Friday, 3 June 2016

Ultra Race Nutrition Revisted

With the ultra marathon season upon us I thought it would be a good idea to revisit the idea of ultra race nutrition. Through my own training and racing I tried many approaches to my nutrition and through readings and trial and error I have come to follow the following guidelines. 

At the core of race nutrition is the idea of consuming small amounts of carbs every 15mins and to start each workout or race fully loaded and not getting behind in calories. Also the longer the event the more calories needed. 

In my readings by Trent Stellingwerff and Asker's Jeukendrup, Trent drives home the point of 15grams of carbs every 15mins in 150ml of fluids and Asker has some specific ideas based on distance.

Asker showed some interesting data showing a pronounced trend that faster times were correlated with higher carb intake per hour in ultra events and suggests that ultra-endurance athletes should aim for up to 90 g/hr of carbs, and he showed some data from Ironman triathlete Chrissie Wellington who set a new Ironman world record in 2010 using this approach.

Asker's guidelines with suggestions based on Trent's "Rule of 15"
  • less than 1hr: no carbs needed 
  • 1-2 hr: up to 30 g/hr
    • 10 grams of carbs every 15mins 
  • 2-3 hr: up to 60g/hr
    • 15 grams of carbs every 15mins 
  • 3-20 hrs: up to 90g/hr
    •  20 grams of carbs every 15mins
(Trent's rule of 15 is adjusted slightly when moving to the ultra marathon)

In terms of tolerating high carb intake, it’s definitely an individual thing, but you do get better at tolerating high loads with practice. In his example of triathlete Chrissie Wellington, she was consuming 86 g/hr in 2007 and in 2011 was apparently taking quite a bit more than that, because she’s managed to train her system to tolerate it. 

Another change Wellington made was that she takes just carbs, no protein. In Asker’s opinion he found no benefit from adding protein — so eliminating the protein might make it easier on the gut.

Also he noted that his recent studies have found no difference in absorption rate for bars, gels and  fluids, so you can mix and match to find what your stomach tolerates best. He makes no reference to non sport nutrition products in terms of absorption rate but I would think that certain foods such as cooked sweet potato would also be a good addition to your mix of foods. 

The thing that stands out for me is that when you consume food like soups, potatoes etx in an ultra event be very careful to keep to the rule of 15 in that you do not consume more than 25grams of carbs in 15mins as your body will not be able to tolerate the large increase in calories, i.e. do not come into transition and sit down and consume a pizza, have the pizza cut up into small pieces in a zip lock and consume in small portions as you walk the uphills. 

It takes about an hour for the rate of carb uptake to reach maximum. So if you only start taking carbs after an hour, there will be a delay before those carbs are being fully utilized, so it is best to start right from the start utilizing the rule of 15 deciding how you want to consume the calories utilizing gels, bars, sports drink and in what combination. 

Given all this, the thing that strikes you the most, is how am I going to carry all these calories so that I can consume them in such small amounts throughout the event. This is where a little planning can go a long way and breaking down the legs and deciding how long each leg will take and how many calories  you will need using any number of hydration packs and handhelds.

The take home message in my mind is not so much what you use as fuel but how you consume that fuel and if you can take small sips, small bites and start early you will stay well stocked and energy levels will remain even throughout your event. 

Hope that helps.