High-intensity interval training (HIIT) is one of the most popular exercise methods in the world today. This title examines the history of this versatile way to work out. It also explains both the physical and mental benefits HIIT provides, complete with instructions for a variety of HIIT exercises. Features include a glossary, references, websites, source notes, and an index. Aligned to Common Core Standards and correlated to state standards. Essential Library is an imprint of Abdo Publishing, a division of ABDO.