Layering Basics for Ultrarunners

As we welcome the new year, most runners will claim winter running season has officially begun. With the arrival of winter comes moderate to cold weather, depending on your region, and running through the season can be incredibly enjoyable and rewarding. However, it’s helpful to understand clothing construction and optimal layering in order to stay warm and avoid cramming too many unnecessary items into your running pack. With adequate planning, patience and gear procurement, you can embrace the season ahead.

For starters, it’s important to know your own physiology. Some runners have relatively high sweat rates, while others are apt to become cold easily or overheat quickly. It might surprise you that one can get hypothermia at temperatures as high as 50 degrees, and humans lose body heat 25 times faster when wet. Keep in mind your individual factors as you consider the recommendations below. The general idea is to maintain a safe and comfortable core body temperature as you personalize your layering approach to your own training and climate.

When it comes to fabric, it’s helpful to understand the fundamentals of construction as materials offer slightly different characteristics. There are two general classifications: synthetic (manufactured, usually from a petroleum-based plastic) and natural fibers. Nylon, polyester and spandex are all synthetic which are predictably lightweight, pliable and quick-drying. These fabrics wick sweat away from the body quite well, but the drawbacks include absorption of pungent odors and a reduced amount of breathability compared to natural fibers. When we look at natural fibers, the most commonly utilized ones for athletic clothing include wool and cotton. Natural fibers offer enhanced breathability and softness to the touch. Wool’s superhero power is its ability to keep you warm even when wet, while the disadvantages are its fragility and weight—it becomes especially heavy when wet. Cotton’s positive attributes are the fact it is lightweight, relatively inexpensive and offers ease of care. However, be warned, it does not dry quickly. Hence, using cotton as a base layer next to your skin in cold temperatures is ill-advised as layers may become soaked with sweat, can penetrate outer layers — or both. This scenario can drag down your core temperature rapidly which can spiral quickly into a dangerous situation such as hypothermia. It’s never a good idea to use a cotton piece as your base layer and you’re probably best served to leave all cotton layers at home for cold weather outings. Luckily, most well-constructed outdoor clothing will blend synthetic and natural fiber to create pieces that offer athletes the best of all options. Still, verifying the fiber content of a piece of clothing can increase your awareness which enables you to compare various materials. From there, you will be able to decipher how each piece performs in various conditions.

Now comes the question of how to combine your layers. There is no single correct approach, but several light layers hold an advantage over fewer heavy layers. Wearing a puffy down coat over a tank top would likely lead to being too cold or too hot. Of course, that’s going to extremes, but you understand the concept. Opting for several layers will allow you to modulate your core temperature, and you can easily add or pack away a layer with this ideal approach. A predominantly synthentic fabric that is tight against your skin is a good starting point. This will establish a personal microclimate where your body heat will be well contained. Beyond that, arm sleeves or a light half-zip long sleeve layer that is mostly synthetic should come next. Arm sleeves can be slid up and down easily, but they can be challenging to adjust when buried beneath layers. Experiment with sleeves before using them, as they’re not everyone’s preference but can be a very modular alternative to a complete top, especially in cool (vs. cold) temperatures. Next, consider adding a jacket for temperatures below approximately 40 degrees. Here again, characteristics matter immensely. Windy conditions can steal a lot of your body heat and you’ll be glad for a windproof jacket at the top of a blustery ridge or peak. If you anticipate the chance of precipitation, choose a waterproof jacket. Be aware that waterproof layers are typically less breathable, so be prepared to vent by adjusting the zipper so that you don’t create an unnecessary amount of sweat.

Let us not neglect the lower half of the body. Usually in dry temperatures above 45 degrees, or in cooler temperatures when you’re aiming for a quick, short training session and have stable weather conditions, you can probably wear shorts and be comfortable. Consider light or mid-length tights for wet conditions between 30-45 degrees. When the mercury dips to freezing or below, grab those full-length tights. To top off your layering strategy, a hat, buff and gloves will help you stay comfortably warm. It’s easy to adjust your body temperature slightly as conditions change throughout your workout by stowing and/or restoring these smaller items.

The above recommendations apply to most moderate and cold weather conditions. If you’re facing very cold temperatures—well below the freezing point at any point in your outing—add another layer or two to your pack. Be sure to check the weather forecast before every run so that you know what to anticipate. An insulated jacket (down or synthetic both work terrific and pack down to a very manageable size) and possibly some rain pants can be life-saving if you find yourself in very stormy weather. If there’s a possibility that you’ll need those extra layers, you won’t regret having them.

With a wise approach to layering, it’s possible to stay warm and dry and avoid concern for hypothermia or frostbite. Empower yourself to be confident, comfortable and safe in a wide range of weather conditions. Fine-tune your system using the basic suggestions above as a starting point and test your layering tactics against whatever the elements deliver. Most of all, enjoy what winter running has to offer.