Isokinetic assessment and interpretation in paediatric populations: Why do we know relatively little?

Our understanding of the age and sex associated development in dynamic strength is based on a relatively small evidence base. This may be due in part to the proposed ethical difficulties in assessing paediatric populations combined with the expense associated with longitudinal studies. Despite this isokinetic testing of children has doubled in the last 5 years and has started to include data on clinical populations. A number of studies have demonstrated that isokinetic testing in children can be reliable given appropriate adaptations to equipment as well as the application of paediatric specific procedures, especially the inclusion of extensive habituation and familiarisation sessions. Data on the age and sex associated differences in dynamic strength are relatively consistent, indicating little sex differences up until the age of about 13/14 years. However changes in dynamic strength with age and maturation appear to be both muscle group and muscle action specific. Where comparisons of children of differing chronological or biological age are to be made appropriate allometric scaling techniques need to be employed to control for differences in body size. Studies on dynamic strength in children should begin to move away from descriptive studies and start to explore the mechanisms associated with the changes in strength, as well as applying findings to practical situations (for example injury prevention). More studies are needed on clinical populations to help to define decrements in dynamic strength and to help in applying appropriate strengthening programmes to enhance quality of life.