Rearfoot Strike Pattern Research Articles

In-shoe multi-segment foot kinematics measurement during the stance phase of running using a stretch strain sensor

Multi-segment foot kinematics during shod running are difficult to investigate in clinical settings. Stretch strain sensors can measure foot kinematics; however, whether they can evaluate foot kinematics during shod running or at the midfoot kinematics remains unclear. The aim of this study was to investigate the stretch strain sensor could reveal differences between shod and barefoot conditions and midfoot kinematics during running.Eighteen healthy adults were included in the study. A stretch strain sensor and three-dimensional motion capture system were used to measure foot kinematics during barefoot and shod running with a rearfoot strike pattern. The correlation between the amplitudes of the two signals during barefoot running was investigated, and the similarity between the two signals was evaluated using the cross-correlation coefficient. Statistical parametric mapping was used to compare shod and barefoot conditions.Shod running had significantly lower sensor strain from 30 % to 100 % stance compared to barefoot running (p < 0.05). The sensor amplitude was significantly correlated with the shank–rearfoot frontal (r = 0.668, p = 0.002), the rearfoot–midfoot transverse (r = 0.546, p = 0.02), and the midfoot–forefoot sagittal planes (r = 0.563, p = 0.01). A high cross-correlation was observed between the sensor signal and the shank–rearfoot sagittal, frontal, and transverse planes and the midfoot–forefoot sagittal plane.This sensor can be used to investigate foot kinematics during shod running. The sensor signal mainly reflects the shank–rearfoot frontal and midfoot–forefoot sagittal planes, as well as the maximum kinematic range of the rearfoot-midfoot transverse plane.

Effects of a 10-week footstrike transition programme on tibial stress fracture probability; a randomized controlled intervention using finite element and probabilistic modelling

Introduction: The aim of this study was to undertake a randomized control trial examining the effects of a 10-week footstrike transition program on tibial stress fracture risk compared to control. Material and methods: Twenty habitual rearfoot strike runners were randomly assigned to either footstrike or control groups. The footstrike group undertook a graduated 10-week program which allowed them to convert their habitual rearfoot strike pattern, whereas the control group maintained their normal training regime without any alterations to their strike pattern. Running biomechanics were collected using an eight-camera motion capture system, and ground reaction forces using a force plate. Tibial strains were quantified using finite element modelling and stress fracture probability calculated via probabilistic modelling over 100 days of running. The primary outcome: tibial stress fracture probability, and secondary outcomes: running biomechanics, muscle forces, joint contact forces, and tibial strain indices were measured at baseline and after 10 weeks. Results: Intention-to-treat analyses revealed no significant alterations in the primary outcome (Footstrike: baseline = 12.82% &amp; 10-weeks = 10.82%, Control: baseline = 15.43% &amp; 10-weeks = 13.39%) between arms. However, alterations in the strike index (Footstrike: baseline = 21.79% &amp; 10-weeks = 65.74%, Control: baseline = 13.61% &amp; 10-weeks = 12.41%) and the loading rate (Footstrike: baseline = 165.85BW/s &amp; 10-weeks = 100.01 BW/s, Control: baseline = 170.13 BW/s &amp; 10-weeks = 197.87 BW/s) were significantly greater in the footstrike group compared to the control one. Conclusion: This trial concludes that the footstrike intervention adopted in this study was not effective in mediating improvements in tibial stress fracture risk, although future intervention trials could examine the efficacy of footstrike modification on other musculoskeletal injuries in runners.

Effects of gait retraining using minimalist shoes on the medial gastrocnemius muscle-tendon unit behavior and dynamics during running.

The effects of a 12-week gait retraining program on the adaptation of the medial gastrocnemius (MG) and muscle-tendon unit (MTU) were investigated. 26 runners with a rearfoot strike pattern (RFS) were randomly assigned to one of two groups: gait retraining (GR) or control group (CON). MG ultrasound images, marker positions, and ground reaction forces (GRF) were collected twice during 9 km/h of treadmill running before and after the intervention. Ankle kinetics and the MG and MTU behavior and dynamics were quantified. Runners in the GR performed gradual 12-week gait retraining transitioning to a forefoot strike pattern. After 12-week, (1) ten participants in each group completed the training; eight participants in GR transitioned to non-RFS with reduced foot strike angles; (2) MG fascicle contraction length and velocity significantly decreased after the intervention for both groups, whereas MG forces increased after intervention for both groups; (3) significant increases in MTU stretching length for GR and peak MTU recoiling velocity for both groups were observed after the intervention, respectively; (4) no significant difference was found for all parameters of the series elastic element. Gait retraining might potentially influence the MG to operate at lower fascicle contraction lengths and velocities and produce greater peak forces. The gait retraining had no effect on SEE behavior and dynamics but did impact MTU, suggesting that the training was insufficient to induce mechanical loading changes on SEE behavior and dynamics.

Normative Running Kinematics in Healthy Adolescent Runners: A 2-Dimensional Video Analysis.

The literature on the running kinematics of youth distance runners is limited. We sought to describe 2-dimensional (2D) video analysis of running kinematics in healthy adolescent distance runners, which has not been previously described. We conducted an observational study of healthy, competitive runners between the ages of 14 and 18 years, prospectively recruited through local running clubs and our hospital's outreach between August 2019 and July 2023. Participants ran on a treadmill at a self-selected speed with markers attached to the thorax, pelvis, and lower extremities. A high-definition video camera recorded the runners in the sagittal and frontal planes. Kinematic measurements were completed using Dartfish software and reported as means and standard deviations. Of the 53 participants (51% boys, mean age: 16.0 ± 1.4 years) included in the 2D running analysis, 91% ran with a rearfoot strike pattern, with a mean foot inclination angle of 10.2° ± 6.2°. Knee flexion angle at initial contact was 13.2° ± 3.8°, tibia inclination angle was 8.5° ± 3.2°, and peak knee flexion was 44.5° ± 3.6°. Cadence was 168.7° ± 8.6°. Contralateral pelvic drop was 6.0° ± 2.2° and peak rearfoot eversion was 11.8° ± 3.6°. This study is the first to describe running kinematics as captured by 2D video in healthy adolescent runners and to identify kinematic variables that may differ from those of adult runners. Further research is required to determine if adult recommendations are applicable to adolescent populations.

Rearfoot Strike Run Retraining forAchilles Tendon Pain: A Two-patient Case Series.

Running-related injuries are prevalent in the military and are often related to physical fitness test training. Non-rearfoot striking while running is known to increase the risk of Achilles tendon injuries because of the high eccentric energy absorption by the elastic components of the planarflexor muscle-tendon complex. However, there is limited evidence to suggest benefits of converting runners with Achilles tendon pain to use a rearfoot strike. This is a case series of two active-duty Service members with chronic, running-related Achilles tendon pain that utilized a natural non-rearfoot strike pattern. Both patients were trained to utilize a rearfoot strike while running through the use of real-time visual feedback from wearable sensors. The trained rearfoot strike pattern was retained for over one month after the intervention, and both patients reported improvements in pain and self-reported function. This case series demonstrated the clinical utility of converting two non-rearfoot strike runners to a rearfoot strike pattern to decrease eccentric demands on the plantarflexors and reduce Achilles tendon pain while running.

Influence of foot strike patterns and cadences on patellofemoral joint stress in male runners with patellofemoral pain

ObjectivesThis study aimed to determine the effect of foot strike patterns and cadences in male runners with patellofemoral pain (PFP). DesignCross-sectional study. SettingBiomechanics lab. Methods20 male runners with PFP were instructed to randomly complete six running conditions (three cadence conditions in rearfoot strike pattern (RFS) or forefoot strike (FFS)) under a preferred running speed. Main outcome measuresThe primary outcomes were peak knee joint and moment, and secondary outcomes were patellofemoral joint stress. ResultsRunning with increased cadence has a lower flexion angle (P = 0.027, η2 = 0.45), lower extension moment (P = 0.011, η2 = 0.29), lower internal rotation moment (P = 0.040, η2 = 0.17), lower patellofemoral stress (P = 0.029, η2 = 0.52) than preferred cadence. FFS running performed significantly lower flexion angle (P = 0.003, η2 = 0.39), lower extension moment (P < 0.001, η2 = 0.91), lower adduction moment (P = 0.020, η2 = 0.25) lower patellofemoral stress (P < 0.001, η2 = 0.81) than RFS running for all cadence. ConclusionsPreliminary findings provide new perspectives for male runners with PFP to unload patellofemoral joint stress in managing PFP through the combination of the FFS pattern and increased cadence.

The effectiveness of telehealth gait retraining in addition to standard physical therapy treatment for overuse knee injuries in soldiers: a protocol for a randomized clinical trial

IntroductionRunning is the most common cardiovascular exercise in the military. However, there is a high incidence of running-related overuse injuries that reduces military readiness. Gait retraining is a common intervention to treat running-related injuries, but the high cost of equipment and lack of clinician expertise and availability reduces utilization. Gait retraining intervention in a telehealth format might improve feasibility. The purpose of this randomized clinical trial is to determine the effectiveness of a telehealth gait retraining intervention on pain, self-reported function, and biomechanical risk factors for injury in service members who present to a Military Health System physical therapy clinic with an overuse knee injury.MethodsThis is a parallel, two-arm, single-blind randomized clinical trial. The two independent variables are intervention (2 levels: telehealth gait retraining intervention with standard of care or only standard of care) and time (3 levels: baseline, 10 weeks or post-intervention, 14 weeks). Participants between the ages of 18 to 60 years will be included if they report knee pain during and/or after running to be anywhere from a 3 to a 7 on the numerical pain rating scale and demonstrate a rearfoot strike pattern. The primary dependent variables are as follows: (1) pain (worst pain during and/or after running) and (2) foot strike pattern (conversion rate from rearfoot to non-rearfoot foot strike pattern during running). Secondary outcomes include patient self-reported function and running biomechanics.DiscussionThe effectiveness of a telehealth gait retraining intervention to reduce pain and modify foot strike pattern is not known. The results of this study may help determine the effectiveness and feasibility of a telehealth gait retraining intervention to reduce pain, change foot strike, improve function, and improve running gait biomechanics.Trial registrationClinicalTrials.gov, NCT04269473. Registered 05 February 2020.

Effects of a 12-week gait retraining program on the Achilles tendon adaptation of habitually shod runners.

This study investigated the effects of a 12-week gait retraining program on the morphological and mechanical properties of the Achilles tendon (AT) during running on the basis of real-time dynamic ultrasound imaging. A total of 30 male recreational runners who were used to wearing cushioned shoes with a rearfoot strike (RFS) pattern were recruited. They were randomized into a retraining group (RG, n = 15) and a control group (CG, n = 15). The RG group was asked to run in five-fingered minimalist shoes with a forefoot strike (FFS) pattern, and the CG group was asked to keep their strike pattern. Three training sessions were performed per week. All the participants in RG uploaded running tracks obtained through a mobile application (.jpg) after each session for training supervision. The ground reaction force, kinematics, and kinetics of the ankle joint at 10 km/h were collected using an instrumented split-belt treadmill and a motion capture system. The morphological (length and cross-sectional area) and mechanical characteristics (force, stress, strain, etc.) of AT invivo were recorded and calculated with a synchronous ultrasonic imaging instrument before and after the intervention. Repeated two-way ANOVA was used to compare the aforementioned parameters. A total of 28 participants completed the training. The strike angle of RG after training was significantly smaller than that before training and significantly smaller than that of CG after training (F (1, 13) = 23.068, p < 0.001, partial η2 = 0.640). The length (F (1, 13) = 10.086, p = 0.007, partial η2 = 0.437) and CSA (F (1, 13) = 7.475, p = 0.017, partial η2 = 0.365) of AT in RG increased after training. A significant main effect for time was observed for the time-to-peak AT force (F (1, 13) = 5.225, p = 0.040, partial η2 = 0.287), average (F (1, 13) = 7.228, p = 0.019, partial η2 = 0.357), and peak AT loading rate (F (1, 13) = 11.687, p = 0.005, partial η2 = 0.473). Preliminary evidence indicated that a 12-week gait retraining program could exert a beneficial effect on AT. 57% (8/14) runners in RG shifted from RFS to FFS pattern. Although not all runners were categorized as FFS pattern after the intervention, their foot strike angle was reduced. Retraining primarily positively promoted AT morphological properties (i.e., CSA and length) to strengthen AT capability for mechanical loading.

Added mass increases Achilles tendon stress in female runners

ContextAchilles tendon (AT) injuries are common in female runners and military personnel where increased AT loading may be a contributing factor. Few studies have examined AT stress during running with added mass. The purpose was to examine the stress, strain, and force placed on the AT, kinematics and temporospatial variable in running with different amounts of added mass. DesignRepeated measure design MethodsTwenty-three female runners with a rear-foot strike pattern were participants. AT stress, strain, and force were measured during running using a musculoskeletal model that used kinematic (180 Hz) and kinetic data (1800 Hz) as input. Ultrasound data were used to measure AT cross sectional area. A repeated measures multivariate analysis of variance (α = 0.05) was used on AT loading variables, kinematics and temporospatial variables. ResultsPeak AT stress, strain, and force were greatest during the 9.0 kg added load running condition (p < .0001). There was a 4.3% and 8.8% increase in AT stress and strain during the 4.5 kg and 9.0 kg added load conditions, respectively, compared to baseline. Kinematics at the hip and knee changed with added load but not at the ankle. Small changes in temporospatial variables were seen. ConclusionAdded load increased stress on the AT during running. There may be an increased risk for AT injury with added load. Individuals may consider slowly progressing training with added load to allow for increased AT loading.

Characterizing the mechanical function of the foot’s arch across steady-state gait modes

The arch of the human foot has historically been likened to either a truss, a rigid lever, or a spring. Growing evidence indicates that energy is stored, generated, and dissipated actively by structures crossing the arch, suggesting that the arch can further function in a motor- or spring-like manner. In the present study, participants walked, ran with a rearfoot strike pattern, and ran with a non-rearfoot strike pattern overground while foot segment motions and ground reaction forces were recorded. To quantify the midtarsal joint’s (i.e., arch’s) mechanical behavior, a brake-spring-motor index was defined as the ratio between midtarsal joint net work and the total magnitude of joint work. This index was statistically significantly different between each gait condition. Index values decreased from walking to rearfoot strike running to non-rearfoot strike running, indicating that the midtarsal joint was most motor-like when walking and most spring-like in non-rearfoot running. The mean magnitude of elastic strain energy stored in the plantar aponeurosis mirrored the increase in spring-like arch function from walking to non-rearfoot strike running. However, the behavior of the plantar aponeurosis could not account for a more motor-like arch in walking and rearfoot strike running, given the lack of main effect of gait condition on the ratio between net work and total work performed by force in the plantar aponeurosis about the midtarsal joint. Instead, the muscles of the foot are likely altering the motor-like mechanical function of the foot’s arch, the operation of these muscles between gait conditions warrants further investigation.

Alterations in Achilles tendon stress and strain across a range of running velocities

ABSTRACT Running has a high incidence of overuse injuries. Achilles tendon (AT) injuries may occur due to high forces and repetitive loading during running. Foot strike pattern and cadence have been linked to the magnitude of AT loading. The effect of running speed on AT stress and strain, muscle forces, gait parameters and running kinematics is not well addressed in recreational runners with lower pace of running. Twenty-two female participants ran on an instrumented treadmill between 2.0 and 5.0 m/s. Kinetic and kinematic data were obtained. AT cross-sectional area data were collected using ultrasound imaging. Inverse dynamics with static optimization was used to calculate muscle forces and AT loading. AT stress, strain and cadence increased with greater running speed. Foot inclination angle indicated a rearfoot strike pattern among all participants, which increased as running speed increased but the latter plateaued after 4.0 m/s. The soleus contributed more force in running compared to the gastrocnemius throughout all speeds. Highest running speeds had the most stress on the AT, with changes to foot inclination angle and cadence. Understanding the relation of AT loading variables with running speed may aid in understanding how applied load may influence injury.

Transitioning to Barefoot Running Using a Minimalist Shoe Intermediary: A Prospective Cohort Study.

The objectives of this study are, first, to investigate the probability of runners successfully transitioning from running in a traditional shoe to barefoot. Second, to identify prognostic indicators of failure of transition to barefoot running. Over 20 wk, 76 healthy runners (female, 40; age, 35.04 yr [SD, 8.9 yr]; body weight, 69.9 kg [SD 13.4 kg]) attempted to transition from running in traditional shoes to running barefoot. A minimalist shoe was used as an intermediary. Participants ran for 4 wk exclusively in provided traditional shoes followed by 4 wk of transitioning to minimalist shoes. This process was repeated to transition to barefoot running. Participants were followed up until they withdrew from the study or successfully transitioned to running barefoot. A survival analysis examined the weeks of successful transition. Along with sex and age, baseline measures of traditional shoe overall comfort, footstrike pattern, midfoot width mobility and plantar foot pressure pain threshold were examined as prognostic variables for failure to transition using Cox regression. The cumulative probability of successful transition to running barefoot was 70.8% (95% confidence interval [CI], 61%-83%). The primary footwear-related reason for withdrawal was pain, primarily in the foot ( n = 7), two runners had confirmed injuries. Runners exhibiting a rearfoot strike pattern and higher midfoot width mobility were more likely to fail to transition (hazard ratios [HR], 4.02; 95% CI, 1.33-12.16 and HR, 1.22; 95% CI, 1.05-1.42). Most runners who wish to run barefoot will be able to transition. Our study indicates that there may be biomechanical and anatomical characteristics that are prognostic of failing to transition when using a 20-wk transition period and an intermediary minimalist shoe. Whether a different transition process increases the probability of a success remains to be seen.

Validity and reliability of inertial measurement units measurements for running kinematics in different foot strike pattern runners.

This study aimed to assess the validity and reliability of the three-dimensional joint kinematic outcomes obtained by the inertial measurement units (IMUs) for runners with rearfoot strike pattern (RFS) and non-rearfoot strike pattern (NRFS). The IMUs system and optical motion capture system were used to simultaneous collect 3D kinematic of lower extremity joint data from participants running at 12km/h. The joint angle waveforms showed a high correlation between the two systems after the offset correction in the sagittal plane (NRFS: coefficient of multiple correlation (CMC) = 0.924-0.968, root mean square error (RMSE) = 4.6°-13.7°; RFS: CMC = 0.930-0.965, RMSE = 3.1°-7.7°), but revealed high variability in the frontal and transverse planes (NRFS: CMC = 0.924-0.968, RMSE = 4.6°-13.7°; RFS: CMC = 0.930-0.965, RMSE = 3.1°-7.7°). The between-rater and between-day reliability were shown to be very good to excellent in the sagittal plane (between-rater: NRFS: CMC = 0.967-0.975, RMSE = 1.9°-2.9°, RFS: CMC = 0.922-0.989, RMSE = 1.0°-2.5°; between-day: NRFS: CMC = 0.950-0.978, RMSE = 1.6°-2.7°, RFS: CMC = 0.920-0.989, RMSE = 1.7°-2.2°), whereas the reliability was weak to very good (between-rater: NRFS: CMC = 0.480-0.947, RMSE = 1.1°-2.7°, RFS: CMC = 0.646-0.873, RMSE = 0.7°-2.4°; between-day: NRFS: CMC = 0.666-0.867, RMSE = 0.7°-2.8°, RFS: CMC = 0.321-0.805, RMSE = 0.9°-5.0°) in the frontal and transverse planes across all joints in both types of runners. The IMUs system was a feasible tool for measuring lower extremity joint kinematics in the sagittal plane during running, especially for RFS runners. However, the joint kinematics data in frontal and transverse planes derived by the IMUs system need to be used with caution.

Changes of the in vivo kinematics of the human medial longitudinal foot arch, first metatarsophalangeal joint, and the length of plantar fascia in different running patterns.

Accurately obtaining the in vivo motion of the medial longitudinal arch (MLA), first metatarsophalangeal joint (MTPJ), and plantar fascia (PF) is essential for analyzing the biomechanics of these structures in different running strike patterns. Most previous studies on the biomechanics of the MLA, first MTPJ, and PF have been based on traditional skin-marker-based motion capture, which cannot acquire the natural foot motion. Therefore, this study aimed to 1) describe the movement of the MLA, first MTPJ, and PF during running by using the high-speed dual fluoroscopic imaging system (DFIS) and 2) explore changes of the in vivo kinematics of the MLA and first MTPJ, and the length of the PF during the stance phase of running with different foot strike patterns. Fifteen healthy male runners all of whom ran with a regular rearfoot strike (RFS) pattern were required to run with forefoot strike (FFS) and RFS patterns. Computed tomography scans were taken from each participant's right foot for the construction of 3D models (the calcaneus, first metatarsal, and first proximal phalanges) and local coordinate systems. A high-speed DFIS (100Hz) and 3D force platform (2,000Hz) were used to acquire X-ray images of the foot bones and ground reaction force data during the stance phase of running (3m/s ± 5%) simultaneously. Then, 3D-2D registration was used to obtain the in vivo kinematic data of the MLA and first MTPJ and the length of the PF. When compared with RFS, in FFS, 1) the range of motion (ROM) of the medial/lateral (5.84 ± 5.61mm vs. 0.75 ± 3.38mm, p = 0.002), anterior/posterior (14.64 ± 4.33mm vs. 11.18 ± 3.56 mm, p = 0.010), plantarflexion/dorsiflexion (7.13 ± 3.22° vs. 1.63 ± 3.29°, p < 0.001), and adduction/abduction (-3.89 ± 3.85° vs. -0.64 ± 4.39°, p = 0.034) motions of the MLA were increased significantly; 2) the ROM of the anterior/posterior (7.81 ± 2.84mm vs. 6.24 ± 3.43 mm, p = 0.003), superior/inferior (2.11 ± 2.06mm vs. -0.57 ± 1.65 mm, p = 0.001), and extension/flexion (-9.68 ± 9.16° vs. -5.72 ± 7.33°, p = 0.018) motions of the first MTPJ were increased significantly; 3) the maximum strain (0.093 ± 0.023 vs. 0.075 ± 0.020, p < 0.001) and the maximum power (4.36 ± 1.51W/kg vs. 3.06 ± 1.39W/kg, p < 0.001) of the PF were increased significantly. Running with FFS may increase deformation, energy storage, and release of the MLA and PF, as well as the push-off effect of the MTPJ. Meanwhile, the maximum extension angle of the first MTPJ and MLA deformation increased in FFS, which showed that the PF experienced more stretch and potentially indicated that FFS enhanced the PF mechanical responses.

Running footstrike pattern effect on lower extremity work in an individual with transtibial amputation.

Asymmetrical loading favoring the intact limb during running has been associated with increased prevalence of reported knee pain and potential risk factors of knee osteoarthritis in that limb for patients with amputation. Footstrike pattern alterations have been suggested to help alleviate some overloading of the knee, but little is known about how it affects the rest of the limb. The purpose of this case study was to evaluate the effect of footstrike pattern on the distribution of loading throughout the lower extremities during submaximal running of an individual with transtibial amputation (TTA). This study compared loading distribution among the lower extremity joints in a male patient who sustained a TTA and ran using both a rearfoot (RFS) and forefoot strike (FFS) pattern. The results of this case demonstrated that altering footstrike pattern minimally alters the total mechanical work being done by the lower extremities but more so affects the relative amount of work contributed by the individual joints. In the intact limb, the ankle contributes the most to power absorption using a FFS pattern while the knee has a larger role using a RFS pattern. This case suggests that the footstrike pattern affects lower extremity loading distribution at the joint level, and adopting a FFS pattern may alleviate overloading the knee, whereas a RFS pattern may reduce loading at the ankle in individuals with TTA.

Temporal differences in the myoelectric activity of lower limb muscles during rearfoot and forefoot running: A statistical parametric mapping approach

The aim of this study was to apply statistical parametric mapping (SPM) to compare temporal changes in EMG amplitude between rearfoot (RF) and forefoot (FF) running techniques. Eleven recreational runners ran on a treadmill at a self-selected speed, once using a RF strike pattern and once using a FF strike pattern (randomized order). The myoelectric activity of five lower limb muscles [rectus femoris (RFe), biceps femoris (BF), tibialis anterior (TA), medial and lateral gastrocnemius (MG and LG)] was evaluated, using bipolar electromyography (EMG). EMG data from the RF and FF running techniques was then processed and posteriorly compared with SPM, dividing the analysis of the running cycle into stance and swing phases. The MG and LG muscles showed higher activation during FF running at the beginning of the stance phase and at the end of the swing phase. During the end of the swing phase the TA muscle’s EMG amplitude was higher, when the RF running technique was used. A higher level of co-activation between the gastrocnemius and TA muscles was observed at the end of the swing phase during RF running. The myoelectric behaviour of the RFe and BF muscles was similar during both running techniques. These findings highlight the importance of SPM for the accurate assessment of differences in muscle activity during running and strongly suggest that these two running techniques predominately reflect adjustments of the leg and not the thigh muscles.

What differentiates rearfoot strike runners with low and high vertical load rates?

BackgroundRunners with a rearfoot strike pattern typically show high vertical ground reaction force loading rates (LRs), that are associated with injuries, compared with forefoot strikers. However, some runners with a rearfoot strike pattern run in a way that reduces LRs. Our purpose was to identify differences in running mechanics between rearfoot strike runners with high and low vertical LRs. Methods42 healthy runners, 21 with high (≥ 80.5 BW/s) and 21 with low (≤ 46.3 BW/s) LRs, were included in the current study. Lower extremity kinematic and kinetic data were then collected while participants ran along a 30 m runway. Running mechanics were calculated, including sagittal plane knee stiffness during early stance, the components of knee stiffness (Δ knee flexion and flexion moment), sagittal joint angles at initial contact, as well as cadence. The two LR groups were compared for differences in outcome variables using independent t-tests or Mann Whitney U tests. FindingsKnee stiffness was significantly lower in the low LR group (p < 0.01, d = 0.87), due to higher knee flexion excursion (p < 0.01, d = 1.38). At initial contact, the low LR group showed lower hip and knee flexion, but greater ankle and foot dorsiflexion (p = 0.01–0.04, d = 0.64–0.93). No differences were found in cadence. InterpretationThese results provide potential targets, related to gait kinematics and kinetics, for gait retraining aimed at reducing LRs in rearfoot strike runners.

Reversing the Mismatch With Forefoot Striking to Reduce Running Injuries.

Recent studies have suggested that 95% of modern runners land with a rearfoot strike (RFS) pattern. However, we hypothesize that running with an RFS pattern is indicative of an evolutionary mismatch that can lead to musculoskeletal injury. This perspective is predicated on the notion that our ancestors evolved to run barefoot and primarily with a forefoot strike (FFS) pattern. We contend that structures of the foot and ankle are optimized for forefoot striking which likely led to this pattern in our barefoot state. We propose that the evolutionary mismatch today has been driven by modern footwear that has altered our footstrike pattern. In this paper, we review the differences in foot and ankle function during both a RFS and FFS running pattern. This is followed by a discussion of the interaction of footstrike and footwear on running mechanics. We present evidence supporting the benefits of forefoot striking with respect to common running injuries such as anterior compartment syndrome and patellofemoral pain syndrome. We review the importance of a gradual shift to FFS running to reduce transition-related injuries. In sum, we will make an evidence-based argument for the use of minimal footwear with a FFS pattern to optimize foot strength and function, minimize ground reaction force impacts and reduce injury risk.

Cultural variation in running techniques among non-industrial societies.

Research among non-industrial societies suggests that body kinematics adopted during running vary between groups according to the cultural importance of running. Among groups in which running is common and an important part of cultural identity, runners tend to adopt what exercise scientists and coaches consider to be good technique for avoiding injury and maximising performance. In contrast, among groups in which running is not particularly culturally important, people tend to adopt suboptimal technique. This paper begins by describing key elements of good running technique, including landing with a forefoot or midfoot strike pattern and leg oriented roughly vertically. Next, we review evidence from non-industrial societies that cultural attitudes about running associate with variation in running techniques. Then, we present new data from Tsimane forager-horticulturalists in Bolivia. Our findings suggest that running is neither a common activity among the Tsimane nor is it considered an important part of cultural identity. We also demonstrate that when Tsimane do run, they tend to use suboptimal technique, specifically landing with a rearfoot strike pattern and leg protracted ahead of the knee (called overstriding). Finally, we discuss processes by which culture might influence variation in running techniques among non-industrial societies, including self-optimisation and social learning.

Analysis of ground reaction forces and muscle activity in individuals with anterior cruciate ligament reconstruction during different running strike patterns.

Anterior cruciate ligament reconstruction provides successful clinical outcomes. However, reconstruction cannot restore normative lower limb mechanics during running. While numerous studies have investigated running characteristics in individuals with anterior cruciate ligament reconstruction, no study has been compared foot strike patterns among them. If ground reaction forces and lower extremity muscle activities in individuals with anterior cruciate ligament reconstruction and healthy control ones differ during three running strike patterns? In this cross-sectional study, fourteen healthy adult males and fourteen adult males with anterior cruciate ligament reconstruction were recruited to participate. Surface electromyography of selected lower limb muscles and ground reaction forces were measured during three-strike patterns: rearfoot strike pattern, midfoot strike pattern, and forefoot strike pattern during barefoot running (∼ 3.3 m/s). The results revealed that the strike patterns influenced the peak lateral ground reaction force (P < 0.001) and peak vertical impact ground reaction force (P = 0.002) during the stance phase of running for both groups. The strike pattern also influenced the tibialis anterior (P < 0.001) and vastus lateralis (P = 0.035) activities during the early stance phase for both groups. However, the vastus medialis (P = 0.030) presented reduced activity, and the biceps femoris (P = 0.039) presented increased activity in the anterior cruciate ligament reconstruction group. Tibialis anterior (P = 0.021), gastrocnemius medialis (P < 0.001) and vastus medialis (P < 0.001) presented lesser activity irrespective of strike patterns in the anterior cruciate ligament reconstruction group. Running with a forefoot strike pattern may be associated with lesser rearfoot eversion due to lower peak lateral ground reaction forces than running with a rearfoot strike pattern or midfoot strike pattern. Moreover, the altered muscle activities could contribute to the elevated risk of future joint injury in the anterior cruciate ligament reconstruction population.