Does arch height affect impact loading at the lower back level in running?

Effects of physical interventions on pain and disability in chronic low back pain with pronated feet: a systematic review and meta-analysis

BACKGROUND

A link between pronated feet (PF) and chronic low back pain (CLBP) has been reported in the literature. However, physical interventions (PI) like physiotherapy and orthotics mainly target the lower back, neglecting the broader biomechanical impacts of PF that affect the feet, ankles, and overall posture. Currently, there is a lack of comprehensive meta-analyses or systematic reviews on this subject.

OBJECTIVES

This systematic review with a meta-analysis aimed to evaluate the effects of PI on pain and disability in patients having CLBP with PF.

METHODS

From inception until October 15, 2023, Medline/PubMed, Web of Science, and Scopus databases were searched using the desired keywords for randomized control trials (RCTs). The quality of the RCTs was evaluated using the PEDro scale and risk of bias tool.

RESULTS

Four studies involving 268 patients were identified, two compared custom-made foot orthoses to non-biomechanical foot insoles, while the other two used exercises. The meta-analysis included four studies for pain and three for disability. The results showed a significant change in pain [-2.43 (95% CI -2.73 to -2.13, p < .001)] and disability of -6.69 (95% CI -8.04 to -5.33, p < .001)].

CONCLUSIONS

This systematic review and meta-analysis of four RCTs elucidates that PI, specifically targeting PF, significantly alleviate pain and reduce disability in patients having CLBP with PF. These findings advocate for integrating foot-based PI within the treatment protocols for patients suffering from CLBP accompanied by PF.

Ankle and subtalar joint axes of rotation and center of rotation during walking and running in healthy individuals measured using dynamic biplane radiography

The goal of this study was to determine how foot type and activity level affect ankle and hindfoot motion. Dynamic biplane radiography and a validated volumetric registration process was used to measure ankle and hindfoot motion of 20 healthy adults during walking and running. The helical axes of motion (HAM) during stance were calculated at the tibiotalar and subtalar joints. The intersection of each HAM and the rotation plane of interest defined the tibiotalar and subtalar centers of rotation (COR). Correlations between foot type and hindfoot kinematics were calculated using Pearson's correlations. The effect of activity, phase of gait, and dominant vs. non-dominant limb on HAM and COR were evaluated using linear mixed effects models. Activity and phase of gait influenced the superior location of the tibiotalar (p < 0.041) and subtalar (p < 0.044) CORs. Activity and gait phase affected tibiotalar (p < 0.049) and subtalar (p < 0.044) HAM direction during gait. Both HAM orientation and COR location changed with activity and phase of gait. These ankle and hindfoot kinematics have implications for total ankle replacement design and musculoskeletal models that estimate force and moment generating capabilities of muscles.

Examining the Relationship between Pes Planus Degree, Balance and Jump Performances in Athletes

The foot absorbs shocks with its arches, muscles, ligaments and joints, and bodyweight transmission and it pushes the body forward during all movement patterns. Pes planus is more important in sports activities that include balance and sports performance, such as walking, running, jumping, or transferring weight to a single lower limb. This study, conducted with this information in mind, aims to examine the effects of pes planus deformity on balance and vertical jump performance. Fifty athletes were included in the study. The presence of pes planus was evaluated according to the Feiss line. Balance measurements were performed with a Balance System SD Biodex. Vertical jump performance was recorded using an Omegawave jumping mat. The relationship between the pes planus grades of the participants and their balance and jump performances was analyzed using the Spearman correlation method. Vertical jump and Limit of stability (LOS) was significantly correlated with pes planus.

The Effects of a Medial Heel Wedge on the Weight-Bearing Response of Hindfoot Valgus and the Total Weight-Bearing Responses of the Navicular and Talus Bones

OBJECTIVES Medial heel wedges are commonly prescribed to manage the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones. Previous studies have reported that a medial heel wedge is effective in the management of musculoskeletal injuries. However, it remains unclear the effect of a medial heel wedge on the weight-bearing responses of footarch bones in vivo. To clarify the effects of a medial heel wedge on the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones is necessary to understand how best to treat musculoskeletal injuries clinically. The purpose of our study was to clarify the effects of a medial heel wedge on the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones.METHODS Twenty-five healthy males were analyzed. We obtained MRI scanning of the right foot under non-loading (NL) and full weight-bearing (FW) conditions. Participants wore two insole types, a flat insole and a medial heel wedge. To evaluate the weight-bearing response in hindfoot valgus, the hindfoot alignment view (HAV) was measured. We also measured navicular and talus bone positions and calculated the total positional changes of the navicular and talus bones (ΔTPCN, ΔTPCT) from the vertical and medial displacements using the Pythagorean theorem.RESULTS Significant interactions were observed with the HAV. Under both NL and FW conditions, the HAV was smaller on the medial heel wedge than on the flat insole. In addition, the ΔTPCN was significantly smaller on the medial heel wedge than on the flat insole. However, no significant differences were observed for ΔTPCT.CONCLUSIONS Our results suggest that use of a medial heel wedge decreases hindfoot valgus values under both NL and FW conditions and stabilizes the total weight-bearing response of the navicular bone.

Are Biomechanical Features of the Foot and Ankle Related to Lumbopelvic Motor Control?

BACKGROUND

Any pathomechanical change in the foot or ankle is expected to cause adverse biomechanical effects on the lumbopelvic region. However, no objective data can be found in the literature regarding the effects of musculus transversus abdominis (mTrA) and musculus lumbar multifidus (mLM), which are effective muscles in lumbopelvic motor control, or regarding the extent of their effects.

METHODS

Sixty-four healthy young adults were assessed by a physiotherapist (C.K.) experienced in treating feet and a radiologist (Y.D.) specialized in muscular imaging. In the determination of biomechanical properties of the foot, the navicular drop test (NDT), Foot Posture Index (FPI), pedobarographic plantar pressure analysis, and isokinetic strength dynamometer measurements were used in determining the strength of the muscles around the ankle. Ultrasonographic imaging was used to determine mTrA and mLM thicknesses.

RESULTS

Significant correlation was found between NDT results and mTrA and mLM thicknesses (P < .05) and between FPI results and mTrA thicknesses (P < .05). As the peak pressure of the foot medial line increased, mTrA and mLM thicknesses decreased (P < .05). Although dorsiflexion muscle strength was also effective, mTrA and mLM thicknesses were found to increase especially as plantarflexion muscle strength increased (P < .05).

CONCLUSIONS

These results show that the biomechanical and musculoskeletal properties of the foot-ankle are associated with lumbopelvic stability.

Does Plantar Pressure Distribution Influence the Lumbar Multifidus Muscle Thickness in Asymptomatic Individuals? A Preliminary Study

BACKGROUND

Atrophy can occur in the lumbar multifidus (LM) muscle quickly as a result of various musculoskeletal problems. Knowing factors influencing muscle thickness of the LM will provide important clues about lumbopelvic stability.

OBJECTIVES

Although there are several studies in the literature investigating the adverse effects of foot-ankle postural disorders on the lumbopelvic region, to our knowledge there has been no investigation of plantar pressure distribution (PPD) as a factor influencing muscle thickness of the LM. The aim of this study was to determine whether PPD could affect LM muscle thickness.

METHODS

This observational study consisted of 25 asymptomatic individuals. Ultrasonographic imaging was used to determine the thickness of the LM. All participants were subjected to PPD analysis using the Digital Biometry Scanning System and Milletrix software in 9 different plantar pressure zones. The Pearson product-moment correlation coefficients were used to examine the correlations between the LM muscle thickness and other variables. Stepwise multiple linear regression analysis was used to determine the variables with the greatest influence on LM muscle thickness.

RESULTS

Peak pressures of medial and lateral zones of the heel were the significant and independent factors influencing static LM thickness, with 39.5% of the variance; moreover, the peak pressures of heel medial and fourth metatarsal bone were the significant and independent factors influencing dynamic LM thickness, with 38.7% of the variance.

CONCLUSIONS

Plantar pressure distribution could be an important factor influencing LM thickness, although further research is required. Examining foot-ankle biomechanics may provide information about the stability of the LM.

The relationship between static and dynamic foot posture and running biomechanics: A systematic review and meta-analysis

BACKGROUND

Medial longitudinal arch characteristics are thought to be a contributing factor to lower limb running injuries. Running biomechanics associated with different foot types have been proposed as one of the potential underlying mechanisms. However, no systematic review has investigated this relationship.

RESEARCH QUESTION

The aim of this study was to conduct a systematic literature search and synthesize the evidence about the relationship between foot posture and running biomechanics.

METHODS

For this systematic review and meta-analysis different electronic databases (Pubmed, Web of Science, Cochrane, SportDiscus) were searched to identify studies investigating the relationship between medial longitudinal arch characteristics and running biomechanics. After identification of relevant articles, two independent researchers determined the risk of bias of included studies. For homogenous outcomes, data pooling and meta-analysis (random effects model) was performed, and levels of evidence determined.

RESULTS

Of the 4088 studies initially identified, a total of 25 studies were included in the qualitative review and seven in the quantitative analysis. Most studies had moderate and three studies a low risk of bias. Moderate evidence was found for a relationship between foot posture and subtalar joint kinematics (small pooled effects: -0.59; 95%CI -1.14 to - 0.003) and leg stiffness (small pooled effect: 0.59; 95%CI 0.18 to 0.99). Limited or very limited evidence was found for a relationship with forefoot kinematics, tibial/leg rotation, tibial acceleration/shock, plantar pressure distribution, plantar fascia tension and ankle kinetics as well as an interaction of foot type and footwear regarding tibial rotation.

SIGNIFICANCE

While there is evidence for an association between foot posture and subtalar joint kinematics and leg stiffness, no clear relationship was found for other biomechanical outcomes. Since a comprehensive meta-analysis was limited by the heterogeneity of included studies future research would benefit from consensus in foot assessment and more homogenous study designs.

Gender difference in factors affecting the medial longitudinal arch height of the foot in healthy young adults

[Purpose] Medial longitudinal arch (MLA) height is associated with various injuries and diseases and gender differences, if any. This study aimed to examine factors affecting the MLA height associated with gender differences in healthy subjects with no orthopedic disorders. [Subjects and Methods] This study included 36 healthy adults (19 males, 17 females; mean age, 21.8 ± 3.6 years; body mass index, 21.1 ± 2.0 kg/m²). Their height, body weight, foot length, muscle strength of the tibialis posterior muscle (TPM), toe-gripping strength, hallux valgus angle, inversion microdactylia angle, angle of leg-heel alignment, femoro-tibial angle, and navicular height were measured. Correlation between the ratio of arch height and other measurement parameters was examined. [Results] In females, the ratio of arch height was significantly positively correlated with muscle strength of the TPM and toe-gripping strength and negatively correlated with the hallux valgus angle and the leg-heel alignment, whereas in males, only a positive correlation between the ratio of arch height and muscle strength of the TPM was observed. [Conclusion] These results reveal that etiological mechanisms determining MLA height are different between males and females. Overall, the present results indicate that further studies identifying causes of MLA height variation must include gender-based analysis.

Low back pain and disability in individuals with plantar heel pain

BACKGROUND

Lack of response to plantar heel pain (PHP) treatment may be related to unmanaged low back pain (LBP) and low back dysfunction, but a relationship between LBP and PHP has not been established. The purpose of this investigation was to compare the prevalence of LBP among individuals with and without PHP and to assess the association between low back disability and foot/ankle function.

METHODS

A cross-sectional study compared the prevalence and likelihood of LBP in individuals with (n=27) and without (n=27) PHP matched to age, sex, BMI, foot posture, and foot mobility. In individuals with PHP, correlations were examined between foot/ankle function using the foot and ankle ability measure (FAAM), low back disability using the Oswestry low back disability questionnaire (OSW), duration of PHP symptoms, body mass index (BMI), and age.

RESULTS

A greater percentage of individuals with PHP had LBP (74% versus 37% of controls, odds ratio=5.2, P=0.009) and higher levels of low back disability (17% higher OSW score than controls, P<0.001). In individuals with PHP, FAAM scores were correlated with OSW scores (ρ=-0.463, P=0.015), but not with duration of PHP symptoms, BMI, or age (P>0.150).

CONCLUSIONS

Individuals with PHP had a greater prevalence of LBP and higher low back disability that was correlated to reduced foot and ankle function. Treatment to address both local and proximal impairments, including impairments related to LBP, may be warranted to improve the management of PHP.

Muscle activity and kinetics of lower limbs during walking in pronated feet individuals with and without low back pain

The objectives of this study were to investigate whether excessive feet pronation alters the joints' kinematics, kinetics and the activity of involved muscles during gait in low back pain patients.

METHODS

The lower limb joints' motion, moment and power, as well as the activity of involved muscles during walking were measured in a control group, and two experimental groups including a group with excessive feet pronation only, and another group of low back pain patients with excessive feet pronation.

RESULTS

In both experimental groups, ankle inversion, knee flexion and internal rotation, hip internal rotation, plantar flexors' moment, hip flexors' moment, and peak positive ankle power were lower than those in control group (p < .05). Besides, in patients, higher activity of gastrocnemius medialis, gluteus medius, erector spinae, and internal oblique muscles, and lower negative power at the ankle and peak positive power at the knee were observed (p < .05). In conclusion, pronated feet with low back pain was associated with less ankle inversion and knee flexion, higher knee and hip internal rotation, higher muscle activity, less energy absorption at the ankle, and reduced positive power at the knee. This study reveals that strengthening of the muscles especially knee extensors are of great importance in low back pain patients with feet pronation.

Prevalence of Flexible Flat Foot in Adults: A Cross-sectional Study

INTRODUCTION

Flat foot (pes planus) is a commonly observed disorder in clinical practice. The height of Medial Longitudinal Arch (MLA) determines the degree of pes planus. Majority of the previous studies on prevalence of flexible flat foot were done among children.

AIM

The present study was undertaken to determine the prevalence of flexible flat foot among 18-21-year-old Indian adults using Navicular Drop Test (NDT) which is regarded as reliable and valid method to characterise MLA.

MATERIALS AND METHODS

The present study was a cross-sectional study in which Brody's Navicular Drop Test was performed in five hundred healthy subjects (250 males and 250 females) aged 18-21-year-old. Navicular Drop (ND) of ≥ 10 mm was regarded as flexible flat foot. Statistical analysis was done using SPSS version 23.0.

RESULTS

The prevalence of flexible flat foot was 13.6% (for males-12.8%; for females-14.4%). The median with Inter Quartile Range (IQR) for ND among males was 6 mm (4-8) and 6 mm (4-9) for right and left foot respectively. The median with IQR for ND among females was 6mm (4-10) and 7mm (3-8) for right & left respectively. The correlation of Right Side Navicular Drop (RND) with height and weight was significant, but insignificant correlation was found between RND and BMI. The correlation of Left Side Navicular Drop (LND) with height, weight and BMI of individuals was statistically not significant. The difference between the ND of males and female group was statistically not significant.

CONCLUSION

The present study quantified the prevalence of flexible flat foot and gender wise normative values of ND among 18-21-year-old Indian adults. The information obtained by this study will be useful in the field of orthopaedics.

The effect of foot orthoses on joint moment asymmetry in male children with flexible flat feet

INTRODUCTION

It has been widely postulated that structural and functional misalignments of the foot, such as flat foot, may cause mechanical deviations of the lower limb during walking. The aim of this study was to investigate the effect of foot orthoses on lower extremity joint moment asymmetry during the stance phase of walking in children with asymptomatic flexible flat feet.

METHODS

Fourteen volunteer male children, clinically diagnosed with flexible flat feet, participated in this study. Subjects completed 12 walking trials at a self-selected walking speed while 3-dimensional kinematic and kinetic data were collected for two conditions: shod with no orthoses, and shod with orthoses. The gait asymmetry index for each variable for each subject was defined as: (1-(lesser moment/greater moment)) × 100.

RESULTS

Results reveal no significant differences in ankle or knee joint moment asymmetry. However, the use of foot orthoses decreased asymmetry for the hip abduction moment (P = 0.04) compared to walking without orthoses and also resulted in subtle, non-significant increases in frontal plane subtalar and sagittal plane knee and hip joints moment asymmetry.

CONCLUSION

We conclude that foot orthoses decrease frontal plane hip joint moment asymmetry, but have little effect on ankle and knee joint asymmetry.

Are flexible flat feet associated with proximal joint problems in children?

The role of flexible flat feet (FF) in the development of musculoskeletal symptoms at joints proximal to the ankle is unclear. We undertook an observational study to investigate the relationship between foot posture and the proximal joints in children. It was hypothesised that reduced arch height would be associated with proximal joint symptoms and altered gait kinematics and kinetics particularly in the transverse plane at the hip and knee. Ninety-five children between the ages of 8-15 were recruited into this ethically approved study. Foot posture was classified using the arch height index (AHI). The frequency of knee and hip/back pain was documented, and each child underwent three dimensional gait analysis. Reduced arch height was associated with increased odds of knee symptoms (p<0.01) and hip/back symptoms (p=0.01). A flat foot posture was also significantly associated with a reduction in the second peak of the vertical ground reaction force (p=0.03), which concomitantly affected late stance hip and knee moments. A reduced AHI was also associated with increased pelvic retraction and increased knee valgus in midstance. No kinematic and kinetic parameter associated with a flat foot posture related to increased proximal joint symptoms in the FF group. Children with a flatter foot posture are more likely to have pain or discomfort at the knee, hip and back; however, the mechanisms by which this occurs remain unclear. Treating FF without explicit understanding of how it relates to symptoms is difficult, and further work in this area is required.

Foot orthotics for low back pain: The state of our understanding and recommendations for future research

PURPOSE

The purpose of the article is to evaluate the literature on the use of foot orthotics for low back pain and to make specific recommendations for future research.

METHODS

Database searches were conducted using PubMed, EBSCO, GALE, Google Scholar, and clinicaltrials.gov. The biomedical literature was reviewed to determine the current state of knowledge on the benefits of foot orthotics for low back pain related to biomechanical mechanisms and clinical outcomes.

RESULTS

It may be argued that foot orthotics are experimental, investigational, or unproven for low back pain due to lack of sufficient evidence for their clinical effectiveness. This conclusion is based upon lack of high quality randomized controlled trials (RCTs). However, there is extensive research on biomechanical mechanisms underlying the benefits of orthotics that may be used to address this gap. Additionally, promising pilot studies are beginning to emerge in the literature and ongoing large-scale RCTs are addressing effects of foot orthotics on chronic low back pain.

CONCLUSIONS

Based upon the critical evaluation of the current research on foot orthotics related to biomechanical mechanisms and clinical outcomes, recommendations for future research to address the evidence-practice gaps on the use of foot orthotics for low back pain are presented.

Height of the foot longitudinal arch and anterior cruciate ligament injuries

OBJECTIVE:

To evaluate the association between the height of the medial longitudinal arch of the foot and non-contact injuries of the anterior cruciate ligament.

METHODS:

One hundred and five patients were included in this case-control study. The case group consisted of 52 patients with non-contact injury of the anterior cruciate ligament. Fifty-three individuals with no history of symptoms regarding to feet or knees comprised the control group. An anthropometric assessment of the bony arch index was performed, which consisted of measuring the ratio of the height between the navicular bone to the ground and the distance from the most posterior support point of the calcaneus to the first metatarsal-phalangeal joint. Gender, height, weight, body mass index and the frequency of sports practice were also evaluated.

RESULTS:

Subjects in the case group had significantly higher medial longitudinal arches than individuals in the control group.

CONCLUSION:

Individuals with rupture of the anterior cruciate ligament had higher arches than the corresponding controls, suggesting an association between a high medial longitudinal arch of the foot and injury of the anterior cruciate ligament. Level of Evidence III, Case-Control Study

Foot posture, leg length discrepancy and low back pain--their relationship and clinical management using foot orthoses--an overview

Mechanical low back pain (LBP) is a very common, expensive, and significant health issue in the western world. Functional musculoskeletal conditions are widely thought to cause mechanical low back pain. The role of foot posture and leg length discrepancy in contributing to abnormal biomechanics of the lumbopelvic region and low back pain is not sufficiently investigated. This critical review examines the evidence for the association between foot function, particularly pronation, and mechanical LBP. It also explores the evidence for a role for foot orthoses in the treatment of this condition. There is a body of evidence to support the notion that foot posture, particularly hyperpronation, is associated with mechanical low back pain. Mechanisms that have been put forward to account for this finding are based on either mechanical postural changes or alterations in muscular activity in the lumbar and pelvic muscles. More research is needed to explore and quantify the effects of foot orthoses on chronic low back pain, especially their effects on lumbopelvic muscle function and posture. The clinical implications of this work are significant since foot orthoses represent a simple and potentially effective therapeutic measure for a clinical condition of high personal and social burden.

The Effects on Muscle Activation of Flatfoot during Gait According to the Velocity on an Ascending Slope

[Purpose] This study determined the difference between flatfeet and normal feet in humans on an ascending slope using electromyography (EMG). [Subjects] This study was conducted on 30 adults having normal feet (n=15) and flatfeet (n=15), all of whom were 21 to 30 years old. [Methods] A treadmill (AC5000M, SCIFIT,) was used to analyze kinematic features during gait. These features were analyzed at slow, normal, and fast gait velocities on an ascending slope. A surface electromyogram (TeleMyo 2400T, Noraxon Co., USA) was used to measure muscle activity changes. [Results] The activities of most muscles in the subjects with flatfeet were significantly different from the muscle activities in the subjects with normal feet at different gait velocities on an ascending slope. There were significant differences in the vastus medialis and abductor hallucis muscles. [Conclusion] Because muscle activation of the vastus medialis in relation to stability of the lower extremity has a tendency to increase with an increase in gait velocity on an ascending slope, we hypothesized that higher impact transfer to the knee joints occurs in subjects with flatfeet due to the lack of a medial longitudinal arch and that the abductor halluces muscles, which provide dynamic stability to the medial longitudinal arches, do not activate well when they are needed in subjects with flatfeet.

Foot posture, foot function and low back pain: the Framingham Foot Study

OBJECTIVE

Abnormal foot posture and function have been proposed as possible risk factors for low back pain, but this has not been examined in detail. The objective of this study was to explore the associations of foot posture and foot function with low back pain in 1930 members of the Framingham Study (2002-05).

METHODS

Low back pain, aching or stiffness on most days was documented on a body chart. Foot posture was categorized as normal, planus or cavus using static weight-bearing measurements of the arch index. Foot function was categorized as normal, pronated or supinated using the centre of pressure excursion index derived from dynamic foot pressure measurements. Sex-specific multivariate logistic regression models were used to examine the associations of foot posture, foot function and asymmetry with low back pain, adjusting for confounding variables.

RESULTS

Foot posture showed no association with low back pain. However, pronated foot function was associated with low back pain in women [odds ratio (OR) = 1.51, 95% CI 1.1, 2.07, P = 0.011] and this remained significant after adjusting for age, weight, smoking and depressive symptoms (OR = 1.48, 95% CI 1.07, 2.05, P = 0.018).

CONCLUSION

These findings suggest that pronated foot function may contribute to low back symptoms in women. Interventions that modify foot function, such as orthoses, may therefore have a role in the prevention and treatment of low back pain.

The effects of low arched feet on lower limb gait kinematics in children

BACKGROUND

The effects of foot posture on the dynamic function of the lower limb during gait remains relatively unknown.

OBJECTIVES

The purpose of this study was to investigate lower limb kinematics between the normal and low arched foot during the gait cycle, particularly in the transverse plane.

METHOD

Twenty-four children, twelve with normal and twelve with low arched feet, aged 11-12 years underwent a lower limb three dimensional gait analysis. Temporo-spatial parameters and patterns and ranges of motion of kinematic data were examined for the pelvis, hip, knee and ankle throughout the gait cycle.

RESULTS

Overall, there were very few differences found in the kinematics of the lower limbs between the normal and low arched group. Increased external hip rotation (6-7°) in the low arched group was the only bilateral significant difference (p<0.05) between the two foot groups. No significant differences existed in any temporo-spatial parameters between the two groups.

CONCLUSIONS

The increased external hip rotation and greater external foot progression angle in the low arched foot highlights the need to examine gait comprehensively to establish cause or effect of these differences observed and hence determine appropriate treatment.

Influence of shock waves and muscle activity at initial contact on walk-run transition evaluated by two models

The walk-run transition (WRT) is a well-described phenomenon without any known cause; however, mechanical variables related to human gait have been associated with the WRT. This study tested the hypothesis that shock waves in the tibia and 3rd lumbar vertebra in addition to activity of tibialis anterior, vastus lateralis, and erector spinae muscles could be responsible for the WRT. Thirty subjects walked and ran on a treadmill at 80%, 90%, 100%, 110%, and 120% of preferred transition speed. Shock waves were measured with skin-mounted accelerometers and muscle activity by surface electromyography. The influence on the WRT was analyzed with two models. The shock waves and muscle activity tended to a significant increase (p < .05) for both walking and running with increased speed. The only factor that appeared to be involved in the WRT mechanism was the activity of the tibialis anterior; however, this was only confirmed by one of the two models. The use of different models to analyze the same data for the WRT triggers may give different results; thus, a standard model is required to investigate the influence of given factors on biological phenomena.

Determination of normal values for navicular drop during walking: a new model correcting for foot length and gender

Background

The navicular drop test is a measure to evaluate the function of the medial longitudinal arch, which is important for examination of patients with overuse injuries. Conflicting results have been found with regard to differences in navicular drop between healthy and injured participants. Normal values have not yet been established as foot length, age, gender, and Body Mass Index (BMI) may influence the navicular drop. The purpose of the study was to investigate the influence of foot length, age, gender, and BMI on the navicular drop during walking.

Methods

Navicular drop was measured with a novel technique (Video Sequence Analysis, VSA) using 2D video. Flat reflective markers were placed on the medial side of the calcaneus, the navicular tuberosity, and the head of the first metatarsal bone. The navicular drop was calculated as the perpendicular distance between the marker on the navicular tuberosity and the line between the markers on calcaneus and first metatarsal head. The distance between the floor and the line in standing position between the markers on calcaneus and first metatarsal were added afterwards.

Results

280 randomly selected participants without any foot problems were analysed during treadmill walking (144 men, 136 women). Foot length had a significant influence on the navicular drop in both men (p < 0.001) and women (p = 0.015), whereas no significant effect was found of age (p = 0.27) or BMI (p = 0.88). Per 10 mm increase in foot length, the navicular drop increased by 0.40 mm for males and 0.31 mm for females. Linear models were created to calculate the navicular drop relative to foot length.

Conclusion

The study demonstrated that the dynamic navicular drop is influenced by foot length and gender. Lack of adjustment for these factors may explain, at least to some extent, the disagreement between previous studies on navicular drop. Future studies should account for differences in these parameters.

Foot medial longitudinal-arch deformation during quiet standing and gait in subjects with medial tibial stress syndrome

The objective of this study was to investigate (1) if subjects with medial tibial stress syndrome demonstrate increased navicular drop and medial longitudinal-arch deformation during quiet standing and gait compared with healthy subjects, and (2) the relationship between medial longitudinal-arch deformation during quiet standing and gait. Thirty subjects aged 20 to 32 years were included (15 with medial tibial stress syndrome and 15 controls). Navicular drop and medial longitudinal-arch deformation were measured during quiet standing with neutral and loaded foot using a ruler and digital photography. Medial longitudinal-arch deformation was measured during walking gait using 3-dimensional gait analysis. Subjects with medial tibial stress syndrome demonstrated a significantly larger navicular drop (mean +/- 1 SD, 7.7 +/- 3.1 mm) and medial longitudinal-arch deformation (5.9 +/- 3.2 degrees) during quiet standing compared with controls (5.0 +/- 2.2 mm and 3.5 +/- 2.6 degrees, P < .05). Subjects with medial tibial stress syndrome also demonstrated significantly larger medial longitudinal-arch deformation (8.8 +/- 1.8 degrees) during gait compared with controls (7.1 +/- 1.7 degrees, P = .015). There was no correlation between medial longitudinal-arch deformation during quiet standing and gait in either of the 2 groups (r < 0.127, P > .653). The subjects with medial tibial stress syndrome in this study demonstrated increased navicular drop and medial longitudinal-arch deformation during quiet standing and increased medial longitudinal-arch deformation during gait compared to healthy subjects. Medial longitudinal-arch deformation during quiet standing did not correlate with medial longitudinal-arch deformation during gait in either of the 2 groups. ACFAS Level of Clinical Evidence: 5.

The effect of insoles on the incidence and severity of low back pain among workers whose job involves long-distance walking

The prevalence and incidence of low back pain in general society is high. Workers whose job involves walking long distances have an even higher tendency to suffer from low back pain. A positive effect of insoles in reducing low back pain was found in professional sports players. This was not examined on people whose job involves walking long distances. In this double blind prospective study we examined the effectiveness of insoles constructed in a computerized method to placebo insoles in 58 employees whose work entailed extensive walking and who suffered from low back pain. The evaluation was performed by the MILLION questionnaire, which is considered as a valid questionnaire for evaluation of low back pain. We calculated the differences of the pain intensity before and after the intervention, in the employees using the insoles manufactured by computer in comparison to the users of the placebo insoles. In each group, the analysis was performed in comparison to the baseline. A total of 81% of the employees preferred the real insoles as effective and comfortable in comparison to 19% of the users of the placebo insoles (P<0.05). The results of this study indicate a substantial improvement in the low back pain after the use of the true insoles. The average pain intensity according to the MILLION questionnaire before the use of the insoles was 5.46. However, after the use of the real insoles and the placebo insoles, the average pain intensity decreased to 3.96 and 5.11, respectively. The difference of the average pain intensity at the start of the study and after the use of the real insoles was significant: -1.49 (P=0.0001), whereas this difference after the use of the placebo insoles was not significant: -0.31 (P=0.1189). The reported severity of pain also decreased significantly: a level 5 pain and above was reported by 77% of the subjects at the start of the study. After the use of the real insoles only 37.9% of the subjects reported a similar degree of pain severity, and 50% of the subjects did so after the use of the placebo insoles (P< 0.05). We did not find a link between low back pain and other variables such as gender, age, number of offspring, work seniority, smoking, previous use of insoles and previous medication. This study demonstrates that the low back pain decreased significantly after the use of real insoles compared to placebo ones.

High-arched runners exhibit increased leg stiffness compared to low-arched runners

Leg stiffness between high-arched (HA) and low-arched (LA) runners was compared. It was hypothesized that high-arched runners would exhibit increased leg stiffness, increased sagittal plane support moment, greater vertical loading rates, decreased knee flexion excursion and increased activation of the knee extensor musculature. Twenty high-arched and 20 low-arched subjects were included in this study. Leg stiffness, knee stiffness, vertical loading rate and lower extremity support moment were compared between groups. Electromyographic data were collected in an attempt to explain differences in leg stiffness between groups. High-arched subjects were found to have increased leg stiffness and vertical loading rate compared to low-arched runners. Support moment at the impact peak of the vertical ground reaction force was related to leg stiffness across all subjects. High-arched subjects demonstrated decreased knee flexion excursion during stance. Finally, high-arched subjects exhibited a significantly earlier onset of the vastus lateralis (VL) than the low-arched runners. Differences exist in leg stiffness and vertical loading rate between runners with different foot types. Differences in lower extremity kinetics in individuals with different foot types may have implications for new treatment strategies or preventative measures.

Intrinsic pedal musculature support of the medial longitudinal arch: an electromyography study

Much of the work describing support of the medial longitudinal arch has focused on the plantar fascia and the extrinsic muscles. There is little research concerning the function of intrinsic muscles in the maintenance of the medial longitudinal arch. Ten healthy volunteer adults served as subjects for this study, which was approved by the University Investigational Review Board. The height of the navicular tubercle above the floor was measured in both feet while subjects were seated with the foot in a subtalar neutral position and then when standing in a relaxed calcaneal stance. Subtalar neutral was found by palpating for talar congruency. Recordings of muscle activity from the abductor hallucis muscle were performed while the subjects maintained a maximal voluntary contraction in a supine position by plantarflexing their great toes. An injection of lidocaine (1% with epinephrine) was then administered by a Board-certified orthopedic surgeon in the region of the tibial nerve, posterior and inferior to the medial malleolus. Measurements were repeated and compared by using a paired t test. After the nerve block, the muscle activity was 26.8% of the control condition (P =.011). This corresponded with an increase in navicular drop of 3.8 mm. (P =.022). The observation that navicular drop increased when the activity of the intrinsic muscles decreased indicates that the intrinsic pedal muscles play an important role in support of the medial longitudinal arch.

A prospective study of running injuries: the Vancouver Sun Run "In Training" clinics

OBJECTIVES

Seventeen running training clinics were investigated to determine the number of injuries that occur in a running programme designed to minimise the injury rate for athletes training for a 10 km race. The relative contributions of factors associated with injury were also reported.

METHODS

A total of 844 primarily recreational runners were surveyed in three trials on the 4th, 8th, and 12th week of the 13 week programme of the "In Training" running clinics. Participants were classified as injured if they experienced at least a grade 1 injury-that is, pain only after running. Logistic regression modelling and odds ratio calculation were performed for each sex using the following predictor variables: age, body mass index (BMI), previous aerobic activity, running frequency, predominant running surface, arch height, running shoe age, and concurrent cross training.

RESULTS

Age played an important part in injury in women: being over 50 years old was a risk factor for overall injury, and being less than 31 years was protective against new injury. Running only one day a week showed a non-significant trend for injury risk in men and was a significant risk factor in women and overall injury. A BMI of > 26 kg/m(2) was reported as protective for men. Running shoe age also significantly contributed to the injury model. Half of the participants who reported an injury had had a previous injury; 42% of these reported that they were not completely rehabilitated on starting the 13 week training programme. An injury rate of 29.5% was recorded across all training clinics surveyed. The knee was the most commonly injured site.

CONCLUSIONS

Although age, BMI, running frequency (days a week), and running shoe age were associated with injury, these results do not take into account an adequate measure of exposure time to injury, running experience, or previous injury and should thus be viewed accordingly. In addition, the reason for the discrepancy in injury rate between these 17 clinics requires further study.

Biomechanical analysis of the effect of orthotic shoe inserts: a review of the literature

Physical activity is increasingly recognised as an important component of primary disease prevention. Overuse injuries are common sequelae of exercise and sporting activities in general, and of running in particular, frequently resulting in cessation of activity. It has been proposed that there is a link between foot shape, foot function and the occurrence of injury. As a means of treatment and prevention of further injury, orthoses and shoe inserts are widely prescribed in the belief that they can alter the pattern of lower extremity joints' alignment and movement. Although this is an assumption widely made in the treatment of many joint conditions, the manner through which this treatment could be effective is not clear. This article aims to examine the literature to gain an improved understanding of the present state of knowledge regarding the effect of foot shape and orthotic use on foot kinematic and plantar pressure characteristics. The effects of foot type on the occurrence of lower limb injury during sporting activities and different aspects of biomechanics are reviewed, and the effects of applying orthoses on injury treatment and prevention and on various aspects of biomechanics of the lower limb joints are discussed. Further research is required, firstly to establish the casual effect of foot type and function on the risk of lower extremity overuse injury, and secondly to document the specific effect of orthotic therapy on injury treatment and prevention. Specifically, more prospective studies are necessary to investigate the long term effect of orthotic intervention.