Differences in rearfoot, midfoot, and forefoot kinematics of normal foot and flatfoot during running

Effect of foot type on electromyography characteristics and synergy of lower limb muscles during running

The foot structure is associated with different running mechanics. The central nervous system is responsible for using the muscles through synergies during locomotion. The purpose of the present study was to examine the effect of foot structure on the electromyography factors and the synergy of the selected muscles of the lower extremity. Tibialis anterior, extensor digitorum longus, peroneus longus, soleus, biceps femoris, vastus lateralis, gastrocnemius lateralis and medialis muscles activity of 60 barefoot recreational runners with different foot structures was recorded while running at a speed of 3.3 m/s. Muscle activity was measured in the running cycle. Besides, muscle synergies were extracted using non-negative matrix factorization algorithm. The results showed that there were differences between groups with different foot type in muscle activity under different phases of running in some muscles. Furthermore, the findings indicated that the number of synergies was similar in different groups and the relative weight of muscles was not different across groups. In conclusion, despite the difference in muscle activity under different phases of the running cycle, muscle synergies are similar among the groups. This can indicate similar control by the central nervous system in runners with different arch structures while running and the observed changes in muscle activity can be attributed to the type of forces exerted on the body, the length-tension relationship, and changes in the direction of the lower limbs in people with different arch structures.

Acute effects of the short-foot exercise in runners with medial tibial stress syndrome: A quasi-experimental study

OBJECTIVES

Analyze whether there are immediate changes in peak soleus activation and peak hindfoot eversion after short-foot exercise (SFE) in runners with medial tibial stress syndrome (MTSS). Secondarily, establish differences in peak soleus activation and peak hindfoot eversion between asymptomatic individuals and those presenting MTSS.

DESIGN

Quasi-experimental study.

SETTING

University Laboratory.

PARTICIPANTS

Thirty-two runners participated: 16 with MTSS and 16 in the no-pain group (NPG).

MAIN OUTCOME MEASURES

Soleus activation was measured using electromyography, and hindfoot eversion via 3D kinematic analysis. Participants performed SFE, and running data were collected at 9,12 and 15 km/h pre- and post-intervention.

RESULTS

SFE reduced peak soleus activation at 9 (p = 0.017) and 15 km/h (p = 0.019) for the MTSS group and at 15 km/h (p < 0.001) for the NPG, suggesting improved neuromuscular efficiency and potentially reduced tibial stress. SFE did not significantly affect peak hindfoot eversion. Significant correlations were found between ankle dorsiflexion range of motion and muscle activation (r = 0.585 to 0.849, p < 0.05). These findings suggest SFE could improve neuromuscular efficiency and reduce tibial stress, and highlights ankle flexibility's role in muscle activation.

CONCLUSIONS

SFE significantly reduces soleus activation, potentially improving neuromuscular efficiency and decreasing tibial stress.

Test-retest reliability and minimal detectable change in pelvis and lower limb coordination during running assessed with modified vector coding

The objective of this study was to evaluate the reliability of Modified Vector Coding in assessing the coordination and coordination variability of the lower limbs and pelvis during running and to determine the Minimal Detectable Change (MDC). Twenty-five healthy runners participated in a biomechanical analysis of treadmill running using a motion capture system. Modified vector coding was applied to assess the three-dimensional coordination among various pelvis and lower limb segmental couplings. Reliability was assessed using the Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM), MDC, and Bland-Altman analysis to ascertain measurement consistency, agreement, and the smallest clinically meaningful change that exceeds measurement error. The test-retest reliability for 33 of 42 segmental couplings analyzed was good to excellent, with ICC values ranging from 0.613 to 0.928 (p <0.05), which substantiates the robustness of modified vector coding in running biomechanics. However, nine couplings, particularly femur-tibia in the sagittal plane during midstance and foot in the frontal plane-tibia in the transverse plane during late stance, exhibited poor to moderate reliability. These findings underscore the need for cautious interpretation due to significant proportional bias (p <0.05). SEM and MDC provided insights into the precision and minimal clinically significant changes for each coupling. The findings confirm the reliability of modified vector coding for biomechanical analysis in running, with most couplings demonstrating consistent high reliability. Nevertheless, specific couplings should be interpreted with caution due to potential measurement errors. The application of MDC highlights the precision of modified vector coding in biomechanical analyses and emphasizes the importance of careful interpretation to improve clinical and research outcomes in running-related injuries.

A comparison of foot and ankle biomechanics during running drills and distance running

The aim of this study was to compare the foot-ankle joint mechanics of running drills and running. Seventeen long-distance runners performed five popular running drills (A-skip, B-skip, Bounding, Heel flicks, Straight leg running) and a run at 3.88 m/s. Kinematics, kinetics and power values were calculated for the ankle, midtarsal (MT) and metatarsophalangeal (MP) joints. Electromyographic activity was recorded for the soleus, gastrocnemius medialis, lateralis and abductor hallucis muscle. The A-skip, the B-skip and the Heel flicks induced a smaller ankle (p < 0.001, ŋ2 = 0.41), MT (p < 0.001, ŋ2 = 0.43) and MP (p < 0.001, ŋ2 = 0.47) dorsiflexion peak than running. No difference was found between the running drills and running for ankle, MT and MP moment. The Bounding induces a higher positive ankle power than running (diff: 5.5 ± 7.5 J/kg, p = 0.014, d = 1.05). The A-skip (diff: 2.8 ± 2.9 J/kg, p < 0.001, d = 1.5) and the B-skip (diff: 2.7 ± 2.1 J/kg, p < 0.001, d = 1.4) induce a smaller MT positive power than running. This study offers an analysis of the mechanical behaviour of the foot-ankle complex to help track and field coaches select their running drills in an evidence-based manner.

Investigation of inter-rater and test-retest reliability of Y balance test in college students with flexible flatfoot

BACKGROUND

The Lower Quarter Y Balance Test (YBT-LQ) has been widely used to assess dynamic balance in various populations. Dynamic balance in flexible flatfoot populations is one of the risk factors for lower extremity injuries, especially in college populations in which more exercise is advocated. However, no study has demonstrated the reliability of the YBT-LQ in a college student flexible flatfoot population.

METHODS

A cross-sectional observational study. 30 college students with flexible flatfoot were recruited from Beijing Sports University. They have been thrice assessed for the maximal reach distance of YBT under the support of the lower limb on the flatfoot side. Test and retest were performed with an interval of 14 days. The outcome measures using the composite score and normalized maximal reach distances in three directions (anterior, posteromedial, and posterolateral). The relative reliability was reported as the Intraclass Correlation Coefficient (ICC). Minimal Detectable Change (MDC), Smallest worthwhile change (SWC), and Standard Error of Measurement (SEM) were used to report the absolute reliability.

RESULTS

For inter-rater reliability, the ICC values for all directions ranged from 0.84 to 0.92, SEM values ranged from 2.01 to 3.10%, SWC values ranged from 3.67 to 5.12%, and MDC95% values ranged from 5.58 to 8.60%. For test-retest reliability, the ICC values for all directions ranged from 0.81 to 0.92, SEM values ranged from 1.80 to 2.97%, SWC values ranged from 3.75 to 5.61%, and MDC95% values ranged from 4.98 to 8.24%.

CONCLUSIONS

The YBT-LQ has "good" to "excellent" inter-rater and test-retest reliability. It appears to be a reliable assessment to use with college students with flexible flatfoot.

TRIAL REGISTRATION

This trial was prospectively registered at the Chinese Clinical Trial Registry with the ID number ChiCTR2300075906 on 19/09/2023.

Comparison of foot kinematics and ground reaction force characteristics during walking in individuals with highly and mildly pronated feet

BACKGROUND

Individuals with highly pronated feet (PF) are more prone to lower extremity injuries than those with mildly PF. However, whether foot kinematics and ground reaction force (GRF) characteristics differ according to the severity of PF deformity is unclear.

RESEARCH QUESTION

Are there differences in foot kinematics and GRF characteristics during walking between individuals with mildly PF and those with highly PF?

METHODS

Ten individuals with mildly PF and 10 with highly PF (six-item foot posture index scores: 6-9 and 10-12 points, respectively) participated in this study. A three-dimensional motion analysis system measured participants' foot kinematics and GRF characteristics during gait trials.

RESULTS

Participants with highly PF exhibited significantly lower medial longitudinal arch heights than those with mildly PF from 0 % to 90 % of the stance phase (p < 0.05). No significant differences were observed in any of the angles between the foot segments. Additionally, participants with highly PF exhibited significantly larger posterior GRF than those with mildly PF from 2 % to 7 % of the stance phase (p < 0.05). Participants with highly PF also exhibited significantly larger anterior GRF than those with mildly PF, from 62 % to 82 % of the stance phase (p < 0.05).

SIGNIFICANCE

The results of this study suggest that the more severe the PF deformity, the more inefficient the foot ground force transmission, and the stronger the load applied to the foot. These results may be related to the higher incidence of lower extremity injuries in individuals with highly PF than in those with mildly PF.

Influence of the center of pressure on baropodometric gait pattern variations in the adult population with flatfoot: A case-control study

Background: Adult flatfoot is considered an alteration in the foot bone structure characterized by a decrease or collapse of the medial arch during static or dynamic balance in the gait pattern. The aim of our research was to analyze the center of pressure differences between the population with adult flatfoot and the population with normal feet. Methods: A case-control study involving 62 subjects was carried out on 31 adults with bilateral flatfoot and 31 healthy controls. The gait pattern analysis data were collected employing a complete portable baropodometric platform with piezoresistive sensors. Results: Gait pattern analysis showed statistically significant differences in the cases group, revealing lower levels in the left foot loading response of the stance phase in foot contact time (p = 0.016) and contact foot percentage (p = 0.019). Conclusion: The adult population with bilateral flatfoot evidenced higher contact time data in the total stance phase compared to the control group, which seems to be linked to the presence of foot deformity in the adult population.

Differences in the coordination and its variability among foot joints during running in neutral foot and flatfoot

Flatfoot is a well-known foot deformity, with a prevalence of 11.2%-29.0% among adults. Running injuries can occur in individuals with flatfoot; however, the underlying mechanism remains unknown. We investigated the coordination pattern and variability among foot joints while running by comparing participants with neutral foot and with flatfoot. Participants with neutral foot (n = 15) and flatfoot (n = 15) were asked to run at their preferred speed. Using the modified vector coding technique, the coupling angle between the foot joints, representing interjoint coordination, was calculated and categorized into four coordination patterns. The standard deviation of the coupling angle was computed to measure the coordination variability during the stance phase. There were no differences in the spatiotemporal parameters (speed, step length, and cadence) between the groups. In the sagittal rearfoot and sagittal midfoot coordination patterns, the flatfoot group showed a significantly greater proportion of anti-phase with proximal dominancy and a lower proportion of in-phase with proximal dominancy than the neutral foot group during early stance. Coordination variabilities between the sagittal rearfoot and sagittal midfoot (midstance), between the sagittal midfoot and sagittal forefoot (early stance), and between the frontal rearfoot and sagittal midfoot (midstance) were greater in the flatfoot group than in the neutral foot group. This may explain why those with flatfoot are likely to experience running injuries.

Arch volume：a new method for medial longitudinal arch measurement

BACKGROUND

As a flexible and elastic structure, the dynamic morphometry of medial longitudinal arch remains to be an unresolved Issue for clinic. Here we introduce a new measurement named arch volume to describe the morphological changes of the medial longitudinal arch during weight-bearing and compare with present method for measuring MLA.

METHODS

64 healthy participants were enrolled. And the dynamic arch morphology was measured under four weight bearing status with navicular height, arch area and arch volume, respectively.

RESULTS

With the increase of weight loading, the flattening or slightly deformation of medial longitudinal arch was observed by all method (p<0.05). However, as a 3D indicator, arch volume not only showed higher sensitivity than other method, but also provide visualization of MLA during loading changing.

CONCLUSIONS

Compared with navicular height and arch area, arch volume has a significant advantage in describing arch morphological changes under different weight bearing status.