Acute renal failure with severe loin pain and patchy renal ischemia after anaerobic exercise caused by rapid resumption after prolonged detraining

BACKGROUND: We report a case of acute renal failure with loin pain and patchy renal ischemia after anaerobic exercise (ALPE) caused by sudden training resumption. CASE PRESENTATION: A 19‐year‐old Asian man who was a college American football player presented with severe back pain, headache, and malaise. He developed acute kidney injury without myoglobinuria. Based on the typical medical history and symptoms, we made a diagnosis of ALPE. Symptoms improved within a few days, and serum creatinine levels simproved after discharge. He resumed training, adjusting his load step by step. CONCLUSION: During the coronavirus disease 2019 pandemic, many athletes were unable to undergo adequate training. Long‐term de‐training leads to decreased various organ function and reduces the anaerobic threshold. Rapid resumption after prolonged de‐training may put individuals at risk of developing ALPE.