[Instrument for the assessment of middle-aged and older adults' physical activity: design, eliability and application of the German-PAQ-50+].

Existing physical activity questionnaires have focused either on young and middle-aged adults or on the elderly. They have mainly assessed only a portion of possible physical activities or contained nation-specific sports. As there is no gold standard for a questionnaire-based assessment of physical activity in the over-50 population, recommendations for such a questionnaire relating to German-speaking countries were developed. This work included a systematic literature research, a survey of experts, and the design of a questionnaire based on validated measuring instruments. Finally, to test its reliability and application in the field, the complete questionnaire, including a retest, was applied by telephone interview (n = 57). The test-retest-correlation was r = 0.60 for the total time of physical activity and r = 0.52 for total energy expenditure. The researchers determined that the instrument is comprehensive in its coverage of all relevant domains of physical activity for the over-50 population; it is economically feasible and showed good acceptance.