The variance in workout programs and strategies are incredible. Some advocate one style over the other. From my research, it would appear that they both work effectively. The question really is what are the differences and advantages/disadvantages.
So I’m actually a big fan of reverse pyramid training. Reverse pyramid training is a style of training where essentially you start with a heavy set between 4-6 reps you gauge this weight based on your one rep max. To figure out how much you should be lifting in that 4-6 rep range you want to take 75%-85% of your one rep max and progressively overload from there (studies and anecdotal evidence suggests that muscle grows best when you use loads of 75-85% of your maximum as this provides an optimal balance of tension/muscle fibre recruitment). Learn more here https://thinkeatlift.com/reverse-pyramid-training/
Because I prefer reverse pyramid training I am getting the best of both worlds emphasizing the importance of the heavier weight first as it is optimal to be fresh when lifting heavy, remember 75%-85% of your one rep max. So lets talk about the key benefits of lifting heavy to give you a further understanding of its role in your workouts.
Benefits of lifting heavy
When you lift heavy you actually are targeting your fast twitch muscle fibers. Each muscle is composed of two different fibers, fast twitch, and slow twitch. You can think of the fast twitch aiding in explosive power. You can usually trigger these fibers with a weight and a rep range that is under 8-10.
Lifting heavier weights also releases more muscle-growth and fat-burning hormones than lifting light weights. More muscle growth hormones will be released, stimulating faster muscle growth.
Lifting heavy weights burns more body fat than lifting light weights, and the heavier the weight, the more calories you burn with each rep. The reason for this is that the fast twitch fibers tap into the fat stores for energy because it is available more quickly than oxygen. Fat burning hormones continue to release 8 hours after your workout vs only 1 hour with light weight training.
Finally, the fast twitch fibers are a bit thicker. So by targeting these fibers and increasing the size, your muscles will look a lot fuller.
Benefits of lifting lighter
When lifting lighter you recruit mostly slow twitch muscle fibers that are great for endurance those slow-twitch fibers are very resistant to fatigue, which means they can perform many contractions before they become fatigued. They also recover quickly even after hours of use.
While in my opinion there seem to be more benefits with heavier weights we can see it is still essential to incorporate some lighter weight training as well. That is where RPT training is effective.
Most muscles are roughly an even split between fast- and slow-twitch muscle fibers. So, even if one style of training was able to target a specific muscle fiber type, you’d still want to do both high- and low-rep training to get the most muscle growth possible.