Multi-segment trunk kinematics during a loaded lifting task for elderly and young subjects

Acute effects of game-based biofeedback training on trunk motion in chronic low back pain: a randomized cross-over pilot trial

BACKGROUND

Improving movement control might be a promising treatment goal during chronic non-specific low back pain (CLBP) rehabilitation. The objective of the study is to evaluate the effect of a single bout of game-based real-time feedback intervention on trunk movement in patients with CLBP.

METHODS

Thirteen CLBP patients (8female;41 ± 16 years;173 ± 10 cm;78 ± 22 kg) were included in this randomized cross-over pilot trial. During one laboratory session (2 h), participants performed three identical measurements on trunk movement all including: first, maximum angle of lateral flexion was assessed. Secondly, a target trunk lateral flexion (angle: 20°) was performed. Main outcome was maximum angle ([°]; MA). Secondary outcomes were deviation [°] from the target angle (angle reproduction; AR) and MA of the secondary movement planes (rotation; extension/flexion) during lateral flexion. The outcomes were assessed by an optical 3D-motion-capture-system (2-segment-trunk-model). The measurements were separated by 12-min of intervention and/or resting (randomly). The intervention involved a sensor-based trunk exergame (guiding an avatar through virtual worlds). After carryover effect-analysis, pre-to-post intervention data were pooled between the two sequences followed by analyses of variances (paired t-test).

RESULTS

No significant change from pre to post intervention for MA or AR for any segment occurred for the main movement plane, lateral flexion (p > .05). The upper trunk segment showed a significant decrease of the MA for trunk extension/flexion from pre to post intervention ((4.4° ± 4.4° (95% CI 7.06-1.75)/3.5° ± 1.29° (95% CI 6.22-0.80); p = 0.02, d = 0.20).

CONCLUSIONS

A single bout of game-based real-time feedback intervention lead to changes in the secondary movement planes indicating reduced evasive motion during trunk movement.

TRIAL REGISTRATION NO

DRKS00029765 (date of registration 27.07.2022). Retrospectively registered in the German Clinical Trial Register.

Exoskeleton Application to Military Manual Handling Tasks

OBJECTIVE

The aim of this review was to determine how exoskeletons could assist Australian Defence Force personnel with manual handling tasks.

BACKGROUND

Musculoskeletal injuries due to manual handling are physically damaging to personnel and financially costly to the Australian Defence Force. Exoskeletons may minimize injury risk by supporting, augmenting, and/or amplifying the user's physical abilities. Exoskeletons are therefore of interest in determining how they could support the unique needs of military manual handling personnel.

METHOD

Industrial and military exoskeleton studies from 1990 to 2019 were identified in the literature. This included 67 unique exoskeletons, for which Information about their current state of development was tabulated.

RESULTS

Exoskeleton support of manual handling tasks is largely through squat/deadlift (lower limb) systems (64%), with the proposed use case for these being load carrying (42%) and 78% of exoskeletons being active. Human-exoskeleton analysis was the most prevalent form of evaluation (68%) with reported reductions in back muscle activation of 15%-54%.

CONCLUSION

The high frequency of citations of exoskeletons targeting load carrying reflects the need for devices that can support manual handling workers. Exoskeleton evaluation procedures varied across studies making comparisons difficult. The unique considerations for military applications, such as heavy external loads and load asymmetry, suggest that a significant adaptation to current technology or customized military-specific devices would be required for the introduction of exoskeletons into a military setting.

APPLICATION

Exoskeletons in the literature and their potential to be adapted for application to military manual handling tasks are presented.

The influence of age on spinal and lower limb muscle activity during repetitive lifting

This study investigated the effects of age on upper erector spinae (UES), lower erector spinae (LES) and lower body (gluteus maximus; biceps femoris; and vastus lateralis) muscle activity during a repetitive lifting task. Twenty-four participants were assigned to two age groups: 'younger' (n = 12; mean age ± SD = 24.6 ± 3.6 yrs) and 'older' (n = 12; mean age = 46.5 ± 3.0 yrs). Participants lifted and lowered a box (13 kg) repetitively at a frequency of 10 lifts per minute for a maximum of 20 min. EMG signals were collected every minute and normalised to a maximum voluntary isometric contraction. A submaximal endurance test of UES and LES was used to assess fatigue. Older participants showed higher levels of UES and LES muscle activity (approximately 12-13%) throughout the task, but less fatigue compared to the younger group post-task completion. When lifting, lower-limb muscle activity was generally higher in older adults, although temporal changes were similar. While increased paraspinal muscle activity may increase the risk of back injury in older workers when repetitive lifting, younger workers may be more susceptible to fatigue-related effects. Education and training in manual materials handling should consider age-related differences when developing training programmes.

Grasping an object at floor-level: Is movement strategy a matter of age?

Bending down to pick things up off the floor is something that we do every day. This multisegment task can be done in a considerable number of postural configurations because of the large number of degrees of freedom to be controlled when executing it. In this study where volunteers performed a repetitive bending task, multisegment kinematic analysis allowed us to identify seven different bending strategies. Most operators used more than one bending strategy, but no particular strategy-type was found to be specific for a specific age group. However, the number of strategies used by an operator decreased with increasing age. It therefore appears that this factor influences the variability of the strategies used when repeatedly executing a movement involving the lower limbs to collect small objects from floor-level. This decrease in movement variability in senior operators may contribute to their increased risk of developing musculoskeletal disorders.

The Impact of Segmental Trunk Support on Posture and Reaching While Sitting in Healthy Adults

The authors investigated postural and arm control in seated reaches while providing trunk support at midribs and pelvic levels in adults. Kinematics and electromyography of the arm and ipsiliateral and contralateral paraspinal muscles were examined before and during reaching. Kinematics remained constant across conditions, but changes were observed in neuromuscular control. With midribs support, the ipsilateral cervical muscle showed either increased anticipatory activity or earlier compensatory muscle responses, suggesting its major role in head stabilization. The baseline activity of bilateral lumbar muscles was enhanced with midribs support, whereas with pelvic support, the activation frequency of paraspinal muscles increased during reaching. The results suggest that segmental trunk support in healthy adults modulates ipsilateral or contralateral paraspinal activity while overall kinematic outputs remain invariant.

Sagittal plane lumbar loading when navigating an obstacle and carrying a load

The current study quantified lumbar loading while carrying an anterior load mass and navigating an obstacle. Eight healthy male participants walked down a walkway and crossed an obstacle under three randomised LOAD conditions; empty-box (2 KG), five kilogram (5 KG) and ten kilogram (10 KG). Each walk was assessed at two events: left foot mid-stance (LMS) and right toe-crossing (TC) to characterise any changes from approach to crossing. Measures of interest included: trunk pitch, L4/L5 joint moment, compression, joint anterior-posterior shear and erector spinae activation. Findings demonstrate that obstacle crossing extended posture by 50, 41, 44%, respectively for each carried load magnitude. Further, these results indicate that shear rather than compressive loading may be an important consideration during crossing due to increase by 8, 9, 22% from LMS to TC for each load magnitude tested. These results provide insight into sagittal lumbar loading when navigating an obstacle while carrying a load. Practitioner Summary: The risk of carrying while navigating obstacles on the lumbar spine is not completely understood. The forces at the lumbar spine while simultaneously carrying and obstacle crossing were analysed. Data indicate that carrying and obstacle crossing influence lumbar shear loads, thereby moderately increasing the relative risk at lumbar spine.

Age-related differences do affect postural kinematics and joint kinetics during repetitive lifting

BACKGROUND

Age is considered a risk factor for manual handling-related injuries and older workers incur higher injury-related costs than younger co-workers. This study investigated the differences between the kinematics and kinetics of repetitive lifting in two groups of handlers of different ages.

METHODS

Fourteen younger (mean 24.4 yr) and 14 older (mean 47.2 yr) males participated in the study. Participants repetitively lifted a box weighing 13 kg at a frequency of 10 lifts/min for a maximum of 20 min. Postural kinematics (joint and lumbosacral angles and angular velocities) and kinetics (joint moments) were measured throughout the lifting task using motion analysis and ground reaction forces. Muscle fatigue of the erector spinae was assessed using electromyography.

FINDINGS

Peak lumbosacral, trunk, hip and knee flexion angles differed significantly between age groups over the duration of the task, as did lumbosacral and trunk angular velocities. The younger group increased peak lumbar flexion by approximately 18% and approached 99% of maximum lumbosacral flexion after 20 min, whereas the older group increased lumbar flexion by 4% and approached 82% maximum flexion. The younger group had a larger increase in peak lumbosacral and trunk angular velocities during extension, which may be related to the increased back muscle fatigue observed among the younger group.

INTERPRETATION

Older participants appeared to control the detrimental effects of fatigue associated with repetitive lifting and limit lumbar spine range of motion. The higher rates of musculoskeletal injury among older workers may stem from a complex interaction of manual handling risk factors.

Age-related changes in trunk neuromuscular activation patterns during a controlled functional transfer task include amplitude and temporal synergies

While healthy aging is associated with physiological changes that can impair control of trunk motion, few studies examine how spinal muscle responses change with increasing age. This study examined whether older (over 65 years) compared to younger (20-45 years) adults had higher overall amplitude and altered temporal recruitment patterns of trunk musculature when performing a functional transfer task. Surface electromyograms from twelve bilateral trunk muscle (24) sites were analyzed using principal component analysis, extracting amplitude and temporal features (PCs) from electromyographic waveforms. Two PCs explained 96% of the waveform variance. Three factor ANOVA models tested main effects (group, muscle and reach) and interactions for PC scores. Significant (p<.0125) group interactions were found for all PC scores. Post hoc analysis revealed that relative to younger adults, older adults recruited higher agonist and antagonistic activity, demonstrated continuous activation levels in specific muscle sites despite changing external moments, and had altered temporal synergies within abdominal and back musculature. In summary both older and younger adults recruit highly organized activation patterns in response to changing external moments. Differences in temporal trunk musculature recruitment patterns suggest that older adults experience different dynamic spinal stiffness and loading compared to younger adults during a functional lifting task.

Effects of age and its interaction with task parameters on lifting biomechanics

This study investigated the age-related differences in lifting biomechanics. Eleven younger and 12 older participants were instructed to perform symmetric lifting tasks defined by different combinations of destination heights and load magnitudes. Lifting biomechanics was assessed. It was found that the trunk flexion in the starting posture was 32% lower and the peak trunk extension velocity was 46% lower in older participants compared with those in younger ones, indicating that older adults tended to use safer lifting strategies than did younger adults. Based on these findings, we recommend that physical exercise programmes may be a more effective ergonomic intervention for reducing the risks of low back pain (LBP) in lifting among older workers, compared with instructions of safe lifting strategies. As for younger workers, instructions of safe lifting strategies would be effective in LBP risk reduction.

Modelling the spine as a deformable body: Feasibility of reconstruction using an optoelectronic system

The aims of this study were to develop a kinematic model of the spine, seen as a continuous deformable body and to identify the smallest set of surface markers allowing adequate measurements of spine motion. The spine is widely considered as a rigid body or as a kinematic chain made up of a smaller number of segments, thereby introducing an approximation. It would be useful to have at our disposal a technique ensuring accurate and repeatable measurement of the shape of the whole spine. Ten healthy subjects underwent a whole-spine radiographic assessment and, simultaneously, an optoelectronic recording. Polynomial interpolations of the vertebral centroids, of the whole set of markers were performed. The similarity of the resulting curves was assessed. Our findings indicate that spine shape can be reproduced by 5th order polynomial interpolation. The best approximating curves are obtained from either 10- or 9-marker sets. Sagittal angles are systematically underestimated.

Local dynamic stability of the lifting kinematic chain

While a stable trunk and centre of mass (CoM) trajectory are required during lifting, it is unclear how stability is controlled. Thirty healthy participants (15M, 15F) performed repetitive, symmetric lifting at 10 cycles per minute for 3 min with a load-in-hands equivalent to 10% of their maximum back strength. Short- and long-term maximum finite-time Lyapunov exponents (λ(max-s) and λ(max-l)), describing responses to small (local) perturbations, estimated the local dynamic stability of the foot, shank, thigh, pelvis, lower back, and upper back segments. Instability (λ(max-s)) significantly increased when moving up the kinematic chain (p<0.001). Therefore, to maintain trunk equilibrium and accurately regulate CoM trajectory during lifting, stability of the distal (fixed) lower limb segments is prioritized. This is contrary to previous results observed during gait, indicating that trunk control via kinematic chain stability is accomplished differently for walking and lifting.

The kinematics of the scapulae and spine during a lifting task

Simultaneous motion of the scapula and humerus is widely accepted as a feature of normal upper limb movement, however this has usually been investigated under conditions in which purposeful, functional tasks were not considered. The aim of this study was to investigate the synchrony and coordination of the constituent 3D movements of the shoulder girdle and trunk, during a functional activity. 45 healthy women, aged between 20 and 80 years, performed a simple lifting task, moving a loaded box from a shelf at waist level to one at shoulder level and then reversed the movement, during which the linear and angular motions of the scapulae, upper and lower thoracic spine and upper limbs were monitored and analysed using cross-correlation techniques. Results indicated a close and consistent set of coordinated movement patterns, which suggest biomechanical invariance in the responses of the structures adjacent to the upper limb during such a lifting task. These scapulohumeral relationships were, however, more constant and phase-locked when there was a specific purpose to the movement than during periods in which the arm was lowered without load. There were no age-related differences in any movement responses.