Originally Posted by
Iride01
No. You can strengthen muscle without increasing the number or mass of muscle fibers.
It's true that you
can increase muscle strength through neuromuscular recruitment, but that does not mean that muscle mass is not correlated to strength. It is. More muscle mass produces more strength.
It's also true that you don't need to have a calorie surplus to build muscle. You can still build muscle with balanced calories—or even a slight deficit (~200-300 kcal).