Work boot design affects the way workers walk: A systematic review of the literature

The Effect of Anthropometric Shoes on Lactic Acid Reduction in Nurses: A Mixed-Methods Study from Indonesia

Background

The mobilization characteristics of nurses' work, such as standing, walking, and transferring patients for a long time, can increase the risk of musculoskeletal disorders. Repetitive activities nurses perform can cause foot problems such as discomfort and insecurity, characterized by increased lactic acid levels. Anthropometric shoes are specifically designed to reduce complaints on nurses' feet.

Purpose

This study aimed to determine the effect of individual anthropometric shoes on lactic acid levels in nurses at the hospital.

Methods

This study used a mixed-method study design. This study involved 71 nurses in the quantitative study and 15 nurses in the qualitative study. Nurses in Emergency Room, Central Surgical Installation, Inpatient Room, Intensive Care Unit, and Outpatient Installation were randomly selected using a stratified random sampling technique. The instruments used were the Accutrend Lactacyd tool, demographic questionnaire and interview questionnaire. Bivariate data analysis was using Statistical Package for Social Sciences (SPSS) and qualitative data analysis using thematic analysis.

Results

This mixed-method study shows that anthropometric shoes can reduce nurses' lactic acid levels. In the quantitative study; there was a significant difference in lactic acid levels of nurses before and after using anthropometric shoes with the average results of measuring lactic acid levels, namely pre-test (22.48 mg/dL) and post-test (16.27 mg/dL), with a p-value (0.000). The qualitative study data revealed positive results related to increased nurse knowledge, positive views on the effect of shoes on nurse performance, and the impact of using anthropometric shoes in providing comfort and safety, such as decreased muscle fatigue and pain.

Conclusion

The findings of this study highlight the effect of individualized anthropometric shoes on lactic acid levels in nurses in Indonesian hospitals. It is essential to conduct further research and evaluate the results in a broader setting to ensure that anthropometric shoes can directly affect lactic acid levels.

[Stress fractures in the military context]

BACKGROUND

Soldiers, especially as recruits, are exposed to significantly elevated stress patterns of the foot due to occupation-related marching and excessive running. This can lead to military-specific stress fractures of the metatarsals, i.e., marching fractures. The treatment and prevention of stress fractures are of particular importance in the military context due to the impact on operational capability and treatment costs. A uniform classification of these fractures does not yet exist.

OBJECTIVE

Review of stress fractures in the military setting with presentation of the incidence, risk factors, classification, treatment and prevention possibilities.

MATERIAL AND METHODS

A PubMed®-based review of the current literature on stress fractures in the military context was conducted and the results were discussed with a focus on specific military medical treatment options.

RESULTS

There are several possibilities to classify stress fractures, the most well-known being a 4-level magnetic resonance imaging (MRI)-based classification. Prevention and treatment possibilities are multifaceted but so far insufficiently validated.

CONCLUSION

Military-specific stress fractures should be grouped according to a 4-level and MRI-based classification. The treatment options include both conservative and surgical measures and should be implemented taking the patient's individual requirements into account. Preventive measures play a key role in the military context. They include the adaptation of screening tools, training and equipment and require continuous evaluation and development.

Intelligent plantar pressure offloading for the prevention of diabetic foot ulcers and amputations

The high prevalence of lower extremity ulceration and amputation in people with diabetes is strongly linked to difficulties in achieving and maintaining a reduction of high plantar pressures (PPs) which remains an important risk factor. The effectiveness of current offloading footwear is opposed in part by poor patient adherence to these interventions which have an impact on everyday living activities of patients. Moreover, the offloading devices currently available utilize primarily passive techniques, whereas PP distribution is a dynamically changing process with frequent shifts of high PP areas under different areas of the foot. Thus, there is a need for pressure offloading footwear capable of regularly and autonomously adapting to PPs of people with diabetes. The aim of this article is to summarize the concepts of intelligent pressure offloading footwear under development which will regulate PPs in people with diabetes to prevent and treat diabetic foot ulcers. Our team is creating this intelligent footwear with an auto-contouring insole which will continuously read PPs and adapt its shape in the forefoot and heel regions to redistribute high PP areas. The PP-redistribution process is to be performed consistently while the footwear is being worn. To improve adherence, the footwear is designed to resemble a conventional shoe worn by patients in everyday life. Preliminary pressure offloading and user perceptions assessments in people without and with diabetes, respectively, exhibit encouraging results for the future directions of the footwear. Overall, this intelligent footwear is designed to prevent and treat diabetic foot ulcers while enhancing patient usability for the ultimate prevention of lower limb amputations.

The Effects of a Custom-Designed High-Collar Shoe on Muscular Activity, Dynamic Stability, and Leg Stiffness: A Biomimetic Approach Study

High-collar shoes are a biomimetic approach to preventing lateral ankle injuries during high-demand activities; however, the influence of collar stiffness (CS) on parameters related to lateral ankle sprain prevention during running remains unclear. In this study, we investigated the effects of a custom-designed shoe CS on muscular activity, dynamic stability, and leg stiffness (K_leg) during running using a biomimetic design approach inspired by the mechanisms of ankle sprain prevention. Sixteen healthy male participants ran on a treadmill while wearing a custom-designed high-collar shoe with low, medium, and high CS conditions, measured using circumferential ankle pressure (CAP). Lower extremity kinematics and electromyography (EMG) data were recorded simultaneously. One-way repeated-measures ANOVA was conducted to compare the CS conditions. Results indicate that high and medium CS conditions significantly reduce sagittal and frontal ankle ranges of motion (ROMs) compared to the low CS condition, providing improved stability and support against lateral ankle sprain; moreover, there was a trend towards higher dynamic stability and K_leg with increasing CS. Our study highlights the importance of considering the CAP in regulating high-collar stiffness properties and how higher CS may provide better support for the ankle during running. Nevertheless, additional research is necessary to validate the efficacy of the current design in preventing ankle sprains during high-demand activities.

The biomechanical differences of wearing safety shoes compared with everyday shoes on dynamic balance when tripping over an obstacle

Safety shoes are known to challenge dynamic balance, but the interaction between footwear and trips has not been thoroughly explored. This study investigated the biomechanical differences on dynamic balance during unexpected trip perturbations between safety shoes and everyday shoes. The vertical position of the whole-body center of mass (CoM) and the linear momentum of the swing leg from seven females and sixteen males were analyzed in five subsequent gait cycles. Additionally, the recovery strategies (i.e., the displacement of the foot after tripping) were classified. Wearing safety shoes, the linear momentum of the foot and whole leg increased, and the vertical position of the whole-body CoM was lower after the perturbation. Additionally, the recovery strategy when wearing safety shoes demonstrated a lower displacement of the foot. In conclusion, wearing safety shoes was found to have negative biomechanical effects when having to circumvent a trip, and this potentially increased the risk of falling.

Influence of circumferential ankle pressure of shoe collar on the kinematics, dynamic stability, electromyography, and plantar pressure during normal walking

BACKGROUND

The shoe's collar plays a significant role in supporting the ankle during walking. Since the protective effect of the collar requires the circular embracing of the ankle and shank, a stiffer collar might be involved with increased circumferential ankle pressure (CAP). It is not clear how collar CAP affects walking performance. Therefore, this study was aimed at examining the influence of the collar CAP on the kinematics, dynamic stability, electromyography (EMG), and plantar pressure during normal walking.

METHOD

Sixteen healthy male participants walked on a treadmill while wearing a custom-designed high-collar shoe with 10 (low), 30 (medium), and 60 mmHg (high) CAP conditions, and the joint angles, dynamic stability index, EMG, and plantar pressure were measured.

RESULT

While the low CAP condition did not affect the ankle range of motion (ROM), The high CAP condition restricted both the ankle sagittal and frontal ROM, whereas the medium CAP condition limited only the ankle frontal ROM. The knee and hip ROM did not differ between conditions. The dynamic stability for the high and medium CAP cases was comparable but significantly higher than that of the low CAP condition. The ankle muscle activity and corresponding co-contraction increased with increasing CAP for gastrocnemius medialis (GM), soleus (SOL), peroneus longus (PL), tibialis anterior (TA) muscles in the weight acceptance and push-off phases but not in the single limb support. Knee muscle activity, including vastus lateralis (VL) and semitendinosus (SEMI) was similar between all conditions. A higher relative pressure was observed under the lateral aspect of the heel when walking in the high CAP condition.

CONCLUSION

The results suggest that a high-collar shoe with a high CAP may not be an appropriate choice for walking owing to the injury risk factors and limited walking efficiency. A medium CAP is associated with certain advantages and, thus, a superior choice for high-collar shoe design.

The Impact of Footwear on Occupational Task Performance and Musculoskeletal Injury Risk: A Scoping Review to Inform Tactical Footwear

The aim of this scoping review was to investigate the impact of footwear on worker physical task performance and injury risk. The review was guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews protocol and registered in the Open Science Framework. Key search terms were entered into five academic databases. Following a dedicated screening process and critical appraisal, data from the final articles informing this review were extracted, tabulated, and synthesised. Of 19,614 identified articles, 50 articles informed this review. Representing 16 countries, the most common populations investigated were military and firefighter populations, but a wide range of general occupations (e.g., shipping, mining, hairdressing, and healthcare workers) were represented. Footwear types included work safety boots/shoes (e.g., industrial, gumboots, steel capped, etc.), military and firefighter boots, sports shoes (trainers, tennis, basketball, etc.) and various other types (e.g., sandals, etc.). Occupational footwear was found to impact gait and angular velocities, joint ranges of motion, posture and balance, physiological measures (like aerobic capacity, heart rates, temperatures, etc.), muscle activity, and selected occupational tasks. Occupational footwear associated with injuries included boots, conventional running shoes, shoes with inserts, harder/stiffer outsoles or thin soles, and shoes with low comfort scores-although the findings were mixed. Occupational footwear was also linked to potentially causing injuries directly (e.g., musculoskeletal injuries) as well as leading to mechanisms associated with causing injuries (like tripping and slipping).

Effect of work boot shaft stiffness and sole flexibility on boot clearance and shank muscle activity when walking on simulated coal mining surfaces: implications for reducing trip risk

Mining work boot shaft stiffness and sole flexibility variations are likely to affect how a miner moves their foot to clear the ground thus influencing their risk of tripping. Despite the potential negative consequences associated with tripping, limited research has investigated how these boot design features might contribute to a miner's trip risk. Therefore, this study aimed to investigate the effects of systematic variations to boot shaft stiffness and sole flexibility on lower limb alignment and shank muscle activity at toe off and boot clearance during initial swing when 20 males walked across two simulated coal mining surfaces. Although knee and hip alignment remained constant, changes to boot shaft stiffness and sole flexibility significantly interacted to influence the shank muscle activity and ankle alignment displayed at toe off. To reduce the risk of tripping, underground coal miners should avoid a boot with a stiff shaft, regardless of the sole flexibility.

Biomechanics of running: A special reference to the comparisons of wearing boots and running shoes

Boots are often used in sports, occupations, and rehabilitation. However, there are few studies on the biomechanical alterations after wearing boots. The current study aimed to compare the effects of running shoes and boots on running biomechanics. Kinematics and ground reaction forces were recorded from 17 healthy males during running at 3.3 m/s with shoe and boot conditions. Temporal distance gait variables, ground reaction force components as well as lower limb joints angle, moment, and power were compared using Paired t-test and Statistical Parametric Mapping package for time-series analysis. Running with boots was associated with greater stride, step, flight, and swing times, greater flight length, and smaller cadence (p<0.05). The only effect of boots on lower limb joints kinematics during running was a reduction in ankle range of motion (p<0.05). Significantly greater hip flexor, abductor, and internal rotator moments, greater knee extensor and abductor moments, and ankle plantar flexor moments were observed at push-off phase of running as well as greater ankle dorsiflexor moment at early-stance in boot condition (p<0.05). Also, knee joint positive power was greater with a significant temporal shift in boot condition, suggesting a compensatory mechanism in response to limited ankle range of motion and the inability of the ankle joint to generate the required power. Our findings showed that running with boots is physically more demanding and is associated with a greater net contribution of muscles spanning hip and knee joints in order to generate more power and compensate for the ankle joint limitations, consequently, may increase the risk of both musculoskeletal injuries and degenerative joint diseases.

Sickness absence from work in the footwear industry: A longitudinal study

BACKGROUND: Studies on illness in the footwear industry have prioritized specific work sectors and diseases. OBJECTIVES: To analyze the main factors related to sickness absence and the indicators of illness in terms of recurrence and workdays lost among workers at a footwear company, ranging from storage of raw material to distribution of the final product. METHODS: A total of 9072 cases of absence from work were investigated in shoe production units from 2014 to 2017. Univariate models estimated the risk of bodily dysfunction (physiological and psychological) and the severity of recurrence and work days lost. RESULTS: (1) Most production units and work sectors were related to one or more affected bodily functions; (2) Neuromusculoskeletal and movement-related functions and the work sectors of prefabrication; cutting, assembly and finishing; and quality inspection of the final product required a longer recovery time before return to work and had a greater recurrence of leave; and (3) Women seemed to be more affected than men in terms of the reappearance of symptoms. CONCLUSIONS: Illness differs according to occupational sectors. The production sectors present more serious situations due to physical overload, intense rhythm and concentration, monotony and low autonomy.

Knee Pain Reduction Using a Shock-Absorbing Sole

BACKGROUND

The biomechanics of the foot and leg are responsible for shock absorption during human gait. Lack of shock absorption is known to be a key component of knee pain. This study compares a new model of shoe sole with a built-in modification intended to absorb shock with a traditional sole shoe to examine whether shoe design modifications can help alleviate knee pain.

METHODS

A double-blind randomized controlled study was performed. Fifty-two adults with overuse symptoms of knee pain, either unilateral or bilateral, were enrolled and randomly assigned to use the intervention sole or the traditional sole shoes. For 5 weeks, participants wore either the shoe with the intervention sole or the shoe with the traditional sole, rating their knee pain on a 10-point visual analog scale at study onset, midway, and study completion.

RESULTS

After 5 weeks, participants using the intervention sole shoe reported an average reduction in knee pain of 85%, significantly better than participants using the traditional sole shoe (P < .001), whose average pain scores increased. Positive effects on back and foot pain were also observed in those with the intervention sole shoe compared with the traditional sole shoe.

CONCLUSIONS

The intervention shock-absorbing sole represents an approach to midsole and outsole construction that can potentially increase shock absorption and decrease knee pain during prolonged standing and walking.

Identifying lower limb problems and the types of safety footwear worn in the Australian wine industry: a cross-sectional survey

BACKGROUND

The Australian wine industry is a valuable part of the wider Australian economy worth approximately A$45 billion annually and employs 163,790 people either full time or part time. Australian agricultural industries are amongst the nation's most dangerous workplaces with joint, ligament, muscle and tendon injuries being commonplace along with wounds, lacerations and musculoskeletal diseases. It is therefore important to try and minimise the risk of injuries to workers. The aims of this study were to (1) identify whether lower limb problems occur in the Australian wine industry and (2) identify the types of safety footwear worn.

METHODS

Participants were recruited from the Australian wine industry. The study was a cross-sectional anonymous survey of 82 questions with n = 207 respondents. Questions related to job role performed, types of lower limb problems experienced, level of pain, restriction of activities, types of footwear worn, general health and physical health.

RESULTS

The main working roles were winery (73.4%), vineyard (52.2%), laboratory (39.6%), cellar door (32.4%) and office (8.2%), with 63.3% of participants working in more than one role. Lower back pain was the most commonly reported problem at 56% followed by foot pain (36.7%), knee pain (24.6%), leg pain (21.3%), ankle pain (17.9%), hip pain (15.5%), toe pain (13%) and heel pain (11.1%). The most popular footwear used by participants were elastic sided safety boots, followed by high cut lace up safety boots with side zip. Overall, although the pain experienced was moderate, it did not impact the workers ability to perform their duties and the majority self-reported as being in very good general and physical health.

CONCLUSION

To date no data have been published on the types of lower limb problems or the types of safety footwear worn in the Australian wine industry. This study is the first to demonstrate that elastic sided safety boots were the most popular amongst respondents and that lower limb problems occur with workers. Therefore, further research into the safety footwear used in the Australian wine industry is needed to better support workers health while working in their varied roles and conditions.

Sensory Organization Test Conditions Influence Postural Strategy Rather than Footwear or Workload

BACKGROUND

Postural strategies such as ankle, hip, or combined ankle-hip strategies are used to maintain optimal postural stability, which can be influenced by the footwear type and physiological workload.

PURPOSE

This paper reports previously unreported postural strategy scores during the six conditions of the sensory organization test (SOT).

METHODS

Fourteen healthy males (age: 23.6 ± 1.2 years; height: 181 ± 5.3 cm; mass: 89.2 ± 14.6 kg) were tested for postural strategy adopted during SOT in three types of occupational footwear (steel-toed work boot, tactical work boot, low-top work shoe) every 30 min during a 4-h simulated occupational workload. Postural strategy scores were analyzed using repeated measures analysis of variance at 0.05 alpha level.

RESULTS

Significant differences among postural strategy scores were only evident between SOT conditions, and but not between footwear type or the workload.

CONCLUSIONS

Findings indicate that occupational footwear and occupational workload did not cause a significant change in reliance on postural strategies. The significant changes in postural strategy scores were due to the availability of accurate and/or conflicting sensory feedback during SOT conditions. In SOT conditions where all three types of sensory feedback was available, the ankle strategy was predominantly adopted, while more reliance on hip strategy occurred in conditions with absent or conflicting sensory feedback.

The influence of shaft stiffness on joint kinematics and kinetics during hiking

Hiking boots provide an interface for walking in challenging environments, typically equipped with a shaft to provide ankle joint stability in rough terrains. Currently it is unclear if the ankle joint is stabilized to an extent that protects against ankle injuries, and if so, to what degree this added ankle stability sacrifices ankle mobility and hence decreases efficient gait propulsion. The aim of the present study was to compare the effect of shaft construction and stiffness on lower extremity kinematics and kinetics during level and step-down walking to simulate hiking conditions. Thirteen healthy males walked in one low-cut and three shafted commercially available hiking shoes with varying shaft stiffness. Lower extremity kinematics and ground reaction forces were recorded simultaneously. During level walking, ankle plantar-dorsiflexion range of motion was significantly reduced for the stiffest shaft hiking shoe compared to the low-cut shoe. A reduction in the muscle contribution to ankle joint work was found for all shafted shoes compared to the low-cut shoe. The reduced ankle joint work for the shafted shoes conversely increased eccentric knee joint work. Kinematic and kinetic differences between shoes diminished during box step-down walking. The present study shows that shaft height and stiffness can influence ankle joint range of motion, and ankle and knee joint work, with the high-shaft shoes redistributing load from the ankle to the knee joint. This may have implications for gait efficiency and increase the risk of knee joint loading or injuries.

Effects from loaded walking with polyurethane and styrene-butadiene rubber midsole military boots on kinematics and external forces: A statistical parametric mapping analysis

This study compared ground reaction forces (GRF) and lower limb two-dimensional (2D) kinematic waveforms, with and without load carriage, in military personnel walking in two different types of boots. Data were measured in 24-soldiers walking on a 10-m walkway under four randomized crossover trials: wearing two military boots (styrene-butadiene rubber midsole - SBR - 63 Shore A; and polyurethane midsole - PU - 48 Shore A); with and without a 15-kg backpack. GRF traditional parameters were evaluated by two-way ANOVAs. GRF and kinematic waveforms were assessed using a statistical parametric mapping (SPM) method (two-way ANOVA). No interaction effects were observed between footwear and load. GRF at the beginning of stance was lower while wearing the SBR boot condition compared to the PU boot condition. Load carriage increased trunk, hip, and knee flexion. The analyzed military boots did not affect movement patterns during loaded walking and the military boot with SBR midsole material reduced impact to a greater extent. The study demonstrated that the design and materials (e.g., midsole material and thickness) used in boot manufacturing can influence military boot performance.

Safety footwear: A survey of end-users

This paper presents the results of an extensive survey concerning the experience of safety footwear end-users. Safety footwear has been in widespread use across many industries worldwide since the 1970s, and has become an essential part of industrial Personal Protective Equipment. The number of women entering predominantly male industrial environments, and requiring safety footwear is rising, and this is accompanied by anecdotal reports of ill-fitting and uncomfortable footwear. This research proactively compares the opinions of women and men regarding their experience of safety footwear. A systematically designed survey aims to substantiate previously anecdotal knowledge around safety footwear, including key drivers for end-user purchases, wear habits and comfort issues (establishing any differences between women and men). Chi-squared testing was used to assess statistical significance and ensure robustness of findings. The responses and resulting analysis confirmed that comfort and fit were key drivers for all end users; women and men have different wear habits (women wear their safety footwear less frequently and for shorter periods of time than men - likely due to the reported comfort issues); a significant proportion of women (60%) found their safety footwear less comfortable than their regular footwear, however, 45% of men also reported the same, which has not been reported anecdotally. In general, the users of safety footwear accepted a level of discomfort in at least one area of the foot before deeming footwear 'uncomfortable'. The significant analysis performed on the captured data has, to the authors knowledge, never before been undertaken for this breadth of industry, age and gender with 632 responses received. This makes it the largest study of this field to date.

Shorter work boot shaft height improves ankle range of motion and decreases the oxygen cost of work

Work boots featuring design elements implemented to protect the foot and lower limb are common in many industries. However, boot design can have negative unintended consequences such as increases in work related fatigue and injury risk. This study compared joint kinematics and the physiological cost of two commercially available steel-toed work boots with different shaft designs worn throughout a simulated work task. A boot with a lower-cut and scalloped shaft allowed greater sagittal plane range of motion at the ankle joint compared to a boot with a higher-cut straight shaft, particularly in the late stance phase of the gait cycle. This was coupled with a decreased physiological cost of treadmill walking (2.6 and 3.1% improvement in oxygen consumption and walking economy, respectively), likely caused by a more efficient gait pattern. A lower-cut and scalloped shaft could lead to decreases in work-related fatigue and the subsequent risk of injuries in workers. Practitioner summary: Gait kinematics and the physiological cost of work boots with different shaft heights has not previously been investigated. A randomised cross-over study design found that a boot with a lower shaft height and scalloped collar improved ankle range of motion and reduced the physiological cost experienced by the wearers. Abbreviations: ROM: range of motion; FS: full shaft; SS: scalloped shaft; COM: centre of mass; HR: heart rate; RPE: rating of perceived exertion; ES: effect size.

Overuse-Related Injuries of the Musculoskeletal System: Systematic Review and Quantitative Synthesis of Injuries, Locations, Risk Factors and Assessment Techniques

Overuse-related musculoskeletal injuries mostly affect athletes, especially if involved in preseason conditioning, and military populations; they may also occur, however, when pathological or biological conditions render the musculoskeletal system inadequate to cope with a mechanical load, even if moderate. Within the MOVIDA (Motor function and Vitamin D: toolkit for risk Assessment and prediction) Project, funded by the Italian Ministry of Defence, a systematic review of the literature was conducted to support the development of a transportable toolkit (instrumentation, protocols and reference/risk thresholds) to help characterize the risk of overuse-related musculoskeletal injury. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach was used to analyze Review papers indexed in PubMed and published in the period 2010 to 2020. The search focused on stress (overuse) fracture or injuries, and muscle fatigue in the lower limbs in association with functional (biomechanical) or biological biomarkers. A total of 225 Review papers were retrieved: 115 were found eligible for full text analysis and led to another 141 research papers derived from a second-level search. A total of 183 papers were finally chosen for analysis: 74 were classified as introductory to the topics, 109 were analyzed in depth. Qualitative and, wherever possible, quantitative syntheses were carried out with respect to the literature review process and quality, injury epidemiology (type and location of injuries, and investigated populations), risk factors, assessment techniques and assessment protocols.

Minimalist style boot improves running but not walking economy in trained men

This study examined movement economy under load with 1000 g minimalist (MIN) vs. 1600 g traditional (TRD) style boots. Fourteen trained, male participants completed a VO_2peak test (46.6 ± 7.3 ml/kg/min) while wearing a 16 kg external load. Treadmill speeds for the running economy (RE) trials were determined by the slowest pace in which participants completed a full stage with a running gait pattern during the VO_2peak test. Walking economy (WE) pace was 1.6 km/h slower than RE pace. During the second session, participants completed 5-min exercise bouts at WE and RE pace under load wearing MIN and TRD. There were no differences for any measured variables during WE trials. In contrast, RE (MIN = 2.95 ± 0.28 vs. TRD = 3.04 ± 0.30 L/min; p = .003: Cohen's d = 0.32), respiratory exchange ratio (p < .001), and perceptual measures (p < .05) were all improved while wearing MIN. Practitioner summary: In trained men, 1000 g/pair minimalist style boots (MIN) resulted in improvements of approximately 3% and 5% for running economy and respiratory exchange ratio versus 1600 g/pair traditional boots while wearing a 16 kg kit. Perceptual responses, including comfort, also favoured MIN. These effects were not found at walking pace. Abbreviations: MIN: minimalist style boots; TRD: traditional style boots; RE: running economy; WE: walking economy; ES: effect size; RER: respiratory exchange ratio; HR: heart rate.

Effects of Metatarsal Work Boots on Gait During Level and Inclined Walking

Footwear plays an important role in worker safety. Work boots with safety toes are often utilized at mine sites to protect workers from hazards. Increasingly, mining operations require metatarsal guards in addition to safety toe protection in boots. While these guards provide additional protection, the impact of metatarsal guards on gait are unknown. This study aimed to measure the effects of 4 safety work boots, steel toe, and steel toe with metatarsal protection in wader- and hiker-style boots, on level and inclined walking gait characteristics, during ascent and descent. A total of 10 participants completed this study. A motion capture system measured kinematics that allowed for the calculation of key gait parameters. Results indicated that gait parameters changed due to incline, similar to previous literature. Wader-style work boots reduced ankle range of motion when ascending an incline. Hip, knee, and ankle ranges of motion were also reduced during descent for this style of boot. Wader-style boots with metatarsal guards led to the smallest ankle range of motion when descending an inclined walkway. From these results, it is likely that boot style affects gait parameters and may impact a miner's risk for slips, trips, or falls.

Effect of shaft stiffness and sole flexibility on perceived comfort and the plantar pressures generated when walking on a simulated underground coal mining surface

The structural features of work boots worn by underground coal miners affect comfort, foot motion and, in turn, loading of the plantar surface of miners' feet. Although shaft stiffness and sole flexibility appear to be boot design features that could influence perceived comfort and plantar pressures, no study has systematically altered these boot design features to truly understand how they affect these parameters. This study aimed to systematically investigate the effect of changes to shaft stiffness and sole flexibility on perceived comfort and plantar pressures when 20 males walked on a simulated gravel coal mining surface under four different work boot conditions. There were no significant effects of shaft stiffness or sole flexibility on perceived comfort. However, shaft stiffness and sole flexibility each significantly affected the plantar pressures generated under the medial midfoot, heel, middle metatarsals and hallux and, in combination, affected plantar pressures generated beneath the lateral midfoot, medial and lateral metatarsals and lesser toes. Participants preferred a boot with a flexible shaft combined with a stiff sole, citing properties such as fit, moveability, walking effort and support to explain why they perceived one boot as more comfortable than another. We therefore recommend that underground coal mining work boots should be designed to incorporate different flexibility and stiffness between the shaft and sole of the boot to optimise foot movement and, in turn, walking efficiency.

Effect of work boot shaft stiffness and sole flexibility on lower limb muscle activity and ankle alignment at initial foot-ground contact when walking on simulated coal mining surfaces: Implications for reducing slip risk

Design features of safety work boots have the potential to influence how underground coal miners' feet interact with the challenging surfaces they walk on and, in turn, their risk of slipping. Despite the importance of work boot design in reducing the risk of miners slipping, limited research has investigated how boot design features, such as shaft stiffness and sole flexibility, affect the way miners walk. Therefore, this study aimed to investigate the effects of systematic variations to boot shaft stiffness and sole flexibility on lower limb muscle activity and ankle motion in preparation for initial foot-ground contact when 20 males walked across two simulated coal mining surfaces under four mining boot conditions. It was concluded that a boot which has different flexibility and stiffness between the shaft and sole is a better design option to reduce underground coal miners' slip risk than a boot that has a stiff shaft and stiff sole or flexible shaft and flexible sole.

The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism

BACKGROUND

Ankle sprains are a common orthopedic injury in military populations, which may be attributed to occupational demands and footwear. Minimalist military boots have become popular, but their influence on ground reaction force (GRF) attenuation capabilities during an ankle inversion perturbation are unknown. Therefore, the purpose of this study was to examine potential differences in GRFs during an ankle inversion perturbation in a standard issue (STN) and minimalist military boot (MIN) before and after a simulated military workload.

METHODS

Twenty-one healthy adult males completed an ankle inversion perturbation protocol in each footwear condition before and after an incremental treadmill exercise protocol to volitional exhaustion while wearing a 16kg rucksack. The ankle inversion perturbation protocol consisted of stepping down from a 27cm box onto a force platform with a fulcrum (FUL), which created 25° of inversion upon landing, or flat (FLT) outer sole attached to the plantar aspect of the participants' footwear in random order. Peak vertical, anterior/posterior, and medial/lateral components of the GRF during FUL and FLT conditions were assessed, normalized to multiples of body weight in each footwear. Dependent variables were then analyzed using separate 2 (footwear)×2 (time) repeated measures ANOVA (p<0.05).

RESULTS

The MIN footwear demonstrated significantly greater vertical GRF and significantly less medial GRF during the FUL condition.

CONCLUSIONS

These results indicate that various mechanical and design characteristics of military footwear may influence GRF attenuation capabilities and ankle joint loading when the foot/ankle complex is forced into inversion.

Gait characteristics in women's safety shoes

Although workers in Japan are required to wear safety footwear, there is concern about occupational accidents that occur when wearing safety shoes. This study aimed to analyze the effect of wearing hardsoled safety shoes on both spatiotemporal gait characteristics and the muscle activity in the lower extremities. Seventeen young women participated in this study. A 5-m gait trial and a surface electromyography trial were conducted while the women walked in either safety shoes or sports shoes. Paired t-tests were performed to analyze the differences in gait characteristics when walking in the two different pairs of shoes. Walking in safety shoes was associated with a significant increase in vastus lateralis, biceps femoris and tibialis anterior activity. This increased muscle activity in the lower extremities is likely compensating for the lower flexibility of the safety shoes.