As with most things with fitness, this is kind of a gray area. Probably more black and white than other topics, but there is still some guey gray areas in the middle that we still don’t know much about. There are a few different components that I’ll touch on in this article that will hopefully help you follow the rabbit hole of this thing we call the internet.
Do Bigger Muscles Equal More Strength?
When powerlifters are talking about hypertrophy (muscle growth), they’re generally talking about myofibrillar hypertrophy. This is the increase of the myosin and actin proteins within the myofibril, which is the part of the muscle that actually contracts in order to move your body. (full muscle diagram shown below)
The muscle fiber is primarily made up of sarcoplasm and myofibrils. Sarcoplasm is the cytoplasm of striated muscle cells. If we remember cytoplasm from middle school biology, it is basically the fluid that fills our cells. So, looking at the diagram below, we can see that the sarcoplasmic hypertrophy is the increase in sarcoplasm within a cell, and myofibril hypertrophy is the increase in myofibrils within a cell.
So why do we care? This graphic may be slightly deceiving, because sarcoplasmic hypertrophy has greater potential for overall size of the muscle, but will most likely not increase your strength. Myofibrillar hypertrophy, while may not increase the cross sectional area of the muscle as much, is more functional and has a direct relationship with strength gains.
Now we land on the question, how do we train for one type verses the other?
Well, this isn’t exactly proven. What we do know is that bodybuilders tend to have much more sarcoplasm, and powerlifters tend to have more myofibrils. We may be able to surmise that because body builders tend to train in the 8-12 rep range that this causes an increase in sarcoplasm, while powerlifters training in the 3-6 rep range are increasing their number of myofibrils.
This indirect evidence may be because of the way they train, but could also be a sampling error. People who are more prone to sarcoplasmic hypertrophy may just be more likely to be a bodybuilder, and vice versa for powerlifting. While it’s not exactly science, it’s the best evidence we have.
So once you start hitting a plateau with your mass gains, what do you need to do? Most likely you need to be lifting more weight, and that means you need to get stronger.
So More Strength Means Bigger Muscles?
In the long term, probably. Always? Nope.
This answer has two components as well. The first is fairly straightforward.
If you have more muscle mass, you absolutely have additional capacity to be stronger. As mentioned above, additional myofibrils have a direct correlation to strength. However, this is correlation, not causation.
The second is more complex. If you are a new lifter, you may notice that every time you hit the gym you’re hitting a new PR. This doesn’t mean you’re becoming the hulk. This simply means you’re brain is gaining more control over your motor units. Check out another diagram below. A motor unit is a single neuron and it’s accompanying muscle fibers.
When you begin lifting, you aren’t immediately able to utilize all of your muscle each time you lift. Over time, after you gain more of a “mind muscle connection”, you’re able to activate more of these motor units on each lift.
This process is called neural adaptation. This is your body’s ability to try and become more efficient with its movements over time. As you advance from novice to intermediate lifter, these changes will decrease in their severity. If you continue to try new lifts, you most likely will continue to see these neural adaptations, and especially if you lift in the 85%+ 1RM range. Many lifters refer to this as your skill with each lift. As your skill increases, so does your efficiency in that movement, and by default, your strength. These of course has a limit. Once you’re able to move as efficiently as possible, the only way to continue to improve is to build more muscle. AAANNNDDD, now we’re back to hypertrophy.
Bringing It All Home
All of these factors together give you the ability to get huge, and strong. Without increased sarcoplasm, there would be no space for myofibrils. Without myofibrils, you wouldn’t have more contractile tissue to move heavy weights. Without neural adaptations, you would not be able to efficiently control your muscle fibers and motor units.
What this means for you, is that part of your training should be in the 3-6 rep range, and some should be in the 8-10. I personally believe that most people should work to balance both hypertrophy and strength to optimize their results.