I have been really struggling with tight neck/shoulder/upper back pain when running - it usually starts about 3k into a run. I've been doing mobilsation exercises (arm and neck circles, shoulder shrugs etc) prior to starting and have been really trying to keep my shoulders relaxed and my hands down. But still it continues and I'm really struggling to keep my shoulders and upper back relaxed - I usually end up with pain between my shoulder blades from it.
I think my shoulders and neck are pretty tight anyway, but I was wondering if anyone had any tips as to how I can avoid this? Thanks in advance