This brief review addresses current hypotheses concerning the reflex control of circulation during exercise in humans. In particular, the specific objective of this review is to describe how time and frequency domain analysis of blood pressure and heart rate variability signals permitted to gain new insights onto reflex mechanisms of cardiovascular regulation during exercise, without the need of perturbing the cardiovascular system from the outside, utilizing fully noninvasive approaches and avoiding artificially isolating the influence of the different neural pathways involved in the control of the cardiovascular system. Throughout the article, particular emphasis is given to the complexity and plasticity of the neural control of the circulation during exercise, by presenting data that show how the reflex mechanisms involved in cardiovascular regulation, namely, the arterial baroreflex and the muscle metaboreflex, may be differently modulated in relation to the muscular activity being performed, such as the type of exercise, the intensity of exercise and the size of active muscle masses.