The National Kidney Foundation reports that approximately 1 in 10 people will experience a kidney stone at some point during their lives. The prevalence of kidney stones is increasing in the United States for both adults and children. A kidney stone is a hard mass composed of mineral and acid salts that begin to crystallize because the urine becomes too concentrated (i.e., not enough liquid for the amount of waste present). The crystals begin to combine with other elements forming a mass. Some kidney stones are small enough to pass through the body without causing pain; however, if the stone is too large and does not move, a back-up of urine occurs and results in pain.

Risk Factors for Developing Kidney Stones

• dehydration/consuming too little water
• inactivity
• excessive exercise
• high salt or high sugar diet
• obesity
• diabetes mellitus
• hypertension
• infection
• family history
• urinary tract abnormalities
• gastric or intestinal bypass surgery

Symptoms of Kidney Stones

• severe pain in the back or side that may spread to the abdomen or groin area
• painful urination
• blood in the urine
• nausea
• vomiting
• fever and chills

The Role of Exercise in Kidney Stone Formation and Prevention

• Excessive exercise, such as marathon running, can increase the risk of kidney stone formation in susceptible individuals because it can lead to dehydration from fluid lost through sweat. This, in turn, increases the concentration of waste products in the urine and makes it more likely that crystals will form. To prevent dehydration, approximately 16 to 20 fluid ounces of liquid per pound of body weight lost through sweat should be consumed within two hours after completing exercise.
• Inactivity can increase the risk of kidney stone formation because of its role in the development of obesity, diabetes mellitus and hypertension. The National Kidney Foundation recommends that you have a goal of exercising for 30 to 60 minutes on most days of the week to lower your risk for these diseases.

Note: Before beginning an exercise program or increasing the intensity level of a current routine, a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

References
National Kidney Foundation
Up-To-Date: Dietary Factors and Medical Problems that Increase the Risk of Kidney Stones
ACSM Position Stand: Exercise and Fluid Replacement