... ... Nutrition & Hydration - Mile27
Sep 092016
 
Fat burning profile ?

Fat Burning profile

Given an ultra takes a lot longer than 2 hours (the approximate limit of our carbohydrates to supply energy) it is clear that fat is going to be a big contributor to our energy supplies.
The less effective we are at using fat for fuel the more carbohydrates we have to consume during a race to fuel our muscles. The more we have to put into our stomachs the more chance of stomach problems. Given stomach upsets are a major causes of DNF’s and below par performances in ultras it makes sense to work on increasing your bodies ability to burn fat.

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Oct 272015
 
Nutrition for a 100 miler

Salt – do we really need it ?

The ability to measure our sodium losses in sweat during exercise has led some to thinking that we need to replace at least some of what we lose in sweat to ensure our blood sodium levels don’t fall to levels that effect performance or health.

The thinking goes that somewhere between 230-1700mg of sodium can be lost per hour during exercise in hot conditions and we have a typical daily intake of 4g. As a consequence it can take only 2-3 hours before we deplete our sodium stores levels that effect performance. But measuring sweat sodium levels is only part of the picture – our body doesn’t particularly care what our sweat sodium concentration is (and in fact it reduces sweat sodium concentration as it acclimatises to exercising in the heat). What the body very tightly controls is our blood sodium levels and has several mechanisms to keep it within 135-145 mmol/litre range that is required for normal human function.

One thing to understand is its not the actual amount of sodium in our body that is the critical factor, its the concentration of sodium in our blood. If there is less blood then we need less sodium to keep the concentration in normal range.

Deciding we need sodium supplementation based solely on what we sweat out is like basing fat consumption based purely on how much fat we burn during exercise or basing our hydration strategy purely on how much weight we lose or our carb intake on how much energy we burn when we run. What we burn or sweat out doesn’t matter – its whats left in the body that we need to be concerned about. So when we look at fat burnt during exercise we know that we have ample supplies of fat so there is no need to take on additional fat, we know that our carb supplies will eventually run out so we need to take in additional carbs in a race but we know we don’t have to replace the whole amount we burn, we also know that the body can handle a certain level of dehydration with no adverse effects provided we drink to thirst. As far as sodium goes what we should be looking at is what happens to our blood sodium levels during exercise NOT how much sodium we lose in sweat.

Do we need to replace all of our sodium sweat losses, some of them or none of them?

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Sep 162015
 

Nutrition for a 100 miler

Nutrition for a 100 miler


One of the main reasons for a DNF in an ultra is nausea and vomiting (23% of DNFs at the 2009 WSER were for this reason). Even among those that finished, up to 40% of the Western States field experienced nausea and or vomiting that affected race performance. Stomach problems can sabotage all the hard training you have done so it’s critical you have a strategy that works for you going into a big race.

Nutrition is a complicated topic but I’d like to break it down to 4 main questions:

  1. How much should I eat?
  2. What should I eat?
  3. When should I eat?
  4. What to do if something goes wrong?

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Feb 182014
 

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For many years we have been lead to believe that a dehydration level of more than 2% will negatively affect performance and therefore we should drink to limit dehydration to this level. This advice has even been given out by coaches and trainers for years and was the official recommendation of the American College of Sports Medicine in 2007.

Where this 2% rule came from no-one is really sure as there is no research to show that this is the case when applied to athletes in actual races. In fact there is an abundance of research to show the opposite. Continue reading »

Dec 222013
 
Getting checked out by the doc

Getting checked out by the doc

Its been just over a month since I collapsed at the Great North Walk 100 miler. Recovery was relatively quick thankfully and I have spent the last few weeks researching all I can on what happened to me and how to prevent it happening again. I have also heard from many other runners who have experienced the same type of symptoms – echoing in the ears, dizziness, breathlessness, cramping, tingling in my face and hands and extreme fatigue.

So if you have experienced any of those symptoms in training or racing read on and I’ll go through why you experience them and how to prevent them.
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