Stimulates Nitric Oxide Production Maximizes Pumps Improves Muscle Fullness How Do You Pump Up? Pump is a versatile pre-training formula that can be stacked or taken solo. This non-stimulant pre-workout comes in clutch for the night owls who enter the iron dungeon late into the ...Stimulates Nitric Oxide Production Maximizes Pumps Improves Muscle Fullness How Do You Pump Up? Pump is a versatile pre-training formula that can be stacked or taken solo. This non-stimulant pre-workout comes in clutch for the night owls who enter the iron dungeon late into the day and must avoid caffeine in order to get a good night's rest.