Non-stimulant energy boosters, consumed before exercise, can significantly increase your performance without overtaxing your heart.
Their main active ingredients are the blood-boosters L-citrulline, L-arginine and L-ornithine. These are amino acids that stimulate the production of nitric oxide (NO), which, with the right levels of calcium, increases vasodilation, increases blood flow and the amount of nutrients carried by the bloodstream, and also reduces blood pressure due to the increased diameter of the vessel wall. This means that more nutrients will be available to the muscles.
In training, the effects of NO enhancers will be reflected in a feeling of drowsiness and increased power output, with the effects being most pronounced in higher repetition ranges (above 8). But there have been studies which have found that it can also increase explosive power and 1 repetition max. In addition, endurance athletes (runners, swimmers, cyclists, etc.) may also benefit from its performance-enhancing effects.
It often also contains added L-taurine, which enhances brain function and concentration.
The added L-tyrosine enhances concentration in stressful situations such as training or competition.
These types of energy boosters have a slower onset of action, they don't hit as hard, but they don't leave you feeling lethargic after 1.5 to 2 hours of exercise.
As it contains no added caffeine and even has antihypertensive effects, it can be consumed by people with high blood pressure or caffeine sensitivity, but if you have a medical condition, consult a doctor before using any supplement.