How to keep your hands and feet warmer?

During winter training, feet, hands, and head are on the front line against the cold. Despite various layers and textile materials, extremities quickly lose all sensation to the point of becoming painful. So why do our extremities suffer first?

By Pierre-Maxime BRANCHE – Photos: @3bikes.fr

Extremities freeze first due to the phenomenon of heat loss. During activity, but also at rest, the body produces heat through metabolism. As long as we are alive, we produce heat. As the body also naturally loses heat, these losses must be limited to maintain a comfortable situation. The ideal situation that an athlete should naturally strive for during their activity is one of balance, where there is as much heat loss as heat gain. As soon as this balance is broken, for example when more heat is produced than is evacuated, automatic phenomena such as perspiration are triggered: during significant exertion, the entire body heats up. For these calories to dissipate, perspiration brings water to the skin’s surface, and by evaporating, this will reduce the body’s temperature. These mechanisms are automatic; we cannot control them, meaning we don’t decide to sweat or not to sweat.

Vital Organs Rather Than Extremities

To counteract the cold, the phenomenon that automatically develops is vasoconstriction. This means the body has sensors all over its surface. If it sees that its temperature is dropping and, at the same time, its heat production is insufficient compared to losses, it will schematically close the valves, as in a central heating system, starting with the valves of the extremities. It is always through the extremities that one will feel the cold arriving, because vasoconstriction tightens the circulation pipes, i.e., the arteries and veins, which implies a reduced blood flow to the extremities. Less blood flow means less heat supply, so the extremities cool down, which quickly becomes unpleasant, painful, or even agonizing, because one loses sensation. This is an automatic reaction to promote the survival of the organism: by itself, the body prioritizes the temperature of the torso, abdomen, vital areas and organs at the expense of the extremities. Basically, it is ready to sacrifice a hand, a foot for the survival of the rest. That’s why the extremities are on the front line.

A Hat to Keep Your Feet Warm

The only place where there is no vasoconstriction is the head. The torso and head are always connected, which is why we generally don’t feel cold in the head, or else it means the problem is starting to be significant. Very often, we first feel the need to put on gloves before putting on a hat. Nevertheless, it is important to know that even if the head is highly vascularized and not subject to vasoconstriction, cold-sensing receptors are located in the brain, and these are what control the opening or closing of the blood circulation valves. It is therefore important to keep your head warm, meaning to cover it while facilitating breathing. The principle is quite simple: if you keep your head warm, the brain will react by telling itself that it is in a comfortable situation and will thus leave the valves open. Conversely, if your head is cold, the brain will close these same valves to prioritize vital organs and decrease blood circulation to the extremities. This is a simple principle that was explained by Jean-Louis Etienne, a French scientific explorer and doctor, with these words: « If you want warm feet, wear a hat ». In other words, by covering the head, nape, and neck, especially for people with little hair, it promotes circulation and protects the extremities. This applies to any activity, but particularly in cycling where the effect of speed can very quickly break the thermal balance.