The One Workout You Need to Boost VO2 Max

Many runners strive to get faster, and boosting VO2 max is often part of that goal. One way to achieve both: The interval workout known as the Norwegian 4x4.

Forget sit-ups — I’m training for my sixth marathon and use this exercise to strengthen my hips, activate my deep core and build functional alignment

Here's the ab exercise to add to your routine.