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Runterra Bio Tee

Runterra Bio Tee

Odor-resistant + thermoregulating top for daily active wear

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M's Runterra Bio Tee
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William is 6'1" and wears size M Regular fit, Size Chart

Run in it, sweat in it, live in it — then biodegrade it!

The first synthetic-blend running shirt that biodegrades like a 100% cotton tee, our Runterra Bio offers the enhanced moisture and odor control of specially-formulated 37.5® polyester with the comfort and versatility of cotton. This new, innovative fabric breaks down into organic compounds in under four years. Conventional polyester takes four hundred.

Don’t sweat it  this tee will only start to biodegrade in anaerobic (oxygen-poor) environments. It breaks down in the landfill, not in your closet.

Explore more


Runterra Bio is powered by a specially formulated 37.5® polyester with enhanced biodegradation to break down into bio-based compounds in under 4 years in an oxygen-poor environment like a landfill

Premium cotton
Made from long staple, US-grown Supima® cotton for superior softness, strength + durability

Everyday looks
Easy to wear, casual cut with a straight hemline

Active comfort
Blended with 37.5® polyester, a special technology utilizing the natural benefits of microscopic volcanic ash to provide enhanced thermal, vapor + odor regulation to maintain body comfort during activity

Wear more, wash less
The natural odor resistance of cotton is boosted by the volcanic particles which "trap" odors so you can put this top through repeated wear

Modified raglan design
Shoulder seams are rolled back off the top of the shoulders for ergonomic comfort

Shrinkage is natural
This top is made from 70% natural fibers and is not pre-shrunk so some shrinkage may occur, up to half a size

materials + specs

70% Supima® cotton, 30% 37.5® tech polyester

Garment made in Vietnam

103g / 3.6oz (M’s Medium)"


Why do biodegradable synthetics matter? 

While we design Janji gear to last and hold up to the demand of years of running, no tee or running shorts should last forever. With this in mind, we are researching innovative ways to improve end-of-life cycle management of our apparel. While we look into longer-term solutions and circular methods — recycle, repurpose and reuse programs — we also know that most textiles are thrown out and end up in landfills. Conventional synthetics, used heavily in active apparel for their high-performance functionality, do not biodegrade in typical landfill conditions. This includes synthetics made from recycled materials, and is why most plastic seemingly lasts forever.

We are seeking solutions to fix this as a performance apparel company that relies on synthetics, including the use of non-ecotoxic biodegradability within our textiles like this new Runterra Bio. This is the first step on a better path forward.

Runterra is made from premium, long-staple Supima® cotton which is 50% longer and up to 45% stronger than other cottons (and softer, too). The stronger the fiber, the more durable the garment, and therefore the more it can be worn. Supima® cotton is grown by a select few family farms that utilize advanced water and soil management techniques to reduce consumption and ensure the health of the land for optimal renewability.

Runterra fabric is also OEKO-TEX® certified, meaning it is free from harmful chemicals and is fabricated in a way that meets a high environmental standard.

Learn more about our sustainable initiatives here.


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Customer Reviews

Based on 35 reviews
Jesse B.
Wear it for: Everyday wear
Height: 5'4" to 5'6"
Usual Size: S
Size Purchased: S
Crazy comfortable!

One of the most comfy shirts I own. This shirt WILL shrink in the dryer. I’ve had two of them shrink a whole size in the dryer, so I recommend hang drying them or order a size up.

Gilad S.
Wear it for: Running, Climbing, Everyday wear
Product Fit: Runs small
Height: 5'7" to 5'9"
Usual Size: L
Size Purchased: L

M's Runterra Bio Tee

Matthew N.
Wear it for: Running
Product Fit: Spot-on
Height: 5'10" to 6'0"
Usual Size: M
Size Purchased: M
Just the Best

What can I say? This is the best running shirt I have ever used. It's lightweight and it keeps me cool. I ordered one shirt to try it out and ordered three more the same day after trying the first one. I think I will be running in nothing but Janji shirts and shorts for a long time.

Todd M.

M's Runterra Bio Tee

Andrew S.
Wear it for: Running, Everyday wear
Product Fit: Spot-on
Height: 5'10" to 6'0"
Usual Size: M
Size Purchased: M
Nice shirt!

Like the color, lightweight, it is cut shorter in the front and longer in the back. Great customer service, my shirt got lost by the USPS and they sent another out right away. Quality company and service!

Wear it for: Running
Product Fit: Spot-on
Height: 5'7" to 5'9"
Usual Size: S
Size Purchased: S
Must have for all runners!!!

Great run shirt, light, comfortable, cool colors, easy to wash and dry…, i have in four colors.

John M.
Wear it for: Running, Climbing, Everyday wear
Product Fit: Spot-on
Height: 5'10" to 6'0"
Usual Size: M
Size Purchased: M

Comfy and fits well. Regulates temperature we'll. Nice.

Wear it for: Running, Everyday wear
Product Fit: Spot-on
Height: 5'10" to 6'0"
Usual Size: M
Size Purchased: M
Wears like a T-Shirt, works out like running shirt

Has a lightweight material, very comfy I like it because it feels more like your classic cotton shirts and less the synthetic blends. Though it’s great for running and has no odor issues after some hot muggy runs.

Will be getting more

Wear it for: Running
Product Fit: Spot-on
Height: 5'1" to 5'3"
Usual Size: S
Size Purchased: S

Great running shirt!

Nate P.
Wear it for: Running, Hiking, Climbing
Product Fit: Spot-on
Height: 5'7" to 5'9"
Usual Size: M
Size Purchased: M
Love this shirt

It's light weight, it fits really well, it looks great. On my recovery run days I wear it to work and it looks good under a flannel, then I just have to change into shorts to run. I want 4 more in different colors.