Factors are based on:
Muscle? “A”- Strength referring to the ability to exert a force on an external object?
e.g. lifting a weight.
Muscle? “B”- Strength referring to the force exerted by the muscle itself?
e.g. on the place where it inserts into a bone.
Muscle? “C”-Strength of muscle based on its weight?
e.g. pound for pound strength.
Though confusing, I won’t answer a question with a ton of questions ^ (-_-)
I would use series of muscles or groups rather than individual muscles for simplicity sake. But here is my off-the-top answer.
A) Force = Mass * Acceleration. Considering the mass of the leg and the speed at which we can kick our feet, the knee extensors (mainly quadriceps) are a forceful group. They are also primary muscles in many of the heaviest lifts. But I would tend to think the masseter (jaw muscle), just because a single bite can generate something like a half ton of force.
B) Tendon and tissue strength can vary among populations and within one body. However these “connectors” must be able to withstand a contraction of the muscle and therefore limit the muscles ability in a maximum contraction. You can read numerous stories of heavy weightlifters tearing muscles (often biceps) from the bone. Not to mention that it takes years of training and practice to induce only a 90% contraction in muscles. However, that’s only physiology. Biomechanics play a large role in force generation.
But all in all, the gluteus maximus can generate a lot of force on the bones.
C) Again, consider the masseter. Huge amounts of force. Also the uterus, used in child birth. I will not attempt to explain that whole situation.
I guess it would depend upon what type of strength we are referring to.
Is one referring to strength endurance or 1RM strength or somewhere in between? Should one take into consideration the type of muscle fiber of the muscle one considers to be the strongest? Can cardiac muscle which is involuntary and skeletal muscle really be compared as far as strength is concerned?
Is one forgetting that skeletal muscle do not work in isolation.
Having said the above. My answer is I don’t know.