Bycura, DK, Dmitrieva, NO, Santos, AC, Waugh, KL, and Ritchey, KM. Efficacy of a Goal Setting and Implementation Planning Intervention on Firefighters' Cardiorespiratory Fitness. J Strength Cond Res 33(11): 3151-3161, 2019-The purpose of this study was to assess the effectiveness of a goal setting and implementation planning (GSIP) intervention on cardiorespiratory fitness among firefighters. Male career firefighters (N = 20) from a large municipal fire department were assigned to an intervention arm (n = 12) or passive control arm (n = 8) of a 14-week study involving cardiorespiratory exercise. The intervention consisted of GSIP coaching at baseline and support throughout the study. Cardiorespiratory fitness was assessed through a standardized physical protocol for firefighters (Candidate Physical Ability Test) at baseline, at 6 weeks, and at 14 weeks time points, using the Cosmed K4b portable metabolic system to measure physiological variables. Using intention-to-treat principles, we employed a 2-level multilevel model to examine the effect of intervention group on intercept and change over time on primary outcomes of interest: oxygen transport and utilization (VO2), heart rate (HR), and respiratory exchange ratio (R). Results demonstrated that the intervention and control groups both exhibited a significant increase in VO2 (B = 0.143, SE = 0.025, p < 0.001) and a decline in R (B = -0.003. SE = 0.001, p < 0.01) over the course of the study. Although both groups exhibited improvements on 2 of the 3 cardiorespiratory outcomes, subjects assigned to the intervention did not exhibit superior outcomes when compared to the control group. Given the improvements we observed in 2 out of 3 outcomes across both conditions, future research may consider testing effectiveness of interventions consisting of functional training exercises that closely translate to firefighting tasks over time periods sufficient to elicit aerobic metabolic adaptations.