Race nutrition is a sufficiently complex topic as to be considered the 4th discipline of long distance triathlon racing! There are plenty of guidelines given in sports training and nutrition resources, but as any athlete with even a moderate level of experience knows, what works for one person (or even most people) will not necessarily work for you. Standard advice or guidelines is given along the lines of 1 gram of carbs per kg body weight per hour. This is fine as a starting point – by looking at the nutrition contents on packaged foods we can easily work out the correct amount of foods to meet this, but this requirement will vary much depending on the individual according to body composition, metabolism and fat oxidation efficiency, gastric tolerance, long term dietary habits as well as racing intensity and environmental conditions. So, as that 4th discipline, we really should be making a little effort to understand our own nutritional needs and developing strategies to meet these requirements.
Part 1- race day
We need to know what energy forms, and how much, we can tolerate under race conditions, and since it’s very hard to replicate this in training this really comes down to racing experience. I’m preparing to race my 16th Ironman and by this stage I feel that I’ve refined my race day nutrition sufficiently to load-up the bento-box on race morning with confidence. That said, I’m still finding that my requirements do vary according to the race course and conditions, and so with each race there will be a few small tweaks or experiments.
I race at between 50 and 53kg, and my body composition is of relatively high muscle mass, and therefor fast metabolism. On the bike I output about 170W average over 5.5hrs which equates to about 600kJ/hr. I don’t know what my own personal energy conversion efficiency is (you can get this tested), but we’re all somewhere in the region of 25% – which is roughly how kJ equates to kCal. So that 600kJ of work can be taken as a 600 kCal burn. At my racing HR average of 155bpm, my metabolic testing indicates that I’m utilizing 45% fat and 55% CHO, however the periods where I exceed this HR pushing me over Anaerobic Threshold and result in much less fat oxidization and carbs account for a greater proportion of my fuel supply than this average would suggest. I estimate 60% of my energy to be met by CHO.
So using my data as an example, at around 3W/kg that’s 11kCal/kg/hr. At 60% ChO (and there are 4kCal in each gram of carbohydrate) that’s just 2.7g of carbs per kg body weight per hour. For an 80kg athlete that’d be 216g per hour. Clearly it is unfeasible to expect to meet this during the race. Aside from the practicalities of carrying and consuming over a kilo of sugar, there’s a limit to how rapidly we can absorb foods which is further reduced by intense activity and elevated body temperature. I”ve read from various sources that 200-250kCal/hr is about the limit of what most people can process in a race. Assuming that this refers to a ‘typical male’ at 80kg I factor this down to 150/hour for myself and have worked on that. It’s a gel or half a bar every 40 min. Admittedly, I have not tried to consume more than this but have still managed to race well on less.
During the run I use a figure of 90kCal/mile or 13g CHO based on 60% at race intensity. That’s about 1.5kCal/kg/mile (0.25g CHO/kg/mile). For me that’d be 12-13 gels during the run. yuk. So, I assume that the150kCal/hr absorption works for me when running too (seems to be the case, though it may be that more sensitive people need to work with less) and take a gel every 40 min or so, equating to 4-5g CHO/mile (0.9g/kg/mile) plus some sports drink and coke.
As you see, the best we can really hope for is to meet about 1/3 of our carbohydrate needs during the race and so our race week dietary preparations are an important factor in the race nutrition equation. This is the topic of Part II.
Back to race day – my strategy is:
breakfast about 2.5hr before race start – approx 400 kcal some low-fibre carb with fat +protein. in a hotel room this usually is some combination of peanut butter with either yoghurt & oats or a on bagel with cream cheese. and a coffee or two.
that’s it except for sipping water (unless coffee is available in the start area)
on the bike – aiming to consume at least 150 kCal/hr I put 8 gels in a bottle (800kCal) and top it up with water. I also pack a Powerbar cut into halves (100k Cal each half) and an extra gel. My estimated fuel use during a race is 550kCal/hr on the bike and i’ll do 350-400kCal in the swim. Personally, i like to eat some solid food during the day as i find gels down satisfy the ‘hungry’ sensation, but have learned that this must be early in the day if i want to run clear of the porta-loos. So i’ll swig some gel mix in the first 10 min of the bike and the next thing I eat is the bars, 20 and 60 minutes later. From there on it’s a gel swig every 20-30 min. I’ll usually grab a half banana or Powerbar around half way through the ride too. At aid stations I’m picking up sport drink if it’s hot and water. At Nice I had a can of Redbull in one of my bottles. That seemed to work well for me.
On the run – gels, sport drink and coke. I take a caffeinated gel immediately out of transition and go for a gel every 45 min. I take water and sport drink alternately at aid stations, later stages of the run i’ll take coke. In Kona, for the first time I packed a can of Monster in run special needs. Again, that worked for me, but i did wonder how much is psychosomatic- it’s not as if i felt heaps better after consuming it, i just enjoyed having something to look forward to at mile 18.
This feeding strategy is common with the competitive ironman athletes that I know but it is something that I have arrived at through a process of refinement since my first ironman race which was fueled by a much more solid picnic of 9-bars, marzipan, fig rolls and peanuts with just one or two gels on the run. As my Ironman racing has progressed to be more competitive, I’m racing at higher intensities and can less afford to be spending time for loo-breaks and gastric discomfort. I would still recommend a more solid race-day diet for the mid-pack or slower ironman athlete who will be racing at steadier intensity and expects to be out on the course for longer. This person requires greater sustenance and therefor palatability will be of more importance than quick availability, fast energy release and ease of digestion. For this person I’d also recommend packing a good variety of foods – what tastes delicious to you in training, you may just not fancy eating on the day.
Whilst race experience is great – do more races, try more things discover what works and what doesn’t under different circumstances- with so many variables and the memory being unreliable (can you even remember what you ate 3 days ago?!) you need to do a little more than just that. You should keep records of what your nutrition, how you felt, and how the race went plus any other notes for future reference (such as “such and such product melted all over the place/stuck in my teeth/was too hard to unwrap” ) In the same way that you record your training, though a bit tedious, it enables you over time to look back and find trends and patterns. It makes you preparations a lot simpler if you have a set of notes to hand which tell you exactly what you ate and drank in your last successful race as a starting point.