Developing a Criterion Method for Assessing Countermovement Jump Variables in Children Aged 7 to 11 Years

Measuring countermovement jump (CMJ) variables such as instantaneous peak mechanical power output (PPO) in children has been shown to be associated with a wide variety of factors such as measuring bone health and identifying children at risk of motor disorders. Yet, how PPO and other variables are attained lack validity as no criterion method or methods of estimating CMJ variables have been developed for children (aged 7 to 11 years). Therefore, the aim of this thesis was to develop a criterion method for assessing PPO in children. This thesis also sought to develop prediction equations for estimating PPO. Experimental Chapter 1 found absolute differences in unprocessed CMJ variables between elite adults and children highlighting that a new criterion method was needed for children. Experimental Chapter 2 established that CMJ variables that do not account for body size need to represent children by 2 groups, whereas, if body size is accounted then children can be represented as one homogenous group. The findings of this chapter demonstrated that that more than one criterion method was needed to be developed for children. Experimental Chapter 3 developed two criterion methods for assessing PPO from a CMJ for children, reporting a less stringent specification for the children criterion methods when compared to the elite adult criterion method specifications. Having achieved the first part of the thesis aim Experimental Chapter 4 developed a number of regression equations to estimate PPO in children to enable practitioners who do not have access to force platforms to have a means of estimating PPO by easily measured variables in the field such as body mass and flight height. In conclusion, this thesis has made significant steps in providing a standardised method of measuring or estimating PPO and other CMJ variables in children aged 7 to 11 years for future researchers