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.; Looze, M.P. de; Dieën, Jaap H. van

doi:10.1016/j.jbiomech.2018.11.033

Cited by 146 publications

(157 citation statements)

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“…Additionally, differences can be due to lower absolute moments and absence of device hysteresis in static conditions. Indeed, in static bending with the same devices, larger relative effects were found (Koopman et al, 2019). In lifting, during peak compressive loading the movement is upward and therefore peak support of the exoskeletons is 10 Nm lower than expected (Figure 2).…”

Section: Discussionmentioning

confidence: 78%

“…Several exoskeletons, including the exoskeleton tested in the current study, have shown reductions of back muscle activity by 10% to 40% during static holding tasks Kobayashi and Nozaki, 2008;Koopman et al, 2019;Ulrey and Fathallah, 2013a, b). However, in dynamic lifting, peak L5S1 moments are much higher, and can reach for instance 250 Nm when lifting a 15 kg box (Kingma et al, 2001), compared to about 120 Nm in static forward bending without a load (Koopman et al, 2019). If the support level of the exoskeleton cannot be adapted to the high demand in lifting, the relative support provided by an exoskeleton will be much lower during lifting compared to static bending.…”

Section: Introductionmentioning

confidence: 72%

“…A global equation of motion (rather than a segment by segment calculation) was used, as described by (Hof, 1992). Using the method described in Koopman et al (2019), the exoskeleton flexion-extension moment around L5S1 (ML5S1_Laevo) was calculated using a cross product of the 3D moment arm and the 3D chest pad force, predicted based on the Laevo angle, and subtracted from ML5S1_total to calculate the flexion-extension L5S1 moment generated by the subject (ML5S1_subject). Off-line, EMG signals were full-wave rectified and lowpass filtered at 2.5 Hz (Potvin et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, especially if kinematics change with using an exoskeleton, a reduction in back muscle electromyography (EMG) (Alemi et al, 2019;Bosch et al, 2016;Kobayashi and Nozaki, 2008;Ulrey and Fathallah, 2013a, b) does not necessarily imply a reduction in spine loading. In addition, application of supportive extension torques with flexion-relaxation being present may be counterproductive, because, if the sum of the passive moment and the moment provided by the exoskeleton exceeds the net joint moment, the participant will need to activate abdominal muscles to maintain or reach the same posture (Koopman et al, 2019). So, it remains to be seen how effective passive exoskeletons will be in reducing peak L5S1 compression force in dynamical lifting.…”

Section: Introductionmentioning

confidence: 99%

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Effects of a passive back exoskeleton on the mechanical loading of the low-back during symmetric lifting

Koopman

Kingma

Looze

et al. 2020

Journal of Biomechanics

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Low-back pain is the number one cause of disability in the world, with mechanical loading as one of the major risk factors. Exoskeletons have been introduced in the workplace to reduce low back loading. During static forward bending, exoskeletons have been shown to reduce back muscle activity by 10% to 40%. However, effects during dynamic lifting are not well documented. Relative support of the exoskeleton might be smaller in lifting compared to static bending due to higher peak loads. In addition, exoskeletons might also result in changes in lifting behavior, which in turn could affect low back loading.The present study investigated the effect of a passive exoskeleton on peak compression forces, moments, muscle activity and kinematics during symmetric lifting. Two types (LOW and HIGH) of the device, which generate peak support moments at large and moderate flexion angles, respectively, were tested during lifts from knee and ankle height from a near and far horizontal position, with a load of 10 kg.Both types of the trunk exoskeleton tested here reduced the peak L5S1 compression force by around 5-10% for lifts from the FAR position from both KNEE and ANKLE height. Subjects did adjust their lifting style when wearing the device with a 17% reduced peak trunk angular velocity and 5 degrees increased lumbar flexion, especially during ANKLE height lifts.In conclusion, the exoskeleton had a minor and varying effect on the peak L5S1 compression force with only significant differences in the FAR lifts.3

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Section: Discussionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of a passive back exoskeleton on the mechanical loading of the low-back during symmetric lifting

Koopman

Kingma

Looze

et al. 2020

Journal of Biomechanics

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“…Several studies tried to extract the relationship between torques and angles of the hip [23, 24] or other lower body joints [64, 65] by assuming linear slop as quasi-stiffness between moments and angles. These researches are useful to design passive exoskeleton or prosthesis [66, 67]. However, active exoskeletons or prosthesis are capable to use a more advanced approach to generate required torques [68, 69].…”

Section: Discussionmentioning

confidence: 99%

A simple CPG-based model to generate human hip moment pattern in walking by generating stiffness and equilibrium point trajectories

Bahramian

Towhidkhah

Jafari

2019

Preprint

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Equilibrium point hypothesis (its developed version named as referent control theory)presents a theory about how the central nerves system (CNS) generates human movements. On the other hand, it has been shown that nerves circuits known as central pattern generators (CPG) likely produce motor commands to the muscles in rhythmic motions. In the present study, we designed a bio-inspired walking model, by coupling double pendulum to CPGs that produces equilibrium and stiffness trajectories as reciprocal and co-activation commands. As a basic model, it is has been shown that this model can regenerate pattern of a hip moment in the swing phase by high correlation ሺ ߩ ൌ 0 . 9 7 0 ሻ with experimental data. Moreover, it has been reported that a global electromyography (EMG) minima occurs in the mid-swing phase when the hip is more flexed in comparison with the other leg. Our model showed that equilibrium and actual hip angle trajectories match each other in mid-swing, similar to the mentioned posture, that is consistent with previous findings. Such a model can be used in active exoskeletons and prosthesis to make proper active stiffness and torque.controls the body?" [3, 4]. These theories explain how the CNS can release from complex calculations to control movements. According to EPH, at the muscle level, the CNS only determines a specific threshold (ߣ) for muscle [5, 6]. If actual muscle length goes beyond the defined threshold, EMG activity emerges as a result of the gap between actual and threshold muscle lengths. To control the joint, two commands are defined by the CNS: reciprocal (R) command and co-activation (C) command [7]. If joint is considered as rotational spring, R and C commands determine equilibrium point and stiffness of the joint, respectively. In accordance with the referent control theory, for multi-joint system (e.g. leg), it is assumed that initially, global R and C commands are set by CNS, then, by few-to-many mappings, r and c commands for various joints are defined. Finally, ߣ s for agonist and antagonist muscles emerged from these r and c by another mapping [8]. This hierarchical system is effective for making coordination between different joints and muscles [9]. One of the powerful experimental evidence for this hierarchical referent system is the global EMG minima [10]. When the referent (R) and actual configurations approach meet each other, a minimum EMG activity occurs for most of the muscles involved in the task [10]. This phenomena has been confirmed by many studies on various tasks such as walking and jumping [10], monkeys head movement [11], Jete in ballet dancers [12], and hammering [13]. It is shown that during stepping forward, a global EMG minima occurred during mid-swing when the hip flexion of the swing leg is slightly more than the other leg [14].On the other hand, the behavior of the joints as a rotational spring have commonly been used for investigating the relationship between torque(s) and angle(s). These studies are applicable to design anthropomorphic biped robots [15][16][...

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Potential exoskeleton uses for reducing low back muscular activity during farm tasks

Thamsuwan

Milosavljevic

Srinivasan

et al. 2020

American J Industrial Med

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Background: As the sustainability of the agricultural workforce has been threatened by the high prevalence of back pain, developing effective interventions to reduce its burden within farming will contribute to the long-term health and productivity of workers. Passive back-support exoskeletons are being explored as an intervention to reduce the physical demands on the back muscles, and consequently mitigate the risk of back pain, in many industrial sectors. Methods: This study investigated whether exoskeleton use could reduce farmers' low back muscle load. Electromyography was used to evaluate exoskeleton use in field and laboratory settings. A total of 14 farmers (13 males and 1 female) with a mean age of 49 (SD = 12) years and 6 female nonfarmers (mean age 28, SD = 5 years) performed a standardized set of tasks that included symmetric and asymmetric lifting and sustained trunk flexion. Following the standardized tasks, 14 farmers also performed regular, real-world, farm tasks with and without use of the exoskeleton at their farms. Results: Exoskeleton use decreased back muscular load during farming activities up to 65%, 56%, and 48% in static, median, and peak muscle activity, respectively. This indicates potential benefits of exoskeleton use to help farmers work under less muscular load. Paradoxically, exoskeleton use during standardized tasks increased muscle activity for some participants. Conclusions: This study demonstrates the potential effects of using passive exoskeletons in agriculture through observational and experimental research, and is among the first that explores the potential for using exoskeletons during actual work tasks in farm settings. K E Y W O R D S agriculture, back, electromyography, exoskeleton 1 | INTRODUCTION Globally, musculoskeletal disorders (MSDs) are one of the leading causes of disability. In 2017 the 1-year prevalence of MSDs was 17% worldwide and 22% in Canada, and the 1-year prevalence of back pain was 7.5% worldwide and 13% in Canada. 1 MSDs are more prevalent in farmers than nonfarmers in the rural workforce, with the low back being the most commonly affected body region. 2 Previous research on US farmers involved in highly mechanized prairie agriculture demonstrated twice the risk of back pain compared to

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Effects of a passive exoskeleton on the mechanical loading of the low back in static holding tasks

Cited by 146 publications

References 30 publications

Effects of a passive back exoskeleton on the mechanical loading of the low-back during symmetric lifting

Effects of a passive back exoskeleton on the mechanical loading of the low-back during symmetric lifting

A simple CPG-based model to generate human hip moment pattern in walking by generating stiffness and equilibrium point trajectories

Potential exoskeleton uses for reducing low back muscular activity during farm tasks

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