What Is HIIT—and How Can It Boost Your Workouts?
Demystifying that famous fitness acronym. Plus, how to use it in your own routine. Westend61/Adobe Stock All products featured on Self are independently selected by our editors. However, we may receive compensation from retai
The Norwegian 4×4 Workout Could Help Boost Your Endurance
Every so often, a new type of workout seemingly takes the fitness world by storm. The latest in this long line of buzzy fitness fads: the Norwegian 4×4 workout, a high-intensity interval training (HIIT) method that’s b