Grab Your Dumbbells and a Towel, Because This 45-Minute HIIT Workout Heats Up Fast

HIIT workouts are high exertion, Karisa explained. Get your body prepped with a dynamic warmup to slowly raise your heart rate, loosen up your joints, and increase blood flow to the muscles. For this warmup, you'll do each exercise for 30 seconds, resting for 10 seconds in between. Repeat the circuit three times, for a total of 10 minutes.

• Jumping jacks
• Squats
• Forward lunges
• Hamstring and groin stretch (hold your ankles and straighten your legs to stretch your hamstrings, then sink your hips and lift your chest for the groin)
• Butt kicks