03059 A Periodized Approach To Carbohydrate Intake During Training And Racing 700×394

A Periodized Approach to Carbohydrate Intake During Training and Racing

BY Ted Munson

While a restricted-carbohydrate diet can have training adaptation benefits, a periodized approach to carbohydrate intake allows you to fuel for the work required, optimizing both fat metabolism during training and your race-day performance.

Once your annual racing goals are set, it’s time to start thinking about how you should fuel for your best performance—namely with carbohydrate intake. What many athletes don’t understand is that your fueling strategies for training and racing should differ. Fueling for training should support optimal training adaptations where race-day fueling should support maximal performance. And that can mean drastically different carbohydrate ratios depending on where you’re at in your training cycle.

The “Train Low” Approach

When carbohydrate is restricted, enhanced training adaptations are commonly reported, which has been given the term “train low.” Training low appears to enhance fat metabolism and may improve exercise capacity. If race-day fueling is optimal, these enhanced training adaptations can improve race-day performance.

Despite the potential benefits of training low, there are negative implications of persistently training this way:

  • The desired training intensity is unlikely to be maintained because carbohydrate is the primary energy source high-intensity exercise.
  • Immune system functioning can be suppressed, increasing the risk of illness.
  • Muscle protein breakdown is increased. Continually raised muscle protein breakdown can reduce overall muscle mass, which will reduce power output and exercise performance.
  • The body can no longer utilize carbohydrate as effectively during high-intensity exercise, decreasing race-day performance.

A recommended approach to overcome these negatives is a periodized approach to carbohydrate intake.

The “Train Smart” Approach

“Train smart” recommends that an athlete fuels for the work required. Carbohydrate can be restricted for selected training sessions aiming to enhance training adaptations. When the goal is to perform the highest workload possible, a restricted carbohydrate approach isn’t appropriate. In sessions lasting 60-90 minutes or less, performed at a low or moderate intensity, training low is likely to be beneficial.

Multiple train-smart strategies that appear to enhance training adaptations are reported in scientific literature:

  • “Sleep low and train low” uses overnight carbohydrate restriction followed by a moderate-intensity session in the morning. High-intensity sessions are performed in the afternoon or evening after consuming carbohydrate during the day.
  • “Twice-per-day sessions” suggests training twice-per-day every other day rather than once every day. The second session of the day is a train-low session, having restricted carbohydrate intake following the first session.
  • During a train-low session carbohydrate should also be restricted, as consumption of carbohydrate during training appears to blunt enhanced training adaptations.
  • Train-low sessions should be protein-fed rather than fasted to reduce muscle protein breakdown.
  • Consuming caffeine before a train-low session appears to increase exercise performance by mitigating some of the loss in exercise intensity observed when carbohydrate is restricted.

Race Day Strategies

When maximal performance of high-intensity exercise is desired, high carbohydrate intake is key, because carbohydrate is the primary energy source for high-intensity exercise. Contrary to popular belief, one day of carbohydrate loading is just as effective as three days, therefore the day before race day; 8 to 10 grams per kilogram of body mass of primarily high GI carbohydrate such as white bread or energy gels work well.


To maximize performance and carbohydrate loading, training should be tapered leading up to race day. Tapering should begin two weeks prior to race day with a steady reduction in training volume. The final training session should take place in the afternoon or evening two days prior to race day and carbohydrate loading can begin with this post-training meal.

On race day:

  • Large quantities of fiber, protein, fat and fructose should be avoided as these have been associated with stomach problems during exercise— individual preference is also important.
  • The pre-race meal should contain some carbohydrate, however if the individual is sufficiently loaded the day before, it doesn’t have to be especially high in carbohydrate.

Carbohydrate consumed during a race provides an alternative source of energy to muscle glycogen and is used as fast energy. Carbohydrate should also be consumed following high intensity and/or during long-duration exercise to replace used muscle glycogen and to enhance recovery.

Periodized Carbohydrate Intake Recommendations

Train-low sessions:

  • Only for moderate or low-intensity training lasting less than 90 minutes
  • Consume protein beforehand rather than being fasted
  • Consume caffeine approximately 20 minutes beforehand

Carbohydrate-loaded performance sessions:

  • For high-intensity training and/or sessions lasting longer than 90 minutes
  • For events lasting longer than 90 minutes consume 8-10 grams per kilogram of body mass of mainly high GI carbohydrate the day before race day
  • Consume 60-90 grams of carbohydrate every hour during a race, aiming for 20 grams every 20 minutes
  • Consume 1.2 grams per kilogram of body mass of carbohydrate following high-intensity and/or long duration exercise
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About Ted Munson

Ted Munson is the Performance Nutritionist at Science in Sport. He comes from a sports science background having worked in elite sport for the past four years. Ted has worked with athletes in football, rugby and tennis, most recently with Hull City FC as a sports scientist. Ted continues to provide sports science support for teams, alongside his MSc in nutrition and physiology, focusing on hydration markers in elite athletes.For more on training and nutrition by SiS Performance Nutritionist Ted Munson, visit us at scienceinsport.com.

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