Rearfoot Strike Research Articles

Effects of Foot-Strike Patterns on Biomarkers S100 Calcium-Binding Protein B/Neuron-Specific Enolase in Running-A Pilot Study.

Foot-strike patterns (FSP) in running are related to certain impact kinetics during ground contact. A rear-foot strike (RFS) has been associated with higher impact forces, whereas a forefoot strike (FFS) is assumed to minimize these impact forces. This study investigated the effects of running with RFS or FFS on impact-sensitive neuronal biomarkers S100 calcium-binding protein B (S100B), neuron-specific enolase (NSE), and lactate dehydrogenase (LDH). In this randomized crossover study, 18 healthy recreational runners (14 male, mean [SD] age 28.2 [4.7]y, body mass index 22.8 [1.9]) ran 2 separate 5-mile runs with RFS or FFS, respectively. Blood samples were taken before (pre), 30min after (post 0), and 24h after (post 24) the run. S100B, NSE, and LDH concentrations were determined and analyzed (3 × 2 data model). S100B, NSE, and LDH concentrations increased from pre to post 0 and decreased within 24 h back to the baseline level, demonstrating a significant time effect (all P < .01, all ηpart2>.3). No main effect for FSP or any significant interaction effect indicating FSP-specific differences between FFS or RFS was found (all P > .05, all ηpart2<.07), except for LDH (P < .001, ηpart2=.77). NSE, S100B, and LDH concentration increased in the short term after running and returned to normal in 24h. FSP with varying impact forces does not influence the increase of these biomarkers. LDH findings favor peripheral origins, but mixed effects are possible. Thus, further research is needed to estimate the risk of mild traumatic encephalopathy.

Rearfoot strikes more frequently apply combined knee valgus and tibial internal rotation moments than forefoot strikes in females during the early phase of cutting maneuvers

BackgroundAnterior cruciate ligament (ACL) injury often occurs during deceleration maneuvers in sports. Combined knee valgus and tibial internal rotation (VL + IR) moments have been recognized as a risk leading to ACL injury; however, it is unknown how the foot strike pattern (forefoot or rearfoot strike) affects the occurrence rate of the aforementioned combined knee moments during cutting maneuvers. Research questionTo test the hypothesis that rearfoot strikes rather than forefoot strikes show a significantly higher occurrence rate of the combined VL + IR moments during the early stance phase of a cutting maneuver. MethodsTwenty-four females performed 60° cutting maneuvers under rearfoot and forefoot strike conditions. Positional data of lower limb markers and ground reaction force (GRF) were collected. Knee varus/valgus and tibial internal/external rotation moments due to GRF were calculated and time-normalized (0–100 %) to the stance phase. The occurrence rates of combined VL + IR moments were compared between rearfoot and forefoot strike conditions throughout the stance (chi-squared test, p < 0.01). Furthermore, the time patterns of the two knee moments and the position of the GRF acting point were compared using the statistical parametric mapping paired t-test (p < 0.0125). ResultsRearfoot strikes more frequently produced combined VL + IR moments than forefoot strikes (maximum occurrence rates: 73.5 % vs. 27.8 %, p < 0.01) during the first 0–40 % of the stance. Both foot strikes consistently showed an increase in knee valgus moment soon after foot impact; however, rearfoot and forefoot strikes respectively applied opposite internal and external rotation moments during the first 0–7 % of stance (p < 0.0125), indicating that the GRF vector that generated knee valgus moment further applied tibial internal rotation moment when it acted posterior to the tibial rotation axis. SignificanceThe current results suggest that rearfoot strike in cuttings elevates the probability of ACL injury via combined VL + IR moments.

What are the Benefits and Risks Associated with Changing Foot Strike Pattern During Running? A Systematic Review and Meta-analysis of Injury, Running Economy, and Biomechanics.

Running participation continues to increase. The ideal strike pattern during running is a controversial topic. Many coaches and therapists promote non-rearfoot strike (NRFS) running with a belief that it can treat and prevent injury, and improve running economy. The aims of this review were to synthesise the evidence comparing NRFS with rearfoot strike (RFS) running patterns in relation to injury and running economy (primary aim), and biomechanics (secondary aim). Systematic review and meta-analysis. Consideration was given to within participant, between participant, retrospective, and prospective study designs. MEDLINE, EMBASE, CINAHL, and SPORTDiscus. Fifty-three studies were included. Limited evidence indicated that NRFS running is retrospectively associated with lower reported rates of mild (standard mean difference (SMD), 95% CI 3.25, 2.37-4.12), moderate (3.65, 2.71-4.59) and severe (0.93, 0.32-1.55) repetitive stress injury. Studiesprospectively comparing injury risk between strike patterns are lacking. Limited evidence indicated that running economy did not differ between habitual RFS and habitual NRFS runners at slow (10.8-11.0km/h), moderate (12.6-13.5km/h), and fast (14.0-15.0km/h) speeds, and was reduced in the immediate term when an NRFS-running pattern was imposed on habitual RFS runners at slow (10.8km/h; SMD = - 1.67, - 2.82 to - 0.52) and moderate (12.6km/h; - 1.26, - 2.42 to - 0.10) speeds. Key biomechanical findings, consistently including both comparison between habitual strike patterns and following immediate transition from RFS to NRFS running, indicated that NRFS running was associated with lower average and peak vertical loading rate (limited-moderate evidence; SMDs = 0.72-2.15); lower knee flexion range of motion (moderate-strong evidence; SMDs = 0.76-0.88); reduced patellofemoral joint stress (limited evidence; SMDs = 0.63-0.68); and greater peak internal ankle plantar flexor moment (limited evidence; SMDs = 0.73-1.33). The relationship between strike pattern and injury risk could not be determined, as current evidence is limited to retrospective findings. Considering the lack of evidence to support any improvements in running economy, combined with the associated shift in loading profile (i.e., greater ankle and plantarflexor loading) found in this review, changing strike pattern cannot be recommended for an uninjured RFS runner. CRD42015024523.

Conversion to a rearfoot strike pattern during running for prevention of recurrent calf strains: A case report

BackgroundRunning-related injuries are prevalent musculoskeletal complaints in the United States military. Although, run retraining is an extensively researched method for reducing pain and improving function in runners, its clinical utility remains low. Case descriptionThe patient had a seven-year history of recurrent right calf strains. Prior conventional physical therapy failed to resolve symptoms. A biomechanical running analysis revealed a right forefoot strike during running. The patient underwent run retraining that included real-time visual feedback and a faded feedback strategy focused on converting foot strike pattern to rearfoot. Running mechanics were reassessed post-training, and at one and six months post-training. OutcomesFoot strike pattern was successfully converted to rearfoot strike and was maintained up to six months post-training. Reductions in peak ankle dorsiflexion moment and dorsiflexion velocity were noted up to six months post-training. Self-reported function also improved by 20–30% and no calf strains were reported up to six months post-training. DiscussionThis case report details the clinical reasoning and evidence-informed interventions involved in treatment of a patient with chronic calf strains. The management strategy was intended to reduce eccentric calf demands, which allowed the patient to tolerate increased running frequency without any further episodes of calf strains up to six months post-training.

ANKLE JOINT MOMENTS IN DIFFERENT FOOT STRIKE METHODS DURING STAIR DESCENT

The purpose of this study was to compare the ankle joint moments in different foot strike patterns during stair descent and to find a better strategy. Methods: Twenty young subjects participated in this study. Subjects performed two trials of descending stairs in rearfoot strike (RFS) and forefoot strike (FFS) strategies. Kinematic and kinetic data were measured by a motion capture system and force plates. Ankle joint moments, ground reaction forces, and moment arms in three planes of motion were calculated from the measured data. The root-mean-squared means of ankle joint moments, ground reaction forces, and moment arms were compared between different foot strike patterns for each phase of stair descent (weight acceptance, forward continuance, and controlled lowering). Results: In the weight acceptance phase, FFS showed greater ankle joint moments than RFS in all three (dorsi/plantar-flexion, inversion/eversion, and internal/external rotation) directions ([Formula: see text]). In the forward continuance phase, FFS showed greater dorsi/plantar moments than RFS ([Formula: see text]). In controlled lowering phase, FFS showed smaller dorsi/plantar moments than RFS ([Formula: see text]). Discussion: The greater ankle joint moments of FFS in the weight acceptance phase were influenced by both the greater GRF magnitudes and greater moment arms. The greater dorsi/plantar moments of FFS in the forward continuance phase and the smaller dorsi/plantar moment of FFS in the controlled lowering phase were dominated by the greater moment arm and the smaller ground reaction force, respectively. RFS strategy resulted in smaller ankle joint moments in the majority of stair descent phases (weight acceptance and forward continuance), therefore, RFS would be a better strategy than FFS for stair descent in terms of ankle joint load.

COMPARISON OF ANKLE JOINT LOAD IN DIFFERENT FOOT STRIKE STRATEGIES DURING STAIR ASCENT

The purpose of this study was to find a foot strike strategy that can reduce the ankle joint load during stair ascent by comparing the ankle joint load in two strategies of initial contact during stair ascent. Twenty young subjects performed ascending stairs with two strategies, i.e., rearfoot strike (RFS) and forefoot strike (FFS). Kinematic data was measured from 12 cameras and the ground reaction force was measured by a force plate inserted in the second step of four-step stairs. Stance phase was divided into three phase, i.e., weight acceptance, pull up, and forward continuance. Four ankle related kinetic variables were derived from the measured data, i.e., joint reaction force, moment, and the magnitude and moment arm of ground reaction force. Root-mean-square (RMS) was used as the representative value of the variables during each phase was compared between strategies. In the weight acceptance phase, FFS resulted in greater values of all four kinetic variables than RFS. For the pull-up and forward continuance phases, joint reaction force and ground reaction force were not different between strategies but joint moment and moment arm was greater for FFS than RFS. In weight acceptance phase, greater ground reaction forces and longer moment arm of FFS may have resulted from faster weight transfer to the ipsilateral foot and the more anterior location of center of pressure, respectively. Both have contributed greater joint moment of FFS. In pull-up and forward continuance phases, greater ankle moment of FFS was affected mainly by longer moment arms, which may reflect the persistent farther location of center of pressure from the ankle joint. The results suggest that RFS would be more advantageous than FFS in terms of ankle joint load.

Ankle Joint Dynamic Stiffness in Long-Distance Runners: Effect of Foot Strike and Shoes Features

Foot strike mode and footwear features are known to affect ankle joint kinematics and loading patterns, but how those factors are related to the ankle dynamic properties is less clear. In our study, two distinct samples of experienced long-distance runners: habitual rearfoot strikers (n = 10) and habitual forefoot strikers (n = 10), were analysed while running at constant speed on an instrumented treadmill in three footwear conditions. The joint dynamic stiffness was analysed for three subphases of the moment–angle plot: early rising, late rising and descending. Habitual rearfoot strikers displayed a statistically (p &lt; 0.05) higher ankle dynamic stiffness in all combinations of shoes and subphases, except in early stance in supportive shoes. In minimal-supportive shoes, both groups had the lowest dynamic stiffness values for early and late rising (initial contact through mid-stance), whilst the highest stiffness values were at late rising in minimal shoes for both rearfoot and forefoot strikers (0.21 ± 0.04, 0.24 ± 0.06 (Nm/kg/°∙100), respectively). In conclusion, habitual forefoot strikers may have access to a wider physiological range of the muscle torque and joint angle. This increased potential may allow forefoot strikers to adapt to different footwear by regulating ankle dynamic stiffness depending upon the motor task.

Running Propensities of Athletes with Hamstring Injuries.

The current study aims to compare the mechanical propensities between healthy runners and runners with hamstring injuries. Retrospective case-control video analysis was used. A total of 35 (12 male and 23 female) videos of runners with hamstring injuries were compared with videos of sex-, age-, mass-, and height-matched healthy control runners. The main outcome variables were trunk posture angles, overstride angles, and foot strike patterns. An independent t-test and chi-squared tests were employed to analyze the main outcome variables between the runners with hamstring injuries and the healthy control runners. The statistical significance of less than 0.05 (p < 0.05) was used. The runners with hamstring injuries had a 1.6° less forward-trunk posture angles compared with the healthy control runners (p = 0.043). Also, the runners with hamstring injuries demonstrated a 4.9° greater overstride angles compared with the healthy control runners (p = 0.001). Finally, the runners with hamstring injuries had a tendency of rearfoot strike, while the healthy control runners showed a forefoot strike pattern (p = 0.004). In conclusion, the runners with hamstring injuries demonstrated different running mechanical propensities compared with the healthy runners.

Using real‐time biofeedback to alter running biomechanics: A randomized controlled trial

In this study, we assessed the effectiveness of a mobile feedback system on transitioning runners to a non-rearfoot strike (NRFS) pattern and prospectively compared injury incidence rates at one year between rearfoot strike (RFS) and NRFS runners. 128 RFS runners participated in a 2-hour training session to learn a NRFS pattern with 114 completing the 1-year follow-up. Participants were randomized into a control group (CON) with no additional training and a biofeedback group (BFG) where they received equipment to provide real-time biofeedback to augment the transition to a NRFS pattern. Foot strike patterns (FSP) were assessed at baseline, post-training, 6-months, and 1-year. Injury data were collected through weekly email surveys over one year. Eighty percent of runners demonstrated a NRFS pattern following the training session (91/114, P < .001). The percentage of NRFS runners remaining at the one-year follow-up decreased slightly in both groups, but was not significantly different between groups (CON = 69%, P = .29; BFG = 75%, P = .36). Injury rates were similar between RFS runners (37% injured) and NRFS runners (30% injured) after one year (P = .47). The relative risk for knee injury in RFS runners was 5.64 (95% CI: 1.90-16.8; P = .02). In conclusion, both groups had a significant number of participants transition to a NRFS immediately after training and maintain NRFS at the 1-year follow-up. However, compliance with the sensor in the BFG group was very poor due to limitations of the sensor. Regardless of FSP, runners experienced 1-year injury incidence rates between 30%-37%. RFS runners had nearly a six times greater risk for developing a knee injury than NRFS runners.

Multi-segment foot kinematics during running and its association with striking patterns

ABSTRACT There is an ongoing debate regarding the advantages and harms of different running striking patterns. The purpose of this study was to explore the kinematic differences between running with a midfoot- and rearfoot striking (RFS) pattern. Multi-segment foot kinematics of 12 students were assessed while running barefoot at 3.3 m/s (±10%) using a passive optoelectronic motion analysis system. Participants performed multiple running trials while landing on the rearfoot and midfoot. Comparison of the kinematic waveforms was performed using one-dimensional statistical parametric mapping (1DSPM) (paired t-test). The inter-segment angle between the shank and calcaneus was found to be significantly more plantar-flexed, more inverted and more adducted in the midfoot striking (MFS) condition compared to the RFS pattern. The calcaneus-midfoot inter-segment angle was found to be more plantar-flexed in the MFS condition. The downward angulation of the metatarsals and the medial longitudinal arch angle in the late swing phase was found to be more pronounced during MFS. Differences between midfoot and RFS patterns occur in the first sub-phase of stance (0–50% of the stance phase). These findings may be of interest for the kinesiopathological or pathokinesiological reasoning processes when facing foot- and lower limb-related running injuries.

Using A Soft Conformable Foot Sensor to Measure Changes in Foot Strike Angle During Running.

The potential association between running foot strike analysis and performance and injury metrics has created the need for reliable methods to quantify foot strike pattern outside the laboratory. Small, wireless inertial measurement units (IMUs) allow for unrestricted movement of the participants. Current IMU methods to measure foot strike pattern places small, rigid accelerometers and/or gyroscopes on the heel cap or on the instep of the shoe. The purpose of this study was to validate a thin, conformable IMU sensor placed directly on the dorsal foot surface to determine foot strike angles and pattern. Participants (n = 12) ran on a treadmill with different foot strike patterns while videography and sensor data were captured. Sensor measures were compared against traditional 2D video analysis techniques and the results showed that the sensor was able to accurately (92.2% success) distinguish between rearfoot and non-rearfoot foot strikes using an angular velocity cut-off value of 0°/s. There was also a strong and significant correlation between sensor determined foot strike angle and foot strike angle determined from videography analysis (r = 0.868, p < 0.001), although linear regression analysis showed that the sensor underestimated the foot strike angle. Conformable sensors with the ability to attach directly to the human skin could improve the tracking of human dynamics and should be further explored.

Forefoot strike, rear foot strike or running shoes. Does it matter?

The main aim of this article is to provide some insight into evidence-based data in running. The prevalence of a rearfoot strike (RFS) pattern is much more usual than a forefoot strike (FFS) even among elite distance runners. There has been significant pressure on runners to change their running style from RFS to FFS in recent times. Usually, this has been justified by the statement that FFS relates to a lower injury rate. Recent studies have shown however, that this statement is probably not true. Different types of strike pattern have an influence on loading different structures of the lower limbs, but the total incidence of running related injury is the same regardless of the type of foot strike pattern.We want to provide not only an objective view on running technique but also an evidence-based view on the choice of running shoes. There are many recommendations to consider when choosing running shoes, especially in running stores, but only a few of them are supported by research.This article is not a meta-analysis but it provides some evidence based information about running styles and running shoes.

Transition to forefoot strike reduces load rates more effectively than altered cadence

BackgroundExcessive vertical impacts at landing are associated with common running injuries. Two primary gait-retraining interventions aimed at reducing impact forces are transition to forefoot strike and increasing cadence. The objective of this study was to compare the short- and long-term effects of 2 gait-retraining interventions aimed at reducing landing impacts. MethodsA total of 39 healthy recreational runners using a rearfoot strike and a cadence of ≤170 steps/min were randomized into cadence (CAD) or forefoot strike (FFS) groups. All participants performed 4 weeks of strengthening followed by 8 sessions of gait-retraining using auditory feedback. Vertical average load rates (VALR) and vertical instantaneous load rates (VILR) were calculated from the vertical ground reaction force curve. Both cadence and foot strike angle were measured using 3D motion analysis and an instrumented treadmill at baseline and at 1 week, 1 month, and 6 months post retraining. ResultsANOVA revealed that the FFS group had significant reductions in VALR (49.7%) and VILR (41.7%), and changes were maintained long term. Foot strike angle in the FFS group changed from 14.2° dorsiflexion at baseline to 3.4° plantarflexion, with changes maintained long term. The CAD group exhibited significant reduction only in VALR (16%) and only at 6 months. Both groups had significant and similar increases in cadence at all follow-ups (CAD, +7.2% to 173 steps/min; and FFS, +6.1% to 172 steps/min). ConclusionForefoot strike gait-retraining resulted in significantly greater reductions in VALR and similar increases in cadence compared to cadence gait-retraining in the short and long term. Cadence gait-retraining resulted in small reductions in VALR at only the 6-month follow-up.

Consolidation of the atypical rearfoot strike pattern in distance runners and linkage to tibial shocks

Shod rearfoot striking can be subdivided into typical and atypical using plantar pressures (Breine, Malcolm, Frederick, & De Clercq, 2014). The atypical pattern makes an initial rearfoot contact, f...

Recognition of Foot Strike Pattern in Asian Recreational Runners.

Close to 90% of recreational runners rearfoot strike in a long-distance road race. This prevalence has been obtained from North American cohorts of runners. The prevalence of rearfoot strikers has not been extensively examined in an Asian population of recreational runners. Therefore, the aim of this study was to determine the prevalence of rearfoot, midfoot, and forefoot strikers during a long-distance road race in Asian recreational runners and compare this prevalence to reported values in the scientific literature. To do so, we classified the foot strike pattern of 950 recreational runners at the 10 km mark of the Singapore marathon (77% Asian field). We observed 71.1%, 16.6%, 1.7%, and 10.6% of rearfoot, midfoot, forefoot, and asymmetric strikers, respectively. Chi-squared tests revealed significant differences between our foot strike pattern distribution and those reported from North American cohorts (P < 0.001). Our foot strike pattern distribution was similar to one reported from elite half-marathon runners racing in Japan (Fisher exact test, P = 0.168). We conclude that the prevalence of rearfoot strikers is lower in Asian than North American recreational runners. Running research should consider and report ethnicity of participants given that ethnicity can potentially explain biomechanical differences in running patterns.

Immediate Effects of a Textured Insole on Running Biomechanics in Rearfoot Strikers

Running biomechanics are influenced by footwear and insole properties. The sensorimotor system, specifically subcutaneous plantar receptors, play a role in initiating adaptive gait mechanics. Designed to increase afferent signaling via plantar surface deformation, an insole inlaid with a textured heel-plate (TI) is proposed to precipitate gait changes during running. PURPOSE: To compare biomechanical patterns during over-ground running between the TI and a non-textured insole (NI). METHODS: Nineteen rearfoot strike runners (24.9 +/- 5.7 yo; 6 M, 13 F) performed twenty, 35-meter running trials under TI and NI conditions. Insole conditions were counter-balanced, and velocity was controlled (±5%). Plantar sensation was assessed using a 3.61g monofilament applied to seven standardized sites. Thirty-six reflective markers (dia.=16-20 cm), affixed bilaterally to lower extremity bony landmarks, were tracked via a 10-camera motion analysis system (120 Hz), and ground reaction forces were collected (1200 Hz). Visual3D and a custom Matlab script were used to determine lower extremity kinematics and kinetic variables. Perceived insole comfort was scored with a visual analogue scale. Dependent variables were analyzed using paired-samples t-tests; for data that violated assumptions, a Wilcoxon signed-rank test was utilized. RESULTS: Kinetic measures did not differ significantly between insole conditions; impact peak (NI=1.46±0.58 BW, TI=1.50±0.44 BW, p=.74), active peak (NI=2.37±0.16 BW, TI=2.35±0.15 BW, p=.28), loading rate (NI=35.9±12.2 BW/s, TI=34.0±13.2 BW/s, p=.26), peak braking (NI=-.31±.03 BW, TI=-.32±.06 BW, p=.69) and peak propulsion (NI=.27±.05 BW, TI=.27±.04 BW, p=.28). A significant increase in ankle internal rotation angle at initial contact was observed in the TI versus NI (NI=5.9 ± 5.9o; TI=7.3 ± 5.9o; p=.01, d=.24), however, no other significant kinematic differences were detected. NI (mdn=9.0) was rated as significantly more comfortable than TI (mdn=8.0) (z=-2.026 p=.04). CONCLUSION: Because kinematic and kinetic variables did not vary significantly between the TI and NI, the efficacy of the TI as a method of immediately altering running mechanics in a population of rear foot strikers should be further investigated. Insoles provided by: ShoeCue Inc (ShoeCue, Orleans, MA)

Not All Forefoot Striking Is Equal

Rearfoot strike (RFS) runners typically exhibit an impact peak in their vertical ground reaction force caused by heel impact. This impact is associated with high load rates that have been linked to running injuries. The vast majority of forefoot strike (FFS) runners do not exhibit this impact peak and have significantly lower load rates compared with RFS runners. However, some FFS runners do exhibit an impact peak and load rates similar to RFS. The heel descent after initial contact in FFS could help further explain this phenomenon. PURPOSE: To investigate the relationship between heel kinematics and vertical average loading rate (VALR) in FFS runners. METHODS: 30 habitual FFS runners from an ongoing study were included (5F, 25M; age: 35.6±9.3). Ground reaction forces and heel kinematics were collected on an instrumented treadmill at 2.6±0.4m/s. Pearson correlations between VALR and heel height at initial contact (HIC), time to heel contact (THC), heel descent acceleration (HDA) and heel descent excursion (HDE) were extracted. These variables were also compared between runners who exhibit an impact peak (n=9) and those that did not (n=21). RESULTS: VALR was significantly (all p<0.01) correlated with HIC (r=-0.514), THC (r=-0.783) and HDA (r=0.612). A trend was found for the correlation with HDE (r=-0.33, p=0.08). FFS runners with an impact peak exhibited significantly lower HIC, a shorter THC and higher HDA (Table 1). A trend for lower HDE was noted in this group as well. CONCLUSIONS: Lower heel at initial contact, decreased time to heel contact, and higher heel descent acceleration were significantly correlated with greater VALR and were observed by FFS with vertical impact peaks. This suggests that FFS runners with these impacts should be trained to land with more plantarflexion and greater eccentric control of their heel descent to reduce their landing impacts.Supported by FAPESP (2017/26844-1).

Increased Ground Reaction Force Load Rates In Runners With Active Patellofemoral Pain

Increased vertical ground reaction force load rates have been associated with running injuries, and specifically with tibial stress fractures and plantar fasciitis. Inconsistent findings have been reported regarding the role of load rates in runners with patellofemoral pain (PFP), one of the most common injuries in runners. Limited studies in this patient population have been performed and prior investigators did not examine components of load rates beyond the vertical component. PURPOSE: To compare vertical, resultant, posterior, medial and lateral load rates, and peak vertical forces in runners with active PFP to healthy controls. METHODS: 30 runners with active PFP (16F, 14M, 40.2±12.8 yrs, 67.5±10.0 kg) and 30 healthy controls (CON) (18F, 12M, 34.8±10.9 yrs, 70.4±14.0 kg), all habitual rearfoot strikers, completed an instrumented treadmill assessment at a self-selected speed. Controls were matched for speed (PFP=2.50 m/s, CON=2.51 m/s). Load rates (vertical average and instantaneous (VALR, VILR), resultant instantaneous (RILR), posterior instantaneous (PILR), medial instantaneous (MILR) and lateral instantaneous (LILR)) over the first 25% of stance and normalized to bodyweights. Peak vertical ground reaction forces (vGRF) were calculated over all of stance. Values were averaged across 10 consecutive strides. The injured leg was analyzed for the PFP group, and the right/left leg was randomly selected and counterbalanced for CON. RESULTS: Runners in the PFP group showed significantly higher mean VALR (p=0.036, d=0.56), VILR (p= 0.040, d=0.54) and RILR (p=0.036, d=0.55) than CON. No differences were found in PILR (p=0.668), MILR (p=0.193), and LIRL (p=0.367) (Figure 1), or in peak vGRF (Mean difference=0.03 BW, p=0.458). CONCLUSION: Runners with active PFP exhibit higher vertical and resultant load rates.Figure 1: Mean load rates between patellofemoral pain and control groups-VALR, VILR, RILR plotted on left axis; PILR, MILR, and LILR plotted on right

Comparison of plantar loads among runners with different strike patterns

ABSTRACTThis study aimed to explore the plantar loading variables between habitual rearfoot strike (RFS) and non-rearfoot strike (NRFS) during running. 78 healthy males participated in this study (41 RFS, 37 NRFS). In-shoe pressure sensors were used to measure plantar loading while the participants were running on a 15 m indoor runway with their preferred foot strike pattern (FSP) at 12.0 ± 5% km/h. Results indicate that force and pressure parameters were much higher in the rearfoot and midfoot regions during RFS running and relatively greater in forefoot region during NRFS running. However, compared with NRFS running, the contact area, maximum force and force-time-integrals during RFS running on total foot were 21.44% (P < 0.001, ES = 2.29), 13.99% (P = 0.006, ES = 0.64) and 21.27% (P < 0.001, ES = 0.85) higher, respectively. Total foot peak pressure and pressure-time-integral between two FSPs were similar. Higher loads in the rearfoot region may transmit to the knee joint and result in patellofemoral joint injuries. NRFS runners’ higher loads in forefoot seem to be ralated to metatarsal stress fractures and compensatory damage to the Achilles tendon. Therefore, runners should choose proper FSPs according to their unique physical conditions.

Most marathon runners at the 2017 IAAF World Championships were rearfoot strikers, and most did not change footstrike pattern

The aim of this study was to analyze footstrike patterns in elite marathon runners at the 2017 IAAF World Championships. Seventy-one men and 78 women were analyzed in their respective races. Athletes’ footstrike patterns were recorded (120 Hz) at approximately 8.5, 19, 29.5 and 40 km (“Laps 1 – 4”) and categorized as either rearfoot (RFS), midfoot or forefoot striking; the latter two were classified together as non-rearfoot striking (NRFS). The most common footstrike pattern was RFS, with proportions never less than 54% of men or 67% of women at any distance. There were no sex-based differences for proportion of footstrike patterns, and there were no differences between footstrike proportions when comparing the top and bottom 50% of men finishers, or between women during Laps 1 and 2. A greater proportion of the top 50% of women maintained NRFS than amongst the bottom 50%. The proportion of RFS increased with distance run in the men’s race, although more than 75% of athletes across both marathons had consistent footstrike patterns between laps (79 RFS and 36 NRFS). As most athletes were RFS (including the top four finishing men), there appears to be no clear advantage to NRFS in marathon running. Coaches should note that it is normal for elite marathon runners to be either RFS or NRFS; however, forefoot striking was rare. The high proportion of athletes who maintained their footstrike pattern reflected individualized preferences for a given footstrike pattern.