Heart rate variability (HRV) measures have been found to consistently predict macro- and micro-level sport-specific outcomes, including performance during critical moments as well as reflecting differential states of attention, intensity, and mental control, especially when an athlete is under competitive pressure. This chapter explores and explicates HRV in the context of pre-intervention assessment of athlete mind-body-motor and outcome responses and attempts to arrive at an athlete’s individual zone of optimum functioning (IZOF), as well as criterion reference athlete’s profile primary higher-order (AP PHO) constellations with autonomic nervous system (ANS)/psychophysiological measures in both training and real competition. The polar system allows for real-time wireless and telemetry HRV data acquisition and analyses opening up the possibility of isolating specific inter-beat intervals during action. Such a capability facilitates micro-analyses of HRV and heart rate deceleration (HRD) on an unprecedented level, since investigations of HRV/HRD can be carried out during high-intensity training and competition.