A CK-MB test may be used as a follow-up test to an elevated CK in order to determine whether the increase is due to heart damage or skeletal muscle damage.
Scuba organizations say recreational divers shouldn't go below about 130 feet, but one Egyptian diver recently ventured a bit deeper -- going more than 1,000 feet below the ocean surface and setting a world record in the process.
Another one of the key scuba diving safety rules. As you ascend you are ridding your body of nitrogen in your tissues and bloodstream. If you ascend too quickly, you risk the bends or decompression sickness. You should not ascend more than 30 feet per minute.