Effects of footwear on comfort and injury in professional rugby league

The effectiveness of customised 3D-printed insoles on perceived pain, comfort, and completion time among frequent Park Runners: Study protocol for a pragmatic randomised controlled trial (The ZOLES RCT)

BACKGROUND

Running, a popular recreational activity, often leads to the experience of pain and discomfort among participants impacting performance and participation longevity. The ZOLES trial evaluates customised 3D-printed insoles for reducing pain in frequent parkrunners aged 35 and over. An innovative process of foot-scanning and responses to questions relating to size, pain, discomfort, and previous medical conditions are combined leading to the production of personalised 3D-printed orthotics.

METHODS

The ZOLES trial is a pragmatic, outcome assessor blinded, randomised, controlled, superiority trial involving 200 recreational runners, randomised to receive either customised 3D-printed insoles (ZOLES) or to a "do-as-usual" control group. The study follows a robust protocol, ensuring adherence to established guidelines for clinical trials, and is based at St Mary's University, Twickenham, London. The primary outcome is change in running-related pain over a 10-week period, assessed using an 11-point Numeric Rating Scale. Secondary outcomes include overall pain and discomfort, running-related comfort, 5k-completion time, time-loss due to injuries, running exposure, and adherence to the intervention. A balanced-block randomisation process is stratified by sex and parkrun location, and an intention-to-treat analyses will be employed on all outcomes in the primary trial report. The trial includes a 52-week post-market surveillance to assess long-term effects of the customised insoles.

DISCUSSION

The ZOLES trial aims to provide insights into real-world applicability and effectiveness of customised 3D-printed insoles in reducing running-related pain and enhancing overall running experience. Despite the limitation of a subjective primary outcome measure without participant blinding, the methodological rigor, including external outcome assessment and data handling, we anticipate results that are academically credible and applicable in real-world settings The results of this trial may have important implications for runners, clinicians, and the sports footwear industry, as evidence for the use of individualised insoles to improve running experience and prevention of pain may become evident.

TRIAL REGISTRATION

The trial was pre-registered at ClinicalTrials.gov with the trial identifier NCT06034210 on September 4, 2023, and publicly posted on September 13, 2023 (https://clinicaltrials.gov/study/NCT06034210).

PROTOCOL VERSION

Version 1, September 27, 2023.

Acute Effects of Carbon Fiber Insole on Three Aspects of Sports Performance, Lower Extremity Muscle Activity, and Subjective Comfort

Carbon fiber insole (CFI), which is lightweight and stiff to reduce energy loss and help wearers perform better in sports, has recently been introduced. However, reports are scarce on the effects of CFI on sports performance, muscle activation, and wearing comfort. This study investigated the acute effects of CFI on sports performance, lower extremity muscle activity, and subjective comfort. Thirty young healthy males with shoe sizes between 260 and 270 mm performed various sports tasks (power generation, agility, and speed) and treadmill runs with wearable sensors under two experimental insole conditions (benchmark insole as a baseline, CFI). The results showed that, compared to the benchmark insole, CFI significantly improved sports performance in terms of power generation (~1.5%) and agility (~1%). However, it activated more of the Tibialis Anterior (~0.7%) and Gastrocnemius Medialis (~0.8%) muscles, and was perceived to be stiffer and less comfortable. These findings suggested that CFI could improve sports performance, but could cause more lower extremity muscle activation and subjective discomfort.

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.

Effectiveness of Insole Colour on Impact Loading and Lower-Limb Kinematics When Running at Preferred and Nonpreferred Speeds

While colour of red can play a significant role in altering human perception and performances, little is known about its perceptual-motor effect on running mechanics. This study examined the effects of variations in insole colours on impact forces, ankle kinematics, and trial-to-trial reliability at various running speeds. Sixteen male recreational runners ran on instrumented treadmill at slow (90%), preferred (100%), and fast (110%) running speeds when wearing insoles in red, blue, and white colours. We used synchronized force platform and motion capturing system to measure ground reaction force, ankle sagittal and frontal kinematics, and movement variability. A two-way (colour x speed) ANOVA with repeated measures was performed with Bonferroni adjusted post hoc comparisons, with alpha set at 0.05. Data analyses indicated that participants demonstrated higher impact and maximum loading rate of ground reaction force, longer stride length, shorter contact time, and smaller touchdown ankle inversion as well as larger ankle sagittal range of motion (RoM), but smaller frontal RoM in fast speed as compared with preferred (P < 0.05) and slow speeds (P < 0.001). Although insole colour had minimal effect on mean values of any tested variables (P > 0.05), participants wearing red-coloured orthoses showed higher coefficient of variation values for maximum loading rate than wearing blue insoles (P=0.009). These results suggest that running at faster speed would lead to higher impact loading and altered lower-limb mechanics and that colour used on the tops of insoles influences the wearers' movement repeatability, with implications for use of foot insole in running.

Influence of Footwear on Posture and Comfort in Elite Rugby Players

Influence of footwear on posture in athletes is poorly documented despite its potential impact on biomechanics and injury risk. The aim of this study was to investigate effects of different footwear geometries on comfort and posture on a cohort of 48 elite rugby players. Spine posture was characterized by photogrammetry, while center of pressure was measured by means of a force platform. Three different footwear outsoles architectures (one rugby shoe with flat outsole, one rugby shoe with a 10 mm heel rise and foot arch support, and a running shoe with a 10mm heel rise and foot arch support) were compared to non-shod in randomized order. Then comfort felt at the level of foot and spine was also estimated by subjective questionnaires. Compared to the flat rugby model, both other models induced significantly (p<0.05) greater comfort at the level of foot and spine, a slight shift toward of center of pressure and a spinal posture closer to that observed when non-shod. The footwear geometry influences comfort and posture at the level of the foot as well as spine and should be considered in a dual purpose of injury prevention and performance.

Children should be seen and also heard: an explorative qualitative study into the influences on children's choice of footwear, their perception of comfort and the language they use to describe footwear experiences

BACKGROUND

Footwear has an essential role including protection of the feet, overall performance, foot health and potentially, supporting normal development of the foot. In addition to these physical aspects which may influence choice of footwear design, there are psychological influences on what a person chooses to wear. The concept of footwear 'comfort' spans physical and psychological perceptions of comfort in adults. However, there is little understanding of what influences children's footwear choices, how children perceive footwear comfort, or the language used to describe footwear experiences. Therefore, this study aimed to explore these three parameters as the first step to informing the development of a scale to measure footwear comfort in children.

METHODS

A pragmatic qualitative design with thematic analysis as an analytical approach was implemented. Passive observation and short interviews were carried out with 23 children (aged 1-12 years) at a footwear manufactures headquarters and store. Prompts included shoes being tried on and field-notes were taken relating to verbal and non-verbal communication. Field notes were coded then themes were identified, reviewed and named.

RESULTS

Overall, the children equated comfort to softness. However, influences on footwear choice were multidimensional including aesthetics, psychosocial influences, identified 'comfort' and 'discomfort' areas, practical issues and predictive concerns; all interacting with the age of the child.

CONCLUSIONS

For children, footwear comfort is a complex phenomenon having physical, cognitive, social and emotional developmental components. This can be seen in how the children perceive the 'feel' of the shoe and how the shoe is assessed in the context of how the shoe meets the child's physical and psychosocial developmental needs. In younger children footwear preference is related to idiosyncratic tastes in aesthetics, physical ability and comfort. As children age, societal influences begin to expand the social function of footwear denoting group membership, to include themes that transcend the functional and social function of footwear. The knowledge from this study can inform the development of age group specific tools to evaluate comfort.

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.

Effect of Red Arch-Support Insoles on Subjective Comfort and Movement Biomechanics in Various Landing Heights

Red is perceived as a "winning color", which may influence actual and perceived performances in sports, but little effort has been done to assess the added value on colored foot insoles in basketball movements. This study examined if colored foot insole would influence perceived comfort and lower extremity biomechanics during drop landing. Nineteen male basketball players performed drop landing trials with different insoles (red arch-support, white arch-support, and white-flat) and landing heights (0.45 and 0.61 m). Two-way (Insole x Height) ANOVAs with repeated measures were performed on each of the knee and ankle angles and moments variables. Wearing red arch-support insoles induced better perception of forefoot and rearfoot cushioning and overall comfort but smaller plantarflexion moment than the white-flat insoles (p < 0.05). Increased landing height was related to higher ground reaction loading, sagittal flexion angles, range of motion, and joint moments but smaller ankle eversion (p < 0.05). Findings indicate that foot insoles might have influenced comfort perception and joint kinetics, but not joint kinematics. The use of red color in foot insoles could potentially maximize the effectiveness of foot insoles in a way that alters comfort perception and motor control during landing, with implications for risk of injury.

Effects of foot orthoses on dynamic balance and basketball free-throw accuracy before and after physical fatigue

While it is not uncommon for athletes to use foot orthoses to relieve pain and improve sports performance, little has been known about their effects on basketball performance. Free-throw basketball shooting is very important. However, fatigue deteriorates postural balance which might decrease free-throw shooting performance. This study investigated the effects of foot orthoses on dynamic balance and accuracy performance during free-throw shooting before and after physical fatigue was induced. Thirteen male recreational basketball players were tested with two foot orthoses (medial-arch support versus flat control) and fatigue conditions (before and after fatigue), when they performed standard free-throw shooting on a force platform. Results revealed that fatigue significantly increased coefficient of variance of medial-lateral center of pressure (CoP) excursion when participants worn flat control orthoses (p < 0.05). Meanwhile, foot orthoses improved dynamic balance during shooting as they significantly reduced total resultant and anterior-posterior sway excursions as well as resultant and anterior-posterior CoP velocities, and base of support area. Although this study found that fatigue and orthoses did not significantly affect the scores gained by free-throw shooting, the significant improvements in dynamic balance during shooting with the use of foot orthoses could have considerable impact on motor control during basketball shooting.

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.

Anterior cruciate ligament injury risk factors in football

INTRODUCTION

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic injuries in a football (soccer) player's career. There are many injury risk factors related to intrinsic (non-modifiable) and/or extrinsic (modifiable) factors of ACL injury.

EVIDENCE ACQUISITION

Research of the studies was conducted until September 2018 without publication data limitation or language restriction on the following databases: PubMed/MEDLINE, Scopus, ISI, EXCERPTA.

EVIDENCE SYNTHESIS

To date, evidence from the literature suggests that the risk of ACL injury is multifactorial and involves biomechanical, anatomical, hormonal, and neuromuscular factors. Despite this relative complexity, the mechanisms of injury are well known and rationally classified into two categories: mechanisms of injury based on contact or on non-contact with another player, with the non-contact injury mechanisms clearly prevailing over the mechanisms of contact injury. One of the most frequent biomechanical risk factors, associated with ACL non-contact injury, is represented by the valgus knee in the pivoting and cutting movements and in the landing phase after jumping. Gender-related risk factors show female populations to have a higher predisposition to ACL injury than males However, there are still some theoretical and practical aspects that need further investigation such as; genetic risks together with the role of estrogen and progesterone receptors in female populations, and the in-vivo interaction shoe-playing surface. In particular, the genetic risk factors of ACL lesion seem to be an interesting and promising field of investigation, where considerable progress has still to be made.

CONCLUSIONS

This narrative review provides an insight into the risk factors of ACL injury that could be used by practitioners for preventing injury in football (soccer).

Intervention Strategies Used in Sport Injury Prevention Studies: A Systematic Review Identifying Studies Applying the Haddon Matrix

BACKGROUND

Prevention of sport injuries is crucial to maximise the health and societal benefits of a physically active lifestyle. To strengthen the translation and implementation of the available evidence base on effective preventive measures, a range of potentially relevant strategies should be considered.

OBJECTIVE

Our aim was to identify and categorise intervention strategies for the prevention of acute sport injuries evaluated in the scientific literature, applying the Haddon matrix, and identify potential knowledge gaps.

METHODS

Five electronic databases were searched (PubMed, EMBASE, SPORTDiscus, CINAHL, Cochrane) for studies that evaluated the effect of interventions on the occurrence of acute sport injuries. Studies were required to include a control group/condition, prospective data collection, and a quantitative injury outcome measure.

RESULTS

A total of 155 studies were included, mostly randomised controlled trials (43%). The majority of studies (55%) focussed on strategies requiring a behavioural change on the part of athletes. Studies predominantly evaluated the preventive effect of various training programmes targeted at the 'pre-event' phase (n = 73) and the use of equipment to avoid injury in the 'event phase' (n = 29). A limited number of studies evaluated the preventive effect of strategies geared at rules and regulations (n = 14), and contextual modifications (n = 18). Studies specifically aimed at preventing re-injuries were a minority (n = 8), and were mostly related to ankle sprains (n = 5).

CONCLUSIONS

Valuable insight into the extent of the evidence base of sport injury prevention studies was obtained for 20 potential intervention strategies. This approach can be used to monitor potential gaps in the knowledge base on sport injury prevention.

Current Soccer Footwear, Its Role in Injuries and Potential for Improvement

Soccer is the most popular sport in the world and generates great financial revenue. It is also a sport whose practice has evolved considerably in terms of intensity and commitment, and in which the intrinsic risk of injury (not directly related to an interaction with the environment) is particularly high. In this context, the cleated shoe as a major component of soccer equipment may play a key role in the overexposure to injury. Soccer shoe evolution is all the more challenging, because design and mechanical structure differ in many points compared to other modern shoes developed for sports such as running, tennis and basketball. This critical review aims to elucidate the characteristics of modern soccer footwear and their possible link to soccer-specific injuries, focusing on the following areas: (1) ergonomics, comfort and proprioception; (2) shoe mechanical characteristics; (3) field surfaces and shoe design.

Compliance with Sport Injury Prevention Interventions in Randomised Controlled Trials: A Systematic Review

INTRODUCTION

Sport injury prevention studies vary in the way compliance with an intervention is defined, measured and adjusted for.

OBJECTIVE

The objective of this systematic review was to assess the extent to which sport injury prevention randomised controlled trials (RCTs) have defined, measured and adjusted results for compliance with an injury prevention intervention.

METHODS

An electronic search was performed in MEDLINE, PubMed, the Cochrane Center of Controlled Trials, CINAHL (Cumulative Index to Nursing and Allied Health Literature), PEDro (Physiotherapy Evidence Database) and SPORTDiscus. English RCTs, quasi-RCTs and cluster-RCTs were considered eligible. Trials that involved physically active individuals or examined the effects of an intervention aimed at the prevention of sport- or physical activity-related injuries were included.

RESULTS

Of the total of 100 studies included, 71.6 % mentioned compliance or a related term, 68.8 % provided details on compliance measurement and 51.4 % provided compliance data. Only 19.3 % analysed the effect of compliance rates on study outcomes. While studies used heterogeneous methods, pooled effects could not be presented.

CONCLUSIONS

Studies that account for compliance demonstrated that compliance significant affects study outcomes. The way compliance is dealt with in preventions studies is subject to a large degree of heterogeneity. Valid and reliable tools to measure and report compliance are needed and should be matched to a uniform definition of compliance.

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.

Interventions to prevent sports related injuries: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

The effects of methods to prevent injuries have been studied in several systematic reviews. However, no meta-analysis taking into account all randomised controlled intervention trials aiming at the prevention of sports injuries has been published.

OBJECTIVE

To summarise the effects of sports injury prevention interventions.

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

DATA SOURCES

PubMed, MEDLINE, SPORTDiscus, the Cochrane Central Register of Controlled Trials, CINAHL, PEDro, and Web of Science, searched in September 2013. The reference lists of retrieved articles and reviews were hand searched.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

To be selected articles had to examine the effects of any preventive intervention on sports injuries, be randomised/quasi-randomised and controlled trials, published in a peer-reviewed journal. The outcome of the trial had to be injury rate or the number of injured individuals.

RESULTS

Of the 5580 articles retrieved after a search of databases and the relevant bibliography, 68 randomised controlled trials were included in the systematic review and 60 trials were included in the meta-analysis. Insoles (OR 0.51, 95% CI 0.32-0.81), external joint supports (OR 0.40, 95% CI 0.30-0.53), and specific training programmes (OR 0.55, 95% CI 0.46-0.66) appeared to be effective in reducing the risk of sports injuries. Stretching (OR 0.92, 95% CI 0.80-1.06), modified shoes (OR 1.23, 95% CI 0.81-1.87), and preventive videos (OR 0.86, 95% CI 0.44-1.68) seemed not to be effective.

CONCLUSIONS

This meta-analysis showed that certain interventions can reduce the risk of sports injuries. There were limitations regarding the quality of the trials, generalisability of the results, and heterogeneity of the study designs. In future, the mechanisms behind effective methods and the most beneficial elements of preventive training programmes need to be clarified.

In-shoe plantar tri-axial stress profiles during maximum-effort cutting maneuvers

Soft tissue injuries, such as anterior cruciate ligament rupture, ankle sprain and foot skin problems, frequently occur during cutting maneuvers. These injuries are often regarded as associated with abnormal joint torque and interfacial friction caused by excessive external and in-shoe shear forces. This study simultaneously investigated the dynamic in-shoe localized plantar pressure and shear stress during lateral shuffling and 45° sidestep cutting maneuvers. Tri-axial force transducers were affixed at the first and second metatarsal heads, lateral forefoot, and heel regions in the midsole of a basketball shoe. Seventeen basketball players executed both cutting maneuvers with maximum efforts. Lateral shuffling cutting had a larger mediolateral braking force than 45° sidestep cutting. This large braking force was concentrated at the first metatarsal head, as indicated by its maximum medial shear stress (312.2 ± 157.0 kPa). During propulsion phase, peak shear stress occurred at the second metatarsal head (271.3 ± 124.3 kPa). Compared with lateral shuffling cutting, 45° sidestep cutting produced larger peak propulsion shear stress (463.0 ± 272.6 kPa) but smaller peak braking shear stress (184.8 ± 181.7 kPa), of which both were found at the first metatarsal head. During both cutting maneuvers, maximum medial and posterior shear stress occurred at the first metatarsal head, whereas maximum pressure occurred at the second metatarsal head. The first and second metatarsal heads sustained relatively high pressure and shear stress and were expected to be susceptible to plantar tissue discomfort or injury. Due to different stress distribution, distinct pressure and shear cushioning mechanisms in basketball footwear might be considered over different foot regions.

Somatosensory perception of running shoe mass

Running shoes are often marketed based on mass. A total of 50 young adult males participated across two separate experiments to determine how well they could perceive the relative masses of five different running shoes using hands versus feet. For the foot portion, subjects were blindly fitted with the shoes and asked to rank their masses individually using visual analogue scales (VAS) and verbal rankings. For the hand portion, two different methods were used, one presenting all shoes simultaneously and the other presenting the shoes individually. Verbal accuracy and VAS scores correlated across subjects for the hand and foot, but accuracy in mass perception by the feet was 30% compared to 92% or 63% by the hand (depending on the method). These results indicate the foot perceives mass poorly compared to the hand, and that consumers' perception of shoe mass may come more from handling shoes versus wearing them.