I went running yesterday; finally, after so long!
Now, I'm having pain in my arms. I derived this can be associated with lack of proper warm-up.
Furthermore, we tend to swing our arms while running, unconsciously moving them in different positions when we do things like putting both hands on our hip.
It can also be attributed to our posture when we run; the way we position our shoulders will affect and exert pressure on our arm since they are connected. Hence, running also requires good posture.
One thing that I learnt from my Taekwondo lessons in the past is to keep your spine straight and your head straight. When doing things like stretching (sit and reach) or running, sometimes we tend to lower our head. This bends the muscles at the back of our neck, thus exerting pressure on this area. As the neck is close to the shoulders, it ultimately affects our postures and thus exerting pressure on certain parts of our body.
Therefore, to avoid pain in the arms a few days after running, it's best to relax your hands and don't try to position your hands in a particular position.