Elbow Strikes / Step-Ins:

Elbow strikes utilise one of the body's hard, natural weapons and put it to use for close-quarter fighting. This is also one of those short-sharp exercises that acquires great power when it is used in a coordinated movement that takes into account the entire body.  

What's involved: Lateral abs, front hip flexors, shoulders, quads, calves. 

Powered by: Front hip flexors, primarily.

Tip: The faster you can twist on your feet to align your body behind the elbow strike, as you execute it, the more powerful it becomes.