Collection: Rash Guards

A rash guard is a tight-fitting compression top made from synthetic fabric, usually a polyester and spandex blend. It's worn against the skin under a gi, or on its own for no-gi and MMA training.

It does three main jobs. It stops mat burn and friction rashes from skin dragging across the mats and against training partners. It creates a barrier that significantly reduces the transmission of skin infections like ringworm, staph and impetigo, which spread easily in grappling gyms. And it wicks sweat away rather than soaking it up, so you're not leaving puddles on the mats or handing your partner a slippery grip.

Most gyms now require them for no-gi, and many require them under the gi as well. If you're training grappling regularly, it's not optional gear.

Long sleeve gives you the most coverage and the best protection against mat burn on your forearms and elbows, which is where most of it happens. It also covers any existing skin issues, and some gyms require full coverage. The downside is heat, particularly in summer or in a gym without air conditioning.

Short sleeve is cooler and gives you more freedom around the shoulders, but leaves your forearms exposed. It's the more common choice for hot climates and for people who don't mind a bit of mat burn.

If you're buying one, most people start with long sleeve for the extra protection and add a short sleeve later. If you're training in an Australian summer without air conditioning, reverse that order.

Rash guards should fit tight, like a second skin. Loose fabric bunches up, gives your opponent something to grab and defeats the purpose of the compression fit. It will feel noticeably tighter than a normal t-shirt when you first put it on, and that's correct.

Sizing runs on standard S through XXL for adults, but cuts vary a lot between brands, so check the individual size chart on the product page against your chest measurement and height. If you're between sizes, size down for a proper compression fit, or size up if you prefer a slightly more forgiving feel. The guard should stay put when you raise your arms rather than riding up over your stomach.

Rules differ by organisation, so check the ruleset for the event you're entering.

Under IBJJF rules for no-gi, rash guards must be at least 10% of the ranked belt colour and cover the torso to the waistband. Ranked rash guards, meaning ones with a coloured band matching your belt rank, are made specifically for this.

ADCC and most local no-gi events are more relaxed and generally allow any rash guard.

Wash it after every session, cold, and turn it inside out. This is the same infection-control point as the gi, and rash guards sit directly against your skin, so it matters more.

Hang dry in the shade. Never put a rash guard in the dryer, since heat destroys the elastane and the guard loses its compression permanently. High heat also cracks and peels sublimated graphics. Skip fabric softener, which clogs the fibres and kills the moisture-wicking. If it's holding odour, soak it in cold water with a cup of white vinegar for 30 minutes before washing.

Treated this way a good rash guard will last a couple of years. Thrown in a hot dryer, it'll be stretched and saggy within months.