Abstract
Determination of muscle energy expenditure by computer modeling and analysis is of great interest to estimate the whole body energy consumption, while avoiding the complex character of in vivo experimental measurements for some subjects or activities. In previous papers, the authors presented optimization methods for estimating muscle forces in spinal-cord-injured (SCI) subjects performing crutch-assisted gait. Starting from those results, this work addresses the estimation of the whole body energy consumption of a SCI subject during crutch-assisted gait using the models of human muscle energy expenditure proposed by Umberger and Bhargava. First, the two methods were applied to the gait of a healthy subject, and experimentally validated by means of a portable gas analyzer in several 5-min tests. Then, both methods were used for a SCI subject during crutch-assisted gait wearing either a passive or an active knee-ankle foot orthosis (KAFO), in order to compare the energetic efficiency of both gait-assistive devices. Improved gait pattern and reduced energy consumption were the results of using the actuated gait device. Computer modeling and analysis can provide valuable indicators, as energy consumption, to assess the impact of assistive devices in patients without the need for long and uncomfortable experimental tests.
Highlights
In the last decade, many mechanical and, more recently, electromechanical devices have been developed to allow spinal-cord-injured (SCI) patients to stand and walk (White et al, 2014; Cuadrado et al, 2019)
The objective of this work is to estimate the energetic cost of the crutch-orthosis-assisted gait of a SCI subject so that comparison from the energetic point of view may be established between two assistive devices: a passive and an active knee-ankle foot orthosis (KAFO)
As there is no clear relationship between EMG amplitude and muscle force (Hof, 1997), the comparison was focused on the shape of the activity patterns, using normalized values
Summary
Many mechanical and, more recently, electromechanical (or hybrid) devices have been developed to allow spinal-cord-injured (SCI) patients to stand and walk (White et al, 2014; Cuadrado et al, 2019). The additional use of crutches is generally required for gait stability. Despite these technological advances, most SCI subjects prefer the wheelchair to move for energetic efficiency reasons (Merati et al, 2000). Use of a cane or a pair of crutches requires about 33% more energy than normal walking (Mcbeath et al, 1974). Some devices (KAFO), don’t allow some joints to move, which implies another gait pattern even less efficient. Since structures of the upper extremities are designed primarily for prehensile activities, not to walk, many patients suffer from shoulder and arm injuries (Lee and McMahon, 2002)
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