The answer to this isn’t clear cut, it’s given as a range because peoples response to it is subjective i.e. some people are highly responsive whilst some notice little effect at all increasing their risk of overdosing. L- Arginine is an effective vasodilator, in other words it increases the width of your blood vessels enhancing the delivery of oxygen and nutrients to your muscles.
Llewellyn, (2009) suggests an effective dose might be in the region of 3-9g per day. It is advised that people limit the use up to 8-12 weeks followed by approx 8-12 weeks off. Excessive use might increase strain on the cardiovascular system as well as increase the enzyme arginase, which ultimately reduces the bodies nitric oxide production and efficacy of the supplement.