Wearing a good first layer of clothing is essential! Functional underwear, or thermal underwear, will keep you dry and warm, no matter what you're doing or where you are. However, it is far from intended only for winter. You will use it all year round and cover a wide range of activities with it. Unfortunately, there is no one-size-fits-all piece. Therefore, you need to choose a piece that will best suit your needs. In this article, we will introduce the basic selection criteria and also a few current pieces from the Top-ArmyShop offer!
You can use functional underwear in every season and cover a wide range of activities with it. But there probably isn't a universal piece suitable for everything.
What must it meet?
The main task of the first layer, which is worn directly on the body, is to keep you dry. Functional underwear must effectively wick moisture away from the body and transfer it to the second layer (e.g. a functional sweatshirt that can handle moisture further). The key properties are therefore breathability and thermal insulation, i.e. the ability to retain body heat.
Good functional underwear must fit perfectly and hug the body just enough, not too much. The exception is compression functional clothing, where the purpose of compression is to support blood circulation and speed up regeneration. In any case, the underwear should not cut, strangle or in any way hinder the range of movement. In other words, it must be comfortable for all-day (and often multi-day) wear.
TIP: When you try on your underwear, make the same movements you would do in "sharp operation" activities. This is the only way to find out if the underwear allows you the necessary range of movement.
What do I need it for?
Before you start choosing specific pieces of functional underwear, first try to clarify:
If your priority is demanding physical activity or performance sports, look for clothing that is primarily breathable, wicks sweat away from the body well, and dries quickly. For outdoor activities of a quieter nature, look for comfort and quality insulation in cold weather.
- In what conditions will you wear the underwear?
The same applies to clothing for different temperatures. For hot weather, you choose lighter and more breathable clothes than for winter, where you prefer heavier weight and thermal insulation.
Choose functional clothes according to the activities you will perform in them and according to the conditions in which you will wear them.
Weight (or grammage)
The properties of clothing depend on many factors, but you can also be guided by the weight of the material when choosing:
- Lightweight (up to 150 g/m2): thin functional clothing for demanding physical activity, e.g. challenging treks, competitive ski mountaineering.
- Moderate (150-200 g/m2): physical activity that is not extreme but can be in cold conditions, e.g. ski mountaineering, moderate trek, temperatures around zero.
- Heavy (over 200 g/m2): downhill skiing, winter walking, light trekking, extreme cold.
Functional underwear or thermal underwear?
You will often come across the terms "functional underwear" and "thermal underwear" in the shop offer. Is there a difference between them? Basically no. If you come across the term functional underwear for a product, the emphasis is usually on its ability to effectively wick away moisture from the body. Thermal insulation, i.e. the ability to maintain body temperature – due to effective moisture removal, among other things, is often the focus of thermal underwear. So it is one and the same thing, just from a different point of view.
Therefore, although manufacturers and sellers often state that functional underwear is intended for summer, while thermal underwear is suitable for winter, do not take this division literally. The term "thermo" in the true sense of the word does not refer to warm clothes, but to clothes with thermoregulating properties. When distinguishing between summer and winter, the difference is mainly in the grammage and also in whether the clothes are insulated or not. Insulated clothes have a layer with hair on the inside.
Choosing the right first layer is just the beginning. Even the best functional t-shirt can be reliably "killed" by wearing "non-functional" layers over it.
Choose the right material
Another key factor is the material. The fact is that the "one and only" material does not exist. Each has its advantages and disadvantages; quality, weight and overall design also play a big role.
Natural materials
Cotton
Good old cotton is very popular and comfortable to wear, but it does not have good functional properties. Cotton absorbs moisture well, but its disadvantage is that it does not effectively wick it away. Once you sweat, you will be "bathing in your own juice". Anyway, you can reach for it in combination with other materials. But you can also try other natural materials, such as the much more comfortable bamboo.
Merino
Many people confuse the terms "wool" and "merino". Merino is wool, but not all wool is merino. Compared to ordinary wool, merino wool fibers are much softer and do not scratch, so merino clothes are also suitable for sensitive skin. What are the other benefits? Merino wool wicks moisture away from the body well, dries relatively quickly and is breathable. It will keep you warm even if it gets wet.
Merino has the ability to regulate body temperature – it cools in the heat and warms in the winter (of course, with the right grammage). It is hypoallergenic, resistant to UV radiation and naturally antibacterial – it prevents the formation of odors and is also suitable for multi-day wear. The disadvantage of merino wool clothing can be lower dimensional stability and mechanical resistance.
Synthetic materials
Synthetic functional underwear is most often made of polyester, nylon and their various combinations and admixtures, such as elastane. With different manufacturers, you will come across different names of patented materials, but most of them are based on a similar principe.
The main advantage of synthetics is that, unlike cotton, it does not absorb moisture, and in addition, it is stronger, more resistant to abrasion and is more stretchy. Compared to wool or cotton, it is lighter in weight and often dries faster too. It cools slightly and is more suitable for activities that make you sweat. The general disadvantage of this material is that it smells bad, but this does not always apply (the smell is effectively prevented, for example, by the addition of silver). And be careful – synthetics are flammable, so there is a real risk that it may start burning by the campfire.
Mixed materials
Mixed materials combining merino wool and synthetics combine the advantages of both materials and at the same time eliminate their disadvantages. Such material is usually breathable, dries quickly, wicks away moisture well and is mechanically more resistant. An example from our offer is the Primino material (50% merino, 25% polyester, 25% primaloft).
The collar should be of such a height and shape that it fits you well. At the end of the zipper, look for the so-called chinguard, which ensures that you do not pinch your beard when you fasten it.
Functional features: which are really important?
- Anatomic cut is the basis. It takes into account the shape of the human body, is sophisticated and provides greater comfort when wearing and when moving. It also looks better, of course. The sleeves should also have a quality construction to allow the desired range of movement and at the same time maintain shape stability.
- Flat or no seams are also very important and you will appreciate them especially during longer wear. A poor quality seam that starts to cut and chafe after a while (especially in the shoulder area when carrying a heavy backpack) is extremely annoying.
- Extended back part is a definite advantage, especially in cold weather. The t-shirt should not roll up from the pants and expose the hips when moving.
- There may or may not be a collar. It depends entirely on you. In any case, it will protect your neck from the cold. The collar should be the right length and not constricting. For more demanding activities, it is an advantage if you can unbutton it and thus regulate the temperature, in which case choose a collar with a high-quality YKK zipper and a chin guard, i.e. chin protection.
- Thumb loops. Whether or not you want to have this hack on your functional t-shirt is again up to you. The advantage is that it holds the sleeves in place, warms and partly prevents heat from escaping. In combination with gloves or, for example, a functional sweatshirt that also has them, they can get in the way.
However, even the best underwear will not save you if you do not combine it correctly with other functional layers. Therefore, never forget the layering rules.
Thumb loops are practical. However, if you combine several functional layers and each of them has its own holes on the sleeve, they can start to get in your way.
A few tips from the Top-ArmyShop offer
1) Devold® Expedition Merino 235 long-sleeved functional t-shirt
If extreme environments are your second home, you've come to the right place. The Expedition functional t-shirt was created for these conditions and has already completed several expeditions – e.g. Aleksander Gamme wore it during his solo trip to the South Pole. The double-layer material guarantees superior thermal comfort. The inner layer made of 100% merino wool with the Aquadukt function wicks away sweat quickly, and the outer layer, treated with a polyamide admixture, evaporates this moisture just as quickly. Both layers perfectly insulate heat.
However, quality material alone is not enough for a functional t-shirt to withstand movement, sports, cold and wind. It is also important to have a properly designed cut that does not constrict anywhere and does not hinder movement. The Expedition t-shirt is flexible, has an anatomical construction, raglan sleeves for maximum range of motion of the arms, double cuffs for greater shape stability, an extended back part and a stand-up collar with a zipper to the neck. Thanks to the flat seams, it will be comfortable even with a heavy backpack on your back.
Devold® Expedition Merino 235 Man Functional Shirt Long Sleeve
€ 100.3 | In stock
Did you know that…
Polar expeditions
The Norwegian company Devold has been producing clothing from the finest merino wool for over 170 years. Woolen underwear, sweaters and accessories, originally worn by Norwegian fishermen working daily in extreme conditions, were made famous in the 19th and early 20th centuries by icons of adventurous polar expeditions such as Roald Amundsen and Fridtjof Nansen. Since then, Devold clothing appears on expeditions fairly regularly. It was worn, for example, by Liv Arnesen, who in 1994 was the first woman to make a successful solo trip to the South Pole, or Aleksander Gamme, who in 2011 walked alone to the South Pole and from there back to the coast.
Norwegian adventurer Aleksander Gamme wears Devold. He also took this underwear on his solo trip to the South Pole.
2) Devold® Expedition Merino 235 functional underpants
When traveling in freezing weather, one must not forget the legs either. The Expedition Merino 235 underwear is a set with the functional t-shirt of the same name, which is directly intended for extreme conditions. Premium merino wool with the Aquadukt function takes care of quick moisture removal from the body while maintaining optimal breathability. Double-layer material ensures thermal comfort. And what is another advantage of merino wool? It is naturally hypoallergenic, antibacterial and odourless.
Devold® Expedition Merino 235 Longs Man Underwear
€ 91.8 | In stock
Did you know that…
Merino sheep
Only Merino sheep can offer the softest and fluffiest wool. But they are no Barbie dolls. These super-sheep can handle extreme mountain frosts and warm summers thanks to their first-class wool. The ancient Merino breed probably originates from North Africa, from where it reached Spain in the Middle Ages. The Spanish strictly guarded this treasure, the herds were the property of the king and the sheep were not allowed to be exported. It was not until the 18th century that several pieces were smuggled to Europe and then on to Australia. Today they are bred all over the world, but the best quality wool comes mostly from Australia and New Zealand.
3) Montane® Thermo Zip Neck Dart t-shirt
It will keep you warm from spring to autumn, and at the same time it will fit perfectly. The Thermo Zip Neck Dart T-shirt serves as a first layer in winter, or as a separate layer in warmer seasons. This light yet warm t-shirt is made from recycled APEX THERMO ECO material, which is pleasantly soft.
The overall feeling of comfort is also aided by a slightly brushed inner side, flat seams and a low collar profile with a YKK zip covered by a baffle. Thanks to the POLYGIENE antibacterial treatment, which neutralizes the smell, the t-shirt is also suitable for multi-day use.
Montane® Thermo Zip Neck Dart T-shirt
€ 51.2 | In stock
Did you know that…
With Montane to extremes
Montane functional underwear is worn, for example, by members of the British Antarctic Research Institute, which conducts extensive research in Antarctica and the Arctic, and rescue teams of the British Mountain Service. Montane also organizes a series of extreme expedition races, the Montane Spine Expedition Races, which are among the most challenging races in the world and they perfectly check out both the condition and outdoor skills of all participants.
4) Helikon-Tex® LVL 2 winter thermal t-shirt
Here is another representative of functional underwear made of high-quality synthetics. It has a low weight, high breathability and efficiently wicks away sweat. The neck is protected by a turtleneck with a zip to the center of the chest, and the arms are protected by slightly extended ends of the sleeves with thumb holes. Flat seams are a matter of course. The LVL 2 t-shirt is made of polyester with elastane admixture.
Winter Underwear Top LVL 2Helikon-Tex®
€ 30 | In stock
Did you know that…
Helikon-Tex has many faces
The Polish company Helikon-Tex offers several product lines, each of which is designed for a specific purpose. All these series are mutually compatible and combinable. These include the Bushcraft Line full of life hacks for the woodsmen, the Medical Line with multi-purpose first aid kits, the designer Morale Line, the outdoor Outback Line, the tactical Patrol Line, the Range Line for shooters, the classic Surplus Line and the “Low Profile” Urban Line for the city.
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