When hiking, you often alternate between intense activity phases and rest phases. This tends to cause sudden rises and drops in body temperature, which can be dangerous for your health. The role of the first layer and thermal underwear is to regulate this body heat and wick away perspiration. It is therefore important to choose the right base layer for hiking. Explore our tips below.
Choosing the right base layer materials
Natural fibres
Garments made from natural fibres (such as wool, merino wool or bamboo) are widely used for hiking. They provide natural warmth, are lightweight and pleasant to the touch. On top of that, they do not irritate the skin and have natural antimicrobial properties, which allows for excellent odour management. They are however fairly delicate and may take longer to dry than garments made from synthetic fibres.
We recommend using a base layer made from natural fibres if you are heading out on a multi-day hike. You can use them without issue on hikes where you alternate between active phases and rest.
Note that cotton garments should be avoided as a base layer for hiking. They are not breathable and absorb all the moisture produced by the body.
Synthetic fibres
Fibres such as polyester, polypropylene, polyamide or elastane also have many advantages. Garments dry more quickly than those made from natural fibres, they are more durable and easier to care for. They are however heavier, do not manage odours as well and provide less warmth.
You can wear them on a moderate-intensity hike or on an intense but short hike. This gives you an effective base layer without having to put up with odours.
Hybrid garments
Made from a blend of natural and synthetic fibres, hybrid garments also do the job. The materials are distributed effectively across different zones of the body to ensure good breathability and effective body heat regulation.
The importance of garment thickness
When choosing a base layer, the thickness of the garment really matters. Even though the role of the first layer is to allow good breathability and that of the fleece is to provide insulation, the thickness of the garment will affect the warmth it generates. The thicker it is, the more insulating it will be, but also the less breathable. You will therefore choose your base layer based on your needs and the type of environment you will be in.
The fabric weight in grams per square metre is often listed in garment specifications. The higher the number, the thicker and warmer the garment. Here are some figures to give you an idea — they may vary depending on the garment's material:
- Below 150 g/m²: for intense activities or in high-temperature conditions.
- Between 150 and 190 g/m²: versatile year-round use or in temperate to cold conditions.
- Between 190 and 250 g/m²: moderate activity, ideal for colder conditions.
- Above 250 g/m²: low-intensity activity or in very cold weather.
The fit of the base layer for hiking
Another important factor when choosing a base layer for hiking is the fit of the garment. The fit can vary depending on the activity. A fit that is too loose lets heat escape, but allows greater freedom of movement. A fit that is too tight does the opposite: it retains heat better but restricts movement. For hiking, the best approach is to find a middle ground — a base layer that is close enough to the body while still allowing good freedom of movement.
Finally, the choice of seams is also worth considering. More and more base layers are made with no seams or with flat seams. They have the advantage of providing extra comfort as they are unlikely to cause irritation from friction against the body during movement.
Choosing the right base layer for hiking is very important. It allows you to regulate your body heat. Depending on the intensity of your activity, its duration and the time of year, you can choose from a range of different base layer models.
