A repetition (rep) is one completion of an exercise: one chin-up, one squat, one arm curl. A set is the selected number of repetitions before you rest. Let’s say 10 repetitions to 1 set of arm curls. The rest interval is the time between sets. The 1RM or repetition maximum is your personal best or the most you can lift once in any exercise. So 12RM is the most you can lift for 12 repetitions. So if I wrote:
Barbell Arm Curl, 40 pounds 3 X 12 RM, 60 seconds
That would mean 3 sets of 12 maximum arm curls with a weight of 40 pounds with 60 seconds rest in between sets. So how do you know how many reps, sets and what rest time is best for you? Here’s how it works in broad terms. The finer details are for you and your trainer to work on.
- Strength training uses the most weight, least number of repetitions and longest rest.
- Hypertrophy or muscle size training utilizes lighter weights, more repetitions and less rest time.
- Strength endurance has less weight again, with more repetitions and even less rest.
- Power training involves lighter weights and longer rests while concentrating on the speed of the lift.
Now these are general principles, yet people do all sorts of things with the combination of sets, reps, rest and exercise type to find the best combination for them.
Here’s how an exercise program for the bench press might look according to different goals starting from a theoretical personal best of 160 pounds (73 kilos):
Bench Press - 1RM = 160 pounds
- Strength. 140 pounds, 2 X 5, 180 seconds
- Hypertrophy. 120 pounds, 3 X 10, 60 seconds
- Strength Endurance. 100 pounds, 3 X 15, 45 seconds
- Power. 90 pounds, 3 X 8, 120 seconds
One point to note here is that it is mandatory to take adequate rest between heavy loaded sets in strength training in order to achieve best results, In power training, a sufficient rest interval is also important because each lift has to be done at high explosive velocity for best effect. So in strength and power training, make sure you get the required rest in between sets. In hypertrophy and strength endurance it’s not as crucial to use shorter intervals, although perhaps optimum.
Speed of Exercise Execution
Contraction velocity is the speed at which an exercise is performed and this also has an effect on training outcomes. Here are some general guidelines for weight training goals.
- Strength -- 1-2 seconds concentric and eccentric
- Hypertrophy -- 2-5 seconds concentric and eccentric
- Endurance -- 1-2 seconds concentric and eccentric
- Power -- less than 1 second concentric, 1-2 seconds eccentric
According to the US National Strength and Conditioning Association, the theoretical distribution of repetitions against a percentage of 1RM, your maximum lift, is distributed as follows, using the bench press example:
- 100 % of 1RM -- 160 pounds -- 1 repetition
- 85% of 1RM -- 136 pounds -- 6 repetitions
- 67% of 1RM -- 107 pounds -- 12 repetitions
- 65% of 1RM -- 104 pounds -- 15 repetitions
- 60% of 1RM -- 96 pounds -- warmup reps
(Based on: Baechle and Earle, NSCA’s Essentials of Personal Training, 371, 2004.)
This means that you should be able to do 1 lift at your personal best, 6 lifts at 85 percent of your personal best and 15 lifts at 65 percent of your 1RM personal best – and with proportional percentages for any lift in between, and probably below.
Don’t consider this an absolute reference; it’s only a guide and a basis from which to choose appropriate weights for working out. You can see how you can estimate your personal best or 1RM from your 12 RM -- multiply 107 by 100 divided by 67.