I have a few readers who are in the same boat. They started lifting weights, following the general guidelines, but suddenly wondered - why 8-12 reps? Why not 20 or 30? I've gotten this question a few times and thought I would cover some of the basics for those of you who are curious about it.
The rep ranges we use are actually based on percentages of one rep maximum (the amount of weight you could lift one time). What experts have learned is that when we lift weights at above 85% of our one rep maximum, which comes out to about 6 reps per set, the risk of injury increases dramatically. When we train at 65% of our one rep max, about 15-16 reps per set, there's a decrease in strength gains. That leaves 70-80%, or 8-12 reps, as the best range for building strength while avoiding injury.
How many reps do you usually do in your strength training workouts? Leave a comment and tell us about it.
If you're interested in learning more about the basics of weight training, you can check out Weight Training 101 or, if you really want an in-depth class, sign up for this 9-week email course, Beginner's Guide to Strength Training.