If you've watched MMA or trained at a gym, you've probably noticed fighters wearing a tight inner layer beneath their fight shorts. But what exactly are they, and why do so many fighters wear them?
What Are Compression Shorts?
Compression shorts (also called under shorts or MMA under shorts) are tight-fitting shorts worn beneath your main fight shorts. They're typically made from a stretchy, form-fitting material like spandex or polyester blend, sitting close to the skin. Think of them like cycling shorts; snug, supportive, and low-profile.
In MMA, they serve a very specific purpose: protection, coverage, and performance support during training and competition.
Are They Just Boxer Shorts?
A common misconception... they're not. Boxer shorts are loose-fitting and offer no compression or muscle support. MMA compression shorts are a specific garment: tight, performance-focused, and designed to stay in place during explosive movement, grappling, and ground work. Wearing regular boxers underneath your fight shorts won't give you the same coverage, support, or hygiene benefits.
And let's be honest, when you're on the ground, nobody wants to see or touch your sweaty boxer shorts. Your training partners will thank you.
Why Do MMA Fighters Wear Compression Shorts Under Their Fight Shorts?
1. Extra Coverage During Grappling
High split MMA shorts are designed for maximum leg freedom, but those deep side splits can expose more than you'd like when you're on the ground, in guard, or scrambling. Compression shorts keep everything covered no matter what position you end up in.
2. Hygiene
Grappling involves close contact with training partners and mats. A compression layer acts as a barrier between your skin and your outer shorts, reducing sweat transfer and keeping things more hygienic, especially important during sparring or competition.
3. Confidence
Simple but real, knowing you're fully covered lets you focus on training rather than worrying about your kit. Particularly relevant for fighters who spend a lot of time in open guard or working off their back.
Why 2-in-1 MMA Shorts Are Becoming More Popular
Wearing two separate pairs of shorts, an under short and a fight short, works, but it adds bulk and means more kit to wash. That's why 2-in-1 MMA shorts have become increasingly popular.
2-in-1 shorts combine a built-in compression layer with an outer fight short in a single garment. You get all the benefits of compression shorts without the extra layer - less bulk, less hassle, and a cleaner look.
High Split 2-in-1 Shorts
The high split version gives you maximum leg freedom alongside built-in compression. Perfect if you're a striker who also grapples, you get the full range of motion for kicks and knees, with the coverage and security of a compression layer underneath. The best of both worlds.
Shop High Split 2-in-1 MMA Shorts →
Low Split 2-in-1 Shorts
If you prefer a more traditional fit with less side split, the low split 2-in-1 is the one. More coverage on the outer short, still with the built-in compression layer underneath. A solid choice for grapplers and wrestlers who want a cleaner, more covered look without sacrificing the under short protection.
Shop Low Split 2-in-1 MMA Shorts →
Want a Standalone Compression Short?
If you'd rather keep your outer short and under short separate, we also build fully custom compression shorts. Your colours, your design.
Enquire About Custom Compression Shorts →
Do You Need Compression Shorts for MMA?
Not strictly. But most fighters who try them don't go back. If you spend time grappling, rolling, or sparring, the coverage and security make a noticeable difference. And if you want to keep your kit minimal, a 2-in-1 short is the cleanest solution.