25 Oct From GPS data to nutritional guidelines
In most of our blogs, we have discussed how GPS data can help you preparing your players for the match by optimizing training sessions. However, GPS data does not only help you adjust your training sessions, it can also be used to help you optimizing your nutritional guidelines. Therefore, in this blog we will give background information about nutritional guidelines, provide an example of a nutrition schedule during a training week, and discuss how GPS data can be used to optimize the nutritional guidelines.
Before we are getting into the details of nutrition schedules, it is important to know the aims of these schedules in sports. One of the aims is to make sure that the energy stores of the (leg) muscles are ready to deliver high power outputs during a match. Another aim of such a schedule is to accelerate recovery after intense exercise (i.e. training sessions or matches). Therefore, to design a nutritional guideline we need to know what the most important sources of energy production are for team sports activities, and which factors contribute to the recovery process afterward.
Muscle glycogen is known as the predominant substrate of energy production during a match. It is known that 50%(!) of the glycogen stores of the leg muscles are completely emptied at the end of a match. This depletion of energy stores is, therefore, partly responsible for the decrease in (high speed) running demands towards the end of the match. Thus to delay the occurrence of fatigue in a match it is important to promote high muscle glycogen availability before and during the match. Since glycogen is a form of carbohydrate, high carbohydrate availability before and during the match are advised to enhance peak performance.
Considering the energy stores of the leg muscles are (almost) depleted after intense exercise, one of the ways to accelerate recovery is the consumption of high amounts of carbohydrate. However, refilling the energy stores isn’t the only factor that accelerates recovery after intense exercise. Short explosive actions, tackles, and strength exercise all result in muscle damage, which must be repaired to optimize performance in the next session. To stimulate the repair of muscle damage (and possibly stimulate supercompensation) it is important to increase the protein-intake after such intense exercise.
So what could a nutritional guideline look like during a training week when there are 6 days in between the matches (e.g. Saturday-Saturday)? For proteins, there is little variation in the amount of protein that players have to consume per day. The general guidelines are 1.2-2.0 g/kg body weight per day (96-160g for an 80kg player) for professional players, for which the higher ranges are advised for days with a strength session, a conditional training or a match (see figure 1). To make optimal use of these guidelines it is advised to evenly distribute these amounts of protein over 4-6 meals per day. The guidelines for carbohydrate intake show more fluctuation over the week, for which it is especially important to increase the intake of carbohydrates on the day before a match, on matchday itself and on the day after the match (480-800g for an 80kg professional player)(see figure 1). The carbohydrate intake is lowered on the day with a low- or moderate-intensity sessions and increased on the day with a high-intensity conditional session. However, it is known that high glycogen availability will reduce training effects. Therefore, if you want to improve the fitness level of the players with a conditional session it is advised to decrease the carbohydrate intake on that day (and possibly compensate this with increased protein intake).
But how can GPS data support you in optimizing these nutritional guidelines? There are a few cases during which you want to increase the intake of carbohydrates or proteins: (1) a player exceeds his/her own match benchmark (e.g. >130%) or; (2) the training load was >80% of the match benchmark. When one of these two cases happens for the sprint distance, it is important to increase carbohydrate intake (increase towards the higher end of the indicated values), and if this is the case for accelerations and/or decelerations then protein intake should be increased (increase towards the higher end of the indicated values).
We can conclude that, in general, it is important to increase the carbohydrate availability the day before a match, on matchday itself and on the day after a match, and when a high-intensity training session is planned. Furthermore, it is advised to increase protein intake after a match or strength training session. With the help of GPS data, you are able to optimize these nutritional guidelines: when a player exceeds his own benchmarks during matches of training sessions the nutritional guidelines should be adjusted. Carbohydrate availability needs to be increased when more sprinting distance is covered, and protein intake needs to be increased when more accelerations/decelerations were performed.