Change in foot strike patterns and performance in recreational runners during a road race: A cross-sectional study

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.

Well-trained Endurance Runners' Foot Contact Patterns: Barefoot vs. Shod Condition

We aimed to investigate the initial foot contact and contact time in experienced endurance runners at individualized speeds, in running shoes and barefoot. Forty-eight participants (33.71±7.49 y, 70.94±8.65 kg, 175.07±7.03 cm, maximum aerobic speed 18.41±1.54 km.h-1) were distributed into three groups according to athletic performance: highly-trained runners, middle-trained runners, and control group. An incremental running test until exhaustion was performed for assessing maximum aerobic speed. After≥24 h of recovery participants randomly walked and ran, barefoot and in running shoes, over a pressure plate at ~4.7 km.h-1 and 85% of the maximum aerobic speed, respectively. They wore the same model of running shoes with homogeneous lacing pattern. A rearfoot strike was performed by 68.8% and 77.1% of participants when running barefoot and in running shoes, respectively. Considering the tendency to develop a rearfoot strike was lower in the barefoot condition, runners with higher performance may benefit from training in minimalist running shoes because their foot contact pattern could tend towards a non-rearfoot strike. Our results suggest that initial foot contact and contact time are related to running performance and may also be influenced by running shoes.

Time course of muscle activation, energetics and mechanics of running in minimalist and traditional cushioned shoes during level running

The study aimed to compare the ankle muscles activation, biomechanics and energetics of running in male runners during submaximal level run using minimalist (MinRS) and traditional cushioned (TrdRS) running shoes. During 45-min running in MinRS and TrdRS, the ankle muscles pre- and co-activation, biomechanics, and energetics of running of 16 male endurance runners (25.5 ± 3.5 yr) were assessed using surface electromyography (tibialis anterior and gastrocnemius lateralis), instrumented treadmill and indirect calorimetry, respectively. The net energy cost of running (C_r) was similar for both conditions (P = 0.25) with a significant increase over time (P < 0.0001). Step frequency (P < 0.001), and total mechanical work (P = 0.001) were significantly higher in MinRS than in TrdRS with no evolution over time (P = 0.28 and P = 0.85, respectively). The ankle muscles pre- and co-activation during the contact phase did not differ between the two shoe conditions (P ≥ 0.33) or over time (P ≥ 0.15). In conclusion, during 45-min running, Cr and muscle pre- and co-activation were not significantly different between MinRS and TrdRS with significantly higher step frequency and total mechanical work noted in the former than in the latter. Moreover, C_r significantly increased during the 45-min trial in both shoe conditions along with no significant change over time in muscle activation and biomechanical variables.

Adaptive locomotion: Foot strike pattern and limb mechanical stiffness while running over an obstacle

Previous studies of level running suggest runners adjust foot strike to control leg stiffness. This study aimed to determine how runners adjusted mechanical stiffness and foot strike prior to, during, and after a drop in surface height. Ten healthy subjects (5 male, 5 female; 24.32 ± 5.0 years) were video recorded as they ran on an outdoor path with a single drop in surface height (12.5 cm). Foot strike was recorded, while subject velocity, duty factor (DF), normalized maximum ground reaction force (GRF_bw), vertical hip displacement (Δy), leg compression (ΔL), vertical (K_vert) and leg stiffness (K_leg), touchdown (TD) and takeoff angle (TO), and flight (T_f) and contact time (T_c) were calculated. Compared to the step before the drop, T_f, GRF_bw, K_vert, K_leg, and TO increased, while T_c, DF, Δy, ΔL, and TD decreased in the step after the drop. Across trials, runners had either consistent or variable foot strike patterns. Runners using a consistent pattern most often shifted from rear to fore-foot strike in the steps before and after the drop, while those with a variable pattern showed less dramatic shifts. All parameters, except TD, were significantly different (p < 0.04) based on foot strike pattern, and comparisons between steps before and after the drop (except TD) were significantly different (p < 0.004). Runners with a variable foot strike pattern experienced smaller shifts within mechanical parameters when traveling over the drop, suggesting these runners may be able to stabilize limb mechanics on interrupted surfaces.

Foot Strike Patterns During Overground Distance Running: A Systematic Review and Meta-Analysis

Background

Investigations of foot strike patterns during overground distance running have foci on prevalence, performance and change in foot strike pattern with increased distance. To date, synthesised analyses of these findings are scarce.

Objective

The key objectives of this review were to quantify the prevalence of foot strike patterns, assess the impact of increased running distance on foot strike pattern change and investigate the potential impact of foot strike pattern on performance.

Methods

Relevant peer-reviewed literature was obtained by searching EBSCOhost CINAHL, Ovid Medline, EMBASE and SPORTDiscus (inception-2021) for studies investigating foot strike patterns in overground distance running settings (> 10 km). Random effects meta-analyses of prevalence data were performed where possible.

Results

The initial search identified 2210 unique articles. After removal of duplicates and excluded articles, 12 articles were included in the review. Meta-analysis of prevalence data revealed that 79% of long-distance overground runners rearfoot strike early, with prevalence rising to 86% with increased distance. In total, 11% of runners changed foot strike pattern with increased distance and of those, the vast majority (84%) do so in one direction, being non-rearfoot strike to rearfoot strike. Analysis of the relationship between foot strike pattern and performance revealed that 5 studies reported a performance benefit to non-rearfoot strike, 1 study reported a performance benefit to non-rearfoot strike in women but not men, 4 studies reported no benefit to non-rearfoot strike or rearfoot strike, and no studies reported a performance benefit of rearfoot strike over non-rearfoot strike.

Conclusion

Most overground distance runners rearfoot strike early, and the prevalence of this pattern increases with distance. Of those that do change foot strike pattern, the majority transition from non-rearfoot to rearfoot. The current literature provides inconclusive evidence of a competitive advantage being associated with long-distance runners who use a non-rearfoot strike pattern in favour of a rearfoot strike pattern.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-021-00369-9.

Biomechanical Response of the Lower Extremity to Running-Induced Acute Fatigue: A Systematic Review

Objective: To investigate (i) typical protocols used in research on biomechanical response to running-induced fatigue, (ii) the effect of sport-induced acute fatigue on the biomechanics of running and functional tests, and (iii) the consistency of analyzed parameter trends across different protocols.

Methods: Scopus, Web of Science, Pubmed, and IEEE databases were searched using terms identified with the Population, Interest and Context (PiCo) framework. Studies were screened following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and appraised using the methodological index for non-randomized studies MINORS scale. Only experimental studies with at least 10 participants, which evaluated fatigue during and immediately after the fatiguing run were included. Each study was summarized to record information about the protocol and parameter trends. Summary trends were computed for each parameter based on the results found in individual studies.

Results: Of the 68 included studies, most were based on in-lab (77.9%) protocols, endpoint measurements (75%), stationary measurement systems (76.5%), and treadmill environment (54.4%) for running. From the 42 parameters identified in response to acute fatigue, flight time, contact time, knee flexion angle at initial contact, trunk flexion angle, peak tibial acceleration, CoP velocity during balance test showed an increasing behavior and cadence, vertical stiffness, knee extension force during MVC, maximum vertical ground reaction forces, and CMJ height showed a decreasing trend across different fatigue protocols.

Conclusion: This review presents evidence that running-induced acute fatigue influences almost all the included biomechanical parameters, with crucial influence from the exercise intensity and the testing environment. Results indicate an important gap in literature caused by the lack of field studies with continuous measurement during outdoor running activities. To address this gap, we propose recommendations for the use of wearable inertial sensors.

Continuous Tracking of Foot Strike Pattern during a Maximal 800-Meter Run

(1) Background: Research into foot strike patterns (FSP) has increased due to its potential influence on performance and injury reduction. The purpose of this study was to evaluate changes in FSP throughout a maximal 800-m run using a conformable inertial measurement unit attached to the foot; (2) Methods: Twenty-one subjects (14 female, 7 male; 23.86 ± 4.25 y) completed a maximal 800-m run while foot strike characteristics were continually assessed. Two measures were assessed across 100-m intervals: the percentage of rearfoot strikes (FSP_%RF), and foot strike angle (FSA). The level of significance was set to p ≤ 0.05; (3) Results: There were no differences in FSP_%RF throughout the run. Significant differences were seen between curve and straight intervals for FSA_AVE (F [1, 20] = 18.663, p < 0.001, η_p² = 0.483); (4) Conclusions: Participants displayed decreased FSA, likely indicating increased plantarflexion, on the curve compared to straight intervals. The analyses of continuous variables, such as FSA, allow for the detection of subtle changes in foot strike characteristics, which is not possible with discrete classifiers, such as FSP_%RF.