pre-workout
3 interactions related to pre-workout
citrulline + arginine
Oral arginine has poor bioavailability due to extensive first-pass metabolism. Citrulline bypasses the liver and is converted to arginine in the kidneys, sustaining elevated plasma arginine. Combined oral dosing produces a faster and higher plasma arginine peak than either alone, increasing nitric oxide synthesis.
caffeine + yohimbine
Caffeine and yohimbine are both potent stimulants. Yohimbine blocks alpha-2 adrenergic receptors, raising norepinephrine, while caffeine blocks adenosine receptors and amplifies sympathetic output. Combined, they can cause large rises in heart rate and blood pressure, severe anxiety, tremor, panic attacks, arrhythmias, and have been linked to hospital visits and rare cardiovascular events.
caffeine + creatine
Early studies suggested caffeine blunts the ergogenic effect of creatine on muscle phosphocreatine resynthesis and high-intensity performance, but subsequent randomized trials show the combination is generally additive or neutral; the original blunting effect appears specific to chronic co-ingestion during creatine loading rather than acute pre-workout use.