1. LL Andersen, MSc, is a PhD student at the National Research Centre for the Working Environment, Lersø Parkalle 105, DK 2100 Copenhagen, Denmark.
2. M Kjær, DrMedSci, is Professor, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark.
3. CH Andersen, MSc, is Research Assistant, National Research Centre for the Working Environment.
4. PB Hansen, MSc, is Research Assistant, National Research Centre for the Working Environment.
5. MK Zebis, PhD, is Post-Doctoral Fellow, National Research Centre for the Working Environment.
6. K Hansen, BSc (Physiotherapy), is Physiotherapist, National Research Centre for the Working Environment.
7. G Sjøgaard, DrMedSci, is Professor and Head of Research Unit, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.