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What Should You Wear Under Your BJJ Gi: A Rash Guard Shirt Or A T-Shirt?

What Should You Wear Under Your BJJ Gi: A Rash Guard Shirt Or A T-Shirt?

Brazilian Jiu Jitsu is categorized into two classes BJJ Gi and no Gi. Both of these BJJ classes have their own set of rules and regulations. While watching the no gi matches, we observe mostly players wearing the rashguard and BJJ shorts.

BJJ competitors typically use protective gear such as rashguards, spats, headwear, groin protection, and mouth guards. These protective necessities make the Gi comfortable and allow for easy movement. However, most players look forward to wearing the best dress code. They seem perplexed in deciding whether they should wear a Rash guard shirt or a T-shirt.

Here we are going to explore which one can work better for you. Read this blog ahead to get the answers to your questions.

What Is A Rash Guard?

Rash guard” connotation is evident from the name. The phrase “Rashguard” comprises two words: rash and guard. It means they protect the skin from rashes. BJJ athletes wear rashguard shirts to protect from rashes and friction injuries. 

Some people wear regular T-shirts or sweatshirts instead of rashguards. However, these t-shirts do not meet the no gi shirt features. The rules for wearing no gi shirts differ for men and women. These regulations differ between Gi and No Gi Jiu-Jitsu.

No-Gi Competition Rules 

No gi players need to wear rash guards in all No-Gi competitions, whether mentioned by the IBJJF or not. These are mandatory under IBJJF regulations for both men and women. These shirts are made of micro mesh fabric with elasticity which should cover the waistband of shorts for BJJ.

Gi Competition Rules

Now let’s discuss Gi competition rules for male and female players.

For Males

Rash guards are not allowed in IBJJF Gi events for men. Male competitors cannot wear it under their Gi in IBJJF tournaments. Some organizations let male competitors compete while wearing a rash guard below their Gi. The ADCC made wearing rashguards optional for men.

For Females

The female division in BJJ must wear a Rashguard or a tight shirt under their gi. The IBJJF and other organizations have rules that require female participants to wear rash guards under their Gis. 

Rash Guard And T-Shirt Material Varieties

A Rash guard’s goal is to absorb sweat, protect you from friction injuries, and keep your body cool. You must select a no gi shirt with all these characteristics to achieve this goal.

The majority of the no gi BJJ is comprised of a synthetic fiber combination. The rash guard made of spandex, polyester, or nylon is ideal. Spandex is flexible, whereas polyester is hydrophobic (resistant to water). Polyester makes it breathable by evaporating sweat rather than retaining it. It results in a cooling effect during the whole activity.

Nylon has a soft texture and high strength. Rash guards composed of polyester and nylon offer all of the features of a good rash guard, such as strength (cannot rip), flexibility, and breathability.  

Most T-shirts, on the other hand, are made of cotton or a cotton-synthetic combination. The cotton used in the t-shirts is absorbent. As a result, t-shirts absorb sweat. No doubt T-shirts are more comfortable as compared to rash guards. Still, the rash guard has all those premium features that smooth the BJJ players’ journey.

Advantages Of Wearing Rash Guard Shirts

The Rashguard is optional for BJJ practitioners during training. Some practitioners wear rash guards below their Gi, while others do not. Let’s talk about the advantages of wearing a rash guard beneath the Gi.

Way For Respecting Your Opponent

Everyone wants to roll with you if you are sweat-free and dry. Sweating is unavoidable during training and combat. Fighters with hairy and sweaty chests endanger their opponent’s cleanliness.

No one is eager to grapple or spar with you if they anticipate being mounted and having sweat drip into their eyes and face. A rash guard is extremely useful in ensuring a clean fight between two partners or competitors.

Both combatants are too close while grappling. They also require strangling, gripping, mounting, or choking each other. The Gi does not stay in place throughout the match, and the fighter does not have time to manage it over and over again. Every fighter must respect his opponent’s cleanliness and avoid irritating or jeopardizing his opponent’s hygiene by sweating much.  

Compression Of Muscles

Rash guard shirts give muscle support as they are light, compressive, and tight. Rash guards are naturally elastic and flexible. 

Tight rash guards squeeze the body’s muscles. Muscle compression keeps them together and prevents injury. Rash guards and spats also support the body’s joints, muscles, and core.  

Sweat Evaporation

Sweating is normal while grappling. BJJ practitioners train, spar, and work out for long periods. Their bodies sweat the entire time they are at the gym. This constant sweating can result in a rash or other skin problems. Rash guards have the proper vents in the sleeves to ensure the proper airflow.

Furthermore, sweat can make your opponent feel uncomfortable. Rash guards help dissipate sweat rather than absorb it, prohibiting skin diseases.

Increases Gi Longevity

A rash guard keeps your Gi clean and lasts longer. Its material is more durable and offers no wear and tear during the BJJ movements. Gi is primarily made of polyester, cotton and nylon. The perfect material ratio makes it strong enough to resist any color fade and deformity. 

Prevent Skin Infections 

Rash guards absorb sweat and keep skin diseases at bay. In damp and wet skin, fungus and other infection-causing bacteria thrive. Furthermore, rash guards prevent opponents from making skin-to-skin contact, which also benefits skin safety.

Contact with infected skin can spread a variety of skin illnesses. Rash guards defend against such infections.   

Effect Of Cooling

Sweat streaming down practitioners’ faces, hands or eyes during battles might bother them. This constant sweating can also have a negative impact on their performance. Fabrics such as nylon and polyester do not allow sweat to absorb or remain on the skin.

The fabric of the Rash guard repels water. These textiles drain sweat from the skin. This evaporation provides a cooling effect and keeps the skin dry. This cooling action also helps to mitigate the effects of excessive perspiration. 

Advantages Of Wearing A T-Shirt Under A Gi

Some competitors choose to wear a T-shirt instead of a rash guard. T-shirts are far more comfortable than rash guards. People who cannot wear tight rash guards can train in casual t-shirts.

However, some gyms have very rigorous hygiene rules. Such gyms require their students to wear something underneath the Gi, whether a Rash guard or a t-shirt.

A tight Rash guard is uncomfortable for beginners who have just begun their BJJ journey. A T-shirt is an excellent choice for them. 

T-shirts also help the Gi last longer by absorbing sweat. Sweat will be absorbed by t-shirts, keeping Gi clean and long-lasting.

Which Is Better, A Rash Guard Shirt Or A T-Shirt?

Rash guards and t-shirts are both the option to wear beneath the Gi. However, the rash guard is far more effective than t-shirts. Let’s go through some reasons why rash guards are superior to t-shirts.

  • Rash guards are made of polyester or nylon, whereas t-shirts are made of cotton. As a result, rashguards absorb sweat and produce evaporation and cooling effects. On the other hand, T-shirts absorb sweat but cannot stop bacterial or fungal growth and numerous skin illnesses.
  • No gi shirts are effective at protecting the body from hair friction or mat friction. However, T-shirts cannot work against friction.
  • Rashguard are firm and tight. They function like a brace, supporting the body’s muscles and joints. T-shirts, on the other hand, are not compressive.


For training, players wear both rash guard shirts and t-shirts. Although t-shirts are comfy, rash guard perform better. They help in organizing the body by compressing muscles, providing support to joints and muscles, and avoiding skin infections.

The no gi shirt wicks away sweat to allow frictionless activity on the mat while you roll with the opponent. Rashguards serve an essential part in ensuring hygiene during a fight. So, overall, rashguard are the best option to combat successfully.

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