Human foot muscle strength and its association with sprint acceleration, cutting and jumping performance, and kinetics in high-level athletes.

The primary objective of this study was to investigate the relationship between metatarsophalangeal joint (MTPj) flexion torque and sprint acceleration, cutting and jumping performance, and kinetics. A secondary aim was to explore this relationship when MTP flexion strength was associated with other foot and lower limb neuromuscular outputs. After an initial MTPj flexion torque assessment using a custom-built dynamometer, 52 high-level athletes performed the following tasks on a force platform system: maximal sprint acceleration, 90-degree cutting, vertical and horizontal jumps, and foot-ankle hops. Their foot posture, foot passive stiffness and foot-ankle reactive strength were assessed using the Foot Posture Index, the Arch Height Index Measurement System and the Foot-Ankle Rebound Jump Test. Ankle plantarflexion and knee extension isometric torque were assessed using an isokinetic dynamometer. During maximal speed sprinting, multiple linear regressions suggested a major contribution of MTPj flexion torque, foot passive stiffness and foot-ankle reactive strength to explain 28% and 35% of the total variance in the effective vertical impulse and contact time. Ankle plantarflexor and quadriceps isometric torques were aggregately contributors of acceleration performance and separate contributors of cutting and jumping performance. In conclusion, MTPj flexion torque was more strongly associated with sprinting performance kinetics especially at high-speed.

[Avoiding cognitive bias : example of quantified assessment of muscle strength]. / Éviter les biais cognitifs : exemple lors de l'évaluation quantifiée de la force musculaire.

Optimizing treatments requires the prevention of diagnostic errors. The use of shortcuts, cognitive biases, may lead to errors of judgement that can impair clinical reasoning and distort decision-making. Objective, quantifiable and comparable assessment is a safeguard against this, and for instance force quantification is used for this purpose. We will present here the use of hand-held dynamometers with recommendations for best practice as well as simple but essential tools for interpreting the results. Indeed, the use of these easy-to-use dynamometers requires rigour to ensure the quality of measurements and data analysis by/for the clinician. The use of this equipment should be widely promoted and democratized in informed clinical practice.

L'optimisation des traitements passe par la prévention des erreurs de diagnostic. L'utilisation de raccourcis et les biais cognitifs peuvent engendrer des erreurs de jugement nuisant au raisonnement clinique et risquant de pervertir les prises de décision. L'évaluation objective, quantifiable et comparable en est un rempart et la quantification de la force est, par exemple, utilisée à cette fin. Nous présentons ici l'utilisation des dynamomètres à main avec des recommandations de bonne pratique ainsi que des outils d'interprétation des résultats simples mais indispensables. En effet, l'emploi de ces dynamomètres d'utilisation aisée nécessite de la rigueur pour assurer la qualité des mesures et l'analyse des données par/pour le clinicien. Le recours à ce matériel doit être largement promu et démocratisé en pratique clinique éclairée.

Shock Response Spectrum Analysis of Fatigued Runners.

The purpose of this study was to determine the effect of fatigue on impact shock wave attenuation and assess how human biomechanics relate to shock attenuation during running. In this paper, we propose a new methodology for the analysis of shock events occurring during the proposed experimental procedure. Our approach is based on the Shock Response Spectrum (SRS), which is a frequency-based function that is used to indicate the magnitude of vibration due to a shock or a transient event. Five high level CrossFit athletes who ran at least three times per week and who were free from musculoskeletal injury volunteered to take part in this study. Two Micromachined Microelectromechanical Systems (MEMS) accelerometers (RunScribe®, San Francisco, CA, USA) were used for this experiment. The two RunScribe pods were mounted on top of the foot in the shoelaces. All five athletes performed three maximum intensity runs: the 1st run was performed after a brief warmup with no prior exercise, then the 2nd and the 3rd run were performed in a fatigued state. Prior to the 2nd and the 3rd run, the athletes were asked to perform at maximum intensity for two minutes on an Assault AirBike to tire them. For all five athletes, there was a direct correlation between fatigue and an increase in the aggressiveness of the SRS. We noticed that for all five athletes for the 3rd run the average SRS peaks were significantly higher than for the 1st run and 2nd run (p < 0.01) at the same natural frequency of the athlete. This confirms our hypothesis that fatigue causes a decrease in the shock attenuation capacity of the musculoskeletal system thus potentially involving a higher risk of overuse injury.

[Prevention and management of running-related injuries]. / Prévention et prise en charge de la blessure liée à la course à pied.

Running related injury is a complex, multifactorial phenomenon that remains difficult to explain. However, there are available tools for clinicians allowing prevention (primary or tertiary) and rehabilitation optimization, thus reducing the consequences of the injury and time before returning to participation. These tools rely mainly on training load monitoring and clinical evaluation of stride biomechanical analysis. Unfortunately, they currently remain poorly known by practitioners, while allowing the opportunity to address the challenge of managing the injured runner, including a faster return to run, but also the prevention of a potential recurrence. It requires targeted intervention and education of the patient on the factors leading to the injury.

La blessure liée à la course à pied est un phénomène complexe, multifactoriel dont l'explication reste difficile. Cependant, des outils à disposition des cliniciens permettent d'agir de manière préventive (primaire ou tertiaire) et d'optimiser la rééducation afin de réduire les conséquences de la blessure et le délai avant la reprise de l'activité. Ces outils portent principalement sur le suivi de la charge d'entraînement et l'utilisation clinique de l'analyse biomécanique de la foulée. Ils sont toutefois aujourd'hui mal connus par les praticiens alors que leur utilisation permet de répondre à l'enjeu de la prise en charge du coureur comprenant un retour le plus rapide possible à la pratique, mais également la prévention d'une potentielle récidive. Cela sous-tend un travail ciblé et une éducation du patient sur les facteurs entraînant la blessure.

Return to sport decisions after an acute lateral ankle sprain injury: introducing the PAASS framework-an international multidisciplinary consensus.

BACKGROUND: Despite being the most commonly incurred sports injury with a high recurrence rate, there are no guidelines to inform return to sport (RTS) decisions following acute lateral ankle sprain injuries. We aimed to develop a list of assessment items to address this gap. METHODS: We used a three-round Delphi survey approach to develop consensus of opinion among 155 globally diverse health professionals working in elite field or court sports. This involved surveys that were structured in question format with both closed-response and open-response options. We asked panellists to indicate their agreement about whether or not assessment items should support the RTS decision after an acute lateral ankle sprain injury. The second and third round surveys included quantitative and qualitative feedback from the previous round. We defined a priori consensus being reached at >70% agree or disagree responses. RESULTS: Sixteen assessment items reached consensus to be included in the RTS decision after an acute lateral ankle sprain injury. They were mapped to five domains with 98% panellist agreement-PAASS: Pain (during sport participation and over the last 24 hours), Ankle impairments (range of motion; muscle strength, endurance and power), Athlete perception (perceived ankle confidence/reassurance and stability; psychological readiness), Sensorimotor control (proprioception; dynamic postural control/balance), Sport/functional performance (hopping, jumping and agility; sport-specific drills; ability to complete a full training session). CONCLUSION: Expert opinion indicated that pain severity, ankle impairments, sensorimotor control, athlete perception/readiness and sport/functional performance should be assessed to inform the RTS decision following an acute lateral ankle sprain injury. TRIAL REGISTRATION NUMBER: ACTRN12619000522112.

[Ankle sprain in youth athlete]. / Entorse de la cheville chez le jeune sportif.

Lateral ankle sprain is the most frequent musculoskeletal injury in the young athlete. Myths, dogma and common belief are regularly encountered when discussing this injury, for which the scientific literature does not prevail yet. In the youth, the growing skeleton further influences the diagnosis and therapeutic processes, as well as the healing potential. For the athlete, a fast recovery and return to sports without recurrence are a priority. In this specific context, an integrated management of the ankle sprain in the young athlete must be based on an adequate diagnosis, a sound knowledge of pediatrics pitfalls and peer-reviewed physiotherapy recommendations and consensus statements.

Lésion musculosquelettique la plus fréquente chez le jeune sportif, l'entorse de la cheville n'en reste pas moins un sujet médical où foisonnent les idées reçues, les dogmes et les mythes que la science a du mal à faire disparaître. Lorsqu'elle affecte un jeune, les pièges du squelette en croissance et le potentiel de guérison sont des éléments supplémentaires influençant le processus diagnostique et thérapeutique. Chez le sportif, le retour rapide à l'entraînement en évitant tout risque de récidive est une priorité. Dans ce contexte, la prise en charge intégrée de l'entorse de la cheville chez le jeune sportif doit être basée sur un bon diagnostic, une connaissance des pièges pédiatriques et des recommandations physiothérapeutiques basées sur l'évidence et les avis de consensus.

Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium.

Lateral ankle sprain injury is the most common musculoskeletal injury incurred by individuals who participate in sports and recreational physical activities. Following initial injury, a high proportion of individuals develop long-term injury-associated symptoms and chronic ankle instability. The development of chronic ankle instability is consequent on the interaction of mechanical and sensorimotor insufficiencies/impairments that manifest following acute lateral ankle sprain injury. To reduce the propensity for developing chronic ankle instability, clinical assessments should evaluate whether patients in the acute phase following lateral ankle sprain injury exhibit any mechanical and/or sensorimotor impairments. This modified Delphi study was undertaken under the auspices of the executive committee of the International Ankle Consortium. The primary aim was to develop recommendations, based on expert (n=14) consensus, for structured clinical assessment of acute lateral ankle sprain injuries. After two modified Delphi rounds, consensus was achieved on the clinical assessment of acute lateral ankle sprain injuries. Consensus was reached on a minimum standard clinical diagnostic assessment. Key components of this clinical diagnostic assessment include: establishing the mechanism of injury, as well as the assessment of ankle joint bones and ligaments. Through consensus, the expert panel also developed the International Ankle Consortium Rehabilitation-Oriented ASsessmenT (ROAST). The International Ankle Consortium ROAST will help clinicians identify mechanical and/or sensorimotor impairments that are associated with chronic ankle instability. This consensus statement from the International Ankle Consortium aims to be a key resource for clinicians who regularly assess individuals with acute lateral ankle sprain injuries.

2016 consensus statement of the International Ankle Consortium: prevalence, impact and long-term consequences of lateral ankle sprains.

The Executive Committee of the International Ankle Consortium presents this 2016 position paper with recommendations for information implementation and continued research based on the paradigm that lateral ankle sprain (LAS), and the development of chronic ankle instability (CAI), serve as a conduit to a significant global healthcare burden. We intend our recommendations to serve as a mechanism to promote efforts to improve prevention and early management of LAS. We believe this will reduce the prevalence of CAI and associated sequelae that have led to the broader public health burdens of decreased physical activity and early onset ankle joint post-traumatic osteoarthritis. Ultimately, this can contribute to healthier lifestyles and promotion of physical activity.

Evidence review for the 2016 International Ankle Consortium consensus statement on the prevalence, impact and long-term consequences of lateral ankle sprains.

Lateral ankle sprains (LASs) are the most prevalent musculoskeletal injury in physically active populations. They also have a high prevalence in the general population and pose a substantial healthcare burden. The recurrence rates of LASs are high, leading to a large percentage of patients with LAS developing chronic ankle instability. This chronicity is associated with decreased physical activity levels and quality of life and associates with increasing rates of post-traumatic ankle osteoarthritis, all of which generate financial costs that are larger than many have realised. The literature review that follows expands this paradigm and introduces emerging areas that should be prioritised for continued research, supporting a companion position statement paper that proposes recommendations for using this summary of information, and needs for specific future research.

Selection criteria for patients with chronic ankle instability in controlled research: a position statement of the International Ankle Consortium.

While research on chronic ankle instability (CAI) and awareness of its impact on society and health care systems has grown substantially in the last 2 decades, the inconsistency in participant/patient selection criteria across studies presents a potential obstacle to addressing the problem properly. This major gap within the literature limits the ability to generalise this evidence to the target patient population. Therefore, there is a need to provide standards for patient/participant selection criteria in research focused on CAI with justifications using the best available evidence. The International Ankle Consortium provides this position paper to present and discuss an endorsed set of selection criteria for patients with CAI based on the best available evidence to be used in future research and study designs. These recommendations will enhance the validity of research conducted in this clinical population with the end goal of bringing the research evidence to the clinician and patient.

Test-Retest Reliability and Usefulness of a Foot-Ankle Rebound-Jump Test for Measuring Foot-Ankle Reactive Strength in Athletes.

PURPOSE: This study investigated the test-retest reliability and usefulness of the foot-ankle rebound-jump test (FARJT) for measuring foot-ankle reactive strength metrics in athletes. METHODS: Thirty-six highly trained, healthy athletes (5 female; 21.5 [3.9] y; 1.80 [0.10] m; 72.7 [10.4] kg) performed 8 repeated bilateral vertical foot-ankle rebound jumps on 2 testing days. Testing days were 1 week apart, and these sessions were preceded by a familiarization session. Reactive strength metrics were calculated by dividing jump height (in meters) by contact time (in seconds) for the reactive strength index (RSI) and flight time (in seconds) by contact time (in seconds) for the reactive strength ratio (RSR). The mean of 4 jumps (excluding the first and last 2 jumps) on each testing session were considered for RSI and RSR reliability and usefulness analysis. RESULTS: We found a high reliability of the FARJT for RSI (intraclass correlation coefficient [ICC] > .90 and coefficient of variation [CV] = 12%) and RSR (ICC ≥ .90 and CV = 8%). Regarding their usefulness, both RSI and RSR were rated as "marginal" in detecting the smallest worthwhile change (typical error > smallest worthwhile change) and "good" in detecting a moderate change in performance. CONCLUSIONS: The results showed that a FARJT is a highly reliable test for measuring foot-ankle reactive strength in athletes and useful for quantifying changes, for example, following a training block. However, its usefulness as an accurate daily or weekly monitoring tool in practice is questionable.

Development and Validation of the Ankle-GO Score for Discriminating and Predicting Return-to-Sport Outcomes After Lateral Ankle Sprain.

BACKGROUND: Lateral ankle sprain (LAS) is the most common sports-related injury. However, there are currently no published evidence-based criteria to guide the patient's return to sport (RTS) and this decision is generally time-based. The aim of this study was to assess the psychometric properties of a new score (Ankle-GO) and its predictive ability for RTS at the same level of play after LAS. HYPOTHESIS: The Ankle-GO is robust for discriminating and predicting RTS outcomes. STUDY DESIGN: Prospective diagnostic study. LEVEL OF EVIDENCE: Level 2. METHODS: The Ankle-GO was administered to 30 healthy participants and 64 patients at 2 and 4 months after LAS. The score was calculated as the sum of 6 tests for a maximum of 25 points. Construct validity, internal consistency, discriminant validity, and test-retest reliability were used to validate the score. The predictive value for the RTS was also validated based on the receiver operating characteristic (ROC) curve. RESULTS: The internal consistency of the score was good (Cronbach's alpha coefficient of 0.79) with no ceiling or floor effect. Test-retest reliability was excellent (intraclass coefficient correlation = 0.99) with a minimum detectable change of 1.2 points. The 2-month scores were significantly lower than 4-month and control group scores (7.7 ± 4, 13.9 ± 4.6, and 19.6 ± 3.4 points, respectively, P < 0.01). Ankle-GO values were also significantly higher in patients who returned to their preinjury level at 4 months compared with those who did not (P < 0.01). The predictive value of the 2-month Ankle-GO score was fair for a RTS at the same or higher than preinjury level at 4 months (area under ROC curve, 0.77; 95% CI, 0.65-0.89; P < 0.01). CONCLUSION: The Ankle-GO appears to be a valid and robust score for clinicians to predict and discriminate RTS in patients after LAS. CLINICAL RELEVANCE: Ankle-GO is the first objective score to help in the decision-making of the RTS after LAS. At 2 months, patients with an Ankle-GO score <8 points are unlikely to RTS at the same preinjury level.

Hip Arthroscopy Followed by 6-Month Rehabilitation Leads to Improved Periarticular Muscle Strength, Except for Abductors and External Rotators.

Purpose: To evaluate the variations in hip muscles strength following arthroscopy and 6-month rehabilitation in patients treated for femoroacetabular impingement (FAI). Methods: A retrospective analysis was carried out on a series of patients who were arthroscopically treated for FAI at La Tour Hospital between 2020 and 2022. Bilateral isometric strengths of 8 hip-related muscles (abductors, adductors, hamstrings, quadriceps, extensors, flexors, internal and external rotators) were assessed using a handheld dynamometer before surgery and postoperatively after 6 months of rehabilitation in terms of relative strength changes between time points. Results: A total of 29 patients (aged 26.9 ± 7.1 years, 86% of women) were included. Except for the abductors, which remained of comparable strength than before surgery, a statistically significant (P < .05) increase in hip muscle strength on the operated side could be noted at 6 postoperative months for hamstrings (9% ± 17%, P = .041), quadriceps (11% ± 27%, P = .045), extensors (17% ± 32%, P = .006), flexors (17% ± 29%, P = .003), adductors (18% ± 23%, P < .001), and internal rotators (32% ± 36%, P < .001). The proportion of patients who reached a strength level above their preoperative status ranged from 62% (quadriceps) to 86% (adductors and flexors), depending on the muscle studied. The external rotators were the only muscles that remained significantly weakened at 6 months on both operated (-13% ± 26%, P = .002) and nonoperated (-17% ± 25%, P < .001) sides, with a decrease beyond 15% in almost half of the patients (45% and 48%, respectively). Conclusions: Arthroscopic treatment followed by 6-month rehabilitation granted to most FAI patients a higher strength level for several hip muscles, except for abductors and external rotators, which remained comparable and weakened, respectively. Level of Evidence: Level IV, therapeutic case series.

Ankle scientific knowledge is not translated into physiotherapy practice: a thematic analysis of French-speaking physiotherapists clinical behaviors.

CONTEXT: Chronic ankle instability (CAI) is prevalent amongst individuals who sustain a lateral ankle sprain (LAS) injury. The persistent of the characteristic long-standing clinical symptoms of CAI maybe attributable to the lack of adoption of evidence-informed clinical guidelines. OBJECTIVE: To investigate to what extent French-speaking physiotherapists implement the International Ankle Consortium Rehabilitation-Oriented-ASsessmenT (ROAST) framework when providing clinical care for individuals with an acute LAS injury. DESIGN: Cross-sectional study. SETTING: We created an online survey informed by a Delphi process of foot-ankle experts, and disseminated it to French-speaking physiotherapists in France, Switzerland, Quebec-Canada, Belgium, and Luxembourg. PATIENTS OR OTHER PARTICIPANTS: In total, 426 physiotherapists completed the online survey. MAIN OUTCOME MEASURE(S): The online survey comprised closed and open-ended questions organized in 5 sections: (1) participants' demographics, (2) participants' self-assessment expertise, (3) clinical diagnostic assessment (bones and ligaments), (4) clinical evaluation after an acute LAS injury (ROAST framework), and (5) CAI. The qualitative data from the open-ended questions was analyzed using best practice thematic analysis guidelines. RESULTS: Only 6% of the respondents could name all Ottawa Ankle Rules criteria. Only 25% of the respondents cited or described "gold standard" tests from the literature to assess the integrity of the ankle lateral ligaments. Less than 25% of the respondents used some of the International Ankle Consortium ROAST recommended clinical evaluation outcome metrics to inform their clinical care for individuals with an acute LAS injury. In general, the respondents had a greater knowledge of the functional insufficiencies that associated with CAI when compared to the mechanical insufficiencies. CONCLUSION: A minority of French-speaking physiotherapists use the International Ankle Consortium ROAST recommended clinical evaluation outcome metrics to inform their clinical care for individuals with an acute LAS injury. This highlights the responsibility of the scientific community to better disseminate evidence-informed research to clinicians.

Absolute and Normalized Normative Torque Values of Knee Extensors and Flexors in Healthy Trained Subjects: Asymmetry Questions the Classical Use of Uninjured Limb as Reference.

Purpose: To provide normative values of maximal isometric torque of knee extensors and flexors measured at 80° of knee flexion and to characterize the results in healthy subjects practicing activities at risk of anterior cruciate ligament rupture. Methods: Seventy-four trained volunteers (35 male and 39 female) aged 18 to 41 years were recruited. They alternately performed 3 maximal voluntary isometric contractions of knee extension and flexion. The maximal voluntary isometric contraction net torque was computed as the mean value of the peak torques recorded over the 3 trials. Results: For women, the absolute torque for extensors was 143.5 ± 34.4 N⋅m (range, 87.7-253.1 N⋅m) and 66.8 ± 13.8 N⋅m (range, 37.5-93.1) for flexors. For men, the absolute torque for extensors was 199.8 ± 47.3 N⋅m (range, 99.3-311.5 N⋅m) and 89.8 ± 21.0 N⋅m (range, 51.8-137.2 N⋅m) for flexors. For women, the body mass normalized torque for extensors was 2.20 ± 0.51 N⋅m.kg-1 (range, 1.22-3.74 N⋅m.kg-1) and 1.04 ± 0.26 N⋅m.kg-1 (range, 0.41-1.50 N⋅m.kg-1) for flexors. For men, the normalized torque for extensors was 2.74 ± 0.58 N⋅m.kg-1 (range, 1.51-4.08 N⋅m.kg-1) and 1.24 ± 0.30 N⋅m.kg-1 (range, 0.64-2.05 N⋅m.kg-1) for flexors. Conclusions: This study provides absolute and normalized normative values of maximal isometric torque measured at 80° of knee flexion for extensors and flexors in a series of healthy trained subjects practicing activities at risk of anterior cruciate ligament rupture. The considerable level of interlimb asymmetry and the weak association between dominance and strength observed in uninjured subjects call into question the classical use of contralateral side as reference for injured patients. Clinical Relevance: Patients with anterior cruciate ligament (ACL) injuries are the most represented subjects using isokinetic dynamometers in many sport medicine and rehabilitation departments. Clinicians need reference values to compare patients with ACL injuries with comparable healthy subjects. This study may provide this information.

Low Ankle-GO Score While Returning to Sport After Lateral Ankle Sprain Leads to a 9-fold Increased Risk of Recurrence: A Two-year Prospective Cohort Study.

BACKGROUND: Lateral ankle sprain (LAS) is the most common sports injury, leading to a high rate of recurrence and the development of chronic ankle instability. One possible explanation is the lack of objective, evidence-based criteria to inform return to sport decisions following LAS. The aim of this study was therefore to assess the efficacy of a new functional score to distinguish patients at risk of recurrent LAS within two years after the initial injury. METHODS: The Ankle-GO score was used in 64 active patients two months after LAS. This composite score includes 2 self-reported questionnaires and 4 functional tests, for a maximum score of 25 points. The rate of reinjury was prospectively recorded 2 years after inclusion. Potential predictive variables for reinjury were tested using the Chi-square and independent t-tests. The area under the receiver operating characteristics curve (AUC) with the optimal cut-off score was determined to assess the predictive value of the Ankle-GO score for the risk of reinjury. Multivariate logistic regression was then used to determine the influence of risk factors of reinjury. RESULTS: Fifty-four (85%) patients were included (23 men and 31 women, 34.7 ± 13 years old) including 18 (33.3%) with a reinjury. The two-month Ankle-GO score was lower in patients with a recurrent LAS (5.4 ± 2.8 points vs. 9.1 ± 4.5, p = 0.002) and predicted the risk of reinjury (AUC = 0.75). Patients with < 8 points were found to have a significantly higher risk of reinjury (OR = 8.6; 95%CI: 2-37.2, p = 0.001). Women also tend to have a higher risk of recurrence (OR = 3.8; 95%CI: 0.9-15.5, p = 0.065). CONCLUSION: The Ankle-GO score is a new objective criterion for RTS after LAS. Patients with a low score at two months have a 9-fold greater risk of recurrence within two years.

Changes in running mechanics and spring-mass behaviour induced by a 5-hour hilly running bout.

The aim of this study was to investigate changes in running mechanics and spring-mass behaviour with fatigue induced by 5-hour hilly running (5HHR). Running mechanics were measured pre- and post-5HHR at 10, 12 and 14 km · h(-1) on an instrumented treadmill in eight ultramarathon runners, and sampled at 1000 Hz for 10 consecutive steps. Contact (t(c) ) and aerial (t(a) ) times were determined from ground reaction force (GRF) signals and used to compute step frequency (f). Maximal GRF, loading rate, downward displacement of the centre of mass (Δz), and leg length change (ΔL) during the support phase were determined and used to compute both vertical (K(vert) ) and leg (K(leg) ) stiffness. A significant decrease in t(c) was observed at 12 and 14 km · h(-1) resulting in an increase of f at all speeds. Duty factor and F(max) significantly decreased at 10 km · h(-1). A significant increase in K(vert) and K(leg) was observed at all running speeds with significant decreases in Δz and ΔL. Despite the shorter duration, the changes in running mechanics appeared to be in the same direction (increased f and K(vert) , decrease in Δz and F(max) ) but of lower amplitude compared with those obtained after an ultra-trail or an ultramarathon.

Are foot posture and morphological deformation associated with ankle plantar flexion isokinetic strength and vertical drop jump kinetics? A principal component analysis.

Static measurements are clinically useful in characterising foot morphology, but it remains unclear to what extent it can influence dynamic lower limb performance. Therefore, the purpose of this study was to investigate if foot posture or foot morphology deformation relates to ankle plantarflexion isokinetic strength and specific kinetics variables during jumping using principal component analysis (PCA). Thirty-eight physically active participants performed drop vertical jump (DVJ) onto force platforms and ankle plantarflexion contractions in different modalities on an isokinetic dynamometer. Foot posture was assessed using the Foot Posture Index-6 item, whereas foot one-, two- and three-dimensional morphological deformation was calculated using the Arch Height Index Measurement System. A PCA was applied to the ankle plantarflexion and kinetics performance data and correlations between PCs and foot parameters measured. The analysis revealed 3 PCs within the ankle plantarflexion and DVJ kinetics variables that captured more than 80% of the variability within the data, but none of them showed significant correlations (r ≤ 0.27) with any foot variables. While foot posture and foot morphological deformation remain of interest in characterising foot morphology across individuals, these findings highlight the lack of clinical relevance of these static evaluations at characterising lower limb and ankle performance.

Effects of a Single Electrical Stimulation Session on Foot Force Production, Foot Dome Stability, and Dynamic Postural Control.

CONTEXT: Mounting evidence suggests neuromuscular electrical stimulation (NMES) as a promising modality for enhancing lower limb muscle strength, yet the functional effects of a single electrical stimulation session for improving the function of the intrinsic foot muscles (IFM) has not been evaluated. OBJECTIVE: To investigate the immediate effects of an NMES session compared with a sham stimulation session on foot force production, foot dome stability, and dynamic postural control in participants with static foot pronation. DESIGN: Randomized controlled clinical trial. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 46 participants (23 males, 23 females) with static foot pronation according to their Foot Posture Index (score ≥ 6) were randomly assigned to an NMES (n = 23) or control (n = 23) group. INTERVENTION(S): The NMES group received a single 15-minute NMES session on the dominant foot across the IFM. The control group received a 15-minute sham electrical stimulation session. MAIN OUTCOME MEASURE(S): All outcome measurements were assessed before and after the intervention and consisted of foot force production on a pressure platform, foot dome stability, and dynamic postural control. Statistical analysis was based on the responsiveness of the outcome measures and responder analysis using the minimum detectable change scores for each outcome measure. RESULTS: In the NMES group, 78% of participants were classified as responders for at least 2 of the 3 outcomes, compared with only 22% in the control group. The relative risk of being a responder in the NMES group compared with the control group was 3.6 (95% CI = 1.6, 8.1]. Interestingly, we found that all participants who concomitantly responded to foot strength and navicular drop (n = 8) were also responders in dynamic postural control. CONCLUSIONS: Compared with a sham stimulation session, a single NMES session was effective in immediately improving foot function and dynamic postural control in participants with static foot pronation. These findings support the role of NMES for improving IFM function in this population.