Influence of foot, leg and shoe characteristics on subjective comfort

Fit of fire boots: exploring internal morphology using computed tomography

Fit of fire boots is a crucial factor in the safety and performance of firefighters on the hostile fireground. Firefighters have reported that ill-fitting fire boots restrict their lower body movement and sometimes cause very dangerous situations by falling off behind the wearer. By using computed tomography, this study demonstrates the potential to quantify and visualize the fit of fire boots, which previously relied on subjective feedback from the wearers. The high-resolution three-dimensional (3D) models of two fire boot products allowed a detailed observation and measurement of the internal space of the boots. Also, the boot's internal dimension was compared to the foot measurement of local firefighters, showing the significant differences between the two boots. Lastly, simulation wrapping the 3D scanned foot with the boot revealed large void spaces around the toe box and ankle, as well as the narrower ball width of the boot than the foot.

Towards functionally individualised designed footwear recommendation for overuse injury prevention: a scoping review

Injury prevention is essential in running due to the risk of overuse injury development. Tailoring running shoes to individual needs may be a promising strategy to reduce this risk. Novel manufacturing processes allow the production of individualised running shoes that incorporate features that meet individual biomechanical and experiential needs. However, specific ways to individualise footwear to reduce injury risk are poorly understood. Therefore, this scoping review provides an overview of (1) footwear design features that have the potential for individualisation; and (2) the literature on the differential responses to footwear design features between selected groups of individuals. These purposes focus exclusively on reducing the risk of overuse injuries. We included studies in the English language on adults that analysed: (1) potential interaction effects between footwear design features and subgroups of runners or covariates (e.g., age, sex) for running-related biomechanical risk factors or injury incidences; (2) footwear comfort perception for a systematically modified footwear design feature. Most of the included articles (n = 107) analysed male runners. Female runners may be more susceptible to footwear-induced changes and overuse injury development; future research should target more heterogonous sampling. Several footwear design features (e.g., midsole characteristics, upper, outsole profile) show potential for individualisation. However, the literature addressing individualised footwear solutions and the potential to reduce biomechanical risk factors is limited. Future studies should leverage more extensive data collections considering relevant covariates and subgroups while systematically modifying isolated footwear design features to inform footwear individualisation.

What do male netball players want in their footwear? Design recommendations for netball-specific shoes for men

With the increasing professionalisation of men's netball and the high prevalence of foot-related problems and pain, manufacturers must develop shoes with the correct ergonomic design to meet the unique needs of male netball players. This study aimed to determine what factors men consider when selecting a netball-specific shoe and what design features they want in an ideal netball-specific shoe. 279 amateur, sub-elite and elite male netball players completed a 38-question online survey about their footwear habits and preferences. Support was the most influential factor when men selected a netball-specific shoe. A wider toe-box, more durable upper and outsole, and added cushioning and support in the midsole and insole were preferred fit, form and function features for an ideal netball-specific shoe. We recommend that manufacturers develop a range of netball-specific shoes based on the foot dimensions, playing demands and preferences of male netball players to meet men's fit and functionality requirements.

The Foot and Ankle in Ultramarathon Runners: Results of the Ultrarunners Longitudinal TRAcking (ULTRA) Study

Background

The foot and ankle play a critical role in ultramarathon running. Because foot and ankle injuries are the most common location of injury in this group, proper care is essential for prevention. In this sport, small issues can become big problems over such long distances, and understanding the preventative measures taken by ultramarathon runners may provide insight for other athletes looking to avoid similar problems. The purpose of this study was to examine the routine and preventative care of the foot and ankle, as well as injury rates, in this group of high-risk athletes.

Methods

The Ultrarunners Longitudinal TRAcking (ULTRA) Study is the largest known prospective longitudinal study of ultramarathon runners. In this portion of the study, participants reported general health status, running behavior and performance, as well as foot and ankle care, injuries, stretching frequency, and shoewear.

Results

A total of 734 ultramarathon runners participated in the study. This group ran a median of 40.2 km per week. Overall, 71.2% of active ultramarathon runners reported a foot or ankle injury in the previous 12 months. The most common injuries reported were plantar fasciitis (36.3%), Achilles tendinitis (24.0%), nonspecific foot pain (14.0%), and stress fractures (13.4%). Sit and reach flexibility test showed that 63.7% of runners could not reach past their toes. There were no significant correlations for sit and reach flexibility or stretching frequency with injury rate.

Conclusion

The high prevalence of foot and ankle injuries in ultramarathon runners does not appear to be influenced by arch type, foot strike pattern, orthotic usage, stretching behavior, or actual flexibility. A high percentage of the study runners used comfort as a shoe selection method, independent of alignment or foot strike pattern. These findings guide the clinician in shared decision making with runners about routine care, including injury prevention and shoe selection.

Level of Evidence

Level II, prospective study.

Assessing the Subjective Effectiveness of Sensorimotor Insoles (SMIs) in Reducing Pain: A Descriptive Multicenter Pilot Study

This pilot study aimed to investigate the use of sensorimotor insoles in pain reduction, different orthopedic indications, and the wearing duration effects on the development of pain. Three hundred and forty patients were asked about their pain perception using a visual analog scale (VAS) in a pre-post analysis. Three main intervention durations were defined: VAS_post: up to 3 months, 3 to 6 months, and more than 6 months. The results show significant differences for the within-subject factor "time of measurement", as well as for the between-subject factor indication (p < 0.001) and worn duration (p < 0.001). No interaction was found between indication and time of measurements (model A) or between worn duration and time of measurements (model B). The results of this pilot study must be cautiously and critically interpreted, but may support the hypothesis that sensorimotor insoles could be a helpful tool for subjective pain reduction. The missing control group and the lack of confounding variables such as methodological weaknesses, natural healing processes, and complementary therapies must be taken into account. Based on these experiences and findings, a RCT and systematic review will follow.

Evaluating footwear "in the wild": Examining wrap and lace trail shoe closures during trail running

Trail running participation has grown over the last two decades. As a result, there have been an increasing number of studies examining the sport. Despite these increases, there is a lack of understanding regarding the effects of footwear on trail running biomechanics in ecologically valid conditions. The purpose of our study was to evaluate how a Wrap vs. Lace closure (on the same shoe) impacts running biomechanics on a trail. Thirty subjects ran a trail loop in each shoe while wearing a global positioning system (GPS) watch, heart rate monitor, inertial measurement units (IMUs), and plantar pressure insoles. The Wrap closure reduced peak foot eversion velocity (measured via IMU), which has been associated with fit. The Wrap closure also increased heel contact area, which is also associated with fit. This increase may be associated with the subjective preference for the Wrap. Lastly, runners had a small but significant increase in running speed in the Wrap shoe with no differences in heart rate nor subjective exertion. In total, the Wrap closure fit better than the Lace closure on a variety of terrain. This study demonstrates the feasibility of detecting meaningful biomechanical differences between footwear features in the wild using statistical tools and study design. Evaluating footwear in ecologically valid environments often creates additional variance in the data. This variance should not be treated as noise; instead, it is critical to capture this additional variance and challenges of ecologically valid terrain if we hope to use biomechanics to impact the development of new products.

Ten questions in sports engineering: technology in elite women’s football

The use of technology in football is increasing, although, products predominantly focus on men’s football in performance, safety, comfort, and fit considerations. A recent scoping review identified just 32 published scientific articles on technology in women’s football, despite demands of those playing/working in the women’s game increasing. We wish to highlight the progressions made so far and barriers remaining in the elite women’s football technology to shed a light on this topic and prod researchers and manufacturers to help support the evolution of women’s-football-focussed technological considerations. The ten questions presented in this paper address the generic question on whether women’s specific tailoring is needed (Question 1) as well as addressing specific questions on football technology and engineering, such as the progressions made and ongoing issues in the following areas: football kits, religious considerations (hijab designs), sports bras, football boots, balls, football pitches, performance tracking devices, menstrual cycle tracking devices (Question 2–10). It is evidence that certain areas have received more attention than others and with these ten questions we hope to steer readers towards research and engineering gaps for future work.

Novel testing system to determine shoe mechanical properties

BACKGROUND

Shoes play an important role in ankle foot orthosis (AFO) function and alignment. Despite this, shoe mechanical testing systems are rarely colocated with gait analysis systems, limiting their availability and use during AFO-related studies.

OBJECTIVE

The purpose of this study was to evaluate a novel mechanical testing system used to measure shoe heel stiffness and change in height with loading using equipment available in most gait analysis laboratories. The novel testing system will allow for shoe assessment during AFO studies at little additional cost.

STUDY DESIGN

Shoes were tested to determine initial stiffness, terminal stiffness, and total stiffness, and whether these measures changed with repeated compressions (early vs. late).

TECHNIQUE

The novel testing system consists of a baseplate for counterweights, uprights that support a low-friction hinge, and a lever arm with a heel-shaped indenter to apply force to the shoe. Minimal detectable change values were calculated using the standard error of measurement. Intraclass correlation coefficients were calculated in SPSS using a (2, k) model.

RESULTS

No significant differences in mean values, or interactions, were observed between rounds of testing and early and late compressions (P > .05). Intraclass correlation coefficient values were greater than 0.98, and minimal detectable change values were less than 20% of the average for each measure.

CONCLUSIONS

The novel mechanical testing system, combined with pre-existing gait analysis equipment, can be used to reliably assess shoe stiffness and change in height.

Design Methodology and Technology of Textile Footwear

Material selection is an important stage in the design of footwear, which determines not only its appearance, but also the comfort of use. The paper presents the methodology for the design of sports textile footwear manufactured by innovative hybrid technology. The upper part of the footwear, designed in CAD and a graphics program, consisted of two elements. Both of them were characterized by a three-layer knitted and embroidered structure. The air permeability and thermal insulation parameters were determined for each layer and for the whole package. The conducted tests demonstrated that the openwork spacer knitted fabric, as a component of the package, increased the air circulation inside the footwear as well as improved the heat transfer outside.

Contemporary Review: The Foot and Ankle in Long-Distance Running

Distance runners represent a unique patient population. The cyclic activity associated with distance running leads to a high incidence of injury. Gait patterns, the extrinsic and intrinsic muscles of the foot and ankle, foot strike pattern, shoe wear considerations, alignment, and orthotics are also all important considerations that must be considered by the treating provider. The purpose of this work is to review relevant functional anatomy, recent studies on gait patterns in running, orthotics, and theory on how the body moves through space during running in order to better equip the clinician to treat long distance runners.

Footwear comfort: a systematic search and narrative synthesis of the literature

OBJECTIVE

To provide a narrative synthesis of the research literature pertaining to footwear comfort, including definitions, measurement scales, footwear design features, and physiological and psychological factors.

METHODS

A systematic search was conducted which yielded 101 manuscripts. The most relevant manuscripts were selected based on the predetermined subheadings of the review (definitions, measurement scales, footwear design features, and physiological and psychological factors). A narrative synthesis of the findings of the included studies was undertaken.

RESULTS

The available evidence is highly fragmented and incorporates a wide range of study designs, participants, and assessment approaches, making it challenging to draw strong conclusions or implications for clinical practice. However, it can be broadly concluded that (i) simple visual analog scales may provide a reliable overall assessment of comfort, (ii) well-fitted, lightweight shoes with soft midsoles and curved rocker-soles are generally perceived to be most comfortable, and (iii) the influence of sole flexibility, shoe microclimate and insoles is less clear and likely to be more specific to the population, setting and task being performed.

CONCLUSION

Footwear comfort is a complex and multifaceted concept that is influenced not only by structural and functional aspects of shoe design, but also task requirements and anatomical and physiological differences between individuals. Further research is required to delineate the contribution of specific shoe features more clearly, and to better understand the interaction between footwear features and individual physiological attributes.

Relationship of footwear comfort, selected size, and lower leg overuse injuries among infantry soldiers

BACKGROUND

High rates of musculoskeletal injuries such as plantar fasciitis and stress fractures have been observed among physically active military personnel. During service time, infantry soldiers use issued boots daily that should fit well and provide comfort to prevent injuries and decrease lower extremity pain effectively. The association of military boot comfort with overuse injuries remains unclear. This study investigates the relationship between the chosen military boot size, perceived boot comfort and lower leg overuse injury.

METHODS

During the cross-sectional study, 227 (males, n = 213; females, n = 14) active-duty infantry soldiers at a mean age of 29.5 years old, and with an average service time of 7.2 years were assessed for a history of overuse injury, footprint length, appropriate shoe size, and footwear comfort. Males with a history of overuse injury (n = 32) and non-injured age-matched controls (n = 34) were selected for detailed testing and establishing the possible relationship between footwear comfort and lower leg overuse injury.

RESULTS

No relationship was found between footwear comfort and a history of lower leg overuse injury. N = 38 (57.6%) of study subjects were wearing an inappropriate shoe size daily. Inappropriate shoe size usage affected footwear comfort ratings significantly.

CONCLUSIONS

Study results showed that improper boot size was significantly related to comfort ratings but was not associated with a history of lower leg overuse injury.

Gait Retraining With Visual Biofeedback Reduces Rearfoot Pressure and Foot Pronation in Recreational Runners

CONTEXT

Running is a popular sport globally. Previous studies have used a gait retraining program to successfully lower impact loading, which has been associated with lower injury rates in recreational runners. However, there is an absence of studies on the effect of this training program on the plantar pressure distribution pattern during running.

OBJECTIVE

To investigate the short-term effect of a gait retraining strategy that uses visual biofeedback on the plantar pressure distribution pattern and foot posture in recreational runners.

DESIGN

Randomized controlled trial.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Twenty-four recreational runners were evaluated (n = 12 gait retraining group and n = 12 control group).

INTERVENTION

Those in the gait retraining group underwent a 2-week program (4 sessions/wk, 30 min/session, and 8 sessions). The participants in the control group were also invited to the laboratory (8 times in 2 wk), but no feedback on their running biomechanics was provided.

MAIN OUTCOME MEASURES

The primary outcome measures were plantar pressure distribution and plantar arch index using a pressure platform. The secondary outcome measure was the foot posture index.

RESULTS

The gait retraining program with visual biofeedback was effective in reducing medial and lateral rearfoot plantar pressure after intervention and when compared with the control group. In the static condition, the pressure peak and maximum force on the forefoot and midfoot were reduced, and arch index was increased after intervention. After static training intervention, the foot posture index showed a decrease in the foot pronation.

CONCLUSIONS

A 2-week gait retraining program with visual biofeedback was effective in lowering rearfoot plantar pressure, favoring better support of the arch index in recreational runners. In addition, static training was effective in reducing foot pronation. Most importantly, these observations will help healthcare professionals understand the importance of a gait retraining program with visual biofeedback to improve plantar loading and pronation during rehabilitation.

Physical performance and perception of foot discomfort during a soccer-specific match simulation. A comparison of football boots

Football boots are marketed with emphasis on a single key performance characteristic (e.g. speed). Little is known on how design parameters impact players' performance. This study investigated the impact of boot design on performance maintenance and perceived foot comfort during a 90-minute match simulation drill. Eleven male university football players tested two commercially available "sprint boots" known to generate significantly different plantar pressures (high=Boot H and low=Boot L) . Players completed a modified Soccer-specific Aerobic Field Test on a 3G pitch. Heart rate, rated perceived exertion and perceived foot discomfort were assessed for each 15-min interval. Power generation was assessed pre- and post-match simulation. A significantly higher mean heart rate was seen for Boot L in the 60th-75th and 75th-90th minute intervals (P = 0.017, P = 0.012 respectively). Perceived exertion did not differ between boots (P ≥ 0.302). Power generation significantly decreased in Boot H between pre- and post-match (P = 0.042). Both boots increased discomfort with significantly more plantar discomfort felt in the last 30 min in Boot H (75th min: P = 0.037; 90th min: P = 0.048). The results imply that a comfortable boot design may improve maintenance of performance during match-play.

Development and evaluation of a dual density insole for people standing for long periods of time at work

BACKGROUND

Appropriate footwear is important for those who stand for prolonged periods of time at work, enabling them to remain comfortable, healthy and safe. Preferences for different footwear cushioning or hardness are often person specific and one shoe or insole will not be the choice for all. The aim of this study was to develop a range of insole options to maintain comfort during long periods of standing at work and test insole material preferences in the workplace.

METHODS

The study consisted of two parts. Part one evaluated 9 insoles of the same geometry that varied in hardness under 2 different plantar regions (n = 34). Insole preference, plantar pressure and selected anthropometric foot measures were taken. Three insole designs based on the most preferred options were identified from this part. In part two, these three insoles were evaluated with 22 workers immediately after trying them on (1 min) and after a working day. Foot anthropometric measures and subjective questions concerning material hardness preferences and self-reported foot characteristics were used to investigate whether either had a relationship with insole preference.

RESULTS

Part one found insole preference predominantly varied according to material hardness under the medial arch rather than the heel/forefoot. Softer material under the heel and forefoot was associated with a reduction in peak pressures in these regions (p < 0.05). The most preferred insole had lower pressures under the hallux and first metatarsal phalangeal joint, and greater pressures and contact area under the medial midfoot (p < 0.05) compared to the least preferred insole. Height and foot anthropometrics were related to insole preference. In part two, under real world conditions, insole preference changed for 65% of participants between the immediate assessment (1 min) and after a whole workday, with dorsum height related to the latter (p < 0.05). Subjective questions for self-assessed arch height and footwear feel identified 66.7% of the insole preferences after 1 day at work, compared to 36% using immediate assessment of insole preference.

CONCLUSION

Preference for material hardness varies underneath the medial arch of the foot and is time dependent. Simple foot measures and questions about comfort can guide selection of preferred insoles.

Acute effect of engineered thermoplastic polyurethane elastomer knockoff running footwear on foot loading and comfort during heel-to-toe running

BACKGROUND

Better midsole materials and comfort have been incorporated into more expensive shoes and are popular with runners. Consequently, knockoff running shoes are currently widely distributed in the Chinese market and and cost only 30%-50% of the total price of genuine branded products.

RESEARCH QUESTION

Uncertainty exists concerning the beneficial effects of advanced shoe material application in decreasing foot loading or impact force during running. Additionally, using comfort as a criterion to identify genuine branded running shoes may exclude brand factor.

METHODS

Fifteen healthy male volunteers were asked to perform two different tests, including running and a comfort evaluation. Each participant was asked to identify which footwear was the Adidas brand shoe based on their perception of comfort.

RESULTS

Time to the first peak of the vertical ground reaction force occurred significantly later when subjects wore the genuine branded shoe compared to knockoff shoe 1 (p = 0.003) and knockoff shoe 2 (p = 0.015) footwea. The genuine branded shoe (p = 0.005) and knockoff shoe 1 (p = 0.029) were significantly more comfortable compared to the knockoff shoe 2. Only four subjects selected the genuine branded shoe, whereas six subjects selected both the genuine branded shoe and knockoff shoe 1.

SIGNIFICANCE

Knockoff running footwear significantly increases impact loading compared to the genuine branded product, thereby posing greater risk of running injury.

Influence of forefoot bending stiffness on American football performance and metatarsophalangeal joint bending angle

Changes in forefoot bending stiffness have been shown to affect metatarsophalangeal peak bending angles as well as athletic performance. Increasing bending stiffness tends to reduce peak bending angles, which could potentially reduce hyperextension injuries such as turf toe. Limited information is available, however, on the efficacy of increasing forefoot bending stiffness on large-sized athletes such as those that participate in American Football, with prior studies being conducted on smaller athlete populations. Therefore, the purpose of this study was to determine the influence of increased forefoot bending stiffness on metatarsophalangeal joint extension and athletic performance of grid-iron football players. Ten varsity grid-iron football players performed four National Football League combine movements in a motion capture laboratory in three footwear conditions of varying bending stiffness: Soft (12.7 N/mm), Control (23.8 N/mm), Stiff (42.2 N/mm). None of the footwear conditions significantly altered the maximum metatarsophalangeal bending. Therefore, to reduce metatarsophalangeal hyperextension injuries in American football players a greater amount of forefoot bending stiffness may be required. Performance differences were present only during the five-metre sprint acceleration, with athletes having an improved performance in the Control and Stiff conditions. This improved performance was due to an increased horizontal impulse and improvements in power generation at the ankle joint.

Does enhanced footwear comfort affect oxygen consumption and running biomechanics?

Comfort as an essential parameter for running footwear is gaining importance in footwear research and development, and has also been proposed to decrease injury rate and improve metabolic demand in the paradigm of the comfort filter. The aims of this study were to determine differences in oxygen consumption and biomechanical variables associated with lower extremity injuries in response to running shoes of differing comfort. Fifteen male runners attended two testing sessions including an incremental lactate threshold test, a comfort assessment and treadmill running trials for the biomechanical and physiological measurements. Statistical analyses were performed on oxygen consumption, spatio-temporal variables including foot-ground angle and coupling angle variability of 12 couplings in five stride phases. No decrease in oxygen consumption was found in the most preferred shoe condition. Investigation of potential biomechanical contributors to changes in metabolic demands revealed differences in the stride rate between the most and least preferred condition. In coupling angle variability analyses, only one coupling (ankle dorsiflexion/plantarflexion to knee varus/valgus) yielded a significant difference between conditions in the phase including the touch down. Based on the findings of this study, previous suggestions regarding positive effects of enhanced footwear comfort during running cannot be supported - neither on economy nor on injury prevention perspective. However, a prospective study of lower extremity injury combined with measurements of biomechanical and physiological variables seems to be required for a definite support or contradiction of the comfort filter.

Effects of a footwear intervention on foot pain and disability in people with gout: a randomised controlled trial

BACKGROUND

There is limited evidence supporting the long-term effect of a foot care package that includes footwear for people with gout. The aim of this study was to investigate the effectiveness of a footwear intervention on foot pain and disability in people with gout over 6 months.

METHODS

Participants with gout (n = 94) were randomly allocated to either a control group (podiatric care and gout education) or footwear intervention group (podiatric care and gout education plus a commercially available athletic shoe). Measurements were undertaken at baseline and 2, 4, and 6 months. Primary outcome was foot pain severity. Secondary outcomes were overall pain, foot impairment/disability, footwear comfort, fit, ease and weight. Data were analysed using repeated measures models.

RESULTS

Baseline foot pain scores were low, and no differences in foot pain scores were observed between groups over 6 months (adjusted effect estimate: - 6.7, 95% CI - 16.4 to 2.9, P = 0.17). Improvements between groups in overall pain scores (adjusted effect estimate: - 13.2, 95% CI - 22.2 to - 4.3, P < 0.01) and foot impairment/disability scores (- 4.7, 95% CI - 9.1 to - 0.3, P = 0.04) favouring the footwear intervention were observed at 2 months, but not at 4 or 6 months. Improvements between groups in footwear fit (adjusted effect estimate: - 11.1, 95% CI - 21.1 to - 1.0, P = 0.03), ease (- 13.2, 95% CI - 23.8 to - 2.7, P = 0.01) and weight (- 10.3, 95% CI - 19.8 to - 0.8, P = 0.03) favouring the footwear intervention were also observed over 6 months. Similar improvements were observed for footwear comfort at 2 and 4 months. No other differences in secondary outcomes measured were observed at 6 months (P > 0.05).

CONCLUSIONS

Addition of footwear to a foot care package did not improve foot pain in people with gout. Short-term improvements in overall pain and foot impairment/disability and more durable improvements in footwear comfort and fit were observed with the footwear intervention.

TRIAL REGISTRATION

ACTRN12614000209695. Registered 27 February 2014, http://www.anzctr.org.au/TrialSearch.aspx?searchTxt=ACTRN12614000209695&isBasic=True.

How do we fit underground coal mining work boots?

Acceptable footwear fit, particularly width, is subjective and vaguely quantified. Proper shoe fit is important because it affects both comfort and the potential to prevent injury. Although mismatches between the feet of underground coal miners and their internal boot dimensions are known, no research has been undertaken to determine the impact of these mismatches on worker perceptions of fit, comfort and pain. This study aimed to quantitatively assess mining work boot fit relative to underground coal miners' subjectively rated work boot fit and comfort, reported foot problems, lower limb pain and lower back pain in order to develop evidence-based work boot fit recommendations. Traditional footwear fitting methods based predominantly on foot length are insufficient for underground coal mining-specific footwear. Instead, fit at the heel, instep and forefoot must be considered when fitting underground coal mining work boots, in conjunction with the traditional length measurement.Practitioner summary: Underground coal miners report their work boots fit but are uncomfortable. This study assessed actual fit relative to perceived fit, comfort, foot problems, lower limb pain and lower back pain of 197 miners. Fit at the heel, instep and forefoot must be considered when fitting mining work boots.

Comfort assessment of running footwear: Does assessment type affect inter-session reliability?

Assessing comfort of running footwear reliably is challenging. The purpose of this study was to compare the intra-rater reliability between different assessment types, to calculate intra-individual reliability scores and to evaluate the effect of rater selection based on individual reliability scores on group level reliability. Three assessment types: ranking, Visual Analogue Scale (VAS), and Likert Scale (LS) were provided twice in six separate sessions among 30 participants, who assessed comfort of five shoes after treadmill running. Spearman's rho provided an evaluation of inter-session relative reliability and typical error as a measure of absolute reliability for each assessment type. Ranking (r = 0.70, 95% confidence interval [CI] 0.61-0.78) yielded the highest relative reliability for overall comfort, followed by VAS (r = 0.67, 95% CI 0.56-0.75) and LS (r = 0.63, 95% CI 0.52-0.72), with large-scale overlaps of CIs between assessment types. The same order of assessment types was found for the percentage of reliable raters (r ≥ 0.7) with 60% in ranking scale, 47% in VAS and 37% in LS. Forming subgroups corresponding to the intra-individual reliability substantially increased group level reliabilities. Based on measures of relative reliability, an extreme reduction in resolution as provided by the ranking from pairwise comparisons seems to be a valuable tool in footwear comfort assessments if assessment time is of minor importance. No preference can be provided for the two investigated rating scales. Besides the assessment type, a selection of the best raters in additional reliability checks seems to be a prerequisite for further comfort-related studies.

The three-dimensional shapes of underground coal miners' feet do not match the internal dimensions of their work boots

Mining work boots provide an interface between the foot and the ground, protecting and supporting miners' feet during lengthy coal mining shifts. Although underground coal miners report the fit of their work boots as reasonable to good, they frequently rate their boots as uncomfortable, suggesting that there is a mismatch between the shape of their feet and their boots. This study aimed to identify whether dimensions derived from the three-dimensional scans of 208 underground coal miners' feet (age 38.3 ± 9.8 years) differed from the internal dimensions of their work boots. The results revealed underground coal miners wore boots that were substantially longer than their feet, possibly because boots available in their correct length were too narrow. It is recommended boot manufacturers reassess the algorithms used to create boot lasts, focusing on adjusting boot circumference at the instep and heel relative to increases in foot length. Practitioner Summary: Fit and comfort ratings suggest a mismatch between the shape of underground coal miners' feet and their boots exists. This study examined whether three-dimensional scans of 208 miners' feet differed from their boot internal dimensions. Miners wore boots substantially longer than their feet, possibly due to inadequate width.

Segmented Forefoot Plate in Basketball Footwear: Does it Influence Performance and Foot Joint Kinematics and Kinetics?

This study examined the effects of shoes' segmented forefoot stiffness on athletic performance and ankle and metatarsophalangeal joint kinematics and kinetics in basketball movements. Seventeen university basketball players performed running vertical jumps and 5-m sprints at maximum effort with 3 basketball shoes of various forefoot plate conditions (medial plate, medial + lateral plates, and no-plate control). One-way repeated measures ANOVAs were used to examine the differences in athletic performance, joint kinematics, and joint kinetics among the 3 footwear conditions (α = .05). Results indicated that participants wearing medial + lateral plates shoes demonstrated 2.9% higher jump height than those wearing control shoes (P = .02), but there was no significant differences between medial plate and control shoes (P > .05). Medial plate shoes produced greater maximum plantar flexion velocity than the medial + lateral plates shoes (P < .05) during sprinting. There were no significant differences in sprint time. These findings implied that inserting plates spanning both the medial and lateral aspects of the forefoot could enhance jumping, but not sprinting performances. The use of a medial plate alone, although induced greater plantar flexion velocity at the metatarsophalangeal joint during sprinting, was not effective in improving jump heights or sprint times.

An explorative qualitative study to determine the footwear needs of workers in standing environments

Background

Many work places require standing for prolonged periods of time and are potentially damaging to health, with links to musculoskeletal disorders and acute trauma from workplace accidents. Footwear provides the only interaction between the body and the ground and therefore a potential means to impact musculoskeletal disorders. However, there is very limited research into the necessary design and development of footwear based on both the physical environmental constraints and the personal preference of the workers. Therefore, the purpose of this study was to explore workers needs for footwear in the ‘standing’ workplace in relation to MSD, symptoms, comfort and design.

Method

Semi-structured interviews were conducted with participants from demanding work environments that require standing for high proportions of the working day. Thematic analysis was used to analyse the results and gain an exploratory understanding into the footwear needs of these workers.

Results

Interviews revealed the environmental demands and a very high percentage of musculoskeletal disorders, including day to day discomfort and chronic problems. It was identified that when designing work footwear for standing environments, the functionality of the shoe for the environment must be addressed, the sensations and symptoms of the workers taken into account to encourage adherence and the decision influencers should be met to encourage initial footwear choice. Meeting all these criteria could encourage the use of footwear with the correct safety features and comfort. Development of the correct footwear and increased education regarding foot health and footwear choice could help to reduce or improve the effect of the high number of musculoskeletal disorders repeatedly recorded in jobs that require prolonged periods of standing.

Conclusion

This study provides a unique insight into the footwear needs of some workers in environments that require prolonged standing. This user based enquiry has provided information which is important to workplace footwear design.

Effects of forefoot bending stiffness of badminton shoes on agility, comfort perception and lower leg kinematics during typical badminton movements

This study investigated whether an increase in the forefoot bending stiffness of a badminton shoe would positively affect agility, comfort and biomechanical variables during badminton-specific movements. Three shoe conditions with identical shoe upper and sole designs with different bending stiffness (Flexible, Regular and Stiff) were used. Elite male badminton players completed an agility test on a standard badminton court involving consecutive lunges in six directions, a comfort test performed by a pair of participants conducting a game-like practice trial and a biomechanics test involving a random assignment of consecutive right forward lunges. No significant differences were found in agility time and biomechanical variables among the three shoes. The players wearing the shoe with a flexible forefoot outsole demonstrated a decreased perception of comfort in the forefoot cushion compared to regular and stiffer conditions during the comfort test (p < 0.05). The results suggested that the modification of forefoot bending stiffness would influence individual perception of comfort but would not influence performance and lower extremity kinematics during the tested badminton-specific tasks. It was concluded that an optimisation of forefoot structure and materials in badminton shoes should consider the individual's perception to maximise footwear comfort in performance.

Overall Preference of Running Shoes Can Be Predicted by Suitable Perception Factors Using a Multiple Regression Model

OBJECTIVE

This study examined (a) the strength of four individual footwear perception factors to influence the overall preference of running shoes and (b) whether these perception factors satisfied the nonmulticollinear assumption in a regression model.

BACKGROUND

Running footwear must fulfill multiple functional criteria to satisfy its potential users. Footwear perception factors, such as fit and cushioning, are commonly used to guide shoe design and development, but it is unclear whether running-footwear users are able to differentiate one factor from another.

METHODS

One hundred casual runners assessed four running shoes on a 15-cm visual analogue scale for four footwear perception factors (fit, cushioning, arch support, and stability) as well as for overall preference during a treadmill running protocol.

RESULTS

Diagnostic tests showed an absence of multicollinearity between factors, where values for tolerance ranged from .36 to .72, corresponding to variance inflation factors of 2.8 to 1.4. The multiple regression model of these four footwear perception variables accounted for 77.7% to 81.6% of variance in overall preference, with each factor explaining a unique part of the total variance.

CONCLUSION

Casual runners were able to rate each footwear perception factor separately, thus assigning each factor a true potential to improve overall preference for the users. The results also support the use of a multiple regression model of footwear perception factors to predict overall running shoe preference.

APPLICATION

Regression modeling is a useful tool for running-shoe manufacturers to more precisely evaluate how individual factors contribute to the subjective assessment of running footwear.

Assessment of Patterns and Variability in Lower Extremity Coordination Between Genders with Different Shoe Insole Stiffness During Jump-Landing Tasks

Purpose. The study aims to examine how shoe insole cushioning can influence coordination pattern and variability in males and females during the landing phase of a jump-landing task.

Methods. Twenty participants (10 males and 10 females) performed jump-landing tasks, and the continuous relative phase (CRP) and the variability of CRP in foot-shank and shank-thigh couplings were determined during the landing phase.

Results. Women represented lower CRP and CRP variability of foot-shank coupling in non-insole conditions (p < 0.05). Shoe insole stiffness had no significant effect on CRP or variability in CRP (p > 0.05).

Conclusions. Although females are characterised by lower coupling variability in non-insole conditions, they do have the capacity to achieve similar coordination patterns and variability as males, in soft and hard conditions. These findings suggest that with changes in the shoe insole, females can achieve similar joint coupling coordination patterns and variability as compared with males under soft and stiff conditions. In addition, as per this study, changes in shoe insole stiffness may not have an impact on coordinative strategies or variability of lower extremity joints couplings during landing.

The effect of foot orthoses with forefoot cushioning or metatarsal pad on forefoot peak plantar pressure in running

Background

Foot orthoses are frequently used in sports for the treatment of overuse complaints with sufficient evidence available for certain foot-related overuse pathologies like plantar fasciitis, rheumatoid arthritis and foot pain (e.g., metatarsalgia). One important aim is to reduce plantar pressure under prominent areas like metatarsal heads. For the forefoot region, mainly two common strategies exist: metatarsal pad (MP) and forefoot cushioning (FC). The aim of this study was to evaluate which of these orthosis concepts is superior in reducing plantar pressure in the forefoot during running.

Methods

Twenty-three (13 female, 10 male) asymptomatic runners participated in this cross-sectional experimental trial. Participants ran in a randomised order under the two experimental (MP, FC) conditions and a control (C) condition on a treadmill (2.78 ms⁻¹) for 2 min, respectively. Plantar pressure was measured with the in-shoe plantar pressure measurement device pedar-x®-System and mean peak pressure averaged from ten steps in the forefoot (primary outcome) and total foot was analysed. Insole comfort was measured with the Insole Comfort Index (ICI, sum score 0–100) after each running trial. The primary outcome was tested using the Friedman test (α = 0.05). Secondary outcomes were analysed descriptively (mean ± SD, lower & upper 95%-CI, median and interquartile-range (IQR)).

Results

Peak pressure [kPa] in the forefoot was significantly lower wearing FC (281 ± 80, 95%-CI: 246–315) compared to both C (313 ± 69, 95%-CI: 283–343; p = .003) and MP (315 ± 80, 95%-CI: 280–350; p = .001). No significant difference was found between C and MP (p = .858). Peak pressures under the total foot were: C: 364 ± 82, 95%-CI: 328–399; MP: 357 ± 80, 95%-CI: 326–387; FC: 333 ± 81 95%-CI: 298–368. Median ICI sum scores were: C 50, MP 49, FC 64.

Conclusions

In contrast to the metatarsal pad orthosis, the forefoot cushioning orthosis achieved a significant reduction of peak pressure in the forefoot of recreational runners. Consequently, the use of a prefabricated forefoot cushioning orthosis should be favoured over a prefabricated orthosis with an incorporated metatarsal pad in recreational runners with normal height arches.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-016-0176-z) contains supplementary material, which is available to authorized users.

A reliable measure of footwear upper comfort enabled by an innovative sock equipped with textile pressure sensors

Footwear comfort is essential and pressure distribution on the foot was shown as a relevant objective measurement to assess it. However, asperities on the foot sides, especially the metatarsals and the instep, make its evaluation difficult with available equipment. Thus, a sock equipped with textile pressure sensors was designed. Results from the mechanical tests showed a high linearity of the sensor response under incremental loadings and allowed to determine the regression equation to convert voltage values into pressure measurements. The sensor response was also highly repeatable and the creep under constant loading was low. Pressure measurements on human feet associated with a perception questionnaire exhibited that significant relationships existed between pressure and comfort perceived on the first, the third and the fifth metatarsals and top of the instep. Practitioner Summary: A sock equipped with textile sensors was validated for measuring the pressure on the foot top, medial and lateral sides to evaluate footwear comfort. This device may be relevant to help individuals with low sensitivity, such as children, elderly or neuropathic, to choose the shoes that fit the best.

Effects of indoor slippers on plantar pressure and lower limb EMG activity in older women

Open-toe mule slippers are popular footwear worn at home especially by older women. However, their biomechanical effects are still poorly understood. The objective of this study is to therefore evaluate the physical properties of two typical types of open-toe mule slippers and the changes in plantar pressure and lower limb muscle activity of older women when wearing these slippers. Five walking trials have been carried out by ten healthy women. The results indicate that compared to barefoot, wearing slippers results in significant increases in the contact area of the mid-foot regions which lead to plantar pressure redistribution from metatarsal heads 2-3 and the lateral heel to the midfoot regions. However, there is no significant difference in the selected muscle activity across all conditions. The findings enhance our understanding of slipper features associated with changes in biomechanical measures thereby providing the basis of slipper designs for better foot protection and comfort.

Can subjective comfort be used as a measure of plantar pressure in football boots?

Comfort has been shown to be the most desired football boot feature by players. Previous studies have shown discomfort to be related to increased plantar pressures for running shoes which, in some foot regions, has been suggested to be a causative factor in overuse injuries. This study examined the correlation between subjective comfort data and objective plantar pressure for football boots during football-specific drills. Eight male university football players were tested. Plantar pressure data were collected during four football-specific movements for each of three different football boots. The global and local peak pressures based on a nine-sectioned foot map were compared to subjective comfort measures recorded using a visual analogue scale for global discomfort and a discomfort foot map for local discomfort. A weak (r_s = -0.126) yet significant (P < 0.05) correlation was shown between the peak plantar pressure experienced and the visual analogue scale rated comfort. The model only significantly predicted (P > 0.001) the outcome for two (medial and lateral forefoot) of the nine foot regions. Subjective comfort data is therefore not a reliable measure of increased plantar pressures for any foot region. The use of plantar pressure measures is therefore needed to optimise injury prevention when designing studded footwear.

A Multi-Stage Human Factors and Comfort Assessment of Instrumented Insoles Designed for Use in a Connected Health Infrastructure

Wearable electronics are gaining widespread use as enabling technologies, monitoring human physical activity and behavior as part of connected health infrastructures. Attention to human factors and comfort of these devices can greatly positively influence user experience, with a subsequently higher likelihood of user acceptance and lower levels of device rejection. Here, we employ a human factors and comfort assessment methodology grounded in the principles of human-centered design to influence and enhance the design of an instrumented insole. A use case was developed and interrogated by stakeholders, experts, and end users, capturing the context of use and user characteristics for the instrumented insole. This use case informed all stages of the design process through two full design cycles, leading to the development of an initial version 1 and a later version 2 prototype. Each version of the prototype was subjected to an expert human factors inspection and controlled comfort assessment using human volunteers. Structured feedback from the first cycle of testing was the driver of design changes implemented in the version 2 prototype. This prototype was found to have significantly improved human factors and comfort characteristics over the first version of the prototype. Expert inspection found that many of the original problems in the first prototype had been resolved in the second prototype. Furthermore, a comfort assessment of this prototype with a group of young healthy adults showed it to be indistinguishable from their normal footwear. This study demonstrates the power and effectiveness of human factors and comfort assessment methodologies in influencing and improving the design of wearable devices.

Evolution of perceived footwear comfort over a prolonged running session

BACKGROUND

The purpose of this study was to investigate the subjective perception of overall footwear comfort over a prolonged running session.

METHODS

Ten runners performed two similar sessions consisting of a 13-km trail run (5 laps of 2.6 km) as fast as possible. The overall footwear comfort was evaluated before running and at the end of each lap with a 150-mm visual analogic scale, as well as speed, heart rate and rate of perceived exertion.

RESULTS

The results showed that both overall footwear comfort and speed decreased consistently during the run session, and significantly after 44 min of running (i.e. the 3rd lap). It could be hypothesized that the deterioration of overall footwear comfort was explained by mechanical and energetical parameter changes with time and/or fatigue occurring at the whole body, foot and footwear levels.

CONCLUSION

These results justify the use of a prolonged running test for running footwear comfort evaluation.