Protocol for the omnidirectional assessment of manual strength

This study presents a protocol for assessment of manual strength over all directions in three dimensions. The reliability and validity of the protocol was tested on four male subjects. They performed one-handed maximal exertions overthe entire sphere of exertion at hand heights of 1.0 and 1.75 m and at a horizontal foot distance of 0.5 m from the centre of force application. Testing sessions consisted of five 2 min data collection periods interspersed with rest pauses of the subject's own chosen duration. At least four testing sessions performed on separate days were required for a subject to fulfil the criteria for completion of the sphere of exertion. The results showed the methodology to be reliable. Repeat trials at the 1.0 m hand height revealed a high reliability coefficient for the three-dimensional forces (r = 0.96). The protocol was also suitable for assessment of three-dimensional manual strength at the higher hand height of 1.75 m. The distinctive patterns of forces over the sphere of exertion observed at the 1.0 and 1.75 m heights illustrated the importance of hand height on manual strength in three dimensions. The methodology presented in this paper provides a good basis on which to develop future clinical or scientific studies investigating human strength capabilities over all directions.