FitPerez reader Anthony is a little confused about properly utilizing sets and reps in his workout, so he wrote Dynamics of Motion for advice, asking:
Question for you - okay so I am doing weight exercises - but I am confused about sets and reps - if I am doing a fly should I do 12 flys or do I do as many as I can handle before passing out?
Sets are the number of times you repeat the same exercise in a workout. They are broken up by varying degrees of rest, depending on your goals. And reps are the number of times you repeat the same exercise without any rest. We would suggest sticking to a certain number of reps and sets depending upon what you are trying to accomplish in your workouts.
For example, if you are trying to build some muscle and mass, then use enough weight so you can do at least 4 reps but not more than 6. If you are just trying to get in shape and tone up, then 10-15 reps is usually a good goal. Whenever you can get more than a certain number of reps you are trying to achieve, then it is time to go up in weight.
As far as sets go, if you are trying to build muscle and mass, then 4 sets is usually a good number. If you are trying to get in shape, then 3 sets is probably enough, since you are doing more reps. But, remember that it is important to switch things up every few weeks so your body never gets used to the workouts.
In general, burning out is okay for the last set, but just remember you will be burning into reserves that can decrease the quality of the rest of your workout.