Effect of different forefoot rocker radii on lower-limb joint biomechanics in healthy individuals

IntroductionPrevious studies showed that rocker shoes with a stiff forefoot rocker profile significantly reduce peak plantar flexion moment at the ankle (PFM) and peak ankle dorsiflexion (DF). Both parameters are related to Achilles tendon and Plantar Fascia unloading. The shape of an outsole with a forefoot rocker is described with multiple rocker design parameters. The aim of this research is, to determine the relation between different forefoot rocker radii on peak DF and peak PFM at a self-selected walking speed.Methods10 participants walked in standard shoes and three experimental pairs of shoes with different forefoot rocker radii. Lower extremity kinematics and kinetics were collected while walking on an instrumented treadmill at preferred walking speed and analysed with Statistical Parametric Mapping (SPM) (α = .05; post-hoc α = .05/6).ResultsPeak value analyses showed significant decreases in peak DF, peak PFM, and peak ankle power generation for the rocker conditions. No relevant significant differences were found in spatio-temporal parameters and total work at the ankle joint. SPM showed a significant decrease (% gait cycle) in DF (40–69 %), PFM (7–15 %; 41–68 %; 69–81 %), ankle power (10–15 %; 32–51 %; 55–64 %; 64–67 %; 72–80 %) and foot-to-horizontal angle (FHA) (0–4 %; 40–62 %; 92–100 %) and an increased shank-to-vertical angle (SVA) (44–84 %) for the rocker conditions.ConclusionThe results of this study suggest that rocker shoes with a proximally placed apex significantly reduce DF and PFM during the third rocker compared with control shoes. This effect is mainly explained by a change in the FHA. Smaller radii cause the largest reductions in DF and PFM, so therefore, a uniform standardisation of the forefoot rocker radius is essential.     

Effects of rocker radii with two longitudinal bending stiffnesses on plantar pressure distribution in the forefoot

IntroductionOutsole parameters of the shoe can be adapted to offload regions of pain or region of high pressures. Previous studies already showed reduced plantar pressures in the forefoot due to a proximally placed apex position and higher longitudinal bending stiffness (LBS). The aim of this study was to determine the effect of changes in rocker radii and high LBS on the plantar pressure profile during gait.Method10 participants walked in seven shoe conditions of which one control shoe and six rocker shoes with small, medium and large rocker radii and low and high longitudinal bending stiffness. Pedar in-shoe plantar pressure measuring system was used to quantify plantar pressures while walking on a treadmill at self-selected walking speed. Peak plantar pressure, maximum mean pressure and force-time integral were analyzed with Generalized Estimated Equation (GEE) and Tukey post hoc correction (α = .05).ResultsSignificantly lower plantar pressures were found in the first toe, toes 2–5, distal and proximal forefoot in all rocker shoe conditions as compared to the control shoe. Plantar pressures in the first toe and toes 2–5 were significantly lower in the small radius compared to medium and large radii. For the distal forefoot both small and medium radii significantly reduced plantar pressure compared to large radii. Low LBS reduced plantar pressure at the first toe significantly compared to high LBS independent of the rocker radius. Plantar pressures in the distal forefoot and toes 2–5 were lower in high LBS compared to low LBS.ConclusionManipulation of the rocker radius and LBS can effectively reduce peak plantar pressures in the forefoot region during gait. In line with previous studies, we showed that depending on the exact target location for offloading, different combinations of rocker radius and LBS need to be adopted to maximize treatment effects.     

Biomechanics of slow running and walking with a rocker shoe

Evidence suggests a link between the loading of the Achilles tendon and the magnitude of the ankle internal plantar flexion moment during late stance of gait, which is clinically relevant in the management of Achilles tendinopathy. Some studies showed that rocker shoes can reduce the ankle internal plantar flexion moment. However, the existing evidence is not conclusive and focused on walking and scarce in running. Sixteen healthy runners participated in this study. Lower extremity kinetics, kinematics and electromyographic (EMG) signals of triceps surae and tibialis anterior were quantified for two types of shoes during running and walking. The peak ankle plantar flexion moment was reduced significantly in late stance of running (0.27 Nm/kg; p < 0.001) and walking (0.24 Nm/kg; p < 0.001) with the rocker shoe compared to standard shoe. The ankle power generation and plantar flexion moment impulse were also reduced significantly when running and walking with the rocker shoe (p < 0.001). No significant changes in the knee and hip moments were found in running and walking. A significant delay of the EMG peak, approximately 2% (p < 0.001), was present in the triceps surae when walking with rocker shoes. There were no significant changes in the EMG peak amplitude of triceps surae in running and walking. The peak amplitude of tibialis anterior was significantly increased (64.7 μV, p < 0.001) when walking with rocker shoes. The findings show that rocker shoes reduce the ankle plantar flexion moment during the late stance phase of running and walking in healthy people.     

How can push-off be preserved during use of an ankle foot orthosis in children with hemiplegia? A prospective controlled study

Several studies indicated that walking with an ankle foot orthosis (AFO) impaired third rocker. The purpose of this study was to evaluate the effects of two types of orthoses, with similar goal settings, on gait, in a homogeneous group of children, using both barefoot and shoe walking as control conditions. Fifteen children with hemiplegia, aged between 4 and 10 years, received two types of individually tuned AFOs: common posterior leaf-spring (PLS) and Dual Carbon Fiber Spring AFO (CFO) (with carbon fibre at the dorsal part of the orthosis). Both orthoses were expected to prevent plantar flexion, thus improving first rocker, allowing dorsiflexion to improve second rocker, absorbing energy during second rocker, and returning it during the third rocker. The effect of the AFOs was studied using objective gait analysis, including 3D kinematics, and kinetics in four conditions: barefoot, shoes without AFO, and PLS and CFO combined with shoes. Several gait parameters significantly changed in shoe walking compared to barefoot walking (cadence, ankle ROM and velocity, knee shock absorption, and knee angle in swing). The CFO produced a significantly larger ankle ROM and ankle velocity during push-off, and an increased plantar flexion moment and power generation at pre-swing compared to the PLS (<0.01). The results of this study further support the findings of previous studies indicating that orthoses improve specific gait parameters compared to barefoot walking (velocity, step length, first and second ankle rocker, sagittal knee and hip ROM). However, compared to shoes, not all improvements were statistically significant.     

The effect of different running shoes on treadmill running mechanics and muscle activity assessed using statistical parametric mapping (SPM)

BackgroundDifferences in joint mechanics between running shoes are commonly assessed using discrete parameters, yet statistically significant differences in these parameters between shoes are often scarce with small effect sizes. Statistical parametric mapping (SPM) has been suggested as suitable method for analyzing one-dimensional data such as kinematic, kinetic or muscle intensity time series.Research questionThe purpose of this study was to determine differences in treadmill running mechanics between novel running shoes using SPM.MethodsJoint kinematics, muscle activity and ground reaction force were assessed in 19 rearfoot runners in their own shoes and in two test shoes during treadmill running (test shoe 1: 13 distinct rubber elements in the outer sole, springboard within EVA midsole with posterior elements shifted anteriorly by approximately 1.5 cm; test shoe 2: 17 distinct EVA elements with conventional heel geometry). Joint kinematics were measured using an inertial sensor system, and ground reaction force was measured using an instrumented treadmill.ResultsSPM analysis with repeated measures ANOVA revealed significant reductions in the ankle angle and in tibialis anterior, peroneus longus, vastus medialis and lateralis muscle activity during weight acceptance and in peroneus longus muscle activity during early and late swing and in semitendinosus muscle activity during late swing for the test shoes. Significant differences in muscle activity were observed in the interval of the main activity of the respective muscle. SPM on individual data revealed statistically significant and relevant within-subject differences between conditions in kinematic, muscle activity and ground reaction force patterns.SignificanceInertial sensor systems and SPM may provide an efficient way of detecting changes in joint mechanics between running shoes within runners. Detecting within-subject differences in running mechanics between conditions not only requires statistical criteria but also criteria on the relevance of the magnitude of differences.     

Effects of flexible and rigid rocker profiles on in-shoe pressure

Rocker profiles are commonly used in the prevention of diabetic foot ulcers. Rockers are mostly stiffened to restrict toe plantarflexion to ensure proper offloading. It is also described that toe dorsiflexion should be restricted. However, the difference in effect on plantar pressure between rigid rockers that restrict this motion and flexible rockers that do not is unknown. In-shoe plantar pressure data were collected for a control shoe and the same shoe with rigid and flexible rockers with the apex positioned at 50% and 60%. For 29 healthy female adults peak plantar pressure (PP), maximum mean pressure (MMP) and force-time integral (FTI) were determined for seven regions of the foot. Generalized estimate equation was used to analyse the effect of the different shoes on the outcome measures for these regions. Compared to the control shoe a significant increase of PP and FTI was found at the first toe for both rigid rockers and the flexible rocker with the apex positioned at 60%, while MMP was significantly increased in rockers with an apex position of 60% (p < 0.001). PP at the first toe was significantly lower in flexible rockers when compared to rigid rockers (p < 0.001). For both central and lateral forefoot PP and MMP were significantly more reduced in rigid rockers (p < 0.001), while for the medial forefoot no differences were found. The use of rigid rockers results in larger reductions of forefoot plantar pressures, but in worse increase of plantar pressures at the first toe compared to rockers that allow toe dorsiflexion.     

Biomechanics of running with rocker shoes

Objectives

Load reduction is an important consideration in conservative management of tendon overuse injuries such as Achilles tendinopathy. Previous research has shown that the use of rocker shoes can reduce the positive ankle power and plantar flexion moment which might help in unloading the Achilles tendon. Despite this promising implication of rocker shoes, the effects on hip and knee biomechanics remain unclear. Moreover, the effect of wearing rocker shoes on different running strike types is unexplored. The aim of this study was to investigate biomechanics of the ankle, knee and hip joints and the role of strike type on these outcomes.

A comparison of multi-segment foot kinematics during level overground and treadmill walking

Previous work comparing treadmill and overground walking has focused on lower extremity motion and kinetics, with few identified differences. However, a comparison of multi-segment foot kinematics between these conditions has not been previously reported. Sagittal ankle motion using a single rigid body foot model and three-dimensional hindfoot and forefoot kinematics were compared during barefoot, level, overground walking at a self-selected speed and treadmill walking at a similar speed for 20 healthy adults. Slight differences were seen in ankle plantarflexion and hindfoot plantarflexion during first rocker, as well as peak forefoot eversion and abduction, however all changes were less than 3°, and most were within the day-to-day repeatability. These results indicate that foot mechanics as determined using a multi-segment foot model were similar between overground and treadmill walking at similar speeds in healthy adults. Treadmill protocols may provide a controlled method to analyze a patient's ability to adapt to walking at different speeds and surface slopes, which are encountered often during ambulation of daily living.     

The apex angle of the rocker sole affects the posture and gait stability of healthy individuals

BackgroundRocker sole (RS) shoes have been linked to impaired postural control. However, which features of RS design affect balance is unclear.Research questionWhich RS design features affect standing balance and gait stability?MethodsThis study utilized an intervention and cross-over design. Twenty healthy young adults (10 males and 10 females) participated in this study. Standing balance and gait stability were measured using a single force platform and three-dimensional motion analysis system, respectively. The experimental conditions included the control shoe and five RS shoes in the combination of apex position (%) and apex angle (degree) for RS50-95, RS60-95, RS70-95, RS60-70, and RS60-110. The main outcome measures were the area surrounding the maximal rectangular amplitude, mean path length, average displacement of the center of pressure along the lateral and anterior/posterior directions, and maximal center of pressure excursion as the standing balance and lateral margin of stability as the gait stability. Statistical analyses were conducted using a two-way split-plot analysis of variance with repeated measures (with RS design as the within-subject factor and sex as the between-subject factor) and the Bonferroni post hoc test (α = .05).ResultsRegarding the mean path length, RS60-70 was significantly longer than the control shoe, and it showed a significantly increased lateral margin of stability. Thus, RS60-70 was shown to affect standing balance, limit of stability, and gait stability of the frontal plane during gait.SignificanceThese results suggest that the apex angle of the RS design feature affects standing balance and gait stability, and RS60-70 is detrimental to stability. Therefore, when RS with a small apex angle is prescribed, it is necessary to consider the patient’s balance ability.     

Long-term effects of shoe mileage on knee and ankle joints muscle co-contraction during walking in females with genu varus

BackgroundShoe mileage may influence the risk of sustaining injuries during walking.Research questionWhat are the effects of shoe mileage on knee and ankle muscle co-contraction during walking in females with genu varus?MethodsFifteen healthy and 15 women diagnosed with genu varus received a new pair of running shoes. They were asked to wear these shoes over 6 months. Pre and post intervention, muscle activities of the dominant limb were recorded during a walking test at preferred gait speed. Two dependent variables were assessed to examine muscle co-contraction: (1) directed co-contraction ratios of agonists and antagonists, and (2) general joint muscle co-contraction.FindingsResults demonstrated significant main effects of the “shoe” factor for general ankle co-contraction during the push-off phase (p = 0.013, d = 1.503). Irrespective of experimental group, paired comparisons revealed significantly lower general ankle co-contraction during the push-off phase after the intervention. A significant main effects of “shoe” for general knee co-contraction during loading phase (p = 0.025, d = 0.895) was also observed. In both groups, paired comparison revealed significantly lower general knee co-contraction during the push-off phase in the post condition. We did not find any significant main effect of group nor group-by-shoe interaction for general ankle co-contraction during the stance phase. Likewise, we did not observe any significant main effect of “shoe”, “group” and “group-by-shoe” interaction for mediolateral directed knee co-contraction during stance phase of walking (p > 0.05).SignificanceOur findings showed that the shoe mileage but not the genu varus condition affects the general and directed co-contraction of the muscles stabilizing the knee and ankle joints. Together with the observed findings on ankle and knee muscle co-contraction, it is essential to change running shoes after a long wearing time in both healthy and genu varus females.     

Gait alterations in posterior tibial tendonitis: A systematic review and meta-analysis

BackgroundPosterior tibial tendon dysfunction (PTTD) is a common and debilitating tendinopathy that can lead to a profound decrease in gait function. While the clinical diagnosis and treatment of this disorder are well described, the pathomechanics have not been adequately characterized. The purpose of this systematic review and meta-analysis is to compare foot/ankle kinematics and kinetics in patients with PTTD with healthy controls during gait.MethodsRelevant articles were selected thought Medline (Pubmed), Scopus, CINAHL, and Web of Science. Studies focused on foot/ankle kinematics and kinetics in patients with PTTD were involved. Articles were included if they: 1) compared patients with PTTD to healthy controls, 2) utilized kinematics or kinetics as the primary outcome measure, 3) evaluated gait tasks, and 4) were written in English.ResultsEleven articles were included in this systematic review, and 8 studies were synthesized and analyzed. Our meta-analyses indicated increased dorsiflexion and abduction of the forefoot, as well as increased plantarflexion and eversion of hindfoot for patients with PTTD during stance of walking.ConclusionOur results from the meta-analysis showed more conclusive changes in the forefoot (increased dorsiflexion and abduction) and hindfoot (increased plantarflexion and eversion) kinematics during stance of walking, which may be associated with a pathological process of PTTD. This review provides an improved understanding of gait function in patients with PTTD and preliminary knowledge for future research.     

Lower extremity joint loading during level walking with Masai barefoot technology shoes in overweight males

The purpose of this study was to evaluate the effects of Masai barefoot technology (MBT) shoes on lower extremity joint loading in overweight males during level walking. Therefore, lower extremity kinematics, kinetics, and muscle electromyographic signals of the vastus lateralis (VL), biceps femoris (BF), and gastrocnemius medialis (GM) were recorded in 10 overweight males at a self‐chosen walking speed with MBT shoes and conventional shoes. Selected peak joint moments, maximal joint force loading rates, mean muscle intensities, and co‐activation indices of the VL/BF, as well as of the VL/GM were analyzed and compared for the two shoe conditions using paired Student's t‐tests (α=0.05). Results showed that walking with MBT shoes reduced first peak knee adduction moments in overweight subjects. During midstance and terminal stance, increases in VL/GM co‐activation, accompanied by increases in VL and GM (only terminal stance) intensities were found for the MBT situation. Kinetic variables analyzed to assess ankle and hip joint loading did not exhibit any statistical differences. These results suggest that using MBT shoes diminishes medial compartment loads at the knee without overloading hip or ankle joints in overweight males. However, the additional muscle loading should not be overlooked, and warrants further investigation.     

Comparing walking biomechanics of older females in maximal,minimal, and traditional shoes

BackgroundKnee osteoarthritis (OA) is a degenerative joint disease that affects millions of individuals each year. Several biomechanical variables during walking have been identified as risk factors for developing knee OA, including the peak external knee adduction moment (KAM) and the knee flexion angle at initial contact. Many interventions have been studied to help mitigate these risk factors, including footwear. However, it is largely unknown how varying shoe cushioning may affect walking biomechanics related to knee OA risk.Research QuestionWhat is the effect of maximally and minimally cushioned shoes on walking biomechanics compared to a traditionally cushioned shoe in older females?MethodsWalking biomechanics in three shoes (maximal, traditional, minimal) were collected on 16 healthy females ages 50–70 using an 8-camera 3D motion capture system and two embedded force plates. Key biomechanical variables related to knee OA disease risk were compared between shoes using repeated measures ANOVAs.ResultsThe KAM was significantly larger in the maximal shoe (p = 0.005), while the knee flexion angle at initial contact was significantly larger in both the maximal and minimal shoe compared to the traditional shoe (p = .000). Additionally, the peak knee flexion angle (p = .000) and the loading rates of the vertical ground reaction force were (instantaneous: p = 0.001; average: p = .010) were significantly higher in the minimal shoe.SignificanceWhile these results are specific to the shoes used in this study, clinicians should exercise caution in prescribing maximal or minimal shoes to females in this age group who may be at risk of knee OA given these results. Research is needed on the effect of these shoes in patients with knee OA.     

Does running speed affect the response of joint level mechanics in non-rearfoot strike runners to footwear of varying longitudinal bending stiffness?

BackgroundModifying the longitudinal bending stiffness (LBS) of footwear has become a popular method to improve sport performance. It has been demonstrated to influence running economy by altering lower extremity joint level mechanics. Previous studies have only examined within-participant effects at one running speed.Research questionDo joint level mechanics differ in response to varying footwear LBS at a range of running speeds?MethodsThis study utilized a cross-sectional repeated measure study design using a convenience sample. Ten well trained non-rearfoot strike male distance runners ran at 3.89, 4.70, and 5.56 m/s (14, 17, 20 km/hr) in footwear of three different LBS levels. Mechanics and energetics of the metatarsophalangeal joint (MTPJ), ankle, knee, and hip joints during stance phase were assessed using an 8-camera optical motion capture system (f_s = 200 Hz), a force instrumented treadmill (f_s = 1000 Hz) and standard inverse dynamics theory.ResultsRange of motion and negative work decreased and angular stiffness increased for the MTPJ with increasing LBS at all speeds (p < .001). Peak MTPJ moment did not change at any speed in response to increased LBS. Negative work at the ankle decreased in the stiff shoe at 17 km/hr (p = .036). Peak ankle plantar flexion velocity decreased with increasing LBS at all speeds (p < .05).SignificanceWhile changes in MTPJ mechanics were consistent across speeds, decreased negative ankle work was only observed at 17 km/hr in the stiff shoe, suggesting that perhaps tuned footwear LBS may need to focus primarily on metabolically beneficial changes in ankle plantar flexor mechanical behavior to improve performance in distance runners. Tuning footwear stiffness may also be beneficial to clinical populations, as clinicians seek to optimize their patients’ locomotion economy.     

The effects of shoes on the torsion and rearfoot motion in running.

Excessive pronation is accepted as a good indicator for various running injuries. The least amount of pronation takes place when running barefoot. The latest investigations show that this is connected to a large torsional movement between forefoot and rearfoot which can be influenced by the shoe sole construction. The shoes which are in use among runners in track and field are basically of two types, running shoes (in general torsionally stiff) and spikes (torsionally flexible). The possibly varying effect of these shoes on the shoe/foot motion in running is not known. The purpose of this investigation was therefore to show whether the pronation angle and the torsion angle differ when running barefoot, with spikes, and with running shoes (forefoot touchdown, N = 9 left and right). A film analysis provided the angular movements of the lower leg, rearfoot, and forefoot as well as pronation and torsion in the frontal plane. The results show that at touchdown the torsional movements with both shoe types are quite different from those of running barefoot. With shoes, the torsion angle is reduced back to zero--with running shoes more than with spikes--and the pronation angle is increased beyond the barefoot values (P less than 0.01). In order to reduce the risk of injury, both shoe types should be improved--the running shoes with respect to torsion and the spikes with respect to pronation.     

Influence of a novel elastic foot orthosis in foot motion during locomotion in adults with mild flatfoot

BackgroundCollapse of the foot arch is a one of the risk factors in medial tibial stress syndrome. Custom-made foot orthoses are used to reduce the collapse of foot arch, but the orthoses are designed for a specific shoe and cannot be used in other shoes. We developed an elastic foot orthosis that is highly fitted on the foot using thin films, is lightweight, and can be used with any shoe or without shoes. The purpose of this study was to investigate foot kinematics with our elastic foot orthosis during walking and running.MethodsWe recruited 30 participants with asymptomatic flatfoot for this study. Foot kinematic data were recorded for treadmill walking, treadmill running, and over-ground walking. Foot kinematics were recorded in three conditions, barefoot (BF), with the elastic foot orthosis (EFO), and with sham foot orthosis (SFO), and foot strain was measured using a stretch strain sensor. The difference in foot strain from initial contact to maximum strain during gait was calculated as loading arch strain, which was reflected as forefoot eversion excursion. A one-way analysis of variance with Bonferroni test was performed to compare the loading arch strain among the three conditions.ResultsIn all tasks, loading arch strain with the EFO was significantly less than that in the BF and SFO conditions. Loading arch strain with the SFO was significantly more than that of BF in the treadmill gait condition.ConclusionOur results indicate that the EFO decreased foot strain during locomotion compared to without the EFO and is capable of supporting the foot arch during locomotion.     

Ankle fixation need not increase the energetic cost of human walking

We tested whether the metabolic energy cost of walking with the ankles immobilized can be comparable to normal walking. Immobilization of any lower extremity joint usually causes greater energy expenditure. Fixation of the ankle might be expected to eliminate the work it normally performs, to detrimental effect. But fixation using lightweight boots with curved rocker bottoms can also bring some benefits, so that the overall energetic effect might be quite small. We measured oxygen consumption, kinematics, and ground reaction forces in six (N=6) able-bodied human volunteers walking at 1.25m/s in three conditions: normal walking in street shoes, walking with ankles immobilized by walking boots, and normally with ankles free but also weighted to match the mass of the walking boots. We estimated metabolic energy expenditure, joint work, and overall work performed on the body center of mass as a function of ankle fixation. Ankle fixation with walking boots caused the total rate of energy expenditure for walking to increase by 4.1% compared to normal (P=0.003), but differed by an insignificant amount (0.4% less, P=0.78) compared to walking with equivalent ankle weight. Compared to normal walking, ankle fixation can reduce ankle torque and work during the stance phase, most notably during late stance. This apparently makes up for the loss of ability to push-off as normal. With a suitably lightweight apparatus and curved rocker bottom surface, loss of ankle motion need not increase energy expenditure for walking.     

Increased shoe sole hardness results in compensatory changes in the utilized coefficient of friction during walking

Based on mechanical testing, harder soled shoes have been shown to provide less available friction than soft soled shoes. Whether or not humans adjust their utilized coefficient of friction (COFu) and gait kinematics to accommodate the decrease in available friction while wearing hard soled shoes is not known. Fifty-six young adults participated in this study. Ground reaction forces, full body kinematics, stride characteristics and subjective perception of footwear slipperiness were recorded under both hard and soft soled shoe conditions. Paired t-tests were used to identify the differences between two shoes conditions. Results indicated that the peak COFu was significantly less when wearing the hard soled shoes compared to when wearing the soft soled shoes (0.23 vs. 0.26, P < 0.001). The decrease in peak COFu was the result of a decrease in the resultant shear forces at the time of peak COFu as no difference in the vertical ground reaction forces was observed. When wearing hard soled shoes, subjects demonstrated decreased total body center of mass (COM) acceleration prior to and immediately following initial contact, decreased walking velocity, shortened stride length, and reduced ankle dorsiflexion angle at initial contact. Taken together, we believe that these gait modifications represent behavioral adaptations to wearing shoes that are perceived to be more slippery.     

Differences in running biomechanics between a maximal,traditional, and minimal running shoe

ObjectivesPrevious studies comparing shoes based on the amount of midsole cushioning have generally used shoes from multiple manufacturers, where factors outside of stack height may contribute to observed biomechanical differences in running mechanics between shoes. Therefore, the purpose of this study was to compare ground reaction forces and ankle kinematics during running between three shoes (maximal, traditional, and minimal) from the same manufacturer that only varied in stack height.DesignWithin-participant repeated measuresMethodsTwenty recreational runners ran overground in the laboratory in three shoe conditions (maximal, traditional, minimal) while three-dimensional kinematic and kinetic data were collected using a 3D motion capture system and two embedded force plates. Repeated measures ANOVAs (α = .05) compared biomechanical data between shoes.ResultsWhile the loading rate was significantly greater in the minimal shoe compared to the maximal shoe, no other differences were seen for the ground reaction force variables. Peak eversion was greater in the maximal and minimal shoe compared to the traditional shoe, while eversion duration and eversion at toe-off were greater in the maximal shoe.ConclusionsPreviously cited differences in ground reaction force parameters between maximal and traditional footwear may be due to factors outside of midsole stack height. The eversion mechanics in the maximal shoes from this study may place runners at a greater risk of injury. Disagreement between previous studies indicates that more research on maximal running shoes is needed.