“…In relation to the thirty-two cross-sectional studies (26,27,29,(31)(32)(33)(34)(35)(36)(37)(38)(41)(42)(43)(44)(45)(46)(48)(49)(50)(51)(52)55,56,58,(61)(62)(63)(64)(65)(66)(67) , only nine (26,32,33,35,37,44,49,55,58,63,67) were classified as having low risk of bias. The main methodological problems were the evaluation of the UPF without valid and reliable measures (26,29,31,34,36,37,41,44,…”