Abstract
With mechanical loading as the main risk factor for LBP in mind, exoskeletons are designed to reduce the load on the back by taking over a part of the required moment. The present study assessed the effect of a passive exoskeleton on back and abdominal muscle activation, hip and lumbar flexion and on the contribution of both the human and the exoskeleton to the L5/S1 net moment, during static bending at five different hand heights. Two configurations of the exoskeleton (LOW & HIGH) differing in angle-torque characteristics were tested. L5/S1 moments generated by the subjects were significantly reduced (15–20% for the most effective type) at all hand heights. LOW generated 4–11 Nm more support than HIGH at 50%, 25% and 0% upright stance hand height and HIGH generated 4–5 Nm more support than LOW at 100% and 75%. Significant reductions (11–57%) in back muscle activity were found compared to WITHOUT for both exoskeletons for some conditions. However, EMG reductions compared to WITHOUT were highly variable across subjects and not always significant. The device allowed for substantial lumbar bending (up to 70°) so that a number of participants showed the flexion-relaxation phenomenon, which prevented further reduction of back EMG by the device and even an increase from 2% to 6% MVC in abdominal activity at 25% hand height. These results indicate that flexion relaxation and its interindividual variation should be considered in future exoskeleton developments.
| Language | English |
|---|---|
| Pages | 97-103 |
| Number of pages | 7 |
| Journal | Journal of Biomechanics |
| Volume | 83 |
| Issue number | January |
| DOIs | |
| Publication status | Published - 23 Jan 2019 |
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Keywords
- Low-back pain
- Mechanical loading
- Passive exoskeletons
- Static holding
Cite this
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Effects of a passive exoskeleton on the mechanical loading of the low back in static holding tasks. / Koopman, Axel S.; Kingma, Idsart; Faber, Gert S.; de Looze, Michiel P.; van Dieën, Jaap H.
In: Journal of Biomechanics, Vol. 83, No. January, 23.01.2019, p. 97-103.Research output: Contribution to Journal › Article › Academic › peer-review
TY - JOUR
T1 - Effects of a passive exoskeleton on the mechanical loading of the low back in static holding tasks
AU - Koopman, Axel S.
AU - Kingma, Idsart
AU - Faber, Gert S.
AU - de Looze, Michiel P.
AU - van Dieën, Jaap H.
PY - 2019/1/23
Y1 - 2019/1/23
N2 - With mechanical loading as the main risk factor for LBP in mind, exoskeletons are designed to reduce the load on the back by taking over a part of the required moment. The present study assessed the effect of a passive exoskeleton on back and abdominal muscle activation, hip and lumbar flexion and on the contribution of both the human and the exoskeleton to the L5/S1 net moment, during static bending at five different hand heights. Two configurations of the exoskeleton (LOW & HIGH) differing in angle-torque characteristics were tested. L5/S1 moments generated by the subjects were significantly reduced (15–20% for the most effective type) at all hand heights. LOW generated 4–11 Nm more support than HIGH at 50%, 25% and 0% upright stance hand height and HIGH generated 4–5 Nm more support than LOW at 100% and 75%. Significant reductions (11–57%) in back muscle activity were found compared to WITHOUT for both exoskeletons for some conditions. However, EMG reductions compared to WITHOUT were highly variable across subjects and not always significant. The device allowed for substantial lumbar bending (up to 70°) so that a number of participants showed the flexion-relaxation phenomenon, which prevented further reduction of back EMG by the device and even an increase from 2% to 6% MVC in abdominal activity at 25% hand height. These results indicate that flexion relaxation and its interindividual variation should be considered in future exoskeleton developments.
AB - With mechanical loading as the main risk factor for LBP in mind, exoskeletons are designed to reduce the load on the back by taking over a part of the required moment. The present study assessed the effect of a passive exoskeleton on back and abdominal muscle activation, hip and lumbar flexion and on the contribution of both the human and the exoskeleton to the L5/S1 net moment, during static bending at five different hand heights. Two configurations of the exoskeleton (LOW & HIGH) differing in angle-torque characteristics were tested. L5/S1 moments generated by the subjects were significantly reduced (15–20% for the most effective type) at all hand heights. LOW generated 4–11 Nm more support than HIGH at 50%, 25% and 0% upright stance hand height and HIGH generated 4–5 Nm more support than LOW at 100% and 75%. Significant reductions (11–57%) in back muscle activity were found compared to WITHOUT for both exoskeletons for some conditions. However, EMG reductions compared to WITHOUT were highly variable across subjects and not always significant. The device allowed for substantial lumbar bending (up to 70°) so that a number of participants showed the flexion-relaxation phenomenon, which prevented further reduction of back EMG by the device and even an increase from 2% to 6% MVC in abdominal activity at 25% hand height. These results indicate that flexion relaxation and its interindividual variation should be considered in future exoskeleton developments.
KW - Low-back pain
KW - Mechanical loading
KW - Passive exoskeletons
KW - Static holding
UR - http://www.scopus.com/inward/record.url?scp=85057504576&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85057504576&partnerID=8YFLogxK
U2 - 10.1016/j.jbiomech.2018.11.033
DO - 10.1016/j.jbiomech.2018.11.033
M3 - Article
VL - 83
SP - 97
EP - 103
JO - Journal of Biomechanics
T2 - Journal of Biomechanics
JF - Journal of Biomechanics
SN - 0021-9290
IS - January
ER -