This lightweight, streamlined outerwear provides essential core warmth without restricting arm movement, making it ideal for high-output activities like running and fast-hiking. Typically constructed with wind-resistant and water-repellent fabrics, these garments often feature minimal pockets for storing small essentials and reflective elements for enhanced visibility in low-light conditions. An example would be a close-fitting, insulated layer worn over a base layer and under a lightweight shell during cool-weather training runs.
The design prioritizes mobility and breathability, allowing athletes to maintain optimal performance in varying weather conditions. This focus on functionality and lightweight warmth has contributed to the growing popularity of this type of apparel for serious runners and outdoor enthusiasts. Historically, runners often resorted to layering multiple garments, which could be bulky and restrictive. This specialized apparel offers a modern solution, providing the necessary warmth without hindering performance.
