Few exercises will give you as many benefits, as quickly, as Speed Bag Punches. Performed at any speed, anywhere, any time, with zero warm up this is the go-to exercise for increasing hand speed and improving hand-eye coordination. Why? Because hand-eye coordination requires your mind to have a clearly defined mental image of the spatial coordinates your body moves in. If you do not have that automatically your fists will collide (which is painful). If you get tired and your brain does not have enough oxygen you will lose control of your hands. Plus, the exercise works all those supporting muscle groups that make your punches faster by making the way you move your arms faster.    

What's involved: Triceps, shoulders, chest, upp abs, lower back (eventually). 

Powered by: Triceps (primarily). 

Tip: Start slow to warm up and after about 20-30 seconds go as fast as you possible can for as long as you can until you lose track of your fists and they collide. Then start again slowing down just enough to maintain control. You can also reverse the direction so you are rotating your hands in a counter-clockwise direction.