Subjects in the study trained their legs on the leg extension machine 3 times a week for 10 weeks, using one of three different set and rep configurations:
1 set of 10-12 reps (80% 1-RM) performed to voluntary failure (80%-1)
3 sets of 10-12 reps (80% 1-RM) performed to the point of fatigue (80%-3)
3 sets of 30-40 reps (30% 1-RM) performed to the point of fatigue (30%-3)
The figure below shows the change in the size of the quadriceps, measured using magnetic resonance imaging. As you can see, high reps and light weights (30%-3) stimulated just as much muscle growth as heavy weights and low reps (80%-3).