This clinically tested, high-intensity pre-training formula has potent ingredients to help magnify energy, alertness, strength, stamina, pumps and free testosterone during workouts. Nitra flex pre-workout delivers fast, explosive training results for a more powerful body, including energy, stamina, nitric oxide (no) and testosterone levels. It contains proven muscle building l-citrulline malate, l-arginine, l-arginine alpha-ketoglutarate (akg) amino acids and calcium fructoborate (cfb), a natural, high potency form of boron which has been shown to support free testosterone.