The effect of a 12-week custom foot orthotic intervention on muscle size and muscle activity of the intrinsic foot muscle of young adults during gait termination

Long-Term Effects and Impressions of Minimal Footwear in Older Adults

INTRODUCTION

Foot pathologies can lead to difficulty walking and falls in older adults. Intrinsic foot muscles contribute to the structural support and alignment of the foot and provide somatosensory input from the ground. Minimally cushioned footwear may naturally strengthen intrinsic foot muscles and enhance sensory input to the foot; however, these effects are largely unknown in older adults. Further, there is little evidence regarding the prescription of minimal footwear and the perceptions of this footwear by older adults.

METHODS

Twenty-four adults age ≥65 volunteered to use minimal footwear for prescribed times during daily activities for 16 weeks. The cross-sectional area (CSA) of 5 intrinsic foot muscles was measured using ultrasound imaging at baseline, 8 weeks, and 16 weeks. Semi-structured interviews were recorded regarding participants' impressions of the footwear, the progressive wear schedule, the footwear's effects on orthopedic-related pain, balance, and foot awareness/sensation.

RESULTS

Across the cohort, there was no significant difference in CSA of the 5 muscles after 16 weeks of minimal footwear use. Thirteen participants had clinically meaningful increased CSA of the abductor hallucis muscle (Abh). These positive responders had no significant differences in age, grip strength, foot structure, or fall risk scores compared to participants with little to no CSA change. Interview results indicated a generally positive experience with minimal footwear for 68.1% of the cohort. A large percentage of the cohort reported no difficulty with the progressive wear schedule (77.2%), no aggravation of preexisting conditions and no new pain (77.2%), improved balance (63.6%), and improved foot awareness/sensation (72.7%) with minimal footwear use. The progressive wear schedule was perceived as inconvenient by some in the first few weeks (22.8%), but resulted in mild to no adverse effects when followed as prescribed.

CONCLUSION

Sixteen weeks of progressive minimal footwear use in older adults did not lead to changes in intrinsic foot muscle CSA; however, half of the cohort had clinically meaningful increased CSA in the Abh muscle. It is unclear what individual qualities were associated with this positive response. Older adults reported generally positive experiences with minimal footwear with self-reported improvements in balance and foot awareness/sensation. The wear schedule may have been too conservative or not long enough to produce foot muscle hypertrophy, but subjective reports suggest beneficial neuromuscular adaptations and sensory changes occurred. Future research may need a greater length of time and larger samples to further determine the effects of long-term minimal footwear use in older adults.

The effects of foot orthoses on radiological parameters and pain in children with flexible flat feet: a systematic review and meta-analysis

Objective

This study aimed to investigate the impact of foot orthoses on foot radiological parameters and pain in children diagnosed with flexible flatfoot.

Methods

A comprehensive search was conducted across several databases, including PubMed, Web of Science, EMBASE, Cochrane Library, and EBSCO, covering publications from the inception of each database up to 8 June 2024. The study focused on randomized controlled trials investigating the use of foot orthoses for treating flexible flat feet in children. Four researchers independently reviewed the identified literature, extracted relevant data, assessed the quality of the studies, and performed statistical analyses using RevMan 5.4 software.

Results

Six studies involving 297 participants were included. The methodological quality of the included literature ranged from moderate to high. Radiological parameters of the foot improved significantly in older children with flexible flat feet following foot orthotic intervention compared to controls, particularly in the lateral talar-first metatarsal angle [mean difference (MD) = -2.76, 95% confidence interval (95% CI) -4.30 to -1.21, p = 0.0005], lateral talo-heel angle (MD = -5.14, 95% CI -7.76 to -2.52, p = 0.0001) and calcaneal pitch angle (MD = 1.79, 95% CI 0.88-2.69, p = 0.0001). These differences were statistically significant. Additionally, foot orthoses significantly improved the ankle internal rotation angle and reduced foot pain in children with symptomatic flexible flatfoot (MD = -2.51, 95% CI -4.94 to -0.07, p = 0.04).

Conclusion

The use of foot orthoses positively impacts the improvement of radiological parameters of the foot and reduces pain in older children with flexible flat feet. However, in younger children with flexible flat feet, the improvement from foot orthoses was not significant, likely due to challenges in radiological measurements caused by the underdevelopment of the ossification centers in the foot. Further studies are needed. Consequently, the results of this meta-analysis support the implementation of an early intervention strategy using foot orthoses for the management of symptomatic flat feet in older children.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO [CRD42023441229].

Current evidence regarding 2D ultrasonography monitoring of intrinsic foot muscle properties: A systematic review

Background

Ultrasonography can discriminate between intrinsic and extrinsic foot muscle properties and has therefore gained considerable popularity as an indirect strength evaluation. However, an overview on the use of ultrasound for assessing intrinsic foot musculature (IFM) is currently lacking.

Research question

What is the current evidence regarding (1) 2D ultrasonography protocols and its reliability? (2) Reference values for cross-sectional area and dorso-plantar thickness evaluation in asymptomatic and symptomatic persons?

Methods

The PRISMA guidelines were used to conduct this systematic review. Eight databases (PubMed, Embase, Web of Science, Cochrane Library, Scopus, CINAHL, SPORTDiscus and EuropePMC) were searched up to November 1, 2021. Studies reporting quantitative 2D ultrasound findings of the intrinsic foot muscles with no limitation to sex, BMI, ethnicity or physical activity were included. Studies were assessed for methodological quality using the Downs and Black checklist.

Results

Fifty-three studies were retained. Protocols showed an overall good to great reliability, suggesting limits of agreement between 8 and 30% of relative muscle size with minimal detectable changes varying from 0.10 to 0.29 cm² for cross-sectional area and 0.03-0.23 cm for thickness. Reference values are proposed for both cross-sectional area and thickness measurements of the abductor hallucis, flexor digitorum brevis, flexor hallucis brevis and quadratus plantae in asymptomatic persons. This could not be performed in the symptomatic studies due to a limited number of relevant studies addressing the symptomatic population, therefore a clinical overview is outlined. Clinically, IFM properties have been studied in ten distinct pathological conditions, predominantly pointing towards decreased muscle properties of the abductor hallucis.

Significance

We provide a clear and comprehensive overview of the literature regarding 2D ultrasonography of the IFM, making the available evidence more accessible to decision makers and researchers.

Effects of a 9-weeks arch support intervention on foot morphology in young soccer players: a crossover study

Background

A flat foot is a common cause of chronic sports injuries and therefore many opportunities for arch support interventions exist. However, young athletes change their foot morphology due to developmental influences even without intervention. Therefore, developmental influences need to be considered when examining the effects of arch support, but there have not been sufficient longitudinal studies to date. This study aimed to determine the effect of the arch support intervention by performing a 9-weeks arch support intervention on the foot morphology and cross-sectional area of the foot muscles in flat-footed young athletes. Thirty-one elementary school boys (Age 11.4 ± 0.5 years, Height 145.2 ± 7.4 cm, Weight 38.8 ± 8.3 kg, BMI 18.2 ± 2.2 kg/m²) with a decreased medial longitudinal arch in the foot posture index were selected as participants from a local soccer club and randomly divided into two groups.

Methods

In one group, in the intervention period, an existing arch supporter was used to provide arch support, while in the other group, no special intervention was provided in the observation period. To account for developmental effects, the intervention study was conducted as an 18-weeks crossover study in which the intervention and observational phases were switched at 9 weeks after the intervention. Foot morphology was assessed using a three-dimensional foot measuring machine, and the cross-sectional area (CSA) of the internal and external muscles of the foot was assessed using an ultrasound imaging device. We examined the effect of the intervention by comparing the amount of change in the measurement results between the intervention and observation periods using corresponding t-tests and Wilcoxon signed-rank sum test, analysis of covariance methods.

Results

After adapting the exclusion criteria, 14 patients (28 feet) were included in the final analysis. The CSA of the abductor hallucis muscle (ABH) increased 9.7% during the intervention period and 3.0% during the observation period (p = 0.01). The CSA of the flexor digitorum longus muscle (FDL) increased 7.7% during the intervention period and 4.2% during the observation period (p = 0.02).

Conclusion

A 9-weeks arch supporter intervention may promote the development of the ABH and FDL CSA in young flat-footed soccer players.

Stepping Back to Minimal Footwear: Applications Across the Lifespan

Minimal footwear has existed for tens of thousands of years and was originally designed to protect the sole of the foot. Over the past 50 yr, most footwear has become increasingly more cushioned and supportive. Here, we review evidence that minimal shoes are a better match to our feet, which may result in a lower risk of musculoskeletal injury.