The subjects consumed L of Beet It ( mmol of nitrate) or the nitrate-depleted beetroot juice placebo ( mmol of nitrate) for six days. They engaged in treadmill exercise and knee extension tests on days four and five. The nitrate-rich beetroot juice significantly raised plasma nitrite concentration and decreased systolic blood pressure by 4% (5 mm Hg) compared with placebo. The nitrate-rich beverage also lowered the oxygen cost of walking by 12% and moderate- and high-intensity running by 7%. The nitrate-rich juice also increased the time to exhaustion during high-intensity running by 15% and during incremental knee extension exercise by 5%.8
Furthermore, extracellular arginine does appear to be a determinate of nitric oxide release  (the CAT1 transporter that shuttles arginine is highly associated with eNOS  and inhibiting extracellular influx prevents eNOS activation  ) while intracellular arginine concentration does not appear to be associated.  Due to the transport being required but intracellular arginine not being per se required, it is thought that the colocalization of CAT1 with eNOS   may also play a role in stimulation of eNOS activity.
So, I’m 17. I started training with weights in Dec 2013 with absolutely no knowlege/experiece. I got my squat from 80 to now 145lbs. I can deadlift 160lbs easily. Bench press on and off since my bench is broke. So would you say my beginner gains are gone and I need to use creatine? I am going to buy some whey soon. I am also trying to gain weight. I’m 147 right now. Trying to be 155 by mid-June. Any suggestions to add on to this. I did 5×5 training for almost 10 weeks a few months ago (got me to that heavy squat lol 😉 )