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.
Scuba diving is permitted by OSHA regulations to those depths under limited conditions. From 200 to 300 feet, diving rigs using helium and oxygen as a breathing medium are used. To 300 feet, diving is usually performed on a similar mixed gas system, except descents and ascents are done in a bell.