"Hot feet": feet that are hot due to weather or clothing choices
"Hot foot": a condition affecting one or both feet, otherwise known as Metatarsalgia, where the nerves and joint tissues close to the ball of your foot are repeatedly squeezed and aggravated by the long metatarsal bones which run down through the feet to the toes, leading to a burning sensation in the base of the foot.
Hot foot can be debilitating, excruciatingly painful and can turn a long ride into a miserable experience. It's a complex and often misunderstood condition both in terms of what causes it and what should be done to prevent it.
Solutions and prevention
Unfortunately, there is no one solution for hot foot that works for everyone. It's a case of making changes one at a time and trying to first identify and then eliminate the cause(s). Below are some hints that may help you address the causes or alleviate the symptoms.
Hot feet. Feet that are hot tend to swell, causing pressure inside the shoe and adding to the squeezing of the nerves between the metatarsals. Wearing cooling socks or ensuring that shoes have adequate ventilation can help with this. Sometimes pouring ice water on feet on a hot day can have a temporary cooling effect, but this does not really address the true cause of the problem.
Shoe soles. This is a contentious topic as there has been much debate whether a stiffer sole contributes to the pressure on the metatarsal nerves and joint tissue. A study in 2003 found carbon-soled shoes resulted in an average increase in forefoot pressure of 18 percent over more traditional plastic shoes. This makes sense. For example, if the sole is stiff, it won't flex under foot pressure and spread the load to other parts of the foot (imagine the difference between standing on concrete versus standing on a soft mat). However, some people swear that stiffer soles have solved their hot foot issues.
My opinion is this: If the pressure is across the entire ball of the foot then a stiffer sole probably won't help much and perhaps the sufferer should try a more flexible sole which, although less efficient, will flex a little more and spread the load over more of the base of the foot rather than just the ball. However if the pain is centered on a 'hot spot' then this could suggest that a stiffer sole may help with such pain, which could be the result of the pedal causing pressure in one localized spot.
Cleat position. Cleats that are positioned too far forward could be the issue. Sometimes moving them back a fraction can help alleviate pressure, even if they were originally in the correct position. The advice of a professional bike fitter is highly advisable when moving cleats back or forward as saddle height should also be adjusted and cleat positioning can affect other biomechanical issues.