Abstract
The study investigated psychometric properties of the Polish version of the Mindfulness Inventory for Sport (MIS-PL). Following an expert review (stage 1), a sample of 333 athletes voluntarily participated in the study to verify the internal structure of the questionnaire (stage 2). In a final step (stage 3), confirmatory factor analysis and correlation analysis of the MIS-PL subscales with other variables were conducted to demonstrate the stability and reproducibility of the factor structure of the scale and to determine the theoretical validity of the measure. The factor analyses performed confirmed the three-factor structure of the MIS-PL with the following dimensions: 1) awareness, 2) non-judgmental attitude, and 3) refocusing, characterized by acceptable fit indices. Analyses of the correlations between the MIS-PL subscales and conceptually related variables (mindfulness in daily life, worry, concentration disruption, mental toughness, and flow) also proved statistically significant. In summary, the MIS-PL is a valid measure for assessing mindfulness in sport.