Development of a Dynamic Biomechanical Model for Load Carriage: Phase VI: Assessing Physiological and Biomechanical Loading Using the Portable Measurement System and the Dynamic Biomechanical Model

摘要

In this work, factors affecting the physiological cost of load carriage and models for the estimation of metabolic energy cost during load carriage were examined in detail. The dynamic biomechanical model (DBM), designed to analyse the effects of rucksack parameters on forces experienced by a pack wearer, was used to create a stand-alone interactive software tool. It was shown that tri-axial accelerations of the upper torso can be used in static and dynamic conditions to determine alterations in posture and gait, including: heel strike and toe off, forward lean angle, double support time and stride duration. These findings will permit assessment of gait in the field using the portable measurement system, allowing assessment of gait parameters over long durations, under varying terrain and loads. Terrain characteristics are also likely to be reflected in signal parameters other than the rms values examined in this work, permitting further improvement of the predictive models without requiring specific field data such as load, speed and topography. The ability to measure gait alterations using upper body accelerations merits further investigation as the present work was limited in this area. Models to predict metabolic cost during load carriage under conditions of variable speed, load and incline were developed. A model similar to Pandolf's (Pandolf et al. 1977), using field specific data: load, speed and incline, had the highest correlation coefficient (r2 = 0.823) but under-predicted energy cost both at low values and at high values of measured VO2. A second model using upper body acceleration alone showed reasonable predictive ability (r2 = 0.554) but under predicted VO2 at high energy cost levels. Review of the results showed that the energy effect of incline is not captured in the rms acceleration parameters used in the model. Heart rate is well cormoThe Dynamic Biomechanical Model.