Effects of running-induced fatigue on plantar pressure distribution in runners with different strike types

BackgroundRunning induced-fatigue is an important factor in running related injuries. Runners with different strike types have different running mechanics and suffer from different injury patterns. Underlying mechanism of this difference is not well understood.Research questionThe aim of this study was to examine the effects of running-induced fatigue on plantar pressure distribution in runners with different strike types.Methods30 rearfoot (age = 21.56 ± 2.28 years; height = 1.67 ± 0.08 m; mass = 61.43 ± 11.57 kg; BMI = 21.77 ± 2.9 kg∙m⁻²) and 30 forefoot (age = 19.73 ± 1.68 years; height = 1.71 ± 0.08 m; mass = 65.7 ± 13.45; BMI = 22.53 ± 3.39 kg∙m⁻²) strike male and female recreational runners were recruited to this study. Participants ran in 3.3 m/s barefoot along the plantar pressure measuring device (Footscan®, Rsscan International) before and after running-induced fatigue. Fatigue protocol was performed on a treadmill. Peak plantar pressure and peak plantar force (% body weight), contact time and medio-lateral force ratio were calculated while running. Repeated measures ANOVA test was used to investigate the effect of running-induced fatigue on plantar pressure variables (p ≤ 0.05).ResultsAfter running-induced fatigue, in the rearfoot strike group, increases in loading of medial and lateral portions of the heel, first metatarsal and big toe was observed, and in lesser toes and in the forefoot push off phase, the medio-lateral force ratio decreased. While, in the forefoot strike group first to third metatarsals loading increased and fifth metatarsal loading decreased after fatigue, and medio-lateral force ratio in the foot flat and forefoot push off phase increased. In both groups contact time increased after fatigue.SignificanceOur data indicate that running-induced fatigue has different effects on plantar pressure distribution pattern in runners with different strike type. These different effects reflect different adaptation strategies in runners with different strike types, and could explain existence of different injury patterns in runners with different strike types.     

Increased plantar foot pressure in persons affected by leprosy

Although foot pressure has been reported to be increased in people affected by leprosy, studies on foot pressure and its determinants are limited. Therefore, the aim was to assess barefoot plantar foot pressure and to identify clinical determinants of increased plantar foot pressure in leprosy affected persons. Plantar pressure in both feet was assessed using the Novel EMED-X platform in 39 persons affected by leprosy. Peak pressure was determined for the total foot and four regions: hallux, metatarsal heads, midfoot and heel. Potential determinants were: age, weight, nerve function (Neuropathy Disability Score, Pressure Perception Threshold and Vibration Perception Threshold), toe and foot deformities, joint mobility, ankle muscle strength and callus. Increased peak pressure (>600kPa) was observed in 46% of the participants. The highest peak pressure (mean) was found in the metatarsal heads region (right 549 (SD 321)kPa; left 530 (SD 298)kPa). Multilevel regression analysis showed that Neuropathy Disability Score, amputation/absorption of toes and hallux valgus independently contributed to metatarsal heads peak pressure in persons affected with leprosy. To conclude, peak pressure is increased in people affected by leprosy. The highest peak pressure is found in the forefoot region and is significantly associated to Neuropathy Disability Score, toe amputation/absorption and hallux valgus. Screening for clinical characteristics can be used to identify individual persons affected by leprosy at risk of excessive pressure.     

A mechanical model of metatarsal stress fracture during distance running

A model of metatarsal mechanics has been proposed as a link between the high incidence of second and third metatarsal stress fractures and the large stresses measured beneath the second and third metatarsal heads during distance running. Eight discrete piezoelectric vertical stress transducers were used to record the forefoot stresses of 21 male distance runners. Based upon load bearing area estimates derived from footprints, plantar forces were estimated. Highest force was estimated beneath the second and first metatarsal head (341.1 N and 279.1 N, respectively). Considering the toe as a hinged cantilever and the metatarsal as a proximally attached rigid cantilever allowed estimation of metatarsal midshaft bending strain, shear, and axial forces. Bending strain was estimated to be greatest in the second metatarsal (6662 mu epsilon), a value 6.9 times greater than estimated first metatarsal strain. Predicted third, fourth, and fifth metatarsal strains ranged between 4832 and 5241 mu epsilon. Shear force estimates were also greatest in the second metatarsal (203.0 N). Axial forces were highest in the first metatarsal (593.2 N) due to large hallux forces in relationship to the remaining toes. Although a first order model, these data highlight the structural demands placed upon the second metatarsal, a location of high metatarsal stress fracture incidence during distance running.     

The influence of muscle fatigue on electromyogram and plantar pressure patterns as an explanation for the incidence of metatarsal stress fractures

BACKGROUND: Stress fractures are common overuse injuries in runners and appear most frequently in the metatarsals. PURPOSE: To investigate fatigue-related changes in surface electromyographic activity patterns and plantar pressure patterns during treadmill running as potential causative factors for metatarsal stress fractures. STUDY DESIGN: Prospective cohort study with repeated measurements. METHODS: Thirty experienced runners volunteered to participate in a maximally exhaustive run above the anaerobic threshold. Surface electromyographic activity was monitored for 14 muscles, and plantar pressures were measured using an in-shoe monitoring system. Fatigue was documented with blood lactate measurements. RESULTS: The results demonstrated an increased maximal force (5%, P < .01), peak pressure (12%, P < .001), and impulse (9%, P < .01) under the second and third metatarsal head and under the medial midfoot (force = 7%, P < .05; pressure = 6%, P < .05; impulse = 17%, P < .01) toward the end of the fatiguing run. Contact area and contact time were only slightly affected. The mean electromyographic activity was significantly reduced in the medial gastrocnemius (-9%, P < .01), lateral gastrocnemius (-12%, P < .01), and soleus (-9%, P < .001) muscles. CONCLUSION: The demonstrated alteration of the rollover process with an increased forefoot loading may help to explain the incidence of stress fractures of the metatarsals under fatiguing loading conditions.     

Effects of running-induced fatigue on plantar pressure distribution in novice runners with different foot types

This study aimed to assess the effects of running-induced fatigue on plantar pressure parameters in novice runners with low and high medial longitudinal arch. Plantar pressure data from 42 novice runners (21 with high, and 21 with low arch) were collected before and after running-induced fatigue protocol during running at 3.3 m/s along the Footscan^® platform. Peak plantar pressure, peak force and force-time integral (impulse) were measured in ten anatomical zones. Relative time for foot roll-over phases and medio-lateral force ratio were calculated before and after the fatigue protocol. After the fatigue protocol, increases in the peak pressure under the first-third metatarsal zones and reduction under the fourth–fifth metatarsal regions were observed in the low arch individuals. In the high arch group, increases in peak pressure under the fourth–fifth metatarsal zones after the running-induced fatigue was observed. It could be concluded that running-induced fatigue had different effects on plantar pressure distribution pattern among novice runners with low and high medial longitudinal foot arch. These findings could provide some information related to several running injuries among individuals with different foot types.     

The effect of foot type on in-shoe plantar pressure during walking and running

The purpose of this study was to determine if low arch feet have altered plantar loading patterns when compared to normal feet during both walking and running. Fifty healthy subjects (34 normal feet, 16 flat feet) walked and ran five trials each at standard speeds. In-shoe pressure data were collected at 50 Hz. Contact area, peak pressure, maximum force, and force-time integral were analyzed in eight different regions of the foot. Foot type was determined by examining navicular height, arch angle, rearfoot angle, and a clinical score. A series of 2 x 2 repeated measures ANOVAs were used to determine statistical differences (alpha<0.05). A significant interaction existed between foot type and movement type for the maximum force in the medial midfoot. Total foot contact area, maximum force and peak pressure were significantly increased during running. Contact area in each insole area, except for the rearfoot, was significantly increased during running. Peak pressure and maximum force were significantly increased during running in each of the foot regions. However, the force-time integral was significantly decreased during running in the rearfoot, lateral midfoot, middle forefoot, and lateral forefoot. Significant differences between foot types existed for contact area in the medial midfoot and maximum force and peak pressure in the lateral forefoot. The maximum force and peak pressures were significantly decreased for the flat foot type. Therefore, individuals with a flat foot could be at a lower risk for lateral column metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures.     

A comparison of external plantar loading and in vivo local metatarsal deformation wearing two different military boots

The introduction of the M90 boot with a more flexible outer sole to military recruits in Sweden was accompanied by an increase in second metatarsal stress fractures. This study compared the new boot with the previous, stiffer model. A combination of external plantar pressure measurement (two subjects) and an in vivo measurement of dorsal metatarsal strain (six subjects) using strain gauge instrumented staples was implemented. Walking in both boot models resulted in increased plantar pressure under the heads of the lesser metatarsals and generally decreased loading under the remainder of the foot. Dorsal metatarsal tension increased for subjects wearing the new boot throughout a walking protocol.     

Temporal characteristics of foot roll-over during barefoot jogging: reference data for young adults

The purpose of this study was to establish a representative reference dataset for temporal characteristics of foot roll-over during barefoot jogging, based on plantar pressure data collected from 220 healthy young adults. The subjects ran at 3.3 m s⁻¹ over a 16.5 m long running track, having a built-in pressure platform mounted on a force platform. The initial contact, final contact, time to peak pressure and the duration of contact at the lateral and medial heel, metatarsal heads I to V and the hallux were measured. Temporal plantar pressure variables were found to be reliable (93% of ICC coefficients above 0.75) and both gender and asymmetry influences could be neglected. Foot roll-over during jogging started with heel contact followed by a latero-medial contact of the metatarsals and finally the hallux. After heel off, the forefoot started to push off at the lateral metatarsals, followed by a more central push off over the second metatarsal and finally over the hallux. Based on the plantar pressure data, the stance phase during running was divided into four distinct phases: initial contact (8.2%), forefoot contact (11.3%), foot flat (25.3%) and forefoot push off (55.1%). These findings provide a reliable and representative reference dataset for temporal characteristics of foot roll-over during jogging of young adults that may also be relevant in the evaluation of running patterns.     

A biomechanical assessment of the acute hallux abduction manipulation intervention

BackgroundNaturally aligned toes, particularly hallux, have reported with gripping functions during locomotion, thus expanding the forefoot loading area.Research questionThe purpose of this study was aimed to investigate the influence of hallux abduction manipulation on the foot plantar pressure distribution and inter-segment kinematic alterations.MethodsThirteen subjects participated in this toe manipulation study. A Footscan® pressure plate and Vicon motion capture system were utilized for the measurement of plantar pressure distribution and lower extremity and foot inter-segment kinematics during walking and running. Paired-sample t-test from statistical parametric mapping 1d was used to check the kinematic significance.ResultsPeak pressure in third metatarsal (M3) increased significantly during walking under manipulation. Contact area increased in second metatarsal (M2) with manipulation during running. Peak pressure and pressure-time integral illustrated significant increases in M3, and the maximum force and impulse in fourth metatarsal (M4) increased significantly. Arch height index increased while walking with toe manipulation. The foot progression angle in the frontal plane showed significant decrease in mid-swing phase during walking and significant increase in mid-stance phase during running. The hallux relative to forefoot angles presented higher axial rotation in the frontal plane.SignificanceFindings form this study showed centrally and laterally redistributed foot loadings and increased forefoot inter-segment flexibility with manipulation, which may be used as baseline to evaluate toe-manipulation interventions in foot disorders, specifically hallux valgus deformity.     

Comparaison de la répartition des appuis plantaires entre chaussures d'entraînement et chaussures à pointes chez de jeunes sprinters

AimsTo compare plantar patterns between training and spikes shoes in young sprinters.Methods and resultsEleven athletes performed two trials of 2 × 60 m maximal speed with training and spikes shoes, respectively. Contact area was significantly smaller with spikes in total and under the toes; pressure and force were significantly higher with spikes under the forefoot mainly in medial and lateral.ConclusionsWearing spikes shoes, higher loads are applied mainly under the 1st and the 2nd metatarsal heads. This may have relevance in order to clarify the mechanisms of injuries like metatarsalgia or stress fractures of the forefoot.     

Simultaneous measurement of plantar pressure and shear forces in diabetic individuals.

Plantar foot ulceration is a diabetic complication whose underlying causative factors are still not fully understood. The goal of the current work was to simultaneously record plantar pressure and shear and examine the interrelationship of these forces; specifically, if peak shear and pressure occurred at the same site/time and whether adjacent shear forces had a greater tendency to be directed towards or away from each other. A custom built 16 transducer array was used to record forefoot shear and pressure during gait initiation in a cohort of 12 neuropathic diabetic individuals. The individuals were barefoot and the transducers were covered with a 5 mm thick layer of Minorplast. The greatest pressure occurred in the medial metatarsal heads (189 kPa) and the greatest shear in the lateral metatarsal heads (33 kPa). The interaction of the shear forces revealed that the plantar tissue was stretched to a greater magnitude than it was bunched (24 kPa vs 12 kPa, averaged over all regions). Normal distributions were determined for stretching and bunching in both the medial-lateral and anterior-posterior directions. When shear and pressure were considered in combination, half of the neuropathic individuals had peak shear and pressure occurring at the same site. These peak stresses did not occur at the same time (average difference of 0.186 s). The results of this study help to further characterize tissue stresses experienced on the plantar surface of the foot during gait initiation in neuropathic diabetic individuals.     

A functional foot type classification with cluster analysis based on plantar pressure distribution during jogging

The purpose of this study was to establish a reference dataset for peak pressures and pressure-time integrals during jogging, to compare this reference dataset with existing walking data and to develop a foot type classification, all based on plantar pressure data obtained from 215 healthy young adults. The subjects ran at 3.3 m s(-1) over a 16.5 m long running track, with a built-in pressure platform mounted on top of a force platform. Peak pressures, regional impulses and relative regional impulses were measured. These variables were found to be reliable (all intra class correlation coefficients above 0.75) and, except for the heel areas, gender and asymmetry effects could be neglected. Highest peak pressures were found under the heel due to large impact forces during initial contact phase (ICP). In the forefoot, the highest peak pressure was found under the second metatarsal (64.2 +/- 21.1 N cm(-2)). Compared to walking data, overall higher peak pressures and impulses and difference in hallux loading were found during barefoot jogging. Four pressure loading patterns were identified using a K-means cluster analysis, based on the relative regional impulses underneath the forefoot: medial M1 pattern, medial M2 pattern, central pattern and central-lateral pattern. These four pressure loading patterns could help in the functional interpretation of the foot behaviour during the stance phase in slow running.     

The effect of a long-distance run on plantar pressure distribution during running

The purpose of this study was to assess plantar pressure alterations after long-distance running. Prior to and after a 20 km run, force distribution underneath the feet of 52 participants was registered using Footscan(?) pressure plates while the participants ran shod at a constant self-selected pace. Peak force, mean force and impulse were registered underneath different zones of the foot. In addition, temporal data as total foot contact time, time of contact and end of contact were derived for these zones. Furthermore, a medio-lateral pressure distribution ratio was calculated in different phases of the roll-off. After the run, increases in the loading of the forefoot, midfoot and medial heel were noted and decreases in loading of the lateral toes. In the forefoot push off phase a more lateral pressure distribution was observed. The results of this study demonstrated plantar pressure deviations after long-distance running which could give additional information related to several running injuries.     

The effects of off-the-shelf in-shoe heel inserts on forefoot plantar pressure

Off-the-shelf heel inserts are used widely without adequate scientific information regarding their effects upon the forefoot. The aim of this study was to assess whether the use of in-shoe heel inserts affects the plantar pressure distribution under the forefoot. Thirty-five asymptomatic volunteers consented to participate. Six brands of off-the-shelf heel inserts were tested. Subjects walked along a 10 m walkway with no inserts and then with each pair of inserts, in a randomised order. The Pedar system was used to record in-shoe plantar pressure data. The results confirmed that heel inserts increased pressure under the metatarsal heads and altered the biomechanics of the foot even in asymptomatic subjects. The findings suggested that heel inserts should be used with caution especially in people predisposed to foot problems. The classification of these inserts as an over-the-counter product may need to be reviewed.     

Effects of experimentally induced plantar insensitivity on forces and pressures under the foot during normal walking

Pressures under the foot during level walking were measured in 15 healthy young adults (8 females, 7 males, mean age 25.7, S.D. 5.3) before and after immersing the feet in ice-cold water (2 °C) for 30 min to evaluate the role of plantar insensitivity on gait patterns. Following ice water immersion, there was a significant decrease in walking speed. Maximum forces and peak pressures under the foot decreased, with the exception of an increase in loading under the third to fifth metatarsal heads. Contact times increased under all regions of the foot, and force–time and pressure–time integrals increased under the second and third to fifth metatarsal head regions. It is concluded that plantar insensitivity significantly alters the distribution, duration, and to a lesser extent, the magnitude of forces and pressures under the foot when walking. These results suggest that in the neuropathic foot, gait changes caused by plantar insensitivity may be partly responsible for the redistribution and altered duration of loading, whereas the increase in the magnitude of forces and pressures are primarily due to other disease-related factors.     

Comparison of plantar pressure distribution in adolescent runners at low vs. high running velocity

This study aimed to compare foot plantar pressure distribution while jogging and running in highly trained adolescent runners. Eleven participants performed two constant-velocity running trials either at jogging (11.2 ± 0.9 km/h) or running (17.8 ± 1.4 km/h) pace on a treadmill. Contact area (CA in cm(2)), maximum force (F(max) in N), peak pressure (PP in kPa), contact time (CT in ms), and relative load (force time integral in each individual region divided by the force time integral for the total plantar foot surface, in %) were measured in nine regions of the right foot using an in-shoe plantar pressure device. Under the whole foot, CA, F(max) and PP were lower in jogging than in running (-1.2% [p<0.05], -12.3% [p<0.001] and -15.1% [p<0.01] respectively) whereas CT was higher (+20.1%; p<0.001). Interestingly, we found an increase in relative load under the medial and central forefoot regions while jogging (+6.7% and +3.7%, respectively; [p<0.05]), while the relative load under the lesser toes (-8.4%; p<0.05) was reduced. In order to prevent overloading of the metatarsals in adolescent runners, excessive mileage at jogging pace should be avoided.     

Plantar loading changes with alterations in foot strike patterns during a single session in habitual rear foot strike female runners

ObjectivesCharacterize plantar loading parameters when habitually rear foot strike (RFS) runners change their pattern to a non-rear foot strike (NRFS).DesignExperimental.SettingUniversity biomechanics laboratory.ParticipantsTwenty three healthy female runners (Age: 22.17 ± 1.64 yrs; Height: 168.91 ± 5.46 cm; Mass: 64.29 ± 7.11 kg).Main outcome measuresPlantar loading was measured using an in-sole pressure sensor while running down a 20-m runway restricted to a range of 3.52–3.89 m/s under two conditions, using the runner's typical RFS, and an adapted NRFS pattern. Repeated measures multivariate analysis of variance was performed to detect differences in loading between these two conditions.ResultsForce and pressure variables were greater in the forefoot and phalanx in NRFS and greater in the heel and mid foot in RFS pattern, but the total force imposed upon the whole foot and contact time remained similar between conditions. Total peak pressure was higher and contact area was lower during NRFS running.ConclusionsThe primary finding of this investigation is that there are distinctly different plantar loads when changing from a RFS to NRFS during running. So, during a transition from RFS to a NRFS pattern; a period of acclimation should be considered to allow for adaptations to these novel loads incurred on plantar regions of the foot.     

In-shoe pressure distribution in "unstable" (MBT) shoes and flat-bottomed training shoes: a comparative study

BACKGROUND: Footwear comfort in many clinical situations is dependent on the ability of the 'shoe' to redistribute plantar pressure. Offloading the metatarsal heads may be achieved by fitting an insole, but recently a new design of shoe with a curved under sole (Masai Barefoot Technology or "MBT shoe") has been advocated. The aim of this study was to directly assess the effect of such shoes on gait pattern. METHODS: Normal subjects were recruited and asked to walk sequentially in (a) flat-soled training shoes and (b) midfoot bearing shoes (MBT shoe). Mean and peak pressures in four anatomically defined areas of the foot, and the total area of sole contact were measured electronically by an in-shoe system (Pedar Ltd., UK). PRINCIPAL RESULTS: Standing in the Masai shoes resulted in a 21% lesser peak pressure under the midfoot and an 11% lesser peak pressure under the heel in comparison to the figures found when patients wore their training shoes. There was a 76% compensatory increase in pressure under the toes. In essence there was a significant shift in pressure towards the front of the foot.