“The 28 Method” is a classic technique used by bodybuilders, but it works for any guy looking to build muscle.

You’ll do 4 sets of 7 reps of the same exercise back to back. But with each set, you’ll tweak the speed or range of motion to challenge your muscles in new ways.

Altering the tempo of an exercise triggers a different training response in your muscles, says BJ Gaddour. So by doing an exercise more quickly or more slowly than usual, you’ll maximize your gains.

Same goes for isolating one half of a movement at a time.

If you usually do full reps of a Bulgarian split squat, for example, partial reps will be a new stimulus, spurring more gains, Gaddour says. Plus, you’ll preferentially strengthen the muscles most involved in each portion of the exercise.

The result: bigger muscles and enhanced performance.

Here’s how it works: Perform Bulgarian split squats according to the following rep scheme without stopping.

1. 7 slow reps
2. 7 fast reps
3. 7 bottom-half reps
4. 7 top-half reps

You can also do a time-based protocol, performing each variation for 30 seconds.

To make it harder, increase the reps to 8, 9, or 10 in each set or increase the time in 5-second increments. You can also add dumbbells to increase the load.