ROWING

Rowing machines (like the Concept2 rowers you see in many CrossFit gyms) are a great HIIT cardio activity that involve lower body power using the quads, glutes, and hamstrings, as well as the pulling muscles of the upper body (back, biceps, posterior delts). When rowing, make sure to keep your lower back flat (not rounded) and your core tight. This will help keep your lower back safe from injury. As you row, make each "rep" a powerful movement driven mainly by the lower body but also pulling hard with your back and arms.