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Carbohydrates for Performance

Author:Britt Maughan R.D.
1893   1562 

Carbohydrates are one of the three macronutrients (fat, protein and carbohydrate). They provide substantial calories within our diet, and serve as a quick and easy source of energy during physical activity. Carbohydrates are the easiest macronutrient (compared to protein or fat) for your body to break down and use as fuel – and are therefore known as the body’s first energy source. Carbohydrates come in many forms – both simple and complex, and can be found in the diet from foods such as grains, vegetables, and fruits. 

While we could get super nerdy about each type of carbohydrate and their molecular structure – all you need to know is that simple carbs (think fructose) are absorbed faster and complex carbs (starch) are absorbed slower. Many sports nutrition products contain both forms because they require different pathways to be absorbed and metabolized – therefore allowing the body to absorb more calories per hour.

Carbohydrates in the body

When you eat foods such as grains, vegetables or fruits, your body breaks them down and turns them into glucose (a simple sugar that circulates in the blood).  This glucose then gets stored in the muscles and the liver in the form of glycogen.  Glycogen is the multi-branched polysaccharide of glucose that serves as the form of energy storage in our body. Your body can store around 1500-2000 calories of glycogen.

Glucose stored in the liver mainly gets used to regulate blood sugar levels within the body and helps maintain energy throughout the day. Your liver stores up to 90-110 grams at any time, with approximately 19% of the carbohydrates from each meal stored as liver glycogen (1). 

Muscles are the secondary storage for glycogen when the liver has reached its storage capacity. Muscles can have about 400 grams of muscle glycogen that is used for energy during prolonged strenuous activity (1). This is the glycogen that athletes rely upon during training and competition. 

Glycogen use during exercise

The intensity of exercise, together with duration, determines the amount of energy used in the training session. The best way to determine energy usage during training is through oxygen uptake (VO2 max) and respiratory exchange ratio (RER). While the energy usage may differ athlete to athlete, it is known that during exercise, 70% of the major carbohydrate source is muscle glycogen (2). 

VO2 max can vary based on age, activity level, percent body fat, anaerobic threshold and anaerobic capacity. Well trained athletes have an oxidation of roughly 180g (720 calories) of carbohydrate during 1 hour of intense exercise.  During running, energy consumption is about 1 calorie per kg per km – meaning, that an 85kg athlete will use about 850 calories during a 10km run. This is about 200 grams of carbohydrate (2). In general – your muscles only store enough glycogen to fuel your body for about 90 minutes. This is why additional calories and energy intake is vital during long training periods. Glucose must be replenished to avoid negative effects on performance and overall exhaustion.

Fueling before, during and after exercise

As mentioned earlier, the body can use all three macronutrients as fuel (carb, fat, and protein). Depending on your training plan and diet goals – you will want to adjust your fueling strategy to focus on one or all of these macronutrients (fat for fuel for ketogenic athletes, for example). For athletes wanting to focus on carbohydrate as their primary fuel source, we suggest the following guidelines below for fueling before, during and after excise. As always – we recommend testing out your strategy and adjusting based on individual needs before competition. 

Before: Eating prior to training or competition will help you fill your glycogen storage. A good rule of thumb is to fuel 3-4 hours prior to your event with about 300-600 calories (primarily carbohydrate, moderate protein and low fat) – shoot for 2-3g/kg of body weight (3). 

During: Fuel every 45-60 minutes during a long workout. Aim for 30-60 grams of carbohydrate (120-240 calories) per hour. Don’t forget to replenish the body with fluids and electrolytes as well (3).

After: Fueling after will help replenish glycogen storage and aid in overall recovery. Within 30-45 minutes, consume roughly 300-400 calories. A good rule of thumb is following a carb to protein ratio of 2:1 for short/medium intensity workouts and 3:1 for long/high intensity workouts (3).

Carbohydrate Supplements for Performance  

As athletes, it’s important to fuel your body with a balanced diet throughout the week, focusing on quality sources of carbs, proteins and fats – with plenty of vibrant colored fruits and vegetables. In addition to practicing healthy eating habits daily, it helps to add in a few quick and easy supplements that deliver the energy you need during training and competition. Here is quick breakdown of a few carb sources we like to use:

Sports Drinks: Sports drinks can be used anytime you need calories or hydration and are essential for physical activity that is over 60-90 minutes. They offer a quick and effective way to deliver nutrients such as calories, amino acids, proteins, vitamins, minerals and electrolytes. For endurance activities, choose a sports drink that offers calories and carbohydrates (such as Fluid Performance, which offers 100 calories and 24g of carbohydrate per serving). Read more here

Gels: Gels are used primarily to provide quick and convenient energy during exercise to increase overall performance and help delay fatigue. Gels now come in a variety of forms including the honey-like gels we are used to, as well as real food purees and nut butters. Our gels offer anywhere from 8-100g of carbohydrate per serving. Read more here

Energy Chews
: Energy chews offer a fast and easy way to deliver quick energy – and allow the athlete to tailor their calorie intake by eating as many or as little chews as needed. It’s a nice alternative to a gel, if you prefer to actually bite down on the something. Many of our athletes like to alternate every hour between gels and chews during endurance events.  Our chews offer 20-63g of carbohydrate per serving. 

Bars: Bars offer a quick and easy delivery of nutrients for any athlete – and can be used as part of your training or competition nutrition strategy, or simply as a meal replacement or snack on the go. Our bars offer anywhere from 18-38g of carbohydrate per serving. Read more here.

Bottom Line

Carbohydrates offer quick and efficient energy in training and competition. Glycogen must be replenished during exercise that lasts more than 60-90 minutes. Intake before, during, and after training should be adequate to support the intensity and duration of your sport or event. Sports drinks, gels, chews, and bars offer a convenient way to deliver fuel and can be used in a number of combinations to meet your calorie and carbohydrate needs. 


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