Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Kinesiology and Health Science

Committee Chair(s)

Eadric Bressel


Eadric Bressel


Timothy A. Slocum


Dennis Dolny


Guifang Fu


Brennan Thompson


Breanna Studenka


Three neuromuscular characteristics are identified in Sheppard and Young’s model of agility: concentric strength and power, bilateral symmetry, and reactive strength. Measures of reactive strength attempt to model the neuromuscular regulation of tissue stress and strain. The Coefficient of Reactivity (CoR) is the first known assessment of neuromuscular reactivity. The CoR was developed as an assessment of neuromuscular performance in drop jumping. The construct validity of the CoR was placed in question when Warren Young proposed the Reactive Strength Index (RSI). The RSI improved the theoretical validity of reactive strength assessment since it included a component measure (ground contact time) that modelled the interaction of the feet and ground during impact.

There are theoretical issues with the computation and implementation of the CoR and RSI. For example, the CoR and RSI are nonstrength based measures that attempt to measure a strength construct. Further, the CoR and RSI make the theoretical assumption that no biological variability exists in human movement. In the present study, we develop a kinetic (strength)-based paradigm of reactive strength (New and AdjNew) and evaluate it against the CoR and RSI.

Results suggest the AdjNew and RSI attempt to model the same construct. The AdjNew paradigm addresses and solves the theoretical issues with the CoR, RSI, and New. Therefore it may be argued that the AdjNew paradigm improves the theoretical validity of reactive strength assessment and is preferred over the RSI.

In this document we discuss how wearable technologies may be used to carry out our AdjNew paradigm. It is possible that pairing the AdjNew paradigm with wearable sensors will allow for the assessment of reactive strength through the whole-body center of gravity and through limb segment centers of gravity. Looking forward, awearable sensor approach to reactive strength assessment could expand the assessement of neuromuscular reactivity in both sport and clinical populations.