Influence of pressure-relief insoles developed for loaded gait (backpackers and obese people) on plantar pressure distribution and ground reaction forces

The Soft Prefabricated Orthopedic Insole Decreases Plantar Pressure during Uphill Walking with Heavy Load Carriage

This study aimed to investigate the effect of varying the hardness of prefabricated orthopedic insoles on plantar pressure and muscle fatigue during uphill walking with a heavy backpack. Fifteen healthy male recreational athletes (age: 20.4 ± 1.0 years, height: 176.9 ± 5.7 cm, weight: 76.5 ± 9.0 kg) wore prefabricated orthopedic insoles with foot arch support; a heel cup with medium (MI), hard (HI), and soft (SI) relative hardnesses; and flat insoles (FI). They performed treadmill walking on uphill gradients with 25 kg backpacks. The plantar pressure and surface electromyographic activity were recorded separately, in 30 s and 6 min uphill treadmill walking trials, respectively. The HI, MI, and SI significantly decreased peak plantar pressure in the lateral heel compared to FI. The MI and SI significantly decreased the peak plantar pressure in the fifth metatarsal compared to FI. The MI significantly reduced the pressure–time integral in the lateral heel compared to FI. The HI significantly increased the peak plantar pressure and pressure–time integral in the toes compared to other insoles, and decreased the contact area in the metatarsal compared to SI. In conclusion, a prefabricated orthopedic insole made of soft material at the fore- and rearfoot, with midfoot arch support and a heel cup, may augment the advantages of plantar pressure distribution during uphill weighted walking.

A Comparative Analysis of Shoes Designed for Subjects with Obesity Using a Single Inertial Sensor: Preliminary Results

Walking remains a highly recommended form of exercise for the management of obesity. Thus, comfortable and adequate shoes represent, together with the prescription of a safe adapted physical activity, an important means to achieve the recommended physical activity target volume. However, the literature on shoes specific for obese individuals is inadequate. The aim of the present study was to compare the performance of shoes specifically designed for subjects with obesity with everyday sneakers during instrumented 6-min walking test and outdoor 30-min ambulation in a group of subjects with obesity using a single wearable device. Twenty-three obese individuals (mean age 58.96 years) were recruited and classified into two groups: deconditioned (n = 13) and non-deconditioned patients (n = 10). Each participant was evaluated with his/her daily sneakers and the day after with shoes specifically designed for people with obesity by means of a questionnaire related to the comfort related to each model of shoes and instrumentally during the i6MWT and an outdoor walking test. The results showed that the specifically designed shoes displayed the higher score as for comfort, in particular in the deconditioned group. During the i6MWT, the distance walked, and step length significantly increased in the deconditioned group when specifically designed shoes were worn; no significant changes were observed in the non-deconditioned individuals. The deconditioned group displayed longer step length during the outdoor 30-min ambulation test. In the non-deconditioned group, the use of specific shoes correlated to better performance in terms of gait speed and cadence. These data, although preliminary, seem to support the hypothesis that shoes specifically conceived and designed for counteracting some of the known functional limitations in subjects with obesity allow for a smoother, more stable and possibly less fatiguing gait schema over time.

Insoles of uniform softer material reduced plantar pressure compared to dual-material insoles during regular and loaded gait

There is limited evidence on the efficacy of insole materials to reduce plantar pressure during regular walking and loaded walking. In-shoe plantar pressures and subjective footwear comfort were recorded in twenty healthy participants at a self-selected treadmill walking speed in six conditions: two commercial insoles or no insole, and with or without carrying a load in a backpack. A single-material insole, comprised of polyurethane, had reduced density and compressive stiffness compared to a dual-material insole with added viscoelastic material in rearfoot and forefoot regions. Load carriage increased peak pressure across the foot. Both insoles reduced plantar pressure in the rearfoot. Yet, the softer single-material insole also attenuated forefoot pressure and loaded walking did not appear to cause bottoming-out of the polyurethane. Plantar pressure changes did not affect perceived footwear comfort. The softer single-material insole was more effective in reducing plantar pressure, further research would confirm if this influences injury prevalence.

The relationship between neck angles and ground reaction forces in schoolchildren during backpack carriage

Study aim: This study aimed to examine the effect of carrying backpacks on neck posture and ground reaction forces (GRFs) and to investigate the relationship between neck angles and GRFs during backpack carriage in schoolchildren.

Material and methods: The craniohorizontal angle (CHA), craniovertebral angle (CVA), sagittal shoulder posture (SSP) and GRFs were measured in right-handed schoolchildren (14 male and 12 female) with mean age 10.17 ± 1.15 years during loaded and unloading conditions. The Qualisys motion analysis system with a force plate was used to assess the neck angles and GRFs.

Results: During backpack carriage there was a significant increase in the CHA (p = 0.001), significant decrease in the CVA and SSP (p = 0.001, 0.016 respectively), no significant difference in the normalized (scaled to body weight) vertical GRFs (p > 0.05), and a significant increase in the anterior braking and posterior propulsive GRFs (p = 0.035, 0.002 respectively) compared to the unloading condition. While carrying a backpack there was a moderate negative correlation between the SSP and first vertical GRF (r = –0.464) and a strong negative correlation with the second vertical GRF (r = –0.571) and the posterior propulsive GRF (r = –0.587).

Conclusion: Carrying a backpack weighing 15% of the child’s body weight changes the head posture and increases the normalized value of the anterior-posterior shear force. During backpack carriage, decreasing the SSP is associated with increasing the load acceptance, thrusting and posterior propulsive forces. Increasing the shearing force may lead to development of postural abnormities. Consequently, the ideal backpack weight should be considered by parents and teachers.

Use of various obesity measurement and classification methods in occupational safety and health research: a systematic review of the literature

BACKGROUND

This study systematically examined obesity research in occupational safety and health regarding the use of various obesity measurement and classification methods.

METHODS

A systematic search of the PubMed database on English language publications from 2000 to 2015 using related keywords and search of citations resulted in selection of 126 studies. They were categorized into two groups based on their main research question: 1) general physical or mental work-related functioning; and 2) task or body part specific functioning.

RESULTS

Regardless of the study group, body mass index (BMI) was the most frequently used measure. Over 63% of the studies relied solely on BMI to define obesity. In only 22% of the studies, body fat was directly measured by methods such as dual energy x-ray absorptiometry. Abdominal obesity was defined using waist circumference in recent years, and waist-hip ratio in earlier years. Inconsistent cut-offs have also been used across studies investigating similar topics.

CONCLUSIONS

Few authors acknowledged the limitations of using indirect obesity measures. This is in part due to the limited understanding of some occupational safety and health researchers regarding the complex issues surrounding obesity classification and also the mixed recommendations over the past 2-3 decades and across populations. Efforts need to be made to promote appropriate obesity measurement and reporting in this field.

Shoe-Insole Technology for Injury Prevention in Walking

Impaired walking increases injury risk during locomotion, including falls-related acute injuries and overuse damage to lower limb joints. Gait impairments seriously restrict voluntary, habitual engagement in injury prevention activities, such as recreational walking and exercise. There is, therefore, an urgent need for technology-based interventions for gait disorders that are cost effective, willingly taken-up, and provide immediate positive effects on walking. Gait control using shoe-insoles has potential as an effective population-based intervention, and new sensor technologies will enhance the effectiveness of these devices. Shoe-insole modifications include: (i) ankle joint support for falls prevention; (ii) shock absorption by utilising lower-resilience materials at the heel; (iii) improving reaction speed by stimulating cutaneous receptors; and (iv) preserving dynamic balance via foot centre of pressure control. Using sensor technology, such as in-shoe pressure measurement and motion capture systems, gait can be precisely monitored, allowing us to visualise how shoe-insoles change walking patterns. In addition, in-shoe systems, such as pressure monitoring and inertial sensors, can be incorporated into the insole to monitor gait in real-time. Inertial sensors coupled with in-shoe foot pressure sensors and global positioning systems (GPS) could be used to monitor spatiotemporal parameters in real-time. Real-time, online data management will enable ‘big-data’ applications to everyday gait control characteristics.

Stiffness Effects in Rocker-Soled Shoes: Biomechanical Implications

Rocker-soled shoes provide a way to reduce the possible concentration of stress, as well as change movement patterns, during gait. This study attempts to examine how plantar force and spatio-temporal variables are affected by two rocker designs, one with softer and one with denser sole materials, by comparing them with the barefoot condition and with flat-soled shoes. Eleven subjects' gait parameters during walking and jogging were recorded. Our results showed that compared with barefoot walking, plantar forces were higher for flat shoes while lower for both types of rocker shoes, the softer-material rocker being the lowest. The plantar force of flat shoes is greater than the vertical ground reaction force, while that of both rocker shoes is much less, 13.87-30.55% body weight. However, as locomotion speed increased to jogging, for all shoe types, except at the second peak plantar force of the denser sole material rocker shoes, plantar forces were greater than for bare feet. More interestingly, because the transmission of force was faster while jogging, greater plantar force was seen in the rocker-soled shoes with softer material than with denser material; results for higher-speed shock absorption in rocker-soled shoes with softer material were thus not as good. In general, the rolling phenomena along the bottom surface of the rocker shoes, as well as an increase in the duration of simultaneous curve rolling and ankle rotation, could contribute to the reduction of plantar force for both rocker designs. The possible mechanism is the conversion of vertical kinetic energy into rotational kinetic energy. To conclude, since plantar force is related to foot-ground interface and deceleration methods, rocker-design shoes could achieve desired plantar force reduction through certain rolling phenomena, shoe-sole stiffness levels, and locomotion speeds.

Overweight, obesity and work functioning: the role of working-time arrangements

BACKGROUND

Obesity is associated with productivity loss, but little is known about how obese workers function at work and also the role of working-time arrangements on this association is lacking. Therefore, the aim of this study was to examine the association of overweight and obesity with work functioning (WF), and to determine whether the associations differ between workers with different working-time arrangements.

METHODS

A cross-sectional study was conducted within the sampling frame of the 'Shift Your Work' study that examined the effect of irregular working-times in relation to health and functioning at work. We included N = 622 Dutch employees, of which N = 384 (62%) were shift-workers, N = 171 (27%) on-call workers and N = 67 (11%) day-workers. Overweight and obesity were defined as BMI 25-30 and ≥30, respectively. WF was assessed using the Work-Role Functioning Questionnaire.

RESULTS

The prevalences of overweight and obesity were 48% and 10% in all workers, 49% and 11% in shift-workers, 45% and 10% in on-call workers, and 49% and 6% in day workers, respectively. In all workers, obesity was associated with lower WF scores for physical demands (adjusted estimate, aB = -5.5). In shift-workers, obesity was associated with lower WF scores for output and physical demands (aB = -8.8 and -6.8, respectively). In day and on-call workers, overweight and obesity were not associated with WF.

CONCLUSIONS

Overweight and obesity are highly prevalent in the working population. Obesity might reduce the executive function performance beyond physical limitations, and limit the ability to accomplish tasks successfully, especially in shift workers.

The Principal Components of Adult Female Insole Shape Align Closely with Two of Its Classic Indicators

The plantar surface of the human foot transmits the weight and dynamic force of the owner's lower limbs to the ground and the reaction forces back to the musculoskeletal system. Its anatomical variation is intensely studied in such fields as sports medicine and orthopedic dysmorphology. Yet, strangely, the shape of the insole that accommodates this surface and elastically buffers these forces is neither an aspect of the conventional anthropometrics of feet nor an informative label on the packet that markets supplementary insoles. In this paper we pursue an earlier suggestion that insole form in vertical view be quantified in terms of the shape of the foot not at the plane of support (the "footprint") but some two millimeters above that level. Using such sections extracted from laser scans of 158 feet of adult women from the University of Zagreb, in conjunction with an appropriate modification of today's standard geometric morphometrics (GMM), we find that the sectioned form can be described by its size together with two meaningful relative warps of shape. The pattern of this shape variation is not novel. It is closely aligned with two of the standard footprint measurements, the Chippaux-Šmiřák arch index and the Clarke arch angle, whose geometrical foci (the former in the ball of the foot, the latter in the arch) it apparently combines. Thus a strong contemporary analysis complements but does not supplant the simpler anthropometric analyses of half a century ago, with implications for applied anthropology.

The influence of gait cadence on the ground reaction forces and plantar pressures during load carriage of young adults

Biomechanical gait parameters--ground reaction forces (GRFs) and plantar pressures--during load carriage of young adults were compared at a low gait cadence and a high gait cadence. Differences between load carriage and normal walking during both gait cadences were also assessed. A force plate and an in-shoe plantar pressure system were used to assess 60 adults while they were walking either normally (unloaded condition) or wearing a backpack (loaded condition) at low (70 steps per minute) and high gait cadences (120 steps per minute). GRF and plantar pressure peaks were scaled to body weight (or body weight plus backpack weight). With medium to high effect sizes we found greater anterior-posterior and vertical GRFs and greater plantar pressure peaks in the rearfoot, forefoot and hallux when the participants walked carrying a backpack at high gait cadences compared to walking at low gait cadences. Differences between loaded and unloaded conditions in both gait cadences were also observed.

Plantar heel pain and foot loading during normal walking

Plantar heel pain is aggravated by weight-bearing, yet limited evidence exists regarding how people with heel pain load their feet during walking. Knowledge of loading patterns in people with plantar heel pain would enhance the understanding of their foot function and assist in developing intervention strategies. Plantar pressure using the Emed-AT platform (Novel Gmbh, Germany) was collected from 198 people with plantar heel pain and 70 asymptomatic controls during normal walking. Maximum force, force-time integral, peak pressure, pressure-time integral and contact time were measured in four quadrants of the heel, the midfoot and the medial and lateral forefoot. The symptomatic group was sub-divided into equal low-pain and high-pain groups using the Foot Health Status Questionnaire pain score. Following age and body mass comparison, multivariate analyses of covariance were performed to compare the heel pain group to the controls, and the low-pain group to the high-pain group, for each loading variable. The heel pain group displayed lower maximum force beneath the heel, lower peak pressure beneath the postero-lateral heel and lower maximum force beneath the medial forefoot. Force-time integrals were lower beneath the posterior heel regions and higher at the lateral forefoot. People with heel pain also had longer midfoot and forefoot contact time. Higher pain level was associated with lower peak pressure and maximum force beneath regions of the heel. Compared to the controls, people with plantar heel pain demonstrated reduced heel loading and modified forefoot loading consistent with a strategy to offload the painful heel.

Impacts of different types of insoles on postural stability in older adults

The objective of this study was to examine the effects of different types of insoles on postural stability in older adults. Four types of commercially available insoles were selected including the cupped insoles, textured insoles, rigid insoles, and soft insoles. The experiment included a static stance session and a walking session. In the static stance session, the participants stood upright on a force platform as still as possible, with feet together, arms by the side and looking straight ahead. The mean velocity of center-of-pressure time series obtained from the force platform was used to assess static postural stability. In the walking session, the participants walked on a treadmill at their self-selected comfortable speed for 4.5 min in each insole condition. Dynamic postural stability was assessed using the margin of stability. It was found that static postural stability was not affected by insoles, but cupped insoles improved dynamic postural stability, and rigid insole was associated with better dynamic postural stability compared to soft insoles. These findings can aid in better understanding the insole design features associated with improved postural stability in older adults.

Accuracy and repeatability of the gait analysis by the WalkinSense system

WalkinSense is a new device designed to monitor walking. The aim of this study was to measure the accuracy and repeatability of the gait analysis performed by the WalkinSense system. Descriptions of values recorded by WalkinSense depicting typical gait in adults are also presented. A bench experiment using the Trublu calibration device was conducted to statically test the WalkinSense. Following this, a dynamic test was carried out overlapping the WalkinSense and the Pedar insoles in 40 healthy participants during walking. Pressure peak, pressure peak time, pressure-time integral, and mean pressure at eight-foot regions were calculated. In the bench experiments, the repeatability (i) among the WalkinSense sensors (within), (ii) between two WalkinSense devices, and (iii) between the WalkinSense and the Trublu devices was excellent. In the dynamic tests, the repeatability of the WalkinSense (i) between stances in the same trial (within-trial) and (ii) between trials was also excellent (ICC > 0.90). When the eight-foot regions were analyzed separately, the within-trial and between-trials repeatability was good-to-excellent in 88% (ICC > 0.80) of the data and fair in 11%. In short, the data suggest that the WalkinSense has good-to-excellent levels of accuracy and repeatability for plantar pressure variables.