Nutrition Testing

My first 50 mile race is coming up this Saturday ( June 27, 2015 ). The 50 mile event at the Black Hills 100.  I am confident, but nervous.  In order to try to remove some of the many variables involved in a long trail race I went to see Dina Griffin at eNRG Performance to get some tests done. These tests will be used to help me decide what to do about my nutrition during my long races.
The first reason I sought them out was their Metabolic Efficiency test. This measures the body's ability to burn fat at various levels of exertion. If you can train your body to burn more fat and less carbohydrates then you don't need to depend as much on replenishing carbs during the run and even the leanest athletes have enough fat stores to support the longest events.

What I looked like during the Metabolic Efficiency Test

I have been playing around with some Low Carb High/Healthy Fat diets over the past couple of years in hopes of achieving a high fat burning ratio. I wanted to both test my current ability to burn fat and get some customized and professional advise on how to best improve that ability. I purchased a 2 test package and did the first test in early March when I was just starting to train. That test showed that I was reasonably good at burning fat, but had some room for improvement. Most of the test I was hovering in the 50-60% of fat vs carb ratio before hitting the crossover point (50/50 fat/carb) at just past 8:00 minute miles. During today's test I increased pace all the way up to 7:09 min./mile and my ratio never dropped below 60% fat. There are a lot more numbers involved in the full report, but the short story is that after some minor tweaks to my diet and a lot of low intensity training I have a lot less to worry about in the calories part of my race plan.

On the other hand the other test that I did today is a sodium sweat rate test. This measures the amount of sodium in a given volume of sweat. The amount of sodium that each person sweats is different and thought to be genetic so it can not be trained. Fortunately sodium is easier to replace than carbohydrates as long as you know how much to replace. I had previously measured the volume of sweat that I lose on a typical run by weighing myself before and after a run. Put the two together and you know how much sodium needs to be replaced. The volume of sweat will change with the weather so I will want to do some more testing to get a general idea of the range of volume I may lose in different weather conditions, but based on the data we have I'll need to add a lot of sodium to my race plan. On a relatively warm day I will need to replace up to 1600mg of sodium per hour. I haven't been doing anything near that on my training runs up to now. I've been able to get away with that because the runs are relatively short when compared to my races where the losses will add up with each hour that passes.

Overall I feel pretty ready for this first test of 50 miles. I have a fuel plan and know that my body can survive for awhile if I begin to have trouble getting calories in. I am still working on the exact plan for hydration and electrolytes, but now that I know what my body will need I can formulate that plan appropriately and have confidence in it. My training has gone well, now I just need to execute.