If you ask any personal trainer about the number of repetitions of each exercise that you should perform, the trainer would most likely advise you to target somewhere between 7 and 12 reps until you experience muscle fatigue. In other words, you’ll be using a heavy weight for a fairly low number of repetitions.

A new study suggests that there’s another way to build muscle – and it flies in the face of conventional wisdom. According to the study, performing light weights for a high number of repetitions until fatigue also results in similar muscle growth.

For the study, researchers calculated the maximum load for each individual and then broke the participants into one of three groups as follows:

Exercisers perform one set at 80% of the maximum load until fatigue, or
Exercisers perform three sets at 80% of the maximum until fatigue, or
Exercisers perform three sets at 30% of the maximum until fatigue.

Performing sets at 80% of the maximum load usually results in rep ranges of 7 – 12. Training at 30% of the maximum load, on the other, results in much higher rep ranges of 25 – 30.

According to their data, participants in groups 2 and 3 gained the same amount of muscle mass. In other words, training with heavy weights and low reps resulted in the same muscle growth as light weights and high reps. Notably, participants in group 2 – whose training most closely mimics conventional muscle building strategies – resulted in larger strength gains than group 3. Participants in group 1 experienced approximately half the muscle growth as groups 2 and 3.

Because group 2 exercisers experience increased gains in strength, rep ranges of 7 – 12 are still ideal. And, fewer reps means less time at the gym – so lower rep ranges with heavy weights make for a more efficient workout.
But because lower repetition ranges require heavy amounts of resistance, they can be intimidating for beginners. Moreover, heavy amounts of resistance can prevent people with joint issues – and, in particular, older populations – from utilizing the heavy resistance/low rep training strategy.

The implication of this study is obvious: Don’t let current strength training guidelines deter you from lifting weights and thus receiving the associated health benefits. If the heavy levels of resistance associated with lower rep ranges is a limiting factor for you, this new research suggests that light loads can also yield great results.

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