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    Fueling The 70.3 Race
    Jen's Coach Blog

        Fueling The 70.3 Race

By Jennifer Hutchison for Ironman.com.
Posted on Thursday, Aug 17, 2006 at 10:28 AM

The creation of the Ironman 70.3 series and the inaugural Ford Ironman World Championship 70.3 (which is only 12 weeks away) has meant that interest in what was formally known as the “half Ironman” distance has grown dramatically.

There is plenty of information to be found on fueling guidelines for endurance athletes as it relates to the Ironman distance, but not as much can be said for fueling the 70.3 distance.

Race day Ironman success is all about pacing, patience and nutrition. Ironman 70.3 success also requires these elements however, because the duration is less than half the time it takes to complete Ironman, many athletes feel they can “race” this distance the same way they might approach an Olympic distance race. Even though 70.3 race day nutrition evolves from endurance nutrition principles, 70.3 athletes should recognize that the 70.3 plan is not their Ironman plan divided by two.

There are many similarities between the fueling strategies for the 70.3 and Ironman distances. Those include the need to top off fuel stores in the days leading up to the race, the need to consume carbohydrates as the primary race day energy source, the need for fluid to keep the body hydrated to maintain performance and the need for electrolyte replacement.

The biggest differences on how you fuel a 70.3 performance comes from the differences of race duration, race intensity and slightly different environmental conditions you might encounter.

Race duration and intensity The time to complete a 70.3 race can range from sub four hours (pro males) up to 8+ hours (slower competitors), whereas Ironman is an 8 to 17 hour day. Ironman races are truly aerobic in nature with most athletes exerting efforts in 70 to 80% of their maximal heart rate range. The 70.3 race, though still considered aerobic, skirts the upper limits of the anaerobic threshold at times. Some athletes are able to sustain efforts in the 85 to 90% range. Once an athlete goes beyond the 80% mark, the body shifts from using a well balanced mix of fat and carbohydrates for fuel to primarily carbohydrates sources. This is of importance because, as discussed in previous articles, with an increase in race intensity comes the potential for quicker fuel usage (increasing chances of bonking), risk of dehydration (sweat more and drink less) and gut issues. Consider your fueling choices because they may be slightly different than in an Ironman.

Environmental concerns: Another issue to bear in mind is the time of day most athletes start the run. In an Ironman most athletes start the run in the early to late afternoon. For a 7AM Ironman 70.3 race start, athletes can expect to begin their run anywhere between 10AM and 1PM, the time of day when the temperature seems to rise most quickly. Through trial and error during your training you can identify whether or not your sweat rate and fluid intake will be affect by the heat.

Below are a few things to think about when planning for your 70.3 race:

Pre and post race nutrition:

No major differences from Ironman here. Pre race: Carbo-loading through a natural reduction in training during your race week taper combined with a modest increase in carbohydrates with meals and at snacks is a must. Post race: Restore fluid and electrolytes ASAP to get the recovery process started. Carbohydrates and protein consumed in the 30 minutes that follow will help accelerate the healing process especially needed if the 70.3 is being used as part of the Ironman training.

Bike: Leave the mobile buffet at home. Yes you can race on liquids and semi solids alone. Nothing can make a 70.3 race more miserable than a clogged gut. Decrease the risk for gut “shut down” by avoiding overfeeding – taking in more calories or carbohydrates than the stomach and intestines can handle. Remember a higher intensity effort will decrease the rate fuel and fluid empty from the stomach. I will usually advise athletes to stick with carbohydrate based sports drinks (as opposed to ones with protein) and strive for about 50 to 75 calories (10 to 20 grams carbohydrate) less per hour compared to their Ironman fueling plan. So, if an athletes does well with 250 calories per hour during Ironman I may have them decrease to 200 calories per hour for a 70.3 race.

Stay hydrated. This is a “no duh” statement, but some athletes seem to feel they should not have to urinate during this distance. Honestly, if you are finishing in over five hours, in my opinion, you should have to urinate at least one time (towards the end of the bike or during the first few miles of the run). Coming off the bike as hydrated (with sufficient electrolytes, too) as you possibly can will set up you up for a great run. The few seconds you lose for making a pit stop will be more than made up for with a more consistent run split. Hydration should be dialed in during the training season with workouts that are race pace specific conducted at times that are closely related to the times the athletes will actually be out on the course.


The pace for the 70.3 run is certainly more intense than that of Ironman. This can lend itself to GI problems. Again, a sports drink or a combo of water plus gels providing about 25 to 35 grams of carbohydrates per hour should help fuel the body while decreasing the risk of a clogged stomach. Hydration and electrolyte strategy may be dialed down a bit compared to an Ironman race.

As a side note, a trick that has served my heavy sweating body well for both Ironman and the 70.3 distances is to start the run with a water bottle. (I also attach my gel flask to it with a rubber band.) I use a wide mouth bottle so I can fill it will ice and water. Smaller and frequent sips of liquid are known to “sit” better when consumed at higher intensities. It also allows me to bypass a few aid stations, take smaller amounts of gels more frequently (to minimize gut issues) and squirt cool water on my head while others around me are wilting in the heat. Do I look like a geek? You bet, but I am a well fueled and hydrated athlete, usually with a strong finish ;-)

The main purpose of this month’s article is to get you thinking about your 70.3 race day nutrition strategy. Give it as much thought and practice as you would a full Ironman distance race. Gone are the days where you had to win your age group at a “half-Ironman” to qualify for a World Championship slot. If you train hard, eat smart and tweak your Ironman nutrition plan to better suit the 70.3 distance, you may just find your performance qualifies you for the new World Championship in Clearwater this November.

See some of you at the start line in Clearwater, I’ll be racing in my HerSports uniform with a water bottle in my hand during the run!

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