Footstrike Pattern Research Articles

Longer Ground Contact Time Is Related to a Superior Running Economy in Highly Trained Distance Runners.

Tanji, F, Ohnuma, H, Ando, R, Yamanaka, R, Ikeda, T, and Suzuki, Y. Longer ground contact time is related to a superior running economy in highly trained distance runners. J Strength Cond Res 38(5): 985-990, 2024-Running economy is a key component of distance running performance and is associated with gait parameters. However, there is no consensus of the link between the running economy (RE), ground contact time, and footstrike patterns. Thus, this study aimed to clarify the relationship between RE, ground contact time, and thigh muscle cross-sectional area (CSA) in highly trained distance runners and to compare these parameters between 2 habitual footstrike patterns (midfoot vs. rearfoot). Seventeen male distance runners ran on a treadmill to measure RE and gait parameters. We collected the CSAs of the right thigh muscle using a magnetic resonance imaging scanner. The RE had a significant negative relationship with distance running performance ( r = -0.50) and ground contact time ( r = -0.51). The ground contact time had a significant negative relationship with the normalized CSAs of the vastus lateralis muscle ( r = -0.60) and hamstrings ( r = -0.54). No significant differences were found in RE, ground contact time, or normalized CSAs of muscles between midfoot ( n = 10) and rearfoot ( n = 7) strikers. These results suggest that large CSAs of knee extensor muscles results in short ground contact time and worse RE. The effects of the footstrike pattern on the RE appear insignificant, and the preferred footstrike pattern can be recommended for running in highly trained runners.

Effect of surface inclination on vertical loading rate and footstrike pattern in trail and road runners

Effect of surface inclination on vertical loading rate and footstrike pattern in trail and road runners

Foot and Ankle Muscle Isometric Strength in Nonrearfoot Compared With Rearfoot Endurance Runners.

Transitioning to a forefoot strike pattern can be used to manage running-related knee injuries. However, adopting a nonrearfoot strike induces a higher load on foot and ankle structures than rearfoot strike. Sufficient foot muscle strength is also necessary to prevent excessive longitudinal arch (LA) deformation when running with nonrearfoot strike. The aim of this study was to investigate the potential differences in foot-ankle muscle strength between RF and NRF runners. A cross-sectional study including 40 RF and 40 NRF runners was conducted. The foot posture and the maximal voluntary isometric strength (MVIS) of 6 foot-ankle muscles were measured. The footstrike pattern was determined using a 2-D camera during a self-paced run on a treadmill. NRF had higher MVIS for ankle plantar flexor (+12.5%, P = .015), ankle dorsiflexor (+17.7%, P = .01), hallux flexor (+11%, P = .04), and lesser toe flexor (+20.8%, P = .0031). We found a small positive correlation between MVIS of ankle plantar flexor with MVIS of hallux flexor (r = 0.26; P = .01) and lesser toe flexor (r = 0.28; P = .01). In this cross-sectional study, we found that NRF runners on average have a higher MVIS of hallux and lesser toe flexor compared with RF runners. NRF runners also have a higher MVIS of ankle plantar flexor and dorsiflexor than RF runners. We found only a small correlation between ankle plantar flexor and foot muscle strength. Level III, case-control study.

Biomechanics and Injury Prevention for Barefoot/Minimalist Running

Category: Sports; Midfoot/Forefoot Introduction/Purpose: Running-related injuries are common despite technological advances in running shoes. Recently, there has been a movement towards barefoot/minimalist running. Proponents of barefoot running state that this style of running provides beneficial modifications to the gait cycle and prevents running-related injuries. The purpose of this review is to analyze the biomechanical consequences of barefoot/minimalist running and determine if barefoot/minimal style running prevents running- related injuries. Methods: A literature search was done on PUBMED using the keywords: Barefoot running, minimalist running, injury prevention, injury rate, foot-strike pattern, vertical loading rate, biomechanics, and clinical outcomes. Studies were then grouped into biomechanical studies and clinical outcome studies. Biomechanical studies were included if they analyzed outcomes such as: foot strike index/pattern, vertical loading rates, vertical ground reaction forces, joint angles, cadence, step length, or joint energy absorption. Clinical outcome studies were included if they analyzed injury rates and pain. Results: Biomechanical studies indicated that barefoot/minimalist running coincided with a transition to an anterior foot strike, lower vertical loading rates, higher cadences, less energy absorption at the knee joint, and higher energy absorption at the ankle joint. The clinical outcome studies indicated improvement of prior injuries and equivocal injury rates in the barefoot/minimal style running groups. Conclusion: Foot strike pattern is more important than footwear in regard to injury prevention and vertical loading rate. Switching to minimalist footwear improves running biomechanics with a more anterior foot strike, higher cadence, lower vertical loading rate, less knee energy absorption, and a shorter stride length. However, minimalist footwear places higher degrees of stress on the ankle joints and an increased injury rate when abruptly transitioning to barefoot running. Runners must weigh the risks and benefits and take caution to properly strengthen their feet and safely transition to minimalist running.

Effects of different habitual foot strike patterns on in vivo kinematics of the first metatarsophalangeal joint during shod running-a statistical parametric mapping study.

Existing studies on the biomechanical characteristics of the first metatarsophalangeal joint (1st MTPJ) during shod running are limited to sagittal plane assessment and rely on skin marker motion capture, which can be affected by shoes wrapping around the 1st MTPJ and may lead to inaccurate results. This study aims to investigate the in vivo effects of different habitual foot strike patterns (FSP) on the six degrees of freedom (6DOF) values of the 1st MTPJ under shod condition by utilizing a dual-fluoroscopic imaging system (DFIS). Long-distance male runners with habitual forefoot strike (FFS group, n = 15) and rearfoot strike (RFS group, n = 15) patterns were recruited. All participants underwent foot computed tomography (CT) scan to generate 3D models of their foot. The 6DOF kinematics of the 1st MTPJ were collected using a DFIS at 100Hz when participants performed their habitual FSP under shod conditions. Independent t-tests and one-dimensional statistical parametric mapping (1-d SPM) were employed to analyze the differences between the FFS and RFS groups' 1st MTPJ 6DOF kinematic values during the stance phase. FFS exhibited greater superior translation (3.5-4.9mm, p = 0.07) during 51%-82% of the stance and higher extension angle (8.4°-10.1°, p = 0.031) during 65%-75% of the stance in the 1st MTPJ than RFS. Meanwhile, FFS exhibited greater maximum superior translation (+3.2mm, p = 0.022), maximum valgus angle (+6.1°, p = 0.048) and varus-valgus range of motion (ROM) (+6.5°, p = 0.005) in the 1st MTPJ during stance. The greater extension angle of the 1st MTPJ in the late stance suggested that running with FFS may enhance the propulsive effect. However, the higher maximum valgus angle and the ROM of varus-valgus in FFS may potentially lead to the development of hallux valgus.

An Acute Transition from Rearfoot to Forefoot Strike does not Induce Major Changes in Plantarflexor Muscles Activation for Habitual Rearfoot Strike Runners.

Footstrike pattern has received increased attention within the running community because there is a common belief that forefoot strike running (FFS) is more advantageous (i.e., improve performance and reduce running injuries) than rearfoot strike running (RFS) in distance running. Literature reports suggest greater knee joint flexion magnitude and initial knee angle during stance in FFS compared with RFS running We examined the EMG activation of the triceps surae muscles during an acute transition from RFS to FFS strike. We tested the hypothesis that due to larger knee flexion in FFS the gastrocnemius muscles possibly decrease their EMG activity because muscle fascicles operate under unfavorable conditions. Fourteen competitive healthy middle- and long-distance runners who were habitual RFS runners ran on a treadmill at three speeds: 12, 14, and 16 km·h-1. Each running speed was performed with both FFS and RFS patterns. Lower limb kinematics in the sagittal plane and normalized electromyography (EMG) activity of medial gastrocnemius proximal, middle and distal regions, lateral gastrocnemius and soleus muscles were compared between footstrike patterns and running speeds across the stride cycle. Contrary to our expectations, the knee joint range of motion was similar in FFS and RFS running. However, the sagittal plane ankle joint motion was greater (p < 0.01) while running with FFS, resulting in a significantly greater muscle-tendon unit lengthening (p < 0.01) in FFS compared with RFS running. In addition, medial and lateral gastrocnemius showed higher EMG activity in FFS compared with RFS running in the late swing and early stance but only for a small percentage of the stride cycle. However, strike patterns and running speed failed to induce region-specific activation differences within the medial gastrocnemius muscle. Overall, well-trained RFS runners are able to change to FFS running by altering only the ankle joint kinematics without remarkably changing the EMG activity pattern.

An Acute Transition from Rearfoot to Forefoot Strike does not Induce Major Changes in Plantarflexor Muscles Activation for Habitual Rearfoot Strike Runners

Footstrike pattern has received increased attention within the running community because there is a common belief that forefoot strike running (FFS) is more advantageous (i.e., improve performance and reduce running injuries) than rearfoot strike running (RFS) in distance running. Literature reports suggest greater knee joint flexion magnitude and initial knee angle during stance in FFS compared with RFS running We examined the EMG activation of the triceps surae muscles during an acute transition from RFS to FFS strike. We tested the hypothesis that due to larger knee flexion in FFS the gastrocnemius muscles possibly decrease their EMG activity because muscle fascicles operate under unfavorable conditions. Fourteen competitive healthy middle- and long-distance runners who were habitual RFS runners ran on a treadmill at three speeds: 12, 14, and 16 km·h-1. Each running speed was performed with both FFS and RFS patterns. Lower limb kinematics in the sagittal plane and normalized electromyography (EMG) activity of medial gastrocnemius proximal, middle and distal regions, lateral gastrocnemius and soleus muscles were compared between footstrike patterns and running speeds across the stride cycle. Contrary to our expectations, the knee joint range of motion was similar in FFS and RFS running. However, the sagittal plane ankle joint motion was greater (p &lt; 0.01) while running with FFS, resulting in a significantly greater muscle-tendon unit lengthening (p &lt; 0.01) in FFS compared with RFS running. In addition, medial and lateral gastrocnemius showed higher EMG activity in FFS compared with RFS running in the late swing and early stance but only for a small percentage of the stride cycle. However, strike patterns and running speed failed to induce region-specific activation differences within the medial gastrocnemius muscle. Overall, well-trained RFS runners are able to change to FFS running by altering only the ankle joint kinematics without remarkably changing the EMG activity pattern.

Reliability of 2D video analysis assessing running kinematic variables in patients with exercise-related leg pain in a primary care practice

BackgroundSuboptimal lower limb and trunk positionings is known to influence exercise-related leg pain (ERLP). It is unknown whether simple 2D video analysis is useful for recording and interpreting running variables in a primary care practice. Research questionIs 2D video analysis a reliable instrument to assess running variables in patients with ERLP in a primary care practice? MethodsParticipants undergoing an evaluation for ERLP in two primary care practices were studied. In this reliability study, analysis of running variables was performed by 4 blinded raters on one-stride videos captured with non-high speed cameras (30 fps). Intraclass correlation coefficients (two-way random; ICC 2,1) were calculated to determine the inter-rater reliability. The intra-rater reliability was presented by ICC type two-way mixed (3,1). Footstrike pattern was analyzed by calculating the Fleiss’ kappa for inter-rater agreement and Cohen’s kappa for intra-rater agreement. Sample size calculation indicated that 16 participants would be required for answering the research question. ResultsData of all 16 participants (9 males, age 31 ± 10 yr) were of sufficient quality for analysis. The 2D video analysis demonstrated excellent inter-rater reliability with an overall ICC value of 0.999 (95 % CI = 0.998–0.999). The ICC value of the eversion was 0.384 (95 % CI = 0.148–0.66) and after correction of the systematic error, 0.817 (95 % CI = 0.664–0.922). The agreement on footstrike was substantial with a Fleiss kappa of 0.737. The overall intra-rater reliability was excellent with an ICC value of 0.997 (95 % CI = 0.996–0.997). The intra-rater agreement of the footstrike was excellent with a Cohen’s kappa of 0.868. Significance2D video analysis provides a highly reliable, relative inexpensive, feasible and suitable measuring instrument for determining running variables in patients ERLP in a primary care setting. This simple technique may identify possible running variables associated with different types of ERLP and may serve as an instrument for tailor-made gait retraining programs.

The influence of footwear on the human gait

The development of individual gait and running patterns is influenced by internal (anatomical, anthropometric) and external (activity-related, environmental) factors. The predominantly used rearfoot running style is mainly attributed to the use of cushioned shoes, although from an anthropological perspective running barefoot, and thus running forefoot, is considered to be more natural. Numerous studies have shown along-term influence of habitual footwear use on foot morphology, running biomechanics and basic motor skills. It has further been shown that an acute change in footwear, e.g. by running barefoot, immediately changes kinematics and vertical load parameters. However, to date, there is no strong evidence for an influence of habitual footwear use or footstrike patterns on the prevalence of injuries or physical complaints.

Footstrike Pattern and Cadence of the Marathon Athletes at the Tokyo 2020 Olympic Games

Background: The footstrike pattern and cadence are two crucial variables associated with sports performance and injury risks. This study aimed to analyze the footstrike pattern and cadence of male elite athletes who participated in the Tokyo Olympic Games marathon. Methods: Two independent researchers examined the footstrike pattern of the first 51 participants at the 5 km mark of the race. Additionally, the cadences of the top eight athletes (finalists) were analyzed in three different segments of the race (10–20 km, 20–30 km, and 30–40 km). Descriptive statistics were used to present the main variables, and a repeated-measures ANOVA was conducted to explore cadence differences among race sections (p &lt; 0.05). Results: The mean cadence of the eight finalists was 185.5 steps per minute (SD ± 5.1), and no significant differences were observed among race sections. The most common footstrike pattern was midfoot strike, followed by rearfoot strike, then forefoot strike. The cadence results are consistent with previous studies examining elite athletes, indicating higher values compared with research involving recreational runners. Conclusions: Most elite marathon athletes adopt a non-rearfoot strike pattern and maintain a cadence of more than 185 steps per minute.

Adolescents running in conventional running shoes have lower vertical instantaneous loading rates but greater asymmetry than running barefoot or in partial-minimal shoes

ABSTRACT Footwear may moderate the transiently heightened asymmetry in lower limb loading associated with peak growth in adolescence during running. This repeated-measures study compared the magnitude and symmetry of peak vertical ground reaction force and instantaneous loading rates (VILRs) in adolescents during barefoot and shod running. Ten adolescents (age, 10.6 ± 1.7 years) ran at self-selected speed (1.7 ± 0.3 m/s) on an instrumented treadmill under three counter-balanced conditions; barefoot and shod with partial-minimal and conventional running shoes. All participants were within one year of their estimated peak height velocity based on sex-specific regression equations. Foot-strike patterns, peak vertical ground reaction force and VILRs were recorded during 20 seconds of steady-state running. Symmetry of ground reaction forces was assessed using the symmetry index. Repeated-measures ANOVAs were used to compare conditions (α=.05). Adolescents used a rearfoot foot-strike pattern during barefoot and shod running. Use of conventional shoes resulted in a lower VILR (P < .05, dz = 0.9), but higher VILR asymmetry (P < .05) than running barefoot (dz = 1.5) or in partial-minimal shoes (dz = 1.6). Conventional running shoes result in a lower VILR than running unshod or in partial-minimal shoes but may have the unintended consequence of increasing VILR asymmetry. The findings may have implications for performance, musculoskeletal development and injury in adolescents.

A forefoot strike pattern during 18° uphill walking leads to greater ankle joint and plantar flexor loading

BackgroundThe ankle joint is one of the most involved joints in uphill walking. Furthermore, it is well known that toe walking increases the external dorsiflexion moment in the first half of stance during level walking. However, the effects of different foot-strike patterns on plantar flexor muscle forces, ankle joint forces, and other lower limb joint and muscle forces are unknown. Research questionDo foot-strike patterns during 18° uphill walking affect lower limb sagittal joint angles and moments, as well as joint contact and muscle forces? MethodsThis study was based on a data subset from previous publications, analysing uphill walking on an 18° ramp at a preset speed of 1.1 m/s in 18 male participants (34 limbs analyzed, 27 ± 5 years). Participants were divided into two groups based on their foot-strike pattern at initial contact: heel (HC) and forefoot (FC). Lower limb sagittal joint angles and moments as well as joint contact and muscle forces were assessed. Differences between the groups were assessed using two-sample t-tests. ResultsFC showed increased soleus and gastrocnemius muscle forces as well as ankle joint forces during loading response and mid stance compared to HC. The soleus muscle force impulse was 51.1% higher in the FC group than in the HC group (p < 0.001). On the other hand, FC had a lower absolute centre of mass vertical displacement and reduced knee and hip joint, as well as iliopsoas and hamstring muscle force impulses. SignificanceIn terms of plantar flexor and ankle joint loading, it is advantageous to exhibit a heel strike pattern. The current results can be used to recommend foot-strike patterns for uphill walking, particularly in the presence or prevention of musculoskeletal issues.

Influences of altering footstrike pattern and cadence on lower extremity joint coordination and variability among runners with patellofemoral pain.

Patellofemoral pain (PFP) is a common overuse injury among runners. It is not only a hindrance to the runner's training, but also to the runner's quality of life. PFP runners may strategize different running strategies to reduce patellofemoral joint stress, release pain, and improve function. This study aimed to determine the changes in joint coordination and variability under combinations of foot strike pattern and cadence for runners with patellofemoral pain. Twenty male runners with PFP performed six running strategies which were two strike patterns named forefoot (FFS) and rearfoot (RFS) accompanied by three running cadences named slow10%, normal, and fast10%. A modified vector coding technique and circular statistics were respectively used to identify the coordination pattern and variability between hip sagittal-knee frontal (HsKf), hip sagittal-knee sagittal (HsKs) and knee transverse-ankle frontal (KtAf) during stance phase. Coordination patterns which were conformed with anatomical motion pattern was classified as mechanically sound, and the distribution frequency of each coordination pattern was quantified. Switching to FFS, the HsKf couples (p < 0.001, ES = 1.34) and the HsKs couples (p = 0.001, ES = 0.82) displayed significantly greater frequency in mechanically unsound coordination pattern during the initial stance phase. The effect of increasing running cadence on RFS displayed significantly greater frequency in mechanically unsound hip dominancy (p = 0.042, ES = 0.65) and knee dominancy (p = 0.05, ES = 0.70) coordination patterns for HsKf couples as well as for HsKs couples (p = 0.023, ES = 0.86) during the initial stance phase. Combined with FFS and fast10% cadence, HsKs couples showed more hip-dominated mechanical sound coordination pattern (p = 0.002, ES = 1.25). Further, altering footstrike pattern and cadence failed to change the coordination variability. Changing running cadence (± 10%) combined with transfer strike pattern from RFS to FFS could not increase the distribution frequency in mechanically sound coordination patterns and change coordination variability for PFP runners.

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.

The effect of fatigue on the ankle and knee kinematics and kinetics in moderately and highly trained healthy non-rearfoot runners

ABSTRACT The aim of this study was to compare selected ankle and knee kinematic and kinetic parameters before and after a prolonged exhaustive treadmill run between two groups of non-rearfoot footstrike pattern (NRFP) runners with different training volumes. Twenty-eight habitual NRFP runners were assigned to two groups based on their weekly training volume (Highly-trained (HT)/Moderately-trained (MT)). Participants underwent the VO2max test, and the exhaustive treadmill ran with biomechanical analysis at the beginning and the end. The two-way RMANOVA was used to assess differences between the groups and the phase of the run. A paired t-test was used for post-hoc analysis in case of significant interaction effect. Kinetic results showed significant group effect for ankle plantarflexion moment and hip external rotation moment (end-phase: both greater in MT group). Kinematic results showed significant group×phase interaction for ankle dorsiflexion angle (end-phase: greater in MT group) at initial contact (IC), peak knee flexion angle (end-phase: greater in MT group), and peak ankle eversion angle during the stance phase (end-phase: greater in HT group). Additionally, a group effect was found for knee flexion angle at IC (end-phase: greater in HT group). This study suggests that HT healthy NRFP runners may have less potential for increased biomechanical risk of AT overload during an exhaustive run.

Ergogenic distance running shoes: how do we think they work and how can we understand them better?

Recently developed shoes that are highly-cushioned and have a curved stiff plate embedded in the midsole are “ergogenic” in that they reduce the rate of metabolic energy required to run at a defined speed. These energy savings are not due to low mass but rather to their foam midsoles which are unusually compliant and resilient. The function of the plate has not yet been elucidated, but evidence is clear that the plate itself does not act as a spring or a teeter-totter. The plate may act synergistically with the foam to create an area-elastic structure, akin to a gymnastics floor. Future studies of ergogenic shoes should: focus on muscle function using EMG and ultrasound, explore footstrike pattern effects, only utilize stiff treadmills, and seek to define a consistent baseline shoe condition for comparison.

Grizzlies and gazelles: Duty factor is an effective measure for categorizing running style in English Premier League soccer players.

English Premier League soccer players run at multiple speeds throughout a game. The aim of this study was to assess how well the duty factor, a dimensionless ratio based on temporal variables, described running styles in professional soccer players. A total of 25 players ran on an instrumented treadmill at 12, 16, and 20 km/h. Spatiotemporal and ground reaction force data were recorded for 30 s at each speed; video data (500 Hz) were collected to determine footstrike patterns. In addition to correlation analysis amongst the 25 players, two groups (both N = 9) of high and low duty factors were compared. The duty factor was negatively correlated with peak vertical force, center of mass (CM) vertical displacement, and leg stiffness (kleg) at all speeds (r ≥ −0.51, p ≤ 0.009). The low duty factor group had shorter contact times, longer flight times, higher peak vertical forces, greater CM vertical displacement, and higher kleg (p < 0.01). Among the high DF group players, eight were rearfoot strikers at all speeds, compared with three in the low group. The duty factor is an effective measure for categorizing soccer players as being on a continuum from terrestrial (high duty factor) to aerial (low duty factor) running styles, which we metaphorically refer to as “grizzlies” and “gazelles,” respectively. Because the duty factor distinguishes running style, there are implications for the training regimens of grizzlies and gazelles in soccer, and exercises to improve performance should be developed based on the biomechanical advantages of each spontaneous running style.

Does the Achilles Tendon Influence Foot Strike Patterns During an Exhaustive Run?

The study purpose was to investigate whether there is a relationship between the Achilles tendon (AT) length, moment arm length, and the foot strike pattern (FP) change during an exhaustive run (EXR) in nonrearfoot FP runners. Twenty-eight runners were recruited and divided into 2 groups (highly trained/moderately trained) according to their weekly training volume. Participants underwent the graded exercise test, the EXR with biomechanical analysis at the beginning, and at the end, and the magnetic resonance imaging scan of the AT. Correlations were used to assess associations between FP change (value of the difference between end and beginning) and the selected performance and AT variables. AT length significantly correlated with the FP change according to foot strike angle (r = -.265, P = .049). The AT moment arm length significantly correlated with the FP change according to strike index during EXR (r = -.536, P = .003). Multiple regression showed that AT length was a significant predictor for the FP change according to foot strike angle if the second predictor was the graded exercise test duration and the third predictor was training group association. These results suggest that a runner's training volume, along with a longer AT and AT moment arm appear to be associated with the ability to maintain a consistent FP during EXR by nonrearfoot FP runners.

Duty factor and foot-strike pattern do not represent similar running pattern at the individual level

Runners were classified using their duty factor (DF) and using their foot-strike pattern (FSP; rearfoot, midfoot, or forefoot strikers), determined from their foot-strike angle (FSA). High and low DF runners showed different FSPs but DF was assumed to not only reflect what happens at initial contact with the ground (more global than FSP/FSA). Hence, FSP and DF groups should not necessarily be constituted by the same runners. However, the relation between FSP and DF groups has never been investigated, leading to the aim of this study. One hundred runners ran at 9, 11, and 13 km/h. Force data (1000 Hz) and whole-body kinematics (200 Hz) were acquired by an instrumented treadmill and optoelectronic system and were used to classify runners according to their FSA and DF. Weak correlations were obtained between FSA and DF values and a sensitivity of 50% was reported between FSP and DF groups, i.e., only one in two runners was attributed to the DF group supposedly corresponding to the FSP group. Therefore, ‘local’ FSP/FSA and DF do not represent similar running pattern information when investigated at the individual level and DF should be preferred to FSP/FSA when evaluating the global running pattern of a runner.

Effect of Sex-Specific Running Shoes on Female Recreational Runners

Alterations in running shoe design have been studied and used in the prevention of injury and enhancement of performance allowing running shoe companies to market to a variety of runners based on skill level, foot-strike pattern, and even sex. These alterations have been shown to affect biomechanical and physiological variables associated with running. Some shoe companies have designed shoes specifically for biological female runners due to the morphological differences found between male and female feet. The purpose of this study is to determine if sex-specific running shoes can alter female runner biomechanics or physiology. Female runners were asked to run in the male and female models of the Altra Torin 4 Plush shoe to determine if there were differences in ground reaction forces (GRFs), sagittal plane joint angles and moments, oxygen consumption (VO2), respiratory exchange ratio (RER), and perceived level of comfort while running; There were no significant differences in GRFs, sagittal joint angles and moments, VO2, RER, or perceived comfort; There were no differences in measured biomechanical or physiological variables between the female and male version of the shoes suggesting that the alterations made to the female-specific shoe do not provide any additional benefit to female recreational runners.