This 2-move routine is the perfect easy ab workout: a straight-leg jackknife crunch to target your upper and lower abs, and a weighted Russian twist for your obliques and transverse abdominals. This workout uses intervals to maximize calorie burn and fat loss.

This 2-move routine is the perfect easy ab workout: a straight-leg jackknife crunch to target your upper and lower abs, and a weighted Russian twist for your obliques and transverse abdominals. This workout uses intervals to maximize calorie burn and fat loss.