Under Armour MicroThread Apparel - Lightweight Training Shirts & Polos

The weight and behavior of athletic fabric directly impacts performance in ways many athletes overlook. When a standard cotton or basic polyester shirt absorbs sweat, it gains significant weight and clings to the torso. This creates two problems. First, the added weight increases the energy cost of movement, particularly during overhead motions and running. Second, fabric clinging to skin restricts natural range of motion and creates friction that can cause chafing during extended activity. Research into athletic textiles has shown that fabrics which maintain their original drape when wet allow athletes to move more freely and expend less energy on overcoming clothing resistance. The drying speed of a fabric is also critical. A shirt that stays wet holds heat against the body, which can impair thermoregulation in warm environments and cause uncomfortable chilling in cold conditions. Fast-drying fabrics cycle through the wet-to-dry process more efficiently, maintaining a comfortable microclimate between the skin and the garment. The construction method of the fabric matters as much as the material itself. Twisted or textured yarn creates air pockets within the fabric structure that reduce the surface area in contact with skin, which is the primary mechanism behind reduced cling. Four-way stretch construction uses elastane fibers blended with polyester to allow the fabric to extend in every direction and recover its shape, ensuring the garment fits consistently over its lifespan. Anti-odor treatments applied at the fiber level prevent bacterial growth that causes post-workout smell, extending the usable life of each wear between washes. Understanding these textile fundamentals helps athletes choose training apparel that genuinely enhances comfort and supports better performance outcomes.

The MicroThread collection includes both crew-neck training shirts and collared polos, giving you options for different settings. For gym workouts, running, and high-intensity training, the crew-neck shirts provide maximum freedom of movement and a relaxed feel. The polos are ideal for golf, coaching duties, or training environments where a more polished look is expected. If you tend to overheat during workouts, look for the lighter-weight mesh options that maximize airflow. For outdoor training where sun exposure is a factor, pair MicroThread tops with [Under Armour Iso-Chill pieces](/collections/under-armour-iso-chill) for cooling and UV protection on the hottest days.

One of the best things about MicroThread apparel is its versatility. The clean styling and polo options mean you are not limited to wearing these pieces only at the gym. The fast-drying fabric makes MicroThread shirts excellent for travel, where you might need to wash and wear on short turnaround. The anti-odor technology gives you confidence wearing them in social settings after a light workout. For a casual weekend look, pair a MicroThread polo with chinos. Heading to a morning workout followed by errands? A MicroThread crew-neck transitions seamlessly. The fabric's wrinkle-resistant properties mean it looks good straight out of a gym bag.

Pair your MicroThread tops with gear that matches their performance level. [Under Armour training shorts](/collections/under-armour-shorts) provide the same lightweight, stretch-focused construction for your lower half. For footwear, [Under Armour Charged running shoes](/collections/under-armour-charged) deliver responsive cushioning for mixed training sessions. Building a kit from compatible performance pieces means every layer works together to keep you comfortable and unrestricted through any workout.