Are beet juice and arugula cheating me?

Hey all,

I eat arugula daily and when I have a hard workout on the trainer, I will down the beet juice about an hour before the workout. Both make a noticeable difference by making the hard workouts easier to deal with. Lower heart rate, easier breathing, more comfortable in general while I slog through SS stuff on the trainer. My question is, should I be doing this? Am I cheating myself out of gains? Like I said, I eat arugula just about every day with my lunch salad…lots of it. As for beet juice, I only use that when the workout appears to be extra effort. The beet thing is like once or twice a month.

Thanks in advance!