Mental imagery (MI) or visualization can be considered the go-to mental training (MT) method and is used by the vast majority of sport psychology practitioners. MI is addressed in the context of the Theory of Critical Moments and athlete’s profile (AP) models of peak performance construct bases and the brain-heart-mind-body-motor dynamics they advance in regard to intervention efficiency and efficacy. Athlete is tested for Visualization Responsivity (VR) using the Carlstedt Protocol Visualization Responsivity Test-Athlete Version (CPVR-A). This chapter provides some consecutive autonomic nervous system (ANS)-heart rate variability (HRV) reports that emanate from a professional tennis player who was high in hypnotic susceptibility (HS)/subliminal attention (SA), namely the baseline condition, positive-negative and relaxation visualization scenario-based HRV responses. It presents an MI intervention efficacy case study in the context of actual competition using a repeated A-B-A design. Variance explained in a visualization-based or associated outcome measure should be the intervention efficacy benchmark.

This chapter presents interventions and mental training (MT) modalities in order of the hypothesized probability that engaging in a select method will lead to a successful outcome per Carlstedt Protocol (CP) efficacy criteria. There are numerous intervention and MT modalities to choose from, both as a practitioner and an athlete. The American Board of Sport Psychology-Carlstedt Protocol (ABSP-CP) approach to intervention and MT is based on the athlete’s profile (AP) model of individual differences that has isolated key primary higher-order (PHO) factors that are intimately related to critical components of performance: attention, physiological reactivity, and strategic planning/coping, all of which play a mediating role in the intervention and MT process. The chapter addresses interventions in the context of ABSP-CP perspectives, procedures, and methodologies, and, particularly, how a specific MT technique can be applied/used to facilitate in-the-moment peak performance as reflected in heart rate deceleration (HRD).