1 Inclusive and Special Needs Education Unit, Faculty of Behavioural and Social Sciences, University of Groningen, Groningen, the Netherlands. Electronic address: s.houwen@rug.nl.
2 Department of Health & Rehabilitation Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa. Electronic address: bouwiensmits@hotmail.com.
3 LIKES Research Centre for Physical Activity and Health, Jyväskylä, Finland. Electronic address: Piritta.Asunta@likes.fi.
4 Faculty of Education and Psychology, University of Jyväskylä, Jyväskylä, Finland. Electronic address: helena.j.k.viholainen@jyu.fi.
5 Centre for Human Movement Sciences, University of Groningen, University Medical Centre Groningen, Groningen, the Netherlands. Electronic address: m.m.schoemaker@umcg.nl.