[1] Kings Coll London, Fac Life Sci & Med, Div Hlth & Social Care Res, London SE1 1UL, England
[2] Kings Coll London, Fac Life Sci & Med, Ctr Human & Appl Physiol Sci, London SE1 1UL, England
[3] Univ Basque Country, UPV EHU, Fac Med & Nursing, Dept Physiol, Leioa 48940, Spain
[4] Atlas Fisioterapia, Donostia San Sebastian 20008, Spain
[5] Univ Basque Country, UPV EHU, Dept Prevent Med & Publ Hlth, Leioa 48940, Spain
[6] Biodonostia, Hlth Res Inst, San Sebastian, Spain
[7] Spanish Consortium Res Epidemiol & Publ Hlth CIBE, Barcelona, Spain