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Diamond Theory Clothing


Regular price $63.00 USD
Regular price $63.00 USD Sale price $63.00 USD
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The Shirt

Solitude Training Jersey

Why Solitude? Because it is you against you out there.

Oversize Training Fit

Engineered for Performance: Our jersey is tailored to accommodate the dynamic physique of bodybuilders and strongmen, providing ample room for muscle and mass without compromising on movement.

Breathable Comfort: Constructed from advanced moisture-wicking fabric, this jersey keeps you cool and dry even during the most intense workouts. The lightweight material promotes airflow, preventing overheating and allowing you to focus solely on performance.

Durability at its Core: We understand the demands of your training regimen. That's why our jersey is built to withstand the rigours of a tough workout. Reinforced stitching and premium materials guarantee long-lasting performance, wash after wash.

Bold Aesthetics: Be a force to be reckoned with, not just in strength, but in style too. Diamond Theory design cues accentuate your physique.

What is My Fit?

Diamond Theory has 2 Fits for shirts:

Muscle and Mass

  • Muscle: This fit is designed with Bodybuilders in mind as this has an aggressive taper, bringing it right in at the waist.
  • Mass: This fit is designed with Strongmen in mind as this has a less aggressive taper as Strength Athletes tend to have a thicker core.

Please take this as a reference and refer to the size guide with your measurements.


Check our Size Guide. Select the shirt most accurate to your measurements.

This shirt has been engineered from the ground up specifically for real athletes who carry real muscle and mass. Before you order, please make sure you measure yourself and choose your size according to the size guide. Take your chest measurement and your waist measurement. No need to order a size down for a tighter fit.


For the Bodybuilders:

Size Guide, Muscle Fit, Muscle Fit Shirt, Muscle Size Guide



For the Mass Monsters:

Mass Fit Shirt Size Guide


Our Training Fit Size Guide:

Training Fit Size Guide


Our shirts are made of 97% cotton and 3% elastane. Why? Simply put, because this is the best fabric blend to use. Cotton is lightweight and breathable, which means you are comfortable and don’t overheat. We use a small amount of elastane to allow for a little bit of stretch to aid comfort. We don’t use too much so the fabric remains lightweight, breathable and of the highest possible quality.

Shipping & Returns

Free Shipping
For returns please see returns policy for further detail

Care Instructions

Wash on a low heat, air dry and press. Do NOT tumble dry.

  • Free Shipping over £50