Functional Strength

The first thing to consider is that lifting for pure power will always need to involve training for functional strength primarily. In turn, this means that you’re lifting very heavy weights through larger ranges of motion that incorporate lots of muscles into one clean and smooth movement. Examples of ‘compound’ lifts include the squat, the deadlift and the bench press. In each case, all the muscles are working together in unison in order to drive the weight. This means you’re using your legs, your core, your lower back and your arms all at the same time and it means that technique is going to be much more important.

These moves are called ‘functional’ because they mimic the way that you use your body in the real world. In real life, we very rarely use any movements that only utilize one muscle group on its own. When you perform a bicep curl, you’ll move the weight through a set range of motion and the only ‘pivot point’ will be your elbow. There are very few scenarios quite like this outside of the gym.

Conversely, performing a deadlift means coordinating your whole body, which is also what happens when you push your sofa during redecorating, when you wrestle and when you open the garage door. Therefore, it is considered more ‘functional’.

These kinds of compound, functional movements are also favored by many people thanks to their ability to stimulate more anabolic compounds. Deadlifting and squatting both result in the release of more growth hormone and more testosterone and the simple reason for this is that they incorporate more muscles and more of the larger muscles.

This is true to the point that some people claim you can’t build big muscle without using compound movements. This isn’t true as we’ll see... but certainly compound lifts are great for inciting more growth.

Muscle Fiber Types

There’s another factor to consider when lifting very heavy weights and an-other reason that you need the heaviest weights in order to stimulate the most strength.

And this has to do with ‘fast twitch’ and ‘slow twitch’ muscle fiber types.

Fast twitch muscle fibers are the muscle fibers that we use for explosive movements. These rely on glycogen stored in the muscles in order to operate and they are capable of exerting much more force compared with slow twitch fibers. At the same time though, fast twitch muscle fibers also wear out faster and aren’t as energy efficient. A long distance runner then will have more slow twitch muscle fiber, while a powerlifter or a sprinter will have more fast twitch muscle fiber.

Anatomically, this is because fast twitch muscle fibers have more stored glycogen and fewer mitochondria. Mitochondria are what convert glucose from the blood into ATP using the aerobic system. Conversely, glycogen is available for immediate use, though stores are depleted very quickly.

The body will always use the most efficient combination of muscle fibers possible to get the job done. You can’t ‘half’ use a muscle fiber, they are binary in nature. That means each muscle fiber either kicks in, or it doesn’t.

If you lift something light then, your body will likely use a couple of fast twitch fibers but a lot more slow twitch muscle. This will allow you to curl for longer but it means you won’t be tearing/stimulating the fast twitch fibers that give you that maximum strength.

Conversely, when you lift something very heavy though, the muscles will be forced to recruit more fast twitch muscle fiber just to shift that weight.
Therefore, you’ll eventually tear the fast twitch fibers, thus resulting in the stimulation you need to trigger growth. So you really do need to lift heavy in
order to engage the fastest twitch muscle fibers.

Individual Differences

This is where individual differences start to come into play though. Because actually, some people have more fast twitch muscle fiber genetically, while others have more slow twitch. This immediately impacts on the type of training they are going to respond best to. People with more fast twitch muscle fiber might be particularly adept at lifting heavy weights and might find this leads to rapid hypertrophy. On the other hand, those who have a lot more slow twitch fiber, will often find that they actually respond a lot better when they lighten their load and start lifting lighter weights!