Hot yoga pants: what works in a heated room

Hot yoga changes what you need from your clothes. Bikram-style classes are traditionally held at about 40°C (105°F) with around 40 percent humidity, and other heated classes run warm too. You’ll sweat more than in almost any other kind of exercise, and you’ll be bending, twisting and balancing on one leg while you do it. Leggings that are perfectly good in an ordinary class can turn heavy, slip and go see-through.

Leave the cotton at home

Cotton is the most common mistake. It soaks up sweat, holds on to it, and gets heavy and clingy. Wet cotton also stretches and can turn sheer. Twenty minutes into a hot class, cotton leggings can feel like a wet towel wrapped round your legs.

Choose synthetic fabrics instead:

• Nylon and elastane blends are soft, smooth and stretchy, with good recovery. They’re often the most comfortable for long holds.
• Polyester and elastane blends take up very little water and dry quickly, which helps in the sweatiest classes.

Look for fabrics described as moisture-wicking and quick-drying. They move sweat to the outside of the fabric, where it can evaporate, instead of holding it against your skin. Thin, light knits feel coolest, but they still need to be dense enough to stay opaque when stretched.

Length, and grip

In a hot room, less fabric is cooler. There’s another thing to weigh up, though: grip.

• Shorts are the coolest option, and the traditional choice in Bikram classes. Bare skin also grips better than wet, slippery fabric in poses where you hold your leg or press a knee against your arm.
• Capri and 7/8 lengths cover more without trapping heat at the ankle, and they don’t bunch up around wet feet.
• Full-length leggings are fine if you’d rather be covered. Choose the lightest, fastest-drying fabric you can find.

If your hands slide off your legs in balancing poses, the fabric may be the problem rather than your grip. Very smooth, shiny fabrics are the most slippery when wet; a matte, slightly textured surface holds better.

Fit

Hot yoga pants should fit closely. Loose pants fill with sweat, flap about and get in the way of your hands in binds and twists.

• Snug, not compressive. You don’t need firm compression in a heated room. It just traps heat. A gentle, even fit with four-way stretch is better.
• A waistband that lies flat. A mid or high rise with a wide, soft band that doesn’t roll when you fold forward. Drawcords are rarely needed in yoga and can dig in when you lie on your back.
• A gusset. A panel at the crotch removes the seam from where you’d least want one, and gives you room for wide-legged poses.
• Flat seams. Thick seams leave marks when you lie on them and rub when they’re wet.

The sheerness check

Wet fabric is more transparent than dry fabric, and stretched wet fabric is worse. Before taking a new pair to a heated class, do a deep forward fold in front of a mirror, in good light, and look back between your legs. Better still, wear them to an ordinary class first. Dark colours and dense knits are the safest. Light greys and pastels also show sweat, which some people mind and others don’t.

What else helps

• A towel on your mat. Most of the slipping in hot yoga happens on the mat, not in the clothes. A mat towel soaks up sweat and grips better as it gets damp.
• A top in the same kind of fabric. A cotton T-shirt over technical leggings just moves the cotton problem to your top half.
• Water. Drink before the class and bring a bottle into it.

Caring for them

Wash sweat-soaked synthetics after every class: the bacteria behind gym smells thrive in damp synthetic fibres. If you can’t wash them straight away, rinse them and hang them up rather than leaving them in a bag. Wash inside out in cool water, skip the fabric softener, which clogs the fibres and stops them wicking, and hang them to dry. A hot dryer weakens elastane, and when the stretch goes, the fit goes with it.