Individual, task, and environmental influences on balance recovery: a narrative review of the literature and implications for preventing occupational falls

Influences of backpack loading on recovery from anterior and posterior losses of balance: An exploratory investigation

Backpacks are common devices for carrying external posterior loads. However, relatively little is known about how these external loads affect the ability to recover from balance loss. In this exploratory investigation, 16 young adults (8 female, 8 male) performed forward and backward lean-and-release balance recovery trials, while wearing a backpack that was unloaded or loaded (at 15% of individual body weight). We quantified the effects of backpack loading on balance recovery in terms of maximum recoverable lean angles, center-of-mass kinematics, and temporal-spatial stepping characteristics. Mean values of maximum lean angles were 20° and 9° in response to forward and backward perturbations, respectively. These angles significantly decreased when wearing the additional load for only backward losses of balance. During backward losses of balance, the additional load decreased peak center-of-mass velocity and increased acceleration by ∼10 and 18% respectively, which was accompanied by ∼5% faster stepping responses and steps that were ∼9% longer, 11% higher, and had an ∼10% earlier onset. Thus, wearing a backpack decreases backward balance recovery ability and changes backward recovery stepping characteristics.

The Balance Recovery Confidence (BRC) Scale

BACKGROUND

Falls efficacy posits an understanding of the perceived ability to prevent and manage falls. There have been no validated self-reported instruments to measure the perceived ability to recover balance in response to destabilizing perturbations.

PURPOSE

To develop a scale of balance recovery confidence.

METHODS

Stage one had candidate items generated by 12 community-dwelling adults aged 65 and older using the nominal group technique. Stage two had the scale's name, instructions, response options, recall period and the items validated for appropriateness with 28 healthcare professionals and 10 older adults using an e-Delphi technique. Stage three had the scale's psychometric properties evaluated with 84 older adults who had completed self-reported and performance measures. Factor analysis was applied to confirm unidimensionality. The internal structure, reliability and validity of the scale were evaluated using the classical test theory and Rasch measurement theory.

RESULTS

The 19-item scale was developed and validated with experts' consensus. The scale is unidimensional with excellent internal structure (Cronbach's α = 0.975) and test-retest reliability with Intraclass Correlation Coefficient (ICC3,1) = 0.944. Construct validity of the scale was supported by its relationships with the other measures (Activities-specific Balance Confidence scale, Falls Efficacy Scale-International, Late-Life Function and Disability International-Function, handgrip strength dynamometry, 30-second chair stand test, and mini-BESTest).

CONCLUSION

The balance recovery confidence scale is a distinct instrument that measures perceived reactive balance recovery. The scale has good psychometric properties and can be used to complement other measurement instruments to help older adults cope with challenges to balance.

Training Postural Balance Control with Pelvic Force Field at the Boundary of Stability

This study characterizes the effects of a postural training program on balance and muscle control strategies in a virtual reality (VR) environment. The Robotic Upright Stand Trainer (RobUST), which applies perturbative forces on the trunk and assistive forces on the pelvis, was used to deliver perturbation-based balance training (PBT) in a sample of 10 healthy participants. The VR task consisted of catching, aiming, and throwing a ball at a target. All participants received trunk perturbations during the VR task with forces tailored to the participant's maximum tolerance. A subgroup of these participants additionally received assistive forces at the pelvis during training. Postural kinematics were calculated before and after RobUST training, including (i) maximum perturbation force tolerated, (ii) center of pressure (COP) and pelvic excursions, (iii) postural muscle activations (EMG), and (iv) postural control strategies (the ankle and hip strategies). We observed an improvement in the maximum perturbation force and postural stability area in both groups and decreases in muscle activity. The behavior of the two groups differed for perturbations in the posterior direction where the unassisted group moved towards greater use of the hip strategy. In addition, the assisted group changed towards a lower margin of stability and higher pelvic excursion. We show that training with force assistance leads to a reactive balance strategy that permits pelvic excursion but that is efficient at restoring balance from displaced positions while training without assistance leads to reactive balance strategies that restrain pelvic excursion. Patient populations can benefit from a platform that encourages greater use of their range of motion.

Effect of Handrail Height and Age on Trunk and Shoulder Kinematics Following Perturbation-Evoked Grasping Reactions During Gait

OBJECTIVE

To characterize the effect of handrail height and age on trunk and shoulder kinematics, and concomitant handrail forces, on balance recovery reactions during gait.

BACKGROUND

Falls are the leading cause of unintentional injury in adults in North America. Handrails can significantly enhance balance recovery and help individuals to avoid falls, provided that their design allows users across the lifespan to reach and grasp the rail after balance loss, and control their trunk by applying hand-contact forces to the rail. However, the effect of handrail height and age on trunk and shoulder kinematics when recovering from perturbations during gait is unknown.

METHOD

Fourteen younger and 13 older adults experienced balance loss (sudden platform translations) while walking beside a height-adjustable handrail. Handrail height was varied from 30 to 44 inches (76 to 112 cm). Trunk and shoulder kinematics were measured via 3D motion capture; applied handrail forces were collected from load cells mounted to the rail.

RESULTS

As handrail height increased (up to 42 inches/107 cm), peak trunk angular displacement and velocity generally decreased, while shoulder elevation angles during reaching and peak handrail forces did not differ significantly between 36 and 42 inches (91 and 107 cm). Age was associated with reduced peak trunk angular displacements, but did not affect applied handrail forces.

CONCLUSION

Higher handrails (up to 42 inches) may be advantageous for trunk control when recovering from destabilizations during gait.

APPLICATION

Our results can inform building codes, workplace safety standards, and accessibility standards, for safer handrail design.

Young Individuals Are More Stable and Stand More Upright When Using Rollator Assistance During Standing up and Sitting Down

Four-wheeled walkers or rollators are often used to assist older individuals in maintaining an independent life by compensating for muscle weakness and reduced movement stability. However, limited biomechanical studies have been performed to understand how rollator support affects posture and stability, especially when standing up and sitting down. Therefore, this study examined how stability and posture change with varying levels of rollator support and on an unstable floor. The aim was to collect comprehensive baseline data during standing up and sitting down in young participants. In this study, 20 able-bodied, young participants stood up and sat down both 1) unassisted and assisted using a custom-made robot rollator simulator under 2) full support and 3) touch support. Unassisted and assisted performances were analyzed on normal and unstable floors using balance pads with a compliant surface under each foot. Using 3D motion capturing and two ground-embedded force plates, we compared assistive support and floor conditions for movement duration, the relative timing of seat-off, movement stability (center of pressure (COP) path length and sway area), and posture after standing up (lower body sagittal joint angles) using ANOVA analysis. The relative event of seat-off was earliest under full support compared to touch and unassisted conditions under normal but not under unstable floor conditions. The duration of standing up and sitting down did not differ between support conditions on normal or unstable floors. COP path length and sway area during both standing up and sitting down were lowest under full support regardless of both floor conditions. Hip and knee joints were least flexed under full support, with no differences between touch and unassisted in both floor conditions. Hence, full rollator support led to increased movement stability, while not slowing down the movement, during both standing up and sitting down. During standing up, the full support led to an earlier seat-off and a more upright standing posture when reaching a stable stance. These results indicate that rollator support when handles are correctly aligned does not lead to the detrimental movement alterations of increased forward-leaning. Future research aims to verify these findings in older persons with stability and muscle weakness deficiencies.

The Effect of Wave Motion Intensities on Performance in a Simulated Search and Rescue Task and the Concurrent Demands of Maintaining Balance

OBJECTIVE

The purpose of this study was to examine how intensity of wave motions affects the performance of a simulated maritime search and rescue (SAR) task.

BACKGROUND

Maritime SAR is a critical maritime occupation; however, the effect of wave motion intensity on worker performance is unknown.

METHODS

Twenty-four participants (12 male, 12 female) performed a simulated search and rescue task on a six-degree-of-freedom motion platform in two conditions that differed in motion intensity (low and high). Task performance, electromyography (EMG), and number of compensatory steps taken by the individual were examined.

RESULTS

As magnitude of simulated motion increased, performance in the SAR task decreased, and was accompanied by increases in lower limb muscle activation and number of steps taken.

CONCLUSIONS

Performance of an SAR task and balance control may be impeded by high-magnitude vessel motions.

APPLICATION

This research has the potential to be used by maritime engineers, occupational health and safety professionals, and ergonomists to improve worker safety and performance for SAR operators.

The roles of lower-limb joint proprioception in postural control during gait

The objective of the present study was to investigate the roles of lower-limb joint proprioception in postural control during gait. Seventy-two healthy adults including 36 younger and 36 older adults participated in two experimental sessions, i.e., lower-limb joint proprioception assessment session and gait assessment session. Lower-limb joint proprioception was assessed by joint position sense errors measured at the ankle, knee and hip of the dominant side. Postural control during gait was characterized by step length, step width and local dynamic stability. Results showed that hip proprioception contributed the most to postural control during gait among the lower-limb joint proprioception components, and that mechanisms for the hip proprioception effects were different between age groups. These findings highlighted the importance of incorporating hip proprioception enhancement exercises in postural control training programs, and the necessity of considering age-related differences in the effects of hip proprioception when designing these exercises.

The effect of handrail cross-sectional design and age on applied handrail forces during reach-to-grasp balance reactions

Handrails have been shown to reduce the likelihood of falls. Despite common use, little is known about how handrail shape and size affect the forces that people can apply after balance loss, and how these forces and the corresponding ability to recover balance depend on age. Following rapid platform translations, 16 older adults and 16 sex-matched younger adults recovered their balance using seven handrail cross-sections varying in shape and size. Younger adults were able to withstand higher perturbations, but did not apply higher forces, than older adults. However, younger adults achieved their peak resultant force more quickly, which may reflect slower rates of force generation with older adults. Considering handrail design, the 38 mm round handrails allowed participants to successfully recover from the largest perturbations and enabled the highest force generation. Conversely, tapered handrails had the poorest performance, resulting in the lowest force generation and withstood perturbation magnitudes. Our findings suggest that the handrail cross-sectional design affects the magnitude of force generation and may impact the success of recovery. Our findings can inform handrail design recommendations that support effective handrail use in demanding, balance recovery scenarios.

Emerging OSH Issues in Installation and Maintenance of Floating Solar Photovoltaic Projects and Their Link with Sustainable Development Goals

Objective

Emerging issues of occupational safety and health (OSH) in floating solar photovoltaic projects (FSPV) have rarely been addressed to achieve the Sustainable Development Goals (SDGs). The current scoping review has been planned to demonstrate OSH issues experienced by the workers engaged in the installation and maintenance of FSPV projects and existing ergonomics design interventions in the solar photovoltaic industry with a focus on the FSPV sector.

Methods

A literature review was conducted from four major electronic databases (Science Direct, Google Scholar, Web of Science, and Scopus) using predefined keywords and following the PRISMA framework for the period 1965–2020. A total of 49 studies under five headings, namely a) overview of key reasons for the emergence of floating solar photovoltaic projects, b) occupational risks of workers engaged in the solar PV industry/FSPV sector, c) occupational risks in workplaces/occupations similar to floating solar photovoltaics projects, d) availability of training modules and occupational standards, and e) design interventions/approaches in the solar PV industry/floating photovoltaics sector were analyzed.

Results

It emerged that workers are exposed to multifarious occupational risk factors such as heat, solar radiation, ergonomic risks, electrocution, fire, hazardous substances, adverse weather conditions, and psychosocial factors. These risks have not been adequately addressed with required interventions in the FSPV sector. Intervention opportunities include designing innovative tools, lowering of loads, redesigning workplace layouts, introducing job aids, automation, task rotation, job enlargement, design of training modules, OSH standards and changes in work organization/shift, etc.

Conclusion

This review is a first-of-its-kind effort to highlight the contextual risk factors in the emerging FSPV sector and the need for addressing them through ergonomics design interventions for successfully achieving the Sustainable Development Goals.