any issues due to lack of energy availability from your diet.