Instead of recommending alternatives to running, you can try to alleviate the root causes of fibromyalgia and joint inflammation. I have electro hyper-sensitivity syndrom and MCAS. If I eat any non-kosher foods, anything high in fat, preservatives, or sugar, I experience the joint pain and heightened sensitivities to electronics (EMF & RF) as my nerves (mostly up and down the vagus line) also join in the inflammation party. I continue to lift weights and run.
Try a change in diet and see how you feel. We are all experiencing a rising rate of daily exposure to environmental radiation by our high tech lifestyles and the continual radio in our atmosphere that is disrupting electrons in our cells (mitochondria specifically) to disproportionate degree. When mitochondria have their electron pairs disrupted, they go to the nearest organ to borrow more electrons. If this electron theft continues on a constant and regular basis, you will suffer deterioration in the weakest, or most strained, organ.
Do the diet thing and see if it relieves joint issues. Delicious cheeses and bacon are now your enemy. Keep an eye on devices you keep on your lap or near your legs. Electro magnetic radiation is pervasive and works very slowly and is generally being ignored as the root cause of many modern illnesses. Even though there are many case studies done on rats and EMF that prove this organ damage, tumors and cancer is occurring in them over the long term.
consider the following case studies:
10 year study on lab mice done with 900 and 1900mhz:
TOXICOLOGY AND CARCINOGENESIS
STUDIES IN B6C3F1/N MICE EXPOSED TO
WHOLE-BODY RADIO FREQUENCY RADIATION
AT A FREQUENCY (1,900 MHz) AND MODULATIONS
(GSM AND CDMA) USED BY CELL PHONES
the list of symptoms near the last page of this document:
Guideline of the Austrian Medical Association for the diagnosis and treatment of EMF related health problems and illnesses (EMF syndrome)
And one of the most concise documents I have found here:
EUROPAEM EMF Guideline 2016 for the prevention,
diagnosis and treatment of EMF-related health
problems and illnesses