It is generally true that bigger muscles are stronger muscles. On the other hand it is possible that someone with smaller muscles may be stronger than a more muscular counterpart.
Similarly, you can get stronger by developing bigger muscles but you can also get stronger with no increase in muscle size at all. How can this be?
These questions have been researched extensively for many decades, but it is only recently that the reasons have been forthcoming.
We have always known that as we get stronger our muscles get bigger. This is referred to as muscle hypertrophy.
Muscle hypertrophy has been detected after 8 weeks of resistance training, but probably begins to occur much earlier in a strength training program.
Our muscles are made up of individual muscle fibers (myofibrils) and the increase in the cross-sectional area of a hypertrophying muscle is brought about by each of the myofibrils becoming thicker.
The increased “muscle machinery” allows a more forceful contraction. Now, our more learned readers and/or our more regular readers will recall that our muscle fibers may be classified as fast twitch and slow twitch, as we have discussed these fiber types previously in relation to endurance training. In contrast to endurance exercise, however, it is the fast-twitch fibers that respond most to heavy resistance training.
Olympic weightlifters and powerlifters may possess fast-twitch fibers of twice the diameter of the slow-twitch fibers in the same muscle.
In the last decade or two a surprising new hypothesis has been presented to help explain muscle hypertrophy.
Animal studies have provided evidence for resistance training resulting in a proliferation of muscle fibers. Some researchers believe this occurs by fibers splitting to form new ones.
This phenomenon would appear to occur more so in training which incorporates high repetitions of an exercise with a relatively light resistance rather than a few repetitions of a heavyweight.
So, it appears that is not only the size, but the number of muscle fibers that contribute to the hypertrophy associated with resistance training, but even this may only be half the story of strength increase.
Our strength seems also to be determined by the extent to which our muscle mass can be activated through our nervous system.
There is evidence that this activation may be enhanced by training and is referred to as neural adaptation. In other words, we learn to get more out of our muscles — to recruit large numbers of muscle fibers into play during a particular movement, thereby providing greater force production. It also seems likely that strength training leads to an enhanced coordination of muscle groups.
This further enables a more concerted development of force in the required direction — a more effective force production.
Prime moving muscles become more “switched on” to their task with irrelevant muscle groups being “switched on” to their task with irrelevant muscle groups being “switched off”, the latter effectively preventing any impedance to the development of muscle force in the desired direction.
It is clear then that the development of strength is a more complex issue than simply getting bigger muscles.