While cotton can be comfortable for short runs, it is not an ideal fabric to run in because it traps moisture against the skin, which can lead to skin irritation, blistering and chafingchafing. Plus, the added absorption causes you to feel hot & sweaty in warm conditions and cold & damp in lower temperatures. To make matters worse, cotton is typically heavier than synthetic materials and the weight increases dramatically when wet. It’s also a very slow-drying material and does not offer the same performance properties as synthetic fibers.