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for grappling go with a rashguard, if it was kickboxing/boxing/ or Muay tai i would say a shirt.But then again most gyms offer a gi and no gi grappling class.

yep

If you’re worried about messing up your shirt, you really don’t have any business training for MMA. Try Ballet…

John,all my level 2 accounts got banned :p,but if I could,i’d give you a thumbs up.

You should use a rash guard shirt in class/competition. T-shirts are too hot and too loose and can sometimes get in the way, pull out over the eyes, head, etc. Rash guards are meant for protection from sun, chafing, etc. They also lighter in material (nylon, spandex, polyester) than cotton tees and serve to wick away sweat and moisture while keeping a close, form-fitting somewhat "slippery" body profile. Because of the elasticity of the material, it can also help to mold and support the joints and muscles of the body, just like wrist and ankle supports in kickboxing would.
Of course in the street, you’ll be wearing a t-shirt. Just so you know, a t-shirt is sometimes used in the same way as a gi for choking/grabbing but because a rash guard is so form-fitting, there’s almost no chance of any sort of clothing type attacks.