Bodybuilders routinely engage in many dietary and other practices purported to be harmful to kidney health. The development of acute kidney injury, focal segmental glomerular sclerosis (FSGS) and nephrocalcinosis may be particular risks. There is little evidence that high-protein diets and moderate creatine supplementation pose risks to individuals with normal kidney function though long-term high protein intake in those with underlying impairment of kidney function is inadvisable. The links between anabolic androgenic steroid use and FSGS are stronger, and there are undoubted dangers of nephrocalcinosis in those taking high doses of vitamins A, D and E. Dehydrating practices, including diuretic misuse, and NSAID use also carry potential risks. It is difficult to predict the effects of multiple practices carried out in concert. Investigations into subclinical kidney damage associated with these practices have rarely been undertaken. Future research is warranted to identify the clinical and subclinical harm associated with individual practices and combinations to enable appropriate and timely advice.

Increasingly popular, ultra-endurance participation exposes athletes to extremely high levels of functional and structural damage. Ultra-endurance athletes commonly develop acute kidney injury (AKI) and other pathologies harmful to kidney health. There is strong evidence that non-steroidal anti-inflammatory drugs, common amongst ultra-athletes, is linked to increased risk and severity of AKI and potentially ischaemic renal injury, i.e., acute tubular necrosis. Ultra-endurance participation also increases the risk of exertional rhabdomyolysis, exercise-associated hyponatremia, and gastrointestinal symptoms, interlinked pathologies all with potential to increase the risk of AKI. Hydration and fuelling both also play a role with the development of multiple pathologies and ultimately AKI, highlighting the need for individualised nutritional and hydration plans to promote athlete health. Faster athletes, supplementing nitrates, and being female also increase the risk of developing AKI in this setting. Serum creatinine criteria do not provide the best indicator for AKI for ultra-athletes therefore further investigations are needed to assess the practicality and accuracy of new renal biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL). The potential of recurring episodes of AKI provide need for further research to assess the longitudinal renal health impact of ultra-participation to provide appropriate advice to athletes, coaches, medical staff, and event organisers.