Insertion of the force applied to handles into centre of pressure calculation modifies the amplitude of centre of pressure shifts

This study examined situations where handles were used as additional postural supports. It aimed at determining the amplitude of centre of pressure (COP) shifts when considering or not the vertical handles reaction force. Eight healthy male subjects (24 ± 6 years, body mass 65 ± 5 kg and height 175 ± 7 cm) voluntarily took part in the experiment. Subjects had to voluntarily rock on their heels or rise on their toe-tips while using handles. The vertical component of the handles forces and ground reaction force was measured and the shifts of the COP were calculated while inserting or not the handles forces. Significant differences were observed when comparing the amplitude of COP shifts calculated with or without the insertion of the handles forces. This study shows that the measurement of the handles forces should not be omitted, for a rigorous analysis of postural tasks performed in conditions including additional postural supports like handles.