The Biomechanics Research and Innovation Challenge: Development, Implementation, Uptake, and Reflections on the Inaugural Program.

Biomechanics as a discipline is ideally placed to increase awareness and participation of girls and women in science, technology, engineering, and mathematics. A nationwide Biomechanics and Research Innovation Challenge (BRInC) centered on mentoring and role modeling was developed to engage high school girls (mentees) and early-mid-career women (mentors) in the field of biomechanics through the completion of a 100-day research and/or innovation project. This manuscript describes the development, implementation, and uptake of the inaugural BRInC program and synthesizes the research and innovation projects undertaken, providing a framework for adoption of this program within the global biomechanics community. Eighty-seven high school girls in years 9 and 10 (age range: 14-16 y) were mentored in teams (n = 17) by women in biomechanics (n = 24). Using a design thinking approach, teams generated solutions to biomechanics-based problem(s)/research question(s). Eight key reflections on program strengths, as well as areas for improvement and planned changes for future iterations of the BRInC program, are outlined. These key reflections highlight the innovation, impact, and scalability of the program; the importance of a program framework and effective communication tools; and implementation of strategies to sustain the program as well as the importance of diversity and building a sense of community.

'Jump start' childcare-based intervention to promote physical activity in pre-schoolers: six-month findings from a cluster randomised trial.

BACKGROUND: Participation in adequate levels of physical activity during the early years is important for health and development. We report the 6-month effects of an 18-month multicomponent intervention on physical activity in early childhood education and care (ECEC) settings in low-income communities. METHODS: A cluster randomised controlled trial was conducted in 43 ECEC settings in disadvantaged areas of New South Wales, Australia. Three-year-old children were recruited and assessed in the first half of 2015 with follow-up 6 months later. The intervention was guided by Social Cognitive Theory and included five components. The primary outcome was minutes per hour in total physical activity during ECEC hours measured using Actigraph accelerometers. Intention-to-treat analysis of the primary outcome was conducted using a generalized linear mixed model. RESULTS: A total of 658 children were assessed at baseline. Of these, 558 (85%) had valid accelerometer data (mean age 3.38y, 52% boys) and 508 (77%) had valid accelerometry data at 6-month follow-up. Implementation of the intervention components ranged from 38 to 72%. There were no significant intervention effects on mins/hr. spent in physical activity (adjusted difference = - 0.17 mins/hr., 95% CI (- 1.30 to 0.97), p = 0.78). A priori sub-group analyses showed a greater effect among overweight/obese children in the control group compared with the intervention group for mins/hr. of physical activity (2.35mins/hr., [0.28 to 4.43], p = 0.036). CONCLUSIONS: After six-months the Jump Start intervention had no effect on physical activity levels during ECEC. This was largely due to low levels of implementation. Increasing fidelity may result in higher levels of physical activity when outcomes are assessed at 18-months. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12614000597695.

Increasing physical activity among young children from disadvantaged communities: study protocol of a group randomised controlled effectiveness trial.

BACKGROUND: Participation in regular physical activity (PA) during the early years helps children achieve healthy body weight and can substantially improve motor development, bone health, psychosocial health and cognitive development. Despite common assumptions that young children are naturally active, evidence shows that they are insufficiently active for health and developmental benefits. Exploring strategies to increase physical activity in young children is a public health and research priority. METHODS: Jump Start is a multi-component, multi-setting PA and gross motor skill intervention for young children aged 3-5 years in disadvantaged areas of New South Wales, Australia. The intervention will be evaluated using a two-arm, parallel group, randomised cluster trial. The Jump Start protocol was based on Social Cognitive Theory and includes five components: a structured gross motor skill lesson (Jump In); unstructured outdoor PA and gross motor skill time (Jump Out); energy breaks (Jump Up); activities connecting movement to learning experiences (Jump Through); and a home-based family component to promote PA and gross motor skill (Jump Home). Early childhood education and care centres will be demographically matched and randomised to Jump Start (intervention) or usual practice (comparison) group. The intervention group receive Jump Start professional development, program resources, monthly newsletters and ongoing intervention support. Outcomes include change in total PA (accelerometers) within centre hours, gross motor skill development (Test of Gross Motor Development-2), weight status (body mass index), bone strength (Sunlight MiniOmni Ultrasound Bone Sonometer), self-regulation (Heads-Toes-Knees-Shoulders, executive function tasks, and proxy-report Temperament and Approaches to learning scales), and educator and parent self-efficacy. Extensive quantitative and qualitative process evaluation and a cost-effectiveness evaluation will be conducted. DISCUSSION: The Jump Start intervention is a unique program to address low levels of PA and gross motor skill proficiency, and support healthy lifestyle behaviours among young children in disadvantaged communities. If shown to be efficacious, the Jump Start approach can be expected to have implications for early childhood education and care policies and practices, and ultimately a positive effect on the health and development across the life course. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry No: ACTRN12614000597695 , first received: June 5, 2014.

Assessing the effects of foot strike patterns and shoe types on the control of leg length and orientation in running.

This research investigates the stabilization of leg length and orientation during the landing phase of running, examining the effects of different footwear and foot strike patterns. Analyzing kinematic data from twenty male long-distance runners, both rearfoot and forefoot strikers, we utilized the Uncontrolled Manifold approach to assess stability. Findings reveal that both leg length and orientation are indeed stabilized during landing, challenging the hypothesis that rearfoot strikers exhibit less variance in deviations than forefoot strikers, and that increased footwear assistance would reduce these deviations. Surprisingly, footwear with a lower minimalist index enhanced post-landing stability, suggesting that cushioning contributes to both force dissipation and leg length stability. The study indicates that both foot strike patterns are capable of effectively reducing task-relevant variance, with no inherent restriction on flexibility for rearfoot strikers. However, there is an indication of potential reliance on footwear for stability. These insights advance our understanding of the biomechanics of running, highlighting the role of footwear in stabilizing leg length and orientation, which has significant implications for running efficiency and injury prevention.

Do plantar flexor muscle structure and function contribute to medial tibial stress syndrome in long-distance runners? A case report.

Two long-distance runners developed MTSS (male age=26.3 years, female age=47.5 years) after baseline assessment of plantar flexor muscle structure and function and spatiotemporal running variables. B-mode ultrasound and lean leg girth characterized plantar flexor muscle structure. Hand-held dynamometry and a single-leg heel raise to failure protocol characterized plantar flexor muscle function. Finally, spatiotemporal running variables were determined during a treadmill protocol. The two runners who developed MTSS demonstrated less plantar flexor strength and endurance capacity than published comparative control data and marked variability in muscle structure. Reduced plantar flexor strength and endurance capacity were thought to contribute to an impaired ability to resist tibial bending moments during midstance due to earlier muscle fatigue. Earlier muscle fatigue could, in turn, contribute to increased tibial bending moments and MTSS development. Therefore, assessing plantar flexor muscle strength and endurance might help to identify athletes at risk of developing MTSS.

Effectiveness of footwear and foot orthoses in reducing medial metatarsophalangeal joint pressure in women with hallux valgus.

BACKGROUND: Hallux valgus is a common condition where the subluxation of the first metatarsophalangeal joint and lateral deviation of the hallux at the interphalangeal joint creates difficulty with footwear fit. Footwear and foot orthoses are commonly prescribed nonsurgical treatments for hallux valgus. RESEARCH QUESTION: Do extra-width footwear and foot orthoses influence peak pressure at the medial aspect of the metatarsophalangeal and interphalangeal joints in women with hallux valgus? METHODS: Community-dwelling women with symptomatic hallux valgus underwent gait testing when wearing their own shoes and when wearing extra-width footwear fitted with three-quarter length, arch-contouring prefabricated foot orthoses. Peak pressure (kPa) on the medial aspect of the metatarsophalangeal and medial interphalangeal joints and on the plantar surface of the foot (hallux, lesser toes, metatarsophalangeal joint 1, metatarsophalangeal joints 2-5, midfoot and heel) were measured using the novel pedar®-X system with the pedar® pad and pedar® insole, respectively (Novel, GmbH, Munich, Germany). Paired samples t-tests were used to calculate the differences between the two conditions, and the magnitude of observed differences was calculated using Cohen's d. RESULTS: We tested 28 participants (aged 44-80 years, mean 60.7, standard deviation 10.7). Compared to their own footwear, wearing the intervention footwear and orthoses was associated with a statistically significant decrease in pressure on the medial aspect of the metatarsophalangeal joint (58.3 ± 32.8 versus 42.6 ± 32.8, p=0.026, d=0.49), increased pressure under the midfoot (70.7 ± 25.7 versus 78.7 ± 23.6, p=0.029, d=0.33) and decreased pressure underneath the heel (137.3 ± 39.0 versus 121.3 ± 34.8, p=0.019, d=0.45). SIGNIFICANCE: The intervention footwear and orthoses significantly decreased peak pressure on the medial aspect of the first metatarsophalangeal joint but had no significant effect on the interphalangeal joint. Further studies are required to determine whether these changes are associated with improvements in symptoms associated with hallux valgus.

Nonsurgical management of hallux valgus: findings of a randomised pilot and feasibility trial.

BACKGROUND: Hallux valgus is a common and disabling condition. This randomised pilot and feasibility trial aimed to determine the feasibility of conducting a parallel group randomised trial to evaluate the effectiveness of a nonsurgical intervention for reducing pain associated with hallux valgus. METHODS: Twenty-eight community-dwelling women with painful hallux valgus were randomised to receive either a multifaceted, nonsurgical intervention (footwear, foot orthoses, foot exercises, advice, and self-management) or usual care (advice and self-management alone). Outcome measures were obtained at baseline, 4, 8 and 12 weeks. The primary outcome was feasibility, evaluated according to demand (recruitment rate and conversion rate), acceptability, adherence, adverse events, and retention rate. Limited efficacy testing was conducted on secondary outcome measures including foot pain, foot muscle strength, general health-related quality of life, use of cointerventions, and participants' perception of overall treatment effect. RESULTS: Between July 8, 2021, and April 22, 2022, we recruited and tested 28 participants (aged 44 to 80 years, mean 60.7, standard deviation 10.7). This period encompassed two COVID-related stay-at-home orders (July 16 to July 27, and August 5 to October 21, 2021). The predetermined feasibility thresholds were met for retention rate, foot pain, mental health-related quality of life, and use of cointerventions, partly met for acceptability, adverse events, and muscle strength, and not met for demand (recruitment rate or conversion rate), adherence, physical health-related quality of life and perception of overall treatment effect. CONCLUSION: In its current form, a randomised trial of footwear, foot orthoses, foot exercises, advice and self-management for relieving pain associated with hallux valgus is not feasible, particularly due to the low adherence with the intervention. However, it is difficult to determine whether the trial would be feasible under different circumstances, particularly due to COVID-19 stay-at-home orders. Future trials will need to consider improving the aesthetics of the footwear and making the exercise program less burdensome. TRIAL REGISTRATION: Australian and New Zealand Clinical Trial Registry (ACTRN12621000645853).

Insight into the hierarchical control governing leg stiffness during the stance phase of running.

Leg stiffness plays a key role in the storage and release of elastic energy during stance. However, the extent to which a runner is able to reuse stored energy remains a limiting factor in determining their running effectiveness. In this study, ten habitual rearfoot strikers and ten habitual forefoot strikers were asked to run on a treadmill in three footwear conditions: traditional, neutral, and minimal running shoes. We examined the effect of habitual foot strike pattern and footwear on leg stiffness control within three task-relevant phases of stance (i.e. touch-down, loading, unloading). Control was quantified using stride-to-stride leg stiffness time-series and the coefficient of variability and detrended fluctuation analysis (DFA). The results are interpreted within a theoretical framework that blends dynamic systems theory and optimal feedback control. Results indicate that leg stiffness control is tightly regulated by an active control process during the loading period of stance. In contrast, the touch-down and unloading phases are driven mostly by passive allometric control mechanisms. The effect of footwear on leg stiffness control was inconclusive due to inconsistent trends across three shoe types. However, stiffness control was affected by landing technique. Habitual rearfoot strike runners have reduced DFA values during the touch-down and unloading phases. These sub-phases are associated with an allometric control process and suggests that rearfoot strike runners express a reduction in system complexity for leg stiffness control and hence, a less adaptable system.

Footwear, foot orthoses and strengthening exercises for the non-surgical management of hallux valgus: protocol for a randomised pilot and feasibility trial.

BACKGROUND: Hallux valgus is a common and disabling condition. This randomised pilot and feasibility trial aims to determine the feasibility of conducting a fully-powered parallel group randomised trial to evaluate the effectiveness of a multifaceted non-surgical intervention for reducing pain associated with hallux valgus. METHODS: Twenty-eight community-dwelling women with painful hallux valgus will be randomised to receive either a multifaceted, non-surgical intervention (footwear, foot orthoses, foot exercises, advice, and self-management) or advice and self-management alone. Outcome measures will be obtained at baseline, 4, 8 and 12 weeks. The primary outcome is feasibility, which will be evaluated according to demand, acceptability, adherence, adverse events, and retention rate. Limited efficacy testing will be conducted on secondary outcome measures including foot pain (the Manchester-Oxford Foot Questionnaire), foot muscle strength (hand-held dynamometry), general health-related quality of life (the Short Form-12), use of cointerventions, and participants' perception of overall treatment effect. Biomechanical testing will be conducted at baseline to evaluate the immediate effects of the footwear/orthotic intervention on pressure beneath the foot and on the medial aspect of the first metatarsophalangeal joint and hallux. DISCUSSION: This study will determine the feasibility of conducting a fully-powered randomised trial of footwear, foot orthoses, foot exercises, advice and self-management for relieving pain associated with hallux valgus and provide insights into potential mechanisms of effectiveness. TRIAL REGISTRATION: Australian and New Zealand Clinical Trial Registry ( ACTRN12621000645853 ).

Lower leg muscle structure and function are altered in long-distance runners with medial tibial stress syndrome: a case control study.

BACKGROUND: Medial tibial stress syndrome (MTSS) is a common lower leg injury experienced by runners. Although numerous risk factors are reported in the literature, many are non-modifiable and management of the injury remains difficult. Lower leg muscle structure and function are modifiable characteristics that influence tibial loading during foot-ground contact. Therefore, this study aimed to determine whether long-distance runners with MTSS displayed differences in in vivo lower leg muscle structure and function than matched asymptomatic runners. METHODS: Lower leg structure was assessed using ultrasound and a measure of lower leg circumference to quantify muscle cross-sectional area, thickness and lean lower leg girth. Lower leg function was assessed using a hand-held dynamometer to quantify maximal voluntary isometric contraction strength and a single leg heel raise protocol was used to measure ankle plantar flexor endurance. Outcome variables were compared between the limbs of long-distance runners suffering MTSS (n = 20) and matched asymptomatic controls (n = 20). Means, standard deviations, 95 % confidence intervals, mean differences and Cohen's d values were calculated for each variable for the MTSS symptomatic and control limbs. RESULTS: MTSS symptomatic limbs displayed a significantly smaller flexor hallucis longus cross-sectional area, a smaller soleus thickness but a larger lateral gastrocnemius thickness than the control limbs. However, there was no statistical difference in lean lower leg girth. Compared to the matched control limbs, MTSS symptomatic limbs displayed deficits in maximal voluntary isometric contraction strength of the flexor hallucis longus, soleus, tibialis anterior and peroneal muscles, and reduced ankle plantar flexor endurance capacity. CONCLUSIONS: Differences in lower leg muscle structure and function likely render MTSS symptomatic individuals less able to withstand the negative tibial bending moment generated during midstance, potentially contributing to the development of MTSS. The clinical implications of these findings suggest that rehabilitation protocols for MTSS symptomatic individuals should aim to improve strength of the flexor hallucis longus, soleus, tibialis anterior and peroneal muscles along with ankle plantar flexor endurance. However, the cross-sectional study design prevents us determining whether between group differences were a cause or effect of MTSS. Therefore, future prospective studies are required to substantiate the study findings.

Are Leg Muscle, Tendon and Functional Characteristics Associated with Medial Tibial Stress Syndrome? A Systematic Review.

BACKGROUND: Medial tibial stress syndrome (MTSS) is a common overuse injury that lacks effective evidence-based treatment options. Reduced leg girth has been associated with MTSS development because it is hypothesised to impair the ability of the leg to modulate tibial loading generated during foot-ground contact. Measuring total leg girth, however, does not provide specific information about the structural composition or functional capacity of individual leg muscles. Consequently, uncertainty remains as to which specific muscles are compromised and contribute to MTSS development. Therefore, this paper aimed to systematically review the body of literature pertaining to how the structure and function of the leg muscles are thought to be associated with MTSS injury. METHODS: The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P). Medline, PubMed, SCOPUS, SPORTDiscus with Full-texts and Web of Science were searched until March 2021 to identify articles in which lower limb muscle structural or functional variables associated with MTSS injury were investigated. RESULTS: Seventeen studies, which were predominately case-control in design and captured data from 332 individuals with MTSS symptoms and 694 control participants, were deemed appropriate for review. The average Downs and Black Quality Assessment score was 71.7 ± 16.4%, with these articles focussing on leg girth, tendon abnormalities, muscle strength and endurance, shear modulus and neuromuscular control. Of the risk factors assessed in the 17 studies, decreased lean leg girth and higher peak soleus muscle activity during propulsion were most strongly correlated with MTSS development. Individuals with MTSS also displayed deficits in ankle plantar flexor endurance, greater isokinetic concentric eversion strength, increased muscle shear modulus and altered neuromuscular recruitment strategies compared to asymptomatic controls. CONCLUSIONS: Future prospective studies are required to confirm whether decreased lean leg girth and higher peak soleus muscle activity during propulsion are associated with MTSS development and to elucidate whether these structural and functional differences in the leg muscles between MTSS symptomatic and asymptomatic controls are a cause or effect of MTSS.

Repeatability and accuracy of a foot muscle strength dynamometer.

Toe flexor strength is a pivotal biomechanical contributor for effecting balance and gait. However, there are limited reports that evaluate measurement accuracy and repeatability of this important attribute. Dynamometers are designed to measure force which can be used to derive joint torque if the perpendicular distance to the joint axis is known. However, an accurate and reliable measurement method to assess the ability of the toe flexor muscles to produce torque, is lacking. Here we describe a new device and method, designed to quantify the toe flexor torque developed at the metatarsal phalangeal joint. We evaluate measurement bias and the ability of the instrument to consistently measure what it is supposed to measure (Interclass Correlation Coefficient). Results suggest that our device is an accurate tool for measuring angle and torque with a small (0.10° and 0.07 Nm, respectively) bias. When tested for reliability and repeatability in measuring toe flexor torque (n = 10), our device showed high interclass correlation (ICC = 0.99), small bias (-1.13 Nm) and small repeatability coefficient (CR = 3.9). We suggest mean bias and CR to be reported for future measurement methods and our protocol used as standard approach to measure maximal toe flexor torque.

Morphology of the Toe Flexor Muscles in Older Adults With Toe Deformities.

OBJECTIVE: It has been suggested that atrophied or weak toe flexor muscles are associated with the formation of toe deformities, but there is little evidence to support this theory. This study aimed to determine whether the size of the toe flexor muscles differed in older adults with and without toe deformities. METHODS: Forty-four older adults (>60 years) were recruited for the study. Each participant had their feet assessed for the presence of hallux valgus or lesser toe deformities. Intrinsic and extrinsic toe flexor muscles were imaged with an ultrasound system using a standardized protocol. Assessor-blinded measurements of muscle thickness and cross-sectional area were taken using Image J software. RESULTS: Participants with lesser toe deformities (n = 20) were found to have significantly smaller quadratus plantae (P = 0.003), flexor digitorum brevis (P = 0.013), abductor hallucis (P = 0.004), and flexor hallucis brevis (P = 0.005) muscles than the participants without any toe deformities (n = 19). Female participants with hallux valgus (n = 10) were found to have significantly smaller abductor hallucis (P = 0.048) and flexor hallucis brevis (P = 0.013) muscles than the female participants without any toe deformities (n = 10; P < 0.05). CONCLUSION: This is the first study to use ultrasound to investigate the size of the toe flexor muscles in older adults with hallux valgus and lesser toe deformities compared to otherwise healthy older adults. The sizes of the abductor hallucis and flexor hallucis brevis muscles were decreased in participants with hallux valgus, whereas the quadratus plantae, flexor digitorum brevis, abductor hallucis, and flexor hallucis brevis muscles were smaller in the participants with lesser toe deformities.

A protocol to prospectively assess risk factors for medial tibial stress syndrome in distance runners.

BACKGROUND: Medial tibial stress syndrome (MTSS) is a lower leg injury with a reported incidence rate of up to 35% in active individuals. Although numerous prospective studies have tried to identify risk factors for developing MTSS, managing the syndrome remains difficult. One risk factor yet to be extensively explored in MTSS development is reduced lower leg girth. Further investigation of reduced lower leg girth is required due to the important role lower leg musculature plays in attenuating ground reaction forces during the gait cycle. Therefore, the primary aim of this study is to ascertain whether lower leg muscle morphology and function contribute to the development of MTSS. Our ultimate aim is to identify potential risk factors for MTSS that can be targeted in future studies to better manage the injury or, preferably, prevent individuals developing MTSS. METHODS: This study will be prospective in design and will recruit asymptomatic distance runners. All participants will be tested at base line and participants will have their training data longitudinally tracked over the following 12 months to assess any individuals who develop MTSS symptoms. At base line, outcome measures will include bilateral measures of lower limb anthropometry; cross sectional area (CSA) and thickness of the tibialis anterior, peroneals, flexor digitorum longus, flexor hallucis longus and thickness of soleus, medial and lateral head of gastrocnemius. Tibial bone speed of sound, ankle dorsiflexion range of motion, strength of the six previously described muscles, foot alignment and ankle plantar flexor endurance will also be assessed. Participants will also complete a treadmill running protocol where three-dimensional kinematics, plantar pressure distribution and electromyography data will be collected. DISCUSSION: This study will aim to identify characteristics of individuals who develop MTSS and, in turn, identify modifiable risk factors that can be targeted to prevent individuals developing this injury.

Contributions of foot muscles and plantar fascia morphology to foot posture.

BACKGROUND: The plantar foot muscles and plantar fascia differ between different foot postures. However, how each individual plantar structure contribute to foot posture has not been explored. The purpose of this study was to investigate the associations between static foot posture and morphology of plantar foot muscles and plantar fascia and thus the contributions of these structures to static foot posture. METHODS: A total of 111 participants were recruited, 43 were classified as having pes planus and 68 as having normal foot posture using Foot Posture Index assessment tool. Images from the flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus and brevis (PER), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB) and abductor hallucis (AbH) muscles, and the calcaneal (PF1), middle (PF2) and metatarsal (PF3) regions of the plantar fascia were obtained using a Venue 40 ultrasound system with a 5-13 MHz transducer. RESULTS: In order of decreasing contribution, PF3 > FHB > FHL > PER > FDB were all associated with FPI and able to explain 69% of the change in FPI scores. PF3 was the highest contributor explaining 52% of increases in FPI score. Decreased thickness was associated with increased FPI score. Smaller cross sectional area (CSA) in FHB and PER muscles explained 20% and 8% of increase in FPI score. Larger CSA of FDB and FHL muscles explained 4% and 14% increase in FPI score respectively. CONCLUSION: The medial plantar structures and the plantar fascia appear to be the major contributors to static foot posture. Elucidating the individual contribution of multiple muscles of the foot could provide insight about their role in the foot posture.

Feasibility of SHARK: a physical activity skill-development program for overweight and obese children.

This study aimed to assess the feasibility of a community-based physical activity motor development program, called SHARK, among overweight and obese children. Thirteen overweight or obese children aged 8-12 years were recruited to the 10-week program from the Illawarra region of NSW, Australia. Measures at baseline, post-treatment and 9-month follow-up included BMI, motor development, perceived competence, objectively measured physical activity and performance of an activity of daily living. At post-treatment and follow-up motor development, perceived athletic competence and perceived global self-worth had significantly increased. Although recorded minutes in moderate-to-vigorous activity significantly declined at post-treatment and follow-up, activity daily counts did not. The results indicate that community-based activity programs designed to improve the motor development and perceived competence of overweight and obese children are feasible and may have important and sustainable benefits. However, a larger sample size and a comparison group are required to determine whether this approach can impact on activity levels and weight status.

Effects of Age on Strength and Morphology of Toe Flexor Muscles.

Study Design Descriptive, cross-sectional. Background Age-related muscle atrophy is common in lower-limb muscles. We therefore speculated that foot muscles may also diminish with age. However, there is a paucity of literature characterizing foot muscle strength and morphology, and any relationship between these 2, in older people. Objective To compare the strength and size of the toe flexor muscles of older adults relative to their younger counterparts. Methods Seventeen young adults with a normal foot type were matched by sex and body mass index to 17 older adults with a normal foot type, from an available sample of 41 younger (18 to 50 years of age) and 44 older (60 or more years of age) adults. Among the matched groups (n = 34), muscle thickness and cross-sectional area for 5 intrinsic and 2 extrinsic toe flexor muscles were obtained using ultrasound. Toe strength was assessed using a pressure platform. Differences in toe flexor strength and muscle size between the young and older matched groups were determined using analysis of covariance (controlling for height). Correlations between strength and size of the toe flexor muscles of the pooled group (n = 34) were also calculated. Results Toe strength and the thickness and cross-sectional area of most foot muscles were significantly reduced in the older adults (P<.05). Hallux and toe flexor strength values were strongly correlated with the size of the intrinsic toe flexor muscles. Conclusion The smaller foot muscles appear to be affected by sarcopenia in older adults. This could contribute to reduced toe flexion force production and may affect the ability of older people to walk safely. Interventions aimed at reversing foot muscle atrophy in older people require further investigation. J Orthop Sports Phys Ther 2016;46(12):1065-1070. Epub 29 Oct 2016. doi:10.2519/jospt.2016.6597.

Efficacy of a progressive resistance exercise program to increase toe flexor strength in older people.

BACKGROUND: Reduced toe flexor strength is an independent predictor of falls in older people. However it is unknown whether strengthening programs can restore toe flexor strength in older individuals. The aim of this study was to investigate whether a progressive resistance training program, focused specifically on the foot muscles, could improve toe flexor strength in community-dwelling older people. METHODS: After baseline testing, 85 men and women (age range 60-90years) were randomized to either a supervised, progressive resistance training (n=43) or a home-based exercise (n=42) group for 12weeks. A further 32 participants were recruited for a control group. The primary outcome measures were hallux and lesser toe flexor strength pre- and post-intervention. Secondary outcome measures were exercise compliance, components of the Foot Health Status Questionnaire and single-leg balance time. FINDINGS: Average class attendance was 89% with 68 participants from the two intervention groups (80%) completing the follow-up assessments. Participants in the supervised, progressive resistance training group significantly increased their toe strength (up to 36%; P<0.02), whereas there was no change in toe strength in either the home-based or control groups. This increased toe strength was accompanied by a significant improvement in perceived general foot health and single-leg balance time compared to the other groups (P<0.05). INTERPRETATION: Progressive resistance exercises are a viable intervention to increase toe flexor strength in older adults. A clinical trial is now required to determine whether this intervention can reduce the number of falls suffered by older adults.

Obese older adults suffer foot pain and foot-related functional limitation.

There is evidence to suggest being overweight or obese places adults at greater risk of developing foot complications such as osteoarthritis, tendonitis and plantar fasciitis. However, no research has comprehensively examined the effects of overweight or obesity on the feet of individuals older than 60 years of age. Therefore we investigated whether foot pain, foot structure, and/or foot function is affected by obesity in older adults. Three hundred and twelve Australian men and women, aged over 60 years, completed validated questionnaires to establish the presence of foot pain and health related quality of life. Foot structure (anthropometrics and soft tissue thickness) and foot function (ankle dorsiflexion strength and flexibility, toe flexor strength, plantar pressures and spatiotemporal gait parameters) were also measured. Obese participants (BMI >30) were compared to those who were overweight (BMI=25-30) and not overweight (BMI <25). Obese participants were found to have a significantly higher prevalence of foot pain and scored significantly lower on the SF-36. Obesity was also associated with foot-related functional limitation whereby ankle dorsiflexion strength, hallux and lesser toe strength, stride/step length and walking speed were significantly reduced in obese participants compared to their leaner counterparts. Therefore, disabling foot pain and altered foot structure and foot function are consequences of obesity for older adults, and impact upon their quality of life. Interventions designed to reduce excess fat mass may relieve loading of the foot structures and, in turn, improve foot pain and quality of life for older obese individuals.

Ultrasound evaluation of foot muscles and plantar fascia in pes planus.

BACKGROUND: Multiple intrinsic and extrinsic soft tissue structures that apply forces and support the medial longitudinal arch have been implicated in pes planus. These structures have common functions but their interaction in pes planus is not fully understood. The aim of this study was to compare the cross-sectional area (CSA) and thickness of the intrinsic and extrinsic foot muscles and plantar fascia thickness between normal and pes planus feet. METHODS: Forty-nine adults with a normal foot posture and 49 individuals with pes planus feet were recruited from a university population. Images of the flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus and brevis (PER), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB) and abductor hallucis (AbH) muscles and the plantar fascia were obtained using a Venue 40 ultrasound system with a 5-13 MHz transducer. RESULTS: The CSA and thickness of AbH, FHB and PER muscles were significantly smaller (AbH -12.8% and -6.8%, FHB -8.9% and -7.6%, PER -14.7% and -10%), whilst FDL (28.3% and 15.2%) and FHL (24% and 9.8%) were significantly larger in the pes planus group. The middle (-10.6%) and anterior (-21.7%) portions of the plantar fascia were thinner in pes planus group. CONCLUSION: Greater CSA and thickness of the extrinsic muscles might reflect compensatory activity to support the MLA if the intrinsic foot muscle function has been compromised by altered foot structure. A thinner plantar fascia suggests reduced load bearing, and regional variations in structure and function in feet with pes planus.