When temperatures drop, you need to know how to adapt your gear!
But beyond the purely psychological aspect, can we experience specific effects related to low temperatures, and what dangers and pitfalls should be avoided when you want to run or cycle outdoors at 3°C? We're going to tell you everything about practicing outdoor sports in cold weather!
Note that it is essential to listen to your body and respect your rhythm; if the temperature is too cold, it is better not to force yourself and to prioritize indoor activities. And if you have heart, vascular, or pulmonary issues, consult your doctor before starting.
What influence will the cold have on our body?
Some will say, "Even at -1°C, I stay warm when I exercise!" Certainly, my good friends, because the body is an extraordinary machine that knows how to adapt. To maintain its homeostasis (its general balance), it will implement several endogenous thermoregulatory mechanisms. Of course, all physiological adaptations inherent to sports practice remain. But other mechanisms are added, increasing energy expenditure, which is already significant during physical exercise:
Thermoregulation: This represents the set of physiological processes put in place by the body to maintain its internal temperature around 37°C, regardless of the outside temperature or metabolic level. This regulation is based on a constant balance of heat gain and loss. This temperature consistency does not apply to all parts of the body, but only to the center, called the "core," which includes the thoracic and abdominal viscera, skeletal muscles, and the central nervous system. In optimal conditions, the core temperature is 37°C, the reference temperature around which enzymatic reactions and the activation of major intracellular mechanisms occur.
The parts outside the core, consisting of the skin and subcutaneous tissues, can have a variable temperature (from 10°C to 40°C depending on external conditions). Finally, the vascular system allows for rapid energy and temperature exchanges to maintain homeothermy. Maintaining a constant core temperature is only possible thanks to thermoregulation, which represents the balance between the amount of heat lost and produced or received.
Humans exchange heat with the environment via 4 methods: convection (exchanges between the skin and an ambient fluid or gas – the principle of cryotherapy), conduction (exchanges between the skin and an object in direct contact that has a different temperature: e.g., a hot water bottle or an ice cube), radiation (the skin gives off heat in the form of radiation), and evaporation (sweating). This phenomenon occurs continuously, not just during a run or a bike ride, but intensifies during physical activity, especially when climatic conditions are extreme (cold or hot).
Increased thermogenesis: the first thermal response to cold
Thermogenesis is the production of heat by the body through an increase in cellular metabolism. Two systems are implemented in this state:
- Activation of cellular metabolism, particularly in adipose tissue from brown fat. The only problem: an adult has very little brown fat. This mechanism is therefore insufficient to provide a proper adaptive response and warm the body. Nevertheless, this chemical thermogenesis causes an acceleration of metabolism induced by the secretion of adrenaline, glucagon, glucocorticoids, and thyroid hormones (for long-term adaptation).
- Increase in muscle tone which causes shivering: fiber contractions become desynchronized, but the movement is involuntary. If it intensifies, it can become conscious and even quite unpleasant, especially in the jaw and during inhalation.
Vasoconstriction
Cutaneous vasoconstriction: Under the effect of cold, peripheral circulation is reduced by a contraction of the vessels and the closing of certain vascular circuits in order to maintain heat in the body's core. In this instance, blood flow is significantly reduced (from 20mL/min to 1mL/min). This reaction has two objectives: to limit exchanges between the body core and other areas of the body, thus preventing the cooling of the critical zone, and to decrease skin temperature to prevent heat loss.
Vasoconstriction primarily affects the hands and feet when it is cold. Small vessels contract and blood circulation decreases, thus reducing the supply of oxygen, nutrients, and heat to these extremities. Some people are even particularly sensitive if they suffer from Raynaud's syndrome and can develop painful edema or easily get frostbite.
Piloerection, nothing to do with the effect your mother-in-law has on your nerves…
Piloerection is better known as "goosebumps." In reality, the hairs are actually erecting! The goal of this physiological mechanism is to trap a layer of air between the hairs and the skin to insulate against the cold. This reflex was quite useful to our distant, particularly hairy ancestor, but for modern humans with their small, short hairs, it is no longer of much use. We observe the same phenomenon in animals like cats or birds, but it is still much more useful to them given the thickness of their fur!
The brain, the true control tower of regulatory pathways
Everything happens in the hypothalamus, a part of the central nervous system located at the heart of the brain. In this area, there are thermoreceptors that record the temperature of the central core, but also those of the skin and spinal cord. If these receptors detect a temperature variation, they activate thermal regulation mechanisms. For example, when it is cold, their stimulation leads to cutaneous vasoconstriction and heat production.
Peripheral receptors (under the skin, near blood capillaries) and central receptors (wall of intra-abdominal organs, large venous trunks, spinal cord) transmit information about temperature variation to the hypothalamus via nerve impulses. If the blood irrigating the hypothalamus varies by 1°C, it is enough to trigger thermogenesis or thermolysis (heat evacuation). Note that we have more thermoreceptors sensitive to cold than to heat, especially on the face.
What about the danger of outdoor sports in cold weather?
Of course, there is no question of stopping outdoor sports when it gets chilly, otherwise winter sports would be the Hunger Games! However, it is necessary to distinguish between sports practice in a cold but dry environment (aerial cold) and in a cold aquatic environment, a small nuance that is very important. One can indeed move through an icy aerial environment by adapting their outfit; however, since water is an excellent thermal conductor, the body cools down 25 times faster in an aquatic environment.
It is also important to highlight the nuance that exists between perceived temperature and actual temperature. Perceived temperature is determined by wind speed, called the "wind-chill" factor. With clothing that does not provide enough protection, the heat produced during activity may be insufficient to counteract the effects of the temperature coupled with the wind. For example, skiing at -1°C with 30km/h wind is equivalent to skiing at -15°C, thus increasing the risks of hypothermia as well as frostbite.
One must therefore adapt to conditions to avoid several risky situations. We mentioned above the mechanisms that allow organs and the central nervous system to stay warm. However, in the event of intense or prolonged cold, unadapted equipment, or unanticipated extreme situations, the body core temperature can still drop… And below a certain threshold, it becomes a crisis. Here are the situations to prevent and avoid so you do not put yourself in danger:
Hypothermia first and foremost! The primary enemy of the outdoor athlete in cold weather, hypothermia is the decrease in the body's core temperature. If the latter drops below 35°C, a cascade of reactions occurs, and believe me, they are not fun.
It can have different effects and consequences depending on the stage:
- Mild (from 36°C to 32°C) / Defense phase: One then feels significant shivering (or even teeth chattering), pale skin, painful extremities, goosebumps, an accelerated heart rate, an urge to urinate, breathing difficulties, and a sensation of cold. To alleviate this state, you must move a lot, put on an emergency blanket or warm, dry clothing, eat, drink warm or hot liquids, and take shelter from any wind.
- Moderate (from 32°C to 30°C) / Exhaustion phase: You stop shivering but start trembling instead; you feel a certain well-being and your heart rate decreases; you slowly slip into a state of decreased alertness and altered state of consciousness, likely to evolve into a coma. It is then advised not to warm up too quickly, not to rub, and not to move too abruptly. You must warm up slowly and call for help.
- Severe (below 28-30°C) / Paralysis phase: You then enter a coma, with a slowing of vital functions. It is then a vital emergency that must be treated by specialized doctors.
Note that the stages of hypothermia differ slightly according to sources, but it should never be ignored and represents a real risk to which it is necessary to be attentive during and after your practice.
Muscle injuries: Of course, regardless of the weather and temperature, muscle injury remains a risk during a session or sports training. But because cold reduces the oxygen supply to muscles (by contracting blood vessels), they will be less nourished and could potentially snap more quickly. It is therefore essential, in cold weather, to warm up gradually in order to prepare the muscle for exertion and slowly raise body temperature. Do your warm-up indoors before going out to face the elements.
Frostbite: Poorly covered or too exposed to the cold, your extremities, ears, lips, and the tip of your nose can fall victim to frostbite: chapping, cracks, or even frostnip or frostbite (more serious). The cause: the cold, poor circulation, and dry skin, which, combined, can lead to these very unpleasant and often painful lesions. "The stings" (painful numbness that takes a very long time to warm up) can also be accompanied by nausea.
Breathing difficulties: Asthmatic athletes, beware! While dry cold does not pose a danger to your lungs, damp cold is a contraindication to physical activity outdoors. And for all athletes: remember to breathe through your nose rather than your mouth. This way, the air will be warmed before it reaches your lungs!
Dehydration and "the bonk": The sensation of thirst decreases when it is cold, or even disappears entirely. But inhaling cold air and maintaining your internal temperature are processes that dehydrate, so it is essential to hydrate well before, during, and after sports practice.
It is also essential to increase your caloric intake because energy loss will be greater. Remember to bring your adapted BSE, which will provide 280kcal per pouch and will allow you to have the energy to go even further.
Additionally, digestion releases heat. Holyfat is particularly easy to digest and quickly assimilable, to avoid any minor digestive issues during your session.
How to be well equipped in cold weather to go even further?
For your outdoor practice, choose adapted clothing that provides you with a certain level of comfort while avoiding the sauna effect. It is essential not to stay in significant dampness; humidity is conductive, and the body will cool down faster (especially after practice). If the environment is cold and windy, this can increase the risks. Remember the 3-layer rule for the upper body:
- Choose a protective base layer: close to the body, it will absorb moisture and wick away sweat during exertion (synthetic rather than cotton to avoid retaining moisture).
- An insulating garment as a 2nd layer: it must retain heat so as not to let your body cool down. It must be breathable (fleece jacket or sweater, GoreTex or Aquastop fabrics – avoid wool, which is heavier and less breathable).
- A waterproof garment (avoid classic windbreakers that do not protect against bad weather in case of rain or snow).
For the bottom, you can opt for special breathable cold-weather pants or long underwear.
It is also essential to cover your head, hands, neck, and feet well. Still using breathable material, opt for sports gloves and a pair of socks with good insulating quality. No layering of socks, as they would compress the foot too much and prevent good circulation, in addition to causing chafing. For the head, a breathable beanie to cover your noggin and ears is ideal.
Finally, after sports, warm up and hydrate: hot drink, meal, rest. Finish the exertion preferably near your residence or vehicle so as not to remain exposed to the cold for a long time without activity and in damp clothing, and plan for a dry change of clothes if you cannot shower quickly (including underwear!). Don't forget to stretch and possibly take a warm bath to warm up gently.
The cold, a health ally when used correctly
The therapeutic use of cold dates back to ancient times. In Europe, legend attributes its first use to Hippocrates. In Nordic countries, already in the time of the Vikings, people practiced winter bathing in icy water or snow, to which therapeutic virtues were attributed. In certain countries like Finland, many inhabitants perpetuate this tradition and bathe in winter in icy water to stay healthy. This practice is attributed with a reduction in respiratory ailments, joint pain linked to rheumatism, better recovery, and a general sense of well-being.
Medical cryotherapy was born in Japan in the 70s to treat pain, initially linked to rheumatism and then post-traumatic, by exposing the body to temperatures ranging from -140°C to -110°C. Its use for athletes followed. Today, several methods exist and offer athletes the chance to fight against their fatigue and muscle pain via total or partial immersion in intense cold.
From a medical point of view, cryotherapy could potentially have numerous indications, and it seems that cold has positive effects in certain situations. That being said, the benefits remain subjective and certain medium- or long-term adverse effects have been noted. The scientific community acknowledges a lack of perspective on this practice and its real benefits; the treatment remains experimental at the present time. An INSERM study in 2019 revealed that cryotherapy had very few proven beneficial effects but many real side effects (burns, chronic cold urticaria, headaches…) when used in the context of inflammatory or neurological diseases, or sometimes outside of any pathological context. Moreover, this technique is not recognized as a treatment nor reimbursed in France by the national health insurance.
It is therefore essential to be well-informed before considering it and to opt for a technique adapted to the desired effects, while taking into account current contraindications (asthma, cardiac or vascular pathology, neurological issues, skin lesions, etc.).