Which preventative action is recommended for someone experiencing heat cramps?

Moving to shade and initiating cooling measures is the recommended preventative action for someone experiencing heat cramps. Heat cramps are often a result of prolonged physical exertion in hot conditions, accompanied by significant sweating leading to electrolyte loss. By relocating to a cooler environment, the individual can reduce their body temperature and mitigate further complications associated with heat stress.

Adding cooling measures, such as drinking fluids and applying cool packs, helps in restoring the body's temperature regulation. This approach not only addresses the immediate symptoms of heat cramps but also aids in preventing potential progressions to more serious conditions like heat exhaustion or heat stroke.

The other options do not effectively address the immediate need for cooling or hydration, which are critical in managing heat cramps. For instance, warming up the affected muscles can exacerbate the situation, and increasing physical activity would further deplete the body's reserves and exacerbate the symptoms. Remaining indoors until complete recovery may not provide immediate relief, and it is important to start cooling measures as soon as possible to promote safe recovery.