Injuries observed in a prospective transition from traditional to minimalist footwear: correlation of high impact transient forces and lower injury severity

Objectives: Minimalist running is increasing in popularity based upon a concept that it can reduce impact forces and decrease injury rates. The purpose of this investigation is to identify the rate and severity of injuries in runners transitioning from traditional to minimalist footwear. The secondary aims were to identify factors correlated with injuries.

Methods: Fourteen habitually shod (traditional running shoes) participants were enrolled for this prospective study investigating injury prevalence during transition from traditional running shoes to 5-toed minimalist shoes. Participants were uninjured, aged between 22-41 years, and ran at least twenty kilometers per week in traditional running shoes. Participants were given industry recommended guidelines for transition to minimalist footwear and fit with a 5-toed minimalist running shoe. They completed weekly logs for identification of injury, pain using Visual Analogue Scale (VAS), injury location, and severity. Foot strike pattern and impact forces were collected using 3D motion analysis at baseline, 4 weeks, and 12 weeks. Injuries were scored according to a modified Running Injury Severity Score (RISS).

Results: Fourteen runners completed weekly training and injury logs over an average of 30 weeks. Twelve of 14 (86%) runners sustained injuries. Average injury onset was 6 weeks (range 1–27 weeks). Average weekly mileage of 23.9 miles/week prior to transition declined to 18.3 miles/week after the transition. The magnitude of the baseline impact transient peak in traditional shoes and in minimalist shoes negatively correlated with RISS scores (r = ?0.45, p = 0.055 and r = ?0.53, p = 0.026, respectively).

Conclusion: High injury rates occurred during the transition from traditional to minimalist footwear. Non-compliance to transition guidelines and high injury rates suggest the need for improved education. High impact transient forces unexpectedly predicted lower modified RISS scores in this population.     

Effects of barefoot and barefoot inspired footwear on knee and ankle loading during running

Background

Recreational runners frequently suffer from chronic pathologies. The knee and ankle have been highlighted as common injury sites. Barefoot and barefoot inspired footwear have been cited as treatment modalities for running injuries as opposed to more conventional running shoes. This investigation examined knee and ankle loading in barefoot and barefoot inspired footwear in relation to conventional running shoes.

Method

Thirty recreational male runners underwent 3D running analysis at 4.0 m·s^− 1. Joint moments, patellofemoral contact force and pressure and Achilles tendon forces were compared between footwear.

Findings

At the knee the results show that barefoot and barefoot inspired footwear were associated with significant reductions in patellofemoral kinetic parameters. The ankle kinetics indicate that barefoot and barefoot inspired footwear were associated with significant increases in Achilles tendon force compared to conventional shoes.

Interpretation

Barefoot and barefoot inspired footwear may serve to reduce the incidence of knee injuries in runners although corresponding increases in Achilles tendon loading may induce an injury risk at this tendon.     

Minimalist shoe injuries: Three case reports

Running in minimalist shoes continues to increase in popularity and multiple mainstream shoe companies now offer minimalist shoes. While there is no evidence that traditional running shoes prevent injuries, there are concerns that the designs of minimalist shoes may increase injury risk. However, reports of injuries in runners wearing minimalist shoes are rare. We present three injuries occurring in runners that were wearing minimalist shoes at the time of injury. All three of the runners switched immediately to the minimalist shoes with no transition period. We recommend that any transition to minimalist shoe gear be performed gradually. It is our contention that these injuries are quite common and will continue to become more prevalent as more runners change to these shoes.     

A comparison of the spatiotemporal parameters, kinematics, and biomechanics between shod, unshod, and minimally supported running as compared to walking

Recreational running has many proven benefits which include increased cardiovascular, physical and mental health. It is no surprise that Running USA reported over 10 million individuals completed running road races in 2009 not to mention recreational joggers who do not wish to compete in organized events. Unfortunately there are numerous risks associated with running, the most common being musculoskeletal injuries attributed to incorrect shoe choice, training errors and excessive shoe wear or other biomechanical factors associated with ground reaction forces. Approximately 65% of chronic injuries in distance runners are related to routine high mileage, rapid increases in mileage, increased intensity, hills or irregular surface running, and surface firmness. Humans have been running barefooted or wearing minimally supportive footwear such as moccasins or sandals since the beginning of time while modernized running shoes were not invented until the 1970s. However, the current trend is that many runners are moving back to barefoot running or running in “minimal” shoes. The goal of this masterclass article is to examine the similarities and differences between shod and unshod (barefoot or minimally supportive running shoes) runners by examining spatiotemporal parameters, energetics, and biomechanics. These running parameters will be compared and contrasted with walking. The most obvious difference between the walking and running gait cycle is the elimination of the double limb support phase of walking gait in exchange for a float (no limb support) phase. The biggest difference between barefoot and shod runners is at the initial contact phase of gait where the barefoot and minimally supported runner initiates contact with their forefoot or midfoot instead of the rearfoot. As movement science experts, physical therapists are often called upon to assess the gait of a running athlete, their choice of footwear, and training regime. With a clearer understanding of running and its complexities, the physical therapist will be able to better identify faults and create informed treatment plans while rehabilitating patients who are experiencing musculoskeletal injuries due to running.     

Is midsole thickness a key parameter for the running pattern?

Many studies have highlighted differences in foot strike pattern comparing habitually shod runners who ran barefoot and with running shoes. Barefoot running results in a flatter foot landing and in a decreased vertical ground reaction force compared to shod running. The aim of this study was to investigate one possible parameter influencing running pattern: the midsole thickness. Fifteen participants ran overground at 3.3 m s⁻¹ barefoot and with five shoes of different midsole thickness (0 mm, 2 mm, 4 mm, 8 mm, 16 mm) with no difference of height between rearfoot and forefoot. Impact magnitude was evaluated using transient peak of vertical ground reaction force, loading rate, tibial acceleration peak and rate. Hip, knee and ankle flexion angles were computed at touch-down and during stance phase (range of motion and maximum values). External net joint moments and stiffness for hip, knee and ankle joints were also observed as well as global leg stiffness. No significant effect of midsole thickness was observed on ground reaction force and tibial acceleration. However, the contact time increased with midsole thickness. Barefoot running compared to shod running induced ankle in plantar flexion at touch-down, higher ankle dorsiflexion and lower knee flexion during stance phase. These adjustments are suspected to explain the absence of difference on ground reaction force and tibial acceleration. This study showed that the presence of very thin footwear upper and sole was sufficient to significantly influence the running pattern.     

Two Models of Minimalist,Incremental Syntactic Analysis

Minimalist grammars (MGs) and multiple context‐free grammars (MCFGs) are weakly equivalent in the sense that they define the same languages, a large mildly context‐sensitive class that properly includes context‐free languages. But in addition, for each MG, there is an MCFG which is strongly equivalent in the sense that it defines the same language with isomorphic derivations. However, the structure‐building rules of MGs but not MCFGs are defined in a way that generalizes across categories. Consequently, MGs can be exponentially more succinct than their MCFG equivalents, and this difference shows in parsing models too. An incremental, top‐down beam parser for MGs is defined here, sound and complete for all MGs, and hence also capable of parsing all MCFG languages. But since the parser represents its grammar transparently, the relative succinctness of MGs is again evident. Although the determinants of MG structure are narrowly and discretely defined, probabilistic influences from a much broader domain can influence even the earliest analytic steps, allowing frequency and context effects to come early and from almost anywhere, as expected in incremental models.     

Simplification des procédures TAVI : mise au point

After a first procedure carried out in 2002 by Pr Cribier's, Transcatheter Aortic Valve Replacement or TAVR revolutionized the management of aortic stenosis with a constant increase in the number of procedures performed worldwide. Experience of operators and teams and evolution of the technique has been accompanied by a drastic reduction in complications in patients at lower surgical risk. In parallel, the procedure was considerably simplified, carried out more and more under local anesthesia, with percutaneous femoral approach, secondary radial approach, prosthesis implantation without predilatation, rapid pacing on left ventricle wire and early discharge. Thus, the “simplified” TAVR adopted in most centers nowadays is a real revolution of the technique. However, simplified TAVR must be accompanied upstream by a rigorous selection of patients who can benefit from a minimalist procedure in order to guarantee its safety.     

Gait retraining versus foot orthoses for patellofemoral pain: a pilot randomised clinical trial

Objectives

To determine the feasibility of a clinical trial that compares a 6-week, physiotherapist-guided gait retraining program with a foot orthoses intervention in runners with patellofemoral pain.

Acute shoe effects on Achilles tendon loading in runners with habitual rearfoot strike pattern

Objectives: Although the overuse injury rate of the Achilles tendon (AT) for running is high, the effect of shoe conditions on AT loading remains unclear. Hence, this study aims to determine the mechanical properties of AT during running under different shoe conditions (minimalist vs. conventional shoes).Design:This work is a controlled laboratory study.Methods:Sixteen healthy male rearfoot strike runners were recruited to complete over ground running trials at 3.33 m/s (±5%) under two shoe conditions (minimalist shoes: INOV-8 Bare-XF 210; conventional shoes: NIKE AIR ZOOM PEGASUS 34). Sagittal plane ankle kinematics and ground reaction forces were simultaneously recorded. Ankle joint mechanics (ankle joint angle and moment) and the mechanical properties (peak force, impulse, stress, strain, and their corresponding peak rate) of the AT were calculated.Results: In comparison with conventional shoes, wearing minimalist shoes showed significant changes (p < 0.05): (1) decreased strike angle (48.92 ± 9.01 vs. 41.04 ± 8.69°); (2) increased ankle moment (2.34 ± 0.44 vs. 2.55 ± 0.46 Nm/kg); (3) increased peak AT force (5.85 ± 1.22 vs. 6.24 ± 1.13 BW), AT force impulse (0.65 ± 0.13 vs. 0.70 ± 0.13 BW·s), peak AT loading rate (109.94 ± 9.33 vs. 118.84 ± 26.62 BW/s), and average loading rate (48.42 ± 15.64 vs. 54.90 ± 17.47 BW/s); (4) decreased time to peak AT force (126.31 ± 20.68 vs. 117.77 ± 17.62 ms); (5) increased AT stress (66.96 ± 14.59 vs. 71.89 ± 14.74 MPa), strain (8.19 ± 1.77 vs. 8.78 ± 1.80 %), peak AT stress rate (66.96 ± 14.59 vs. 71.89 ± 14.74 MPa/s), and strain rate (148.71 ± 48.52 vs. 167.28 ± 42.82 %/s).Conclusion: Increased AT force, loading rate, and stress were observed in runners who habitually wear conventional shoes with rearfoot strike patterns when they wore minimalist shoes. Hence, we recommend a gradual transition to minimalist shoes for runners who habitually wear conventional shoes with rearfoot strike patterns.