Combat veterans with PTSD have a stronger "fight or flight" response than veterans without PTSD, as shown by higher adrenaline levels and less heart rate control in response to stress. This physiological difference may help explain their increased risk for high blood pressure and heart disease. Cryptosporidium infections from swimming in pools contaminated by infected swimmers have doubled in recent years, causing diarrhea, stomach cramps, nausea or vomiting for up to three weeks. Lifestyle changes like diet and exercise can help prevent osteoarthritis by altering cell metabolism and preventing inflammation in joints.