With 82-days to go until the 2015 Marathon des Sables, I thought it would be a good time to discuss foot blisters. During my 2013 pre-race MdS research, participants were asked to rate whether or not they were prone to blisters. Among the research participants, 10% claimed that they didn’t know whether or not they were prone to blister, 15% of the runners claimed that they were prone to blister and the remaining 75% stated that they were not prone to blisters.
The post-race data showed something very different. Of the participating runners only 11.5% did not report any blisters, however, the remaining 85.5% all reported blisters that ranged from mild to severe. Among the runners who reported blisters, 24% reported ‘large blisters resulting in intense pain and discomfort, my ability to run/walk is greatly impaired’. Another 50% reported ‘medium blisters with moderate discomfort and pain, although painful at times my ability to run/walk is not really impaired’. The remaining 26% reported only minor blisters with little or no negative impact on performance. What is significant is where the blisters developed, 28% were between the toes, 27% developed below the toes, 14% behind the heel, and 5% below the heel. The remainder developed at various other places.
I attempted to establish the cause, yet could find no clear reason. There is no evidence to suggest that high mileage training reduces the likelihood of blisters, nor that specific foot preparation will prevent foot blisters, shoe type, also, played no significant role. (This does not imply that any of these are redundent, I firmly believe that a runner should do as much as possible to prepare adequitely for the MdS or any other race). This leaves only two possible causes, firstly dehydration and secondly surface temperatures. It is known that the Sahara surface temperature may be between 30 and 50degC higher than the air temperature during the day. So on a moderately 40degC day the surface temperature may be between 70 and 90degC. Slower runners will remain in-contact with this excessive heat for a prolonged period of time with an increased effect with sweat build-up in the runner’s shoes. Gaiters will limit the evaporation ability and a combination of heat and moisture may give rise to blisters, especially under and between the toes.
Yet, both proposed causes, dehydration and the effect of surface temperature is manageable. Dehydration can, for the most part, be avoided. A runner can counter the effect of surface heat by replacing socks, and drying his/her feet regularly. However, management may only be able to limit the damage and not prevent it totally.
Some more information on strapping etc. can be found at the following link which refers to a workshop presented - Click Here