Pre-Exercise Carb Intake

Written by: Greg Eskedjian

What are Carbs & Why the Bad Wrap
Now that I introduced the topic of sports nutrition, I can begin to talk about some of its different components. There may be no better place to start then with carbs. Over the past handful of years, carbs have gotten a pretty bad wrap in Western society, and for many reasons, it's warranted. However, this negative stigmatism associated with carbs has little to no place in the realm of athletics.
Lets first begin with what carbs are, without getting too scientific. Carbohydrates are one of the three macronutrients (carbs, fat, protein) that our bodies intake through food. A wide range of foods contain carbs, such as grain products, fruit, dairy, legumes and some vegetables. Carbohydrates are used to produce energy during exercise for our working muscles, either from endogenous (internal) or exogenous (external) sources. Our body stores carbohydrates as glycogen (endogenous stores) and when we exercise, we break down that glycogen into glucose (sugar), which is then used to produce energy. Our glycogen stores associated with exercise are found in our muscles and in the liver. Carbs are very versatile, producing energy in both low-intensity and high-intensity exercise situations. Also, carbs are the main source of fuel for our brain, and a lack of carb availability can affect performance, in areas such as motor skills, concentration and feelings of fatigue.
So why the bad wrap? It all comes back to the ratio I mentioned in my first blog. Today's Western society has adopted a diet that on average has a growing number of carbs (mostly simple sugars), along with a significant decrease in daily activity. When we intake large amounts of carbs and don't use that fuel, the body will store it as fat. Therefore, the bad wrap with carbs comes from excessive caloric intake and lack of exercise, which in turn can result in obesity, insulin resistance and diabetes. However, like I alluded to earlier, the energy demands of an athlete are much different then the average person, which means these carbs become a very useful source of fuel for athletes.

buy panerai replica watches Carb use during training
So as an athlete, what should you be doing? Well, when it comes to carb intake, Louise Burke (head of sports nutrition at the Australian Institute of Sport) and Ronald Maughan (chair of the IOC nutrition group) developed a 3-paradigm process to follow leading up to competition: Train Hard, Train Specific, Train Smart. Although the dietary needs/demands of every athlete will be different, these general guidelines will hopefully lead to productive training sessions and ultimately success during competition.
Train Hard
Train Hard refers to the high-intensity training sessions and athlete under goes to properly prepare for the demands of competition. When it comes to fueling our bodies for these sessions, it is important to meet the energy demands of this training, so that the quality of our sessions is high. That means during times of high-intensity training, especially when we have multiple sessions in a short period of time, we need to make sure our carbohydrate intake is high. The reason is that when we are training at these high intensities, our body uses glycogen (carb stores) as our main source of fuel. Therefore, in order to meet the training demands for the following session, we must replenish those stores with carbs.
So how much do we need? Here is a brief breakdown of the IOC's 2010 guidelines for carb intake for a training diet.
Light
low intensity or skill based work
3-5g/kg/day (grams of carbs per kilogram of body weight per day)

Moderate
moderate exercise program (about 1hr/day)
5-7g/kg/day

High
endurance program (1-3hr/day moderate high intensity exercise)
6-10g/kg/day

Very High
extreme commitment (>4-5hr/day moderate high intensity exercise)
8-12g/kg/day

These values may look confusing, so here is a simpler way to understand them. For example, let's say I weight 177lbs (about 80kg) and need to intake about 6g/kg/day based on my daily training. Then over the period of a day, I should eat about 480grams of carbs. The reason these values are stated this way is because it was found that giving an athlete a total percentage of daily intake (ie. 60% of total intake should be carbs) made it much harder to apply to his/her diet. Therefore, having an approximate number of carbs to eat daily makes it easier to proper follow.
Train Specific
Training specific refers to practicing nutritional strategies that will prepare an athlete for competition time. The old adage practice like you play applies to sports nutrition just as much as it does physical training. Normally athletes eat a lower amount of carbs during training then they do around competition time, which can be problematic. First of all, eating or drinking during exercise isn't always easy on the body, but by practicing those fueling habits, an athlete can train the gut, allowing them to refuel during competition with less adverse effects (ie. intestinal troubles).
Timing of carb intake leading up to competition is just as important as the amount. The 2010 IOC guidelines for carbohydrate intake for a training diet also outlined pre-competition habits regarding carbohydrates. It states that approximately 1-4 hours before competition/training, an athlete should consume about 1-4 grams of carbs per kg of body weight. This may seem like a very broad range, but as I said earlier, every athlete will have different needs. Without professional coaching and testing, it can be tough to find out exactly how much each athlete should be intaking and when. The best way to find what works for you is to alter the carb amount and timing of intake within that ratio until you find what amounts make you feel and perform the best.
Train Smart
This section refers to whether or not athletes should train during times of low carb intake. Training during times of low carb availability or intake has been shown to have both pros and cons. One of the positives that have been found about training Low is that it can stimulate greater metabolic adaptations. However, a con of training Low is that it can be associated with an increased risk of illness and injury, along with the inability to complete high-intensity training sessions. What people need to realize regarding training with high or low carb availability is that during a training cycle, these usually occur naturally. For example, after a meal or close to competition when the quality is still high but the volume of training is lower may both be examples of high carb availability. On the other hand, multiple training sessions in a day, before breakfast or during weight-loss periods are all examples of when someone might be training with low carb availability. Overall, when it comes to training Low is may be useful for lower intensity training sessions, but not recommended around high-intensity training when carbs are needed. There are some possible ways to aid during times of low availability like caffeine use and carb mouth-rinsing, but I will discuss those techniques in a later blog.

Overall
At the end of the day, athletes need to realize that their carbohydrate needs are much different than that of the average Joe. You may be wondering what kinds of carbs to eat and when, but getting too specific would make this blog a novel. To know exactly what you should be eating and when, sitting down with a sports dietician is your best way to optimize your diet. Overall, here are a couple points to take away from what I have discussed:

• Every athletes carbohydrate needs will be different based on their sport, it's intensity and length.
• During intense training periods, make sure to that carb intake is sufficient to properly refuel and meet the demands of training.
• Mimic competition eating/drinking habits during training to prepare your body for the demands/stresses during competition.
• Low Carb availability can be useful to stimulate greater adaptations, but is recommended for less intense training sessions.

Greg Eskedjian
BSc., CSCS, MS Candidate