Roman Trail Women's Merino Wool Base Layer www.romantrail.com

What is a Base Layer and Why You Need One

If you like to be active, a base layer is worth the investment. A base layer is a must-have for those activities that might take place during a range of different temperatures. Read on to learn what a base layer is, why you need one, and how to choose the right one for you.

Why Do I Need A Base Layer?

A base layer is an essential piece of workout gear that works as a “second skin.” It keeps you comfortable during any activity by absorbing and evaporating moisture to keep you dry.  

Types of Base Layers

There are two main types of base layers, natural and synthetic. Natural base layers are made from Merino wool or other natural fibers. The Merino wool base layer is usually a little more expensive but tends to be warmer than synthetic base layers because they trap air between the fibers. Synthetic base layers are often made from polyester or a polyester fabric mix. These base layers are usually lighter and less expensive than natural base layers.

The Benefits of Having a Base Layer

  • Wicking Capability Keeps You Dry
  • Helps Regulate Body Temperature
  • Diminishes the Potential for Chaffing
  • Enhances Recovery (if using a base layer that offers compression)

How To Choose The Right Base Layer For You

It can be challenging to decide whether to purchase a natural fiber or synthetic material base layer. Here are some things to consider for choosing the right base layer for you.

1) What fit do you prefer?

Base layers are supposed to fit snug to wick away moisture effectively, but that doesn’t mean you need to feel uncomfortable while wearing one. Synthetic base layers tend to have a little more compression than natural fibers.

2) What temperatures are you expecting?

There are three different types of base layer weights: lightweight, midweight, and heavyweight. The base layer weight you select depends on the temperatures you expect to endure during your activity. For example, if you live in an area with cold winters, you should wear a base layer ideal for layering, such as a long sleeve base layer, preferably made from Merino wool.

If you live in a warm climate, you should wear something light and breathable. Depending on the amount of sun exposure you are expecting, base layers come in different cuts such as sleeveless, short sleeve, and long sleeve options. In addition, you will want to weigh if you prefer a synthetic base layer or a lightweight natural base layer for warmer temperatures. However, they are both viable options if planning to wear them without layering.

3) How long will your activities take?

If you plan to go hiking or camping for a few days, then a Merino wool base layer is the way to go since they are naturally antimicrobial. This means you can go longer between washes without them beginning to smell. Synthetic materials tend to trap more bacteria, making them start to smell faster.

FAQ

What is the point of a base layer?

The point of a base layer is to keep you dry.

Is a base layer the same as a thermal?

Technically they are the same in cold weather as they help retain body heat.

Do base layers need to be tight?

Base layers should be snug but not so tight that they hinder movement.

Which base layer is best for cold weather?

A Merino wool base layer is best for cold weather due to the naturally porous Merino fibers that help remove moisture to keep you dry.

Can you wear a base layer on its own?

Yes, and with merino this is one of its practical advantages rather than a compromise. A merino base layer in a plain colour reads as an ordinary long sleeve top, so it works as a visible layer in a cafe, on a plane or at dinner in a way a shiny synthetic thermal does not. That versatility is a large part of why one garment can cover a whole trip.

How tight should a base layer actually be?

Close enough to maintain contact with your skin across most of your torso, because moisture transfers where fabric touches skin and a loose garment with an air gap moves less of it. Not so tight that it restricts movement at the shoulder. Compression fits offer no thermal advantage and can be uncomfortable during sustained overhead movement, so aim for continuous light contact with no bunching under outer layers.

The Bottom Line

Base layers can be beneficial year-round for a variety of activities. However, suppose some of your adventures will take place when it is a little colder outside or when temperatures have the possibility of fluctuation. In that case, a base layer is a must-have for your workout gear collection.

 

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About the Author
Katie Pierson

Katie is the creator of MT Girl Fitness and a freelance writer with a passion for the health and wellness industry. She has been a certified health and fitness professional for almost twenty years. She currently holds ten certifications and looks forward to sharing her passion for health and wellness with you.

For a complete guide to choosing and using merino wool base layers for outdoor activity, see our women's merino wool base layer guide. Shop women's merino wool base layers -- 100% Australian merino, no synthetics.

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Remember: results that come fast, go fast. But when you build habits that last, the results will too. So, grab your sneakers, step outside, and start your journey. One step at a time, you’ll get there.

Want to Go Deeper on Merino?

If you're curious about why merino wool outperforms synthetics and cotton in cold weather, don't miss our in-depth guide. We break down layering strategies, performance tips, and why superfine 17.5-micron merino is the gold standard for base layers. Read: The Complete Guide to Merino Wool Base Layers