<s>[INST] My 24 yr  old son has been diagnosed with IgA Nephropathy.  After a kidney biopsy his doctor said that his kidneys had 70% scar tissue and were working at 25%-30%.  He has been doing cross fit training 3-4 days a week and was drinking a high protein recovery drink.  He has since stopped the protein drinks.  My question is "does working out and building muscle cause more damage to his kidneys"? I was told that muscle contains creatinine and when muscle mass is broken down it releases creatinine therefore increasing his creatinine levels which are destroying his kidneys.HIs blood pressure has been as high as 212/130.  With an increase in bp meds it is now around 148/86. [/INST] HIT hanks for the query. If a person has normal kidneys then exercise including muscle building exercise is quite safe. In people with kidney problems like your son, regular aerobic exercise is OK, but he must avoid strenuous weight training. Also, he must not take any protein supplements. All these will add to the work of the already affected kidneys.However, one thing is certain for sure that IGA Nephropathy is not caused by exercise; it is more like an allergic disorder. Hope this helps. Good luck. </s>