Muscle Boost X When lifting weights, it's alright to cheat now and then. Slightly using your body for pumping out a few final reps is a great way to increase your workout volume. Be careful not to do this to the extreme. Stay in control of the speed of your repetitions. Do not compromise your form.Muscle Boost X One problem with muscle building is that some groups take longer to develop than others. In order to target such problem groups, a fill set is a great idea. A fill set is a short set of 25-30 repetitions of exercises that specifically target the questionable group.