This brutal but fun 52 minute HIIT and abs workout will have you swimming in sweat! The HIIT workout is an incredibly effective fat burner that will quickly boost your cardiovascular endurance, and the core workout is going to hit all of the muscles throughout your entire midsection.
Follow the 21-day plan below. Every other day is a rest day to give your muscles a chance to rebuild and become stronger. If the exercise does one leg at a time, do that number of reps on each side. So for the first exercise, the single-leg squat, you'll be doing eight reps on each side for a total of 16 reps. After each day's workout, stretch your glutes by doing the Figure Four.