Muscle strength depends on how well you train your motor neurons

To really achieve your athletic potential, you must strengthen your mind and your muscles. As much as that may sound like a platitude from a motivational poster, it’s actually based on a series of experiments comparing how muscle mass may or may not impact physical strength. Muscles are still the key mechanical actors in these emerging model, but it looks like well-trained motor neurons are the anatomy that can give you access to more of your body’s strength.

Now, nobody is debating the idea that, in general, a larger muscle can do more work than a smaller one. More muscles cells can share the stress of a particular contraction, achieving movement without incurring the damage a smaller muscle would. However, bulky muscles aren’t able to do more work just because they’re big. To get bigger, they’ve presumably been trained along the way, which helps the muscle cells activate simultaneously. Untrained muscles will activate asynchronously, which may protect them from overexertion and damage, but also decrease their effectiveness.

More strength from the same muscle

Not all strength training is turning out to be equal. One on hand, many repetitions of lighter weights is being found to be effective as fewer repetitions of heavier weights to build muscle mass. It may take longer, but lifting lighter weights can help you develop larger muscles. The catch is that lifting larger weights seems to not only train muscles, but also motor neurons, which changes how well you can put your quads, biceps or triceps to work.

This relationship was tested in a variety of ways. One test involved electrically stimulating muscles to see if heavy and light weights produced muscles with different limits on their output. Another test asked participants to do a matching task, and found that the muscles trained on heavier weights didn’t need to work as hard to complete it. In every case, matching muscle sizes didn’t matter as much as the way those muscles had been trained. Researchers aren’t sure why heavier weights are more effective at training our motor neurons in this way, but it suggests that lifting weights close to your limit may be more effective at raising what that limit is.

Source: Why Strength Depends On More Than Muscle, Scienmag