Menthol is a substance found in many products, including toothpastes and chewing gum. This substance brings a feeling of freshness and cold. For several years, many researchers have been interested in using menthol to cool down (or at least to feel colder) in hot conditions.
Menthol acts on a receptor called TRP-M8 (Transient Receptor Potential Melastatin-8) that detects cold. This receptor is present on our skin and even in our mouth. So, when we apply a cream with menthol on our skin, or ingest a menthol solution, we feel a cold sensation. It has even been shown that you don’t actually have to ingest the menthol solution – you can just rinse your mouth with the solution and then spit it out. By rinsing the mouth, the menthol comes into contact with the receptors in the mouth and acts on them to bring a cooling sensation.
Unlike other cooling strategies, such as using a cooling jacket or ingesting slush that reduce the temperature of the body and/or skin, menthol only provides a feeling of cold.
You are probably wondering how bringing a feeling of cold, without actually cooling the skin or body, can be beneficial for performance in hot conditions.
Menthol is beneficial because it somehow makes the brain believe that it is less hot. In other words, menthol helps to fool the brain. It is the brain that allows us to adjust our intensity, or speed, during a competition. Our brain takes into consideration many variables, including the distance remaining to be traveled, the level of pain in our muscles, the temperature of our skin and different regions of the body, our perception of effort and our perception of heat. By altering our perception of heat, we alter how our brain perceives the effort we are providing, which can slightly alter our effort management and allow us to increase our intensity, or speed, a little. Several studies have shown that the ingestion of menthol reduces the feeling of heat and reduces the perception of effort, which has the effect of improving performance during an effort until exhaustion, or a time trial in hot conditions.
It’s important to understand that physiology and psychology are two interrelated fields. Our physiology (how our muscles work during an effort) affects our psychology (e.g. our level of motivation to continue a difficult effort) and vice versa. Interventions that affect our psychology, for example the presence or absence of competitors, the use of music during an effort or the possibility of making money, can have a significant effect on our physiology, and therefore on our performance.
How to ingest menthol during a competition?
Two techniques exist to prepare a menthol drink. The first is more complex and consists of dissolving menthol crystals in a solution of ethanol (ethyl alcohol) to obtain the desired concentration. The second technique is much simpler and involves depositing menthol crystals in water heated to a temperature above 40 °C (between 41 and 44 °C) until the crystals dissociate. You can buy crystals on Amazon, but be sure to buy menthol crystals for food and not menthol crystals to put in the bath. (It says “food grade” on the bag.) A 60 g bag costs about $40.
The concentrations of menthol used generally vary between 0.01 per cent and 0.1 per cent (0.1 g to 1 g per 1 L of water). Afterwards, you can cool the solution and put it in your water bottles. You can add carbohydrates and electrolytes to this drink, too.
On the other hand, if you only want to rinse your mouth with the solution and then spit it out, you can simply put mouthwash with menthol in a small container for gels. For best results, rinse your mouth with menthol solution every 20 minutes – roughly the same frequency that you will drink or take a gel during your competition.
The majority of menthol studies use a menthol drink that participants ingest or use to rinse their mouths, but it is possible that mint lozenges such as Halls could also be effective.
In short, the use of menthol is possibly beneficial for performance in hot conditions. It’s inexpensive and easy to use in competitions, so you have nothing to lose by trying it out. But, obviously, you should never try anything for the first time in a competition, so I suggest you experiment with this strategy a few times in training.