Nothing undermines several months of earnest training like failing to plan nutritionally on race day. All you need is a little bit of nutritional know-how and a disciplined plan in order to access your highest sport potential.
Carbohydrate depletion is one of the primary (and most common) limiters in endurance-sport performance, even among top-tier pros. Your task is to avoid that limiter, which is something pretty easy to get right.
Knowledge Is Power
It is impossible to replace all of the fuel that you will be using during your Ironman event, yet it is possible to obtain an intelligent goal-fuel replacement plan. Your focus should be on replenishing the limited carbohydrate stores in your muscle and liver tissues. The general recommendation of replacing 0.5 grammes of carbohydrate per pound (1.2 grammes of carbohydrate per kg) of total body weight per hour (for events lasting more than two to three hours) is a reasonable start. An even easier method is to use the following online calculator at Powerbar.com/ powercoach.
Since the stresses of racing usually reduce your ability to tolerate and digest food, especially toward the end of a race, you need to find a more accurate and field-tested number. Starting with the personalised carbohydrates per hour as calculated above, see how many calories your body tolerates on your key long efforts (such as five-plus-hour rides, two-plus-hour runs) that mimic race pace. Wear extra clothes if you need to simulate heat conditions. Note your body’s tolerance of that carbohydrate level, and adjust your intake up or down accordingly.
You now have a personalised and field-tested goal of how many grammes of carbohydrate per hour to ingest. This is premium information few race-day athletes are armed with.
What to eat: Your nutrition research and hours of training should teach you what to eat when racing, but it is safe to assume that the majority of your fuel will come from sports drinks, energy bars and energy gels, in the form of carbohydrates. A PowerBar Performance bar contains about 41 to 45 grammes of carbs per one-bar serving, a PowerBar Energy Gel has about 27 grammes per packet, and an Ironman Perform sports drink mix contains 17 grammes of carbs per 240 ml. For context, a common strategy for a 808kg athlete would be to ingest one of each of the above per hour, plus adequate fluid to maintain hydration, for a total of approximately 87 grammes of carbs.
How to eat: The bike should be when you ingest most of your solid food (most athletes find they can tolerate only gels and fluids during the run). On the bike, you can store food in a singlet or jersey back pocket, a food storage bag designed to fit within your handlebar cockpit, or a gel flask mount for your bike frame. Some Ironman athletes attach solid food or gels directly to their bike frames. You can also use electrical tape to attach gel packets by their tear tabs to your top tube for quick access.
A fantastic option for your fluids is an aerobar-mounted bottle that allows you to drink while in the aero position.
During the run, you want your gel flask to be as accessible as possible. Sim- ply holding the flask during the entire run was always my preference, as it required minimal thought, yet its easy access kept it at the front of my mind. Make sure you hold the flask with the opening turned toward the ground so that gravity can keep the gel ready to ingest. A belt with holsters for multiple flasks is also a popular option to wrap around your waist at T2.
Experiment with what works best for you among these options while training and focus on their convenience. Anticipate losing your appetite after several hours out there, and expect fuel intake to become an energy-requiring task. Choose the strategies you find easiest so that you can focus your energy on racing rather than fuelling.
You will be given ample warning of aid station locations, special-needs bag pick- ups, and products and flavours offered on the course. Integrate this knowledge into your training and fuelling plan: Train with exactly what will be at the race. You can rely on aid stations for your liquid fuel and water, but you should plan on bringing all of your solid food and gels, and then use the course food in case of emergency.
Because the stations can sometimes be disorderly, when you enter, you should identify the volunteers who have what you want, then point at them and yell “water!” or “sports drink!” This proactive contact will ensure volunteers are focused on you, and thus you can maximise your chances of a successful handoff. (Don’t forget to thank them.)
At every aid station, an immediate priority should be refilling your aero bottle ((and quickly discarding the empty aid bottle), then replacing the bottles in your regular cages if needed. As your aero bottle empties on the course, continually empty your caged bottle contents into the aero bottle, allowing you to maximise the aero bottle’s convenience. Small systems like this minimise chaos creeping into your day.
You should also utilise the special-needs bag drop off-don’t miss it! Ride slowly through it. That single minute at 18 kph instead of 30 kph will have a far smaller impact on your overall time than missing your 1300-calorie bag. Two fresh bottles of sports drink, a fresh gel flask and two bars make up a sufficient bag. Anticipate the handoff and arrive at the station with empty bottle cages, an empty gel flask and no bars. At the run special-needs station, refill your gel flasks. If you are wearing a belt for your gel flasks while running, you may be able to skip this handoff.
When to eat: When to ingest fuel should be planned. Aim for the most even intake possible throughout the day to avoid surges of blood flow diverting away from your working muscles to absorb carbohydrates. Remove the calculating from your race day by eating a third of your hourly intake (perhaps 20 to 30 grammes of carbs) every 20 minutes by your watch. This can be achieved by fuelling every time the minute display is :00, :20, or :40. Don’t get derailed if this isn’t executed perfectly, but this is a reasonable system to keep you on task.
Matt Erlenbusch is a registered dietitian with an MS in exercise science, an ironman athlete and on PowerBar’s panel of experts.