Men's sports underwear (trail running)

Good underwear may not be visible, but it makes a real difference to your performance and comfort. On a trail run you don't want to deal with chafing, moisture or irritation – and that's exactly where technical sports underwear makes the difference.

What is sports underwear for trail running?

Men's sports underwear is designed specifically for intense exertion. It fits close to the body, wicks sweat away quickly and stays in place, even on long and technical runs. It is often seamless or made with flat seams to minimise friction.

When should you wear sports underwear?

• On every trail run, short or long
• In warm conditions, for optimal ventilation
• Under shorts or tights without a built-in liner
• During races or ultras where comfort is crucial

Whether you're training or racing: good underwear keeps distraction and discomfort out of the way.

What to look for when choosing

Material
Synthetic fabrics are quick-drying and durable, while merino wool resists odour and regulates temperature.

Fit & support
A close fit prevents chafing and offers support without feeling restrictive.

Seams & construction
Flatlock seams or fully seamless designs are ideal for long distances.

Leg length
Longer legs help prevent chafing between the thighs, especially in warm conditions.

Types of men's sports underwear

• Snug boxers (short fit) – light and minimalist
• Long boxers (long fit) – extra protection against chafing
• Briefs – minimal fabric, maximum ventilation
• Merino boxers – comfortable in both warm and cold weather
• Seamless models – maximum softness and minimal irritation

FAQ

Do I wear underwear under shorts with a built-in liner?
Usually not. Many trail shorts have an integrated liner that does the same job.

Which is better: synthetic or merino?
Synthetic dries faster and is more durable; merino is more comfortable and resists odour. The choice depends on your preference and how you'll use it.