Clinical movement screens have become increasingly popular in strength and conditioning programs designed for the tactical athlete. Whereas conventionally administered movement screens are largely not sensitive to behaviors which impact soldierrelevant physical performance, recent evidence suggests that modified screens which incorporate external load-bearing strengthen the relationship between movement behaviors and performance outcomes. It remains unclear, however, which mechanisms may account for this improvement in association. Physical performance is considered a multidimensional construct influenced by several independent factors. Among the factors which influence military physical performance, movement screens may require high levels of strength, balance, and range of motion. This project used penalized interaction models to determine the role of strength, balance, and range of motion in modifying the effects of external load bearing on movement quality and movement. Additional confirmatory analyses examined differences in the abilities of FMS item scores to predict physical performance outcomes when those scores were obtained during control vs. external load-bearing conditions. Results suggest that the effect of load on movement complexity is modified by strength, balance, and range of motion whereas the effect on clinically rated movement quality is modified by only balance and range of motion. While the direction of the observed effects did not always coincide with our hypotheses, the present findings mirror those of previous research with respect to differential validity of weighted vs. control FMS item scores in predicting criterion performance measures.