Early 40s, BMI < 21, was running ~50-60 mpw.
Took 6 months off due to upper hamstring injury, resuming running full time this month and encountering mid-back pain.
Feels like muscles on either side of spinal cord in the mid-back area. Feel it when landing each foot strike. Have never had back issues before in my life.
Is this a core fitness issue? Don't think my form or breathing has changed, although I am running about ~2:00 min/mile slower than 6 months ago.
Started back ~20mpw running 6-7 days per week from zero previously.
Any advice appreciated.