Running at 37°F: Essential Layering, Gear, and Safety for Cold Weather

What should I wear to run at 37?

To run comfortably and safely at 37°F, prioritize a strategic layering system consisting of a moisture-wicking base layer, an insulating mid-layer, and a protective outer shell, complemented by appropriate coverage for your head, hands, and feet.

Understanding the "Dress for 10-20 Degrees Warmer" Rule

When preparing for a run in cold temperatures, a fundamental principle in exercise science is to dress as if the temperature is 10 to 20 degrees Fahrenheit warmer than it actually is. This accounts for the significant metabolic heat your body generates during physical exertion. At 37°F, you should aim to dress for what feels like 47-57°F once you're warmed up and in motion. Overdressing can lead to excessive sweating, which, paradoxically, can cause your body temperature to drop rapidly once you slow down or stop, increasing the risk of hypothermia.

The Core Principle: Layering for Optimal Thermoregulation

Layering is not merely about adding clothes; it's about creating a dynamic system that allows you to adapt to changing body temperature and environmental conditions. Each layer serves a specific physiological purpose:

• Trapping Warm Air: Multiple thin layers trap insulating pockets of air more effectively than one thick layer.
• Moisture Management: Layers work in conjunction to move sweat away from your skin and allow it to evaporate.
• Adaptability: As your body temperature rises, you can easily shed a layer to prevent overheating, and put it back on if you cool down.

Essential Layers for 37°F Running

Base Layer (Next to Skin)

The base layer is arguably the most critical component. Its primary function is to wick moisture (sweat) away from your skin to prevent chilling.

• Recommended Materials:
  • Synthetic Fabrics: Polyester, polypropylene, and blends are excellent for wicking and quick-drying properties.
  • Merino Wool: Offers superb wicking, insulation even when damp, and natural odor resistance. It's often more comfortable against the skin than traditional wool.
• Avoid: Cotton. Cotton absorbs moisture and holds it against your skin, leading to rapid heat loss and discomfort in cold weather.

Mid-Layer (Insulation)

This layer provides insulation, trapping body heat to keep you warm.

• Recommended Materials:
  • Fleece (Polyester): Lightweight, warm, and highly breathable. Opt for a medium-weight fleece for 37°F.
  • Thicker Merino Wool: Can also serve as an effective mid-layer, offering superior warmth.
• Considerations: A quarter-zip or full-zip design allows for easy ventilation adjustments as you warm up.

Outer Layer (Protection)

The outermost layer acts as a barrier against wind, rain, or snow, while still allowing internal moisture to escape.

• Recommended Materials:
  • Lightweight, Breathable Running Jacket: Look for fabrics that are wind-resistant and water-repellent (DWR coating) or waterproof, but crucially, also breathable.
  • Softshell Jackets: Offer a good balance of wind resistance, water resistance, and breathability.
• Considerations: Vents (pit zips, back vents) are beneficial. The jacket should be light enough to be tied around your waist or packed if conditions improve.

Protecting Extremities and Head

Your head and extremities are particularly vulnerable to heat loss due to their high surface area-to-volume ratio and proximity to major blood vessels.

• Head:
  • Beanie or Hat: A thin, moisture-wicking hat or beanie is essential to prevent significant heat loss from your head.
  • Headband: If you prefer less coverage, a fleece or wool headband can protect your ears.
• Hands:
  • Gloves: Lightweight running gloves, made from synthetic or merino wool, are usually sufficient at 37°F.
  • Convertible Mittens: Options that convert from gloves to mittens provide extra warmth if needed.
• Feet:
  • Moisture-Wicking Socks: Choose socks made from synthetic blends or merino wool. Avoid cotton.
  • Thickness: A medium-thickness sock is generally appropriate.
  • Running Shoes: Your regular running shoes are usually fine, but consider shoes with slightly more water resistance or a GORE-TEX lining if precipitation is likely. Ensure they are not too tight when wearing thicker socks, as this can restrict circulation.

Lower Body Considerations

• Running Tights: Insulated or thermal running tights made from synthetic blends are ideal. They provide warmth, wick sweat, and offer compression.
• Layering (Optional): Some runners might prefer a thin pair of running shorts over tights for modesty or extra wind protection, but for 37°F, well-insulated tights are usually sufficient on their own.

Safety and Visibility

Cold weather often brings reduced daylight and overcast conditions, making visibility a critical safety factor.

• Reflective Gear: Ensure your clothing has reflective elements, especially if running during dawn, dusk, or night. Consider a reflective vest or armbands.
• Lighting: A headlamp or chest lamp is highly recommended for illuminating your path and making yourself more visible to others.
• Traction: If there's any chance of ice or slippery surfaces, consider shoes with better traction or add-on traction devices.

Post-Run Protocol

Once your run is complete, your body's heat production will rapidly decrease, and lingering moisture can quickly lead to a chill.

• Change Immediately: Remove wet layers as soon as possible and change into dry, warm clothing.
• Rehydrate and Refuel: Replenish fluids and nutrients to aid recovery and support your body's thermoregulation.

Listening to Your Body

Ultimately, clothing choices are individual. Factors like your metabolism, intensity of your run, individual cold tolerance, and wind chill will influence what feels right. Start slightly cooler than you think you need, as you'll warm up quickly. Pay attention to how your body feels during the first 10-15 minutes of your run and adjust by shedding or adding layers as necessary. The goal is to feel comfortably cool, not warm, at the start of your run.