This is normal, because all the movements at both ends of the practice are centripetal bending and contraction. As long as you bear the weight, your related joints, tendons and ligaments are in a state of tension, which is just a matter of pressure.

Also, your weight must be heavy, because if your muscles can't completely control the stretching and contraction during each exercise, the extra weight will definitely fall on your joints! That's why you have a headache. I tell you, the top professional bodybuilders in the world do barbell bending, with only 5kg and 10kg on one side, but how many arms do they have? How old are they, man! Don't be fooled by the illusion that the gym is powerful =NX. You will often see that people with thicker and thinner arms tend to use less weight, but some people play with their arms in their thirties or even less, but everyone feels sore and bloated after finishing a group. It's not obvious that I'm bored after finishing three groups.

Why not go and see what real bodybuilders do when they do movements and find out the gap? I have begun to think that bodybuilding strength is everything. Even when the barbell is added to 15kg, my body shakes violently. . . But after three years, the bending weight of my barbell is only 2.5kg on one side, but the arm dimension is getting thicker and thicker!