Many athletic onesies include quick-dry and moisture-wicking treatments; some listings also note moisture-management or odor-resistant finishes.
Onesies commonly use high-stretch, performance-grade fabrics—often described as super-stretch or 4-way stretch—to allow contouring and full freedom of movement.
Children's styles often use breathable, stretchy materials and may include mesh shoulder straps to increase airflow and help keep young athletes cool during training and practice.
Athletic onesies commonly use neoprene, nylon, polyester, recycled polyester, and polyester- or nylon-based blends with spandex; exact fiber ratios vary by item.