Validity of instruments to measure physical activity may be questionable due to a lack of conceptual frameworks: a systematic review
Citation
Gimeno-Santos E, Frei A, Dobbels F, Rüdell K, Puhan MA, Garcia-Aymerich J. Validity of instruments to measure physical activity may be questionable due to a lack of conceptual frameworks: a systematic review. Health and Quality of Life Outcomes. 2011;9:86. DOI: 10.1186/1477-7525-9-86







