Size vs. Strength
I’m sure you’ve read a large number of articles which describe the differences between mass building and mass shaping exercises – the first group includes heavy weight and the second consists of exercises with which you cannot use a heavy weight. When an exercise activates more than one muscle, a heavier weight can be lifted, which doesn’t mean that any of the muscles targeted by that lift is working harder than it would if it was working alone during an isolated exercise. Muscles cannot tell if other muscles are assisting their work – they only keep on working as hard as possible to make that lift happen.
But bigger muscles won’t necessarily give you greater strength. There are actually two very different types of hypertrophy that can take place within the muscle: myofibrillar hypertrophy (denser muscle fibers) and sarcoplasmic hypertrophy (bulkier muscle fibers).
Most martial artists and non-heavy weight lifters will choose myofibrillar hypertrophy, since their goal is having strong muscles but keeping their weight down, while bodybuilders favor sarcoplasmic hypertrophy which increases muscle size but it’s generally viewed as form over function.
In other words, myofibrillar hypertrophy leads to a greater density of the contractible myofibrils which increases the ability to exert strength and is best accomplished by training heavy weights with low reps, and sarcoplasmic hypertrophy is an increase in the volume of the non-contractible muscle cell fluid called sarcoplasm (which makes up to 30% of the muscle’s size), doesn’t lead to an increase in muscular strength and can be achieved by performing high-rep, low-load training. So for optimal results regarding both mass and strength, you will need a combination of those two types of training.
Keep working hard, balance your workouts with a proper diet and don’t believe everything you hear – growth is the only possible visible change that can happen in any muscle with the help of any exercise there is. Throw the “shaping“, “toning“ and “separation“ exercises out the window and focus on building both strength and mass.