exercise
2 interactions related to exercise
l-arginine + l-citrulline
L-arginine is the direct precursor to nitric oxide, but a large share of an oral dose is degraded by intestinal arginase and first-pass liver metabolism, so plasma levels peak quickly and fall within an hour or two. L-citrulline largely bypasses that metabolism and is converted to L-arginine in the kidneys, sustaining the rise for longer. Taken together they raise plasma arginine higher and for longer than either alone, supporting nitric-oxide-dependent effects.
caffeine + creatine
Daily high-dose caffeine taken throughout a creatine loading week may modestly blunt creatine's strength benefit, but ordinary pre-workout caffeine in someone already taking creatine daily is at worst neutral and often additive. There is no safety concern at normal intakes.