One of the basic bodybuilding principles is a bigger muscle is a stronger muscle. So in order to get bigger, you need to get stronger. Progressive overload is the cornerstone of all successful workouts. You need to gradually increase the weights you are lifting over time in order to make progress.
During the early phases of a starting a workout program beginners can make fast gains because all training stimulus is new at this stage. A lot of their initial strength gains come not only from increasing muscle strength, but also from improved lifting technique and better coordination.
However, once you get past the initial beginners phase, your strength
gains come more slowly. When this happens a lot of lifters will simply
do fewer reps so they can continue to increase the weights.
For example, if I can lift 100 lbs. for 10 reps, maybe I could drop the reps to 8 and lift 120 lbs., or drop the reps to 6 and lift 140 lbs., etc… While this may work to some degree to get you growing again, there comes a point where it can back fire and bring your gains to a screeching halt.
Is there a better way?
Lifting heavier weights for lower reps increases your risk of getting an injury such as a muscle tear. When you are doing fewer than 5 reps per set you lose a lot of the "mind muscle" connection. The lift becomes an end in itself, and no longer a means for building muscle. Lifting too heavy makes it harder to concentrate on feeling the muscles you are working, your focus switches to simply moving the weight and not getting crushed under a heavy barbell.
Now this doesn't mean that heavy low rep training doesn't have it's place. Advanced lifters can successfully incorporate phases of heavy low rep training cycles into their workouts from time to time. But they shouldn't be your primary training focus.
For
bodybuilding purposes try to stay within the 6-12 rep range most of the time. This is the "sweet spot" for hypertrophy because it keeps your muscles under tension long
enough to establish a good mind-muscle connection and stimulate growth, while still allowing relatively heavy
weights to be lifted.
