Introduction- Due to the importance of physical activity in frailty prevention among the elderly, it is important to assess their motives for physical activity. In the elderly population, reading difficulties must be added to those negative feelings also experimented in general population, as fatigue, boredom or frustration in data collection. Using single-item measures could overcome those difficulties and increase feasibility when multidimensional constructs are assessed, which is the case of Self-determination theory of motivation. This theory establishes that coaches’ interpersonal style can impact on basic psychological needs satisfaction, which can predict motives for physical activity which in turn can anticipate feelings of vitality and engagement in an activity. Objectives- The aim of this study is to gather validity evidence for the single-item measures, developed in early stages of this study, based on an empirical test of the expected nomological network. Design/Methodology- Seventy elderly adults who attended to physical activity programs participated in this study. It was heteroadministered the full-form of Coaches’ interpersonal style questionnaire, the Basic psychological needs satisfaction scale, the Behavioral regulation exercise questionnaire, the Subjective vitality scale and three engagement items. Short-form was self-reported. We performed a correlation network analysis for each questionnaire form with qgraph package of R software using polychoric correlations due to ceiling and floor effects. Results- Both network analyses reproduce a similar correlation pattern showing differences in the strength of the relationship between variables. Due to the small sample size, some items of the long form were deleted due to non-variance, indicating low discrimination of those items. Conclusions- More validity evidences should be provided for the assessment of motives for physical activity in the elderly with short and long measures. Decision-making consequences related to feasibility and psychometric properties are discussed