About Marathon Des Sables

The Marathon Des Sables (MdS) is known as the toughest footrace on Earth. The distance covered is 243km's in the Sahara desert, run in 49 degrees Celsius heat while every athlete carries his or her own equipment, food etc. weighing in at around 9-13kg's.

This blog is aimed at telling my story. I will record my preparation for the MdS 2013 in detail in the hope that it will help my fellow runners.

Sunday 6 October 2013

KAEM 2013 Pre-Race Report

Introduction

With the Kalahari Augrabies Extreme Marathon (KAEM) in less than two weeks, my race pack has been sorted and is waiting to be carried through the "green desert". After repacking my pack numerous times it is now the lightest it has ever been. Wet my pack weighs in at 10,5kg's on the start time. By the time I start my long run my pack weight would have decreased by 1,54kg's which means that my wet weight would be around 9kg's.     

 

I have shed most of the luxuries, all of which I am confident I can live without for the seven days in the desert.

Below are a number of tables with the specifics of what is in my race pack.


I always carry my food in a pack that seals it from dust, sand and water. This way I am confident that my food remains uncontaminated. I also don't repackage my food but keep it in its original packaging. Possible bacterial contamination outweighs the potential weight reduction that may be achieved through repackaging.  


The following is a detailed composition of my nutrition for the 2013 KAEM. It is based upon my research done during the 2013 Marathon des Sables (MdS). I approach my nutrition and overall weight pack composition from two central points. Firstly the MdS data indicated that the optimal nutrition used during the MdS for males came to 0.91kCal per kilogram of body weight per kilometer of race distance. The second element pegged the optimal race pack weight to runner body weight at 12.5%. 

 

My nutrition came in at 0.93kCal per kilogram of body weight per kilometer of race distance as published by the KAEM team. This exceeds the optimal nutritional value derived from the MdS data by 2.2% which is well within the optimal range that tops out at 1,09kCal/kg per race km.



Race regulations require a minimum of 2,000kCals/day while Basel metabolic rate calculations peg the survival rate at 2,500kCals/day. My total race food energy consist of 19,312kCal which translates to 2,759kCals per day. Although this exceeds the basic survival rate by only 10%, research seems to indicate that this is sufficient, even under extreme endurance conditions. 

Other elements that is important to me besides, total energy value, and the ratio between protein, fat and carbohydrates are sodium and potassium. Research indicates that the body has roughly 8,000mg of sodium in reserve at any given time. Added to this my food contains an addition 37,074mg of sodium, this means that on the start line of the KAEM I will have available sodium of 45,074mg. At an average sodium requirement of around 3,500mg per day, my seven day requirement comes in at 24,500mg. There are, for me, therefore no need to take additional sodium as my food has more than enough.

With only 1,332mg of potassium in my diet and with an average requirement of 75mg/running hour means that my nutrition only has sufficient potassium for 18 running hours. As this exceeds my estimated race time it means that there are insufficient potassium in my food. Potassium supplementation is an option which I still need to decide on.

Nutrition Specifics
     
The following is my daily menu:








To ensure that I start the final race day with the required 2,000kCals as per the race regulations some of the extra food packed for the rest day will stand over to the final day.

With my food sorted and the weight of of it coming in at 4.873kg's I had that basis from which to determine what other equipment to take with. The weight ceiling derived from the MdS research pegged pack weight at 12,5% of the runners body weight. For me that meant that my pack weight had to be limited to 10,63kg's.   

Race Pack Equipment

Presently my pack weighs in wet (including 1,5kg of water) at 10,46kg's. This is 170g less than the MdS suggested ceiling.

The following equipment is included in my race pack, it includes all mandatory equipment plus some additional elements that will ensure that I can deal with the majority of issues that may come-up.









Race Pace

So what is left for me to do is to set a race pace. During KAEM 2012, some inexperience and continued problems with my heels meant that I maintained an average pace of 3,8km/h. During the MdS this year my race pace was slightly faster at 3,9km/h. During the first three days of the MdS I averaged a 4,3km/h race pace, however, with my heel problems flaring up on the long run I had to slow down. Hopefully the inners will last the entire race and I will have my first multi-stage with little to no heel pain...if it does I am setting a race pace of 5km/h.

Conclusion
This is my last posting for October, my next article will be my KAEM post-race report.

Thank you for reading my blog.

Genis