Simple, affordable and effective.

Plenty of research touts the importance of cardiorespiratory fitness (CRF)—also known as cardio fitness, cardiovascular endurance, and aerobic fitness—as a health marker, as well as an athletic ...

If you want to boost your cardio fitness, you’ve got two ways to level up your workouts: push harder or faster, or keep at it for longer. Each option comes with its own challenges. The first can ...