It’s a debate as old as time, at least in the gym world. Should you do low reps heavyweight to gain muscle? Will it elicit enough muscle damage for hypertrophy? What about 20 reps of a lightweight? Will that produce more metabolic stress?
If you, like many, are confused by low or high reps, we’re here to help.
Do low reps if:
Low reps are a great option for strength building. If your aim is to be able to deadlift double your bodyweight and feel physically strong, you need to be working in the one to five rep range. Remember that strength is not necessarily reflective of size; someone can be big and bulky but not physically very strong.
If you’re working for strength, choose weights that are 80 to 90 percent of your one-rep max. Your one-rep max is as it sounds, it’s the heaviest weight possible for you, that you can only manage to do one rep with. Using heavy weights for low reps stimulates type II muscle fibers because you need explosive power to lift a heavyweight.
Do high reps if:
High reps are for those who want to increase their endurance. Perhaps you are a marathon runner and want to improve endurance in your calves, working in the 15+ rep range will stimulate type I muscle fibers. Obviously you can’t lift a very heavy weight for 20 reps, so choose a weight that you can lift for the given number of reps; it’s usually up to 40 percent of your one-rep max.
Contrary to popular belief, you can still build muscle with a lower weight and higher reps. A study by Burd et al (2010) found that in a small group of participants, this method of training led to increased muscle protein synthesis compared to a group that did higher weights, lower reps.
Training high reps with a lower weight helps to build ‘strength repetition’, this means your muscles become better accustomed to the specific movement, leading to increases in maximum strength i.e. a higher one-rep max. Training for strength repetition has also been shown in research to work type I muscle fibers more.
Do moderate reps if:
If you want to increase the size of your muscles, known as ‘hypertrophy’, you want to be working in the eight to 12 rep range. This rep range stimulates a combination of type I and type II muscle fibers, working at 60 to 80 percent of your one rep max.
Working out in a moderate rep range causes a buildup of lactic acid which induces a boost of anabolic (muscle building) hormones, to help build and retain muscle mass. The increased time under tension during a moderate rep range with moderate resistance recruits more muscle fibers, leading to more muscle damage which is imperative for muscle growth.
Ultimately, your rep range depends on your goals. For the average person who wants to lose a bit of fat and build a bit of muscle, the optimal workout combines all rep ranges to target strength, endurance, and hypertrophy.
