What you wear under training clothes

Short answer: The layer under your workout clothes decides how the whole session feels. It sits against the skin, and that is where friction and moisture build up, so choose a thin layer with flat seams.

It sits against the skin the whole time

All the friction you feel during a workout comes from the innermost layer. That fabric moves against your skin with every step and every arm movement. A thin, soft layer moves with the body instead of rubbing against it. That is why the inner layer deserves the same care as the workout clothes themselves.

Seams turn into pressure points

Under tight workout clothes, every thick seam becomes noticeable after ten minutes. The outer layer presses the inner one against the body, and a seam you would never notice pushes on the same spot again and again. Look for flat seams and as few as possible, especially at the shoulders, waist and thighs. See bamboo slips as a smooth layer under loose clothing.

Moisture needs to leave the skin

When you sweat, moisture collects in the layer closest to the skin. A layer that holds on to it turns heavy and clingy and adds friction. A thin fabric that lets moisture move on feels lighter through the whole session. This applies to the upper body and to the feet, where sweat builds up fastest.

Close fit, not tight

The layer underneath should sit close enough to follow the body without folding. A loose layer bunches up under workout clothes, and the folds become pressure points. At the same time it should not squeeze the waist or thighs, or the edges will dig in as you move. Walk, bend and lift your arms before taking a new layer to training.

Socks count too

The sock is also a layer underneath, and it wears hardest of all. It sits between foot and shoe for the whole session and takes both moisture and pressure. A pair that stays in place and has no thick seam across the toes makes a clear difference. See socks for women.

Before and after the session

The layer underneath is also what you wear before training starts and while you cool down. A soft layer on top keeps you warm on the way there and comes off once you are warm. After training it feels good to pull something dry and soft over your head. See bamboo sweatshirts for women.

Change the inner layer afterwards

After training the inner layer is damp with sweat and cools the skin as soon as you stop moving. Swap it for a dry layer before you head home. Put the damp clothes in a separate bag so the rest stays dry, and take them out as soon as you get home.

Washing that keeps the fabric soft

Clothes worn close to the skin during training should be washed after every use. Wash at a moderate temperature with a mild detergent and let them air dry. Skip fabric softener, as it can build up in the fabric. That keeps the layer soft and comfortable session after session.

Frequently asked questions

What should you wear under workout clothes

A thin layer with flat seams that moves moisture away. It is the only thing touching your skin for the whole session.

Why do seams matter so much under workout clothes

Because workout clothes fit close. A thick seam gets pressed against the skin and turns into a pressure point within ten minutes, especially at the shoulders and waist.

Can you train without a layer underneath

Yes, but it means more friction against the skin. A thin layer in between makes most sessions more comfortable and takes the sweat first.