I work out regularly with heavier weights and haven't had an issue. With this workout, I used 5lb weights. There was a lot of swinging movements (using momentum instead of purposeful movements), and they became faster and more erratic as the exercise went on in order to limit it to 10 minutes. I tried to keep the same speed, but I believed it caused a twinge in my back. I don't think I'll be doing this workout again, or if I do, I will modify it to prevent injury.