This study investigated lower-limb kinematics and ground reaction force (GRF) during moderate high-heeled jogging and running. Subjects were divided into groups of experienced wearers and inexperienced wearers. A three-dimensional motion analysis system with a configured force platform captured lower-limb joint movements and GRF.
A limited number of studies have explored lower-limb biomechanics during high-heeled jogging and running, and most studies have failed to clarify the wearing experience of subjects. This protocol describes the differences in lower-limb kinematics and ground reaction force (GRF) between experienced wearers (EW) and inexperienced wearers (IEW) during moderate high-heeled jogging and running. A three-dimensional (3D) motion analysis system with a configured force platform was used to synchronously capture lower-limb joint movements and GRF. 36 young females volunteered to participate in this study and were asked about high-heeled shoe-wearing experience, including frequency, duration, heel types, and heel heights. Eleven who had the experience of 3 to 6 cm heels for a minimum of three days per week (6 h per day) for at least two years and eleven who wore high heels less than twice per month participated. Subjects performed jogging and running at comfortable low and high speeds, respectively, with the right foot completely stepping onto a force platform when passing by along a 10 m walkway. EW and IEW adopted different biomechanical adaptations while jogging and running. IEW exhibited a generally larger range of joint movement, while EW showed a dramatically larger loading rate of GRF during running. Hence, further studies on the lower-limb biomechanics of high-heeled gait should strictly control the wearing experience of the subjects.
High-heel design has always been one of the popular features of women's footwear. Forcing the ankle into a passive plantar-flexed state, high-heeled shoes considerably alter walking kinematics and kinetics. Despite reported adverse effects on the musculoskeletal system1, social and fashion customs encourage the continued use of high-heeled shoes2.
Optical tracking systems, currently used in the majority of gait-analysis laboratories for both clinical and research purposes, give accurate and reliable measurement of 3D lower-limb joint motions3. This technology provides a "gold standard" for gait analysis4. Consistent results based on the technique have revealed that higher heel heights lead to larger knee flexion and ankle inversion when compared with flat shoes5,6,7. GRF is another commonly used parameter in gait analysis. The shift of GRF toward the medial forefoot, reduced GRF during mid-stance, increased vertical GRF at heel-strike, and increased peak anterior-posterior GRF have also been observed in high-heeled walking1,6,7,8.
Previous studies referenced above use methods based mainly on level walking. In modern society, running for a bus, darting across a busy street, or dashing to catch the last train push more and more women to use higher speeds every now and then. There are limited studies concerning lower-limb biomechanics during high-heeled jogging and running. Gu et al. noted that the joint motion range of knee abduction-adduction and hip flexion-extension increased significantly as the heel height increased during jogging9. The limitation of this study is that they only recruited habitual high-heel wearers. The frequent use of high-heeled shoes can potentially induce structural adaptions in lower-limb muscles. Zöllner et al. created a multiscale computational model revealing that muscle is able to gradually adjust to its new functional length due to the use of high heels after a chronic loss of sarcomeres in series10. Evidence also demonstrates that kinematic accommodations in gait caused by high-heeled shoes vary between experienced and inexperienced wearers11. Data collected from both experienced and inexperienced subjects may mask statistical results12. It is important to explore whether the biomechanical changes are similarly obvious in inexperienced and experienced users.
The purpose of this study was to investigate the differences in lower-limb kinematics and vertical GRF between experienced wearers (EW) and inexperienced wearers (IEW) during moderate high-heeled jogging and running. It was hypothesized that EW would show faster self-preferred jogging and running speeds, less joint motion, and larger vertical GRF during jogging and running.
This study has been approved by the Human Ethics Committee of Ningbo University (ARGH20150356). All subjects gave their informed consent for inclusion in the study, and they were informed of the goal, requirements, and experimental procedures of the study.
1. Gait Laboratory Preparation
2. Subject Preparation
Figure 1: Experimental protocol. 8 infrared cameras capture lower-limb motion while the subject jogs and runs along the runway. The right foot naturally strikes and completely contacts the force platform when passing by. Kinematic and kinetic data were collected synchronically. Please click here to view a larger version of this figure.
3. Static Calibration
4. Dynamic Trials
Figure 2: User interface for dynamic data collection. Please click here to view a larger version of this figure.
5. Post-processing using Proprietary Tracking Software
6. Data Analysis
7. Statistical Analysis
All results are presented here as the mean ± standard deviation. The running speed was significantly greater than the jogging speed, regardless of wearing experience (EW: Jog vs. Run: 2.50 ± 0.14 vs. 3.05 ± 0.14, p = 0.010; IEW: Jog vs. Run: 2.24 ± 0.26 vs. 2.84 ± 0.29, p = 0.028; in m/s) (Table 1). No significant difference in the corresponding jogging/running speeds between EW and IEW was found. Generally, the stride length of EW was larger than that of IEW (Jog: EW vs. IEW: 1.86 ± 0.06 vs. 1.49 ± 0.20, p = 0.016; Run: EW vs. IEW: 2.15 ± 0.14 vs. 1.79 ± 0.16, p = 0.004; in m), while the stride frequency showed the opposite (Jog: EW vs. IEW: 82.43 ± 3.48 vs. 90.74 ± 2.92, p = 0.024; Run: EW vs. IEW: 85.84 ± 3.39vs. 96.16 ± 3.00, p = 0.015; in steps/min) (Table 1). IEW showed a significantly larger stride length (p = 0.025) and frequency (p = 0.010), and EW showed significantly larger stride length (p = 0.017), while running as compared to jogging.
In the sagittal plane, statistical results from paired independent t-tests showed that the ankle ROM of EW was significantly less than that of IEW (Jog: EW vs. IEW: 39.40±4.44 vs. 47.88±2.59, p=0.000; Run: EW vs. IEW: 36.16±2.42 vs. 43.89±3.70, p=0.006; in degrees) (Figure 3). Also, the ankle plantar-flexion at heel-strike of EW was significantly less than that of IEW (Jog: EW vs. IEW: -10.95 ± 2.15 vs. -14.34 ± 2.31, p = 0.014; Run: EW vs. IEW: -9.97 ± 0.85 vs. -13.63 ± 0.72, p = 0.011; in degrees) (Table 3). The knee ROM of EW during jogging was significantly larger compared to that of IEW (Jog: EW vs. IEW: 30.37 ± 2.11 vs. 29.90 ± 2.67, p = 0.030; Run: EW vs. IEW: 30.97 ± 0.86 vs. 30.16 ± 1.79; in degrees) (Figure 3). On the contrary, the knee peak flexion of EW during jogging was significantly less (Jog: EW vs. IEW: 39.47 ± 1.80 vs. 45.01 ± 2.04, p = 0.017; Run: EW vs. IEW: 42.73 ± 2.13 vs. 44.16 ± 2.07; in degrees) (Table 2). The hip peak flexion (Jog: EW vs. IEW: 27.70 ± 2.82 vs. 27.69 ± 4.00; Run: EW vs. IEW: 36.02 ± 2.94 vs. 29.15 ± 4.10, p = 0.000; in degrees) and flexion at heel-strike (Jog: EW vs. IEW: 27.54 ± 2.84 vs. 27.61 ± 3.92; Run: EW vs. IEW: 35.99 ± 2.96 vs. 29.09 ± 4.10, p = 0.000; in degrees) of EW during running were significantly larger compared to those of IEW (Table 2 and Table 3). In addition, statistical results from paired sample t-tests showed that IEW presented significantly less plantar-flexion at heel-strike (Jog vs. Run: -14.34 ± 2.31 vs. -13.63 ± 0.72, p = 0.044; in degrees) (Table 3) and EW presented significantly larger hip ROM (Jog vs. Run: 39.22 ± 3.73 vs.46.12 ± 3.88, p = 0.010; in degrees), peak flexion (Jog vs. Run: 27.70 ± 2.82 vs. 36.02 ± 2.94, p = 0.000; in degrees), and flexion at heel-strike (Jog vs. Run: 27.54 ± 2.84 vs. 35.99 ± 2.96, p = 0.000; in degrees) while running as compared to jogging (Figure 2, Table 2, and Table 3).
In the frontal plane, the ankle ROM (Jog: EW vs. IEW: 4.90 ± 0.48 vs. 6.66 ± 0.26, p = 0.001; Run: EW vs. IEW: 5.76 ± 0.46 vs. 6.30 ± 0.44; in degrees) and peak inversion (Jog: EW vs. IEW: 5.51 ± 0.40 vs. 7.51 ± 0.43, p = 0.022; Run: EW vs. IEW: 6.80 ± 0.23 vs. 7.73 ± 0.33, p = 0.040; in degrees) of EW was less compared to those of IEW, and significant differences existed in the ROM during jogging and peak inversion during jogging and running (Figure 2 and Table 2). The knee showed similar results to the ROM (Jog: EW vs. IEW: 7.23 ± 2.17 vs. 11.27 ± 1.20, p = 0.010; Run: EW vs. IEW: 9.19 ± 1.15 vs. 11.04 ± 1.63; in degrees) and peak abduction (Jog: EW vs. IEW: 4.57 ± 0.60 vs. 5.16 ± 0.58; Run: EW vs. IEW: 5.84 ± 0.69 vs. 7.12 ± 0.89; in degrees) with the ankle, but significant a difference only existed in the ROM during jogging (Figure 2 and Table 2). As to the hip, only the peak abduction showed a significant difference between EW and IEW (Jog: EW vs. IEW: 6.80 ± 0.89 vs. 12.62 ± 1.23, p = 0.000; Run: EW vs. IEW: 7.73 ± 1.01 vs. 13.37 ± 2.07, p = 0.000; in degrees) (Table 2). When comparisons were made between jogging and running, the ankle peak inversion of EW (Jog vs. Run: 5.51 ± 0.40 vs. 6.80 ± 0.23, p = 0.042; in degrees) and the knee peak abduction of IEW (Jog vs. Run: 5.16 ± 0.58 vs. 7.12 ± 0.89, p = 0.017; in degrees) showed to be larger, with statistical significance during running (Table 2).
In the transvers plane, the running speed showed obvious effect on EW who exhibited significantly larger external rotation of the ankle (Jog vs. Run: -23.58 ± 1.05 vs. -26.82 ± 1.90, p = 0.023; in degrees) and the knee (Jog vs. Run: 12.13 ± 2.19 vs. 15.95 ± 1.62, p = 0.012; in degrees) while running as compared to jogging (Table 2). During running, EW also exhibited significantly less knee ROM (Jog: EW vs. IEW: 16.91 ± 2.21 vs. 18.34 ± 1.08; Run: EW vs. IEW: 16.26 ± 1.72 vs. 19.97 ± 1.26, p = 0.009; in degrees) and larger hip peak internal rotation (Jog: EW vs. IEW: 15.34 ± 1.53 vs. 14.69 ± 0.95; Run: EW vs. IEW: 16.91 ± 1.56 vs. 14.72 ± 0.99, p = 0.028; in degrees) compared to IEW (Figure 2 and Table 2).
Figure 4 shows the ensemble averages of the vertical GRF under the conditions of EW-Jog, EW-Run, IEW-Jog, and IEW-Run. The GRF-time curve of EW is characterized by an initial peak immediately followed by a small wave during the shock absorption period, particularly during running. In contrast, that of IEW is relatively fluent after the initial peak. There is no significant difference in the impact force between EW and IEW, and no significant difference was observed between jogging and running (Figure 4). Compared with IEW, EW showed significantly larger peak force, regardless of speed (Jog: EW vs. IEW: 2.42 ± 0.12 vs. 2.05 ± 0.24, p = 0.035; Run: EW vs. IEW: 2.51 ± 0.14 vs. 2.27 ± 0.12, p = 0.042; in bodyweight). The VALR presented to be the highest under the condition of EW-Run and was significantly higher than the conditions of EW-Jog (EW-Run vs. EW-Jog: 102.66 ± 4.99 vs. 62.40 ± 10.46, p = 0.000; in bodyweight%) and IEW-Run (EW-Run vs. IEW-Run: 102.66 ± 4.99 vs. 78.15 ± 17.00, p = 0.000; in bodyweight%).
Figure 3: Joint ROM during the stance phase (EW: n=11; IEW: n=11). (X) In the sagittal plane. (Y) In the frontal plane. (Z) In the transverse plane. * Statistical significance. Error bars refer to standard deviations. Please click here to view a larger version of this figure.
Figure 4: Ensemble averages of vertical GRF under four conditions (EW: n=11; IEW: n=11; Mean±SD). (a) EW-Jog. (b) EW-Run. (c) IEW-Jog. (d) IEW-Run. The shaded areas refer to the standard deviation. Fi represents the impact force. Fp represents the peak force. VALR represents the vertical average loading rate. BW means bodyweight. a significant difference between EW-Jog and EW-Run; c significant difference between EW-Jog and IEW-Jog; d significant difference between EW-Run and IEW-Run. Please click here to view a larger version of this figure.
Parameters | EW (n=11) | IEW (n=11) | ||
Jog | Run | Jog | Run | |
Speed (m/s) | 2.50 ± 0.14a | 3.05 ± 0.14 | 2.24 ± 0.26b | 2.84 ± 0.29 |
Stride length (m) | 1.86 ± 0.06a,c | 2.15 ± 0.14d | 1.49 ± 0.20b | 1.79 ± 0.16 |
Stride frequency (steps/min) | 82.43 ± 3.48c | 85.84 ± 3.39d | 90.74 ± 2.92b | 96.16 ± 3.00 |
asignificant difference between EW jog and EW run; | bsignificant difference between IEW jog and IEW run; | csignificant difference between EW jog and IEW jog; | dsignificant difference between EW run and IEW run. |
Table 1: Spatio-temporal parameters (Mean ± SD).
Dimensions | Joint (Degree) | EW (n=11) | IEW (n=11) | ||
Jog | Run | Jog | Run | ||
Sagittal plane | Ankle | 12.86 ± 2.10 | 10.64 ± 0.86 | 12.94 ± 1.88 | 10.73 ± 1.02 |
Knee | 39.47 ± 1.80c | 42.73 ± 2.13 | 45.01 ± 2.04 | 44.16 ± 2.07 | |
Hip | 27.70 ± 2.82a | 36.02 ± 2.94d | 27.69 ± 4.00 | 29.15 ± 4.10 | |
Frontal plane | Ankle | 5.51 ± 0.40a,c | 6.80 ± 0.23d | 7.51 ± 0.43 | 7.73 ± 0.33 |
Knee | 4.57 ± 0.60 | 5.84 ± 0.69 | 5.16 ± 0.58b | 7.12 ± 0.89 | |
Hip | 6.80 ± 0.89c | 7.73 ± 1.01d | 12.62 ± 1.23 | 13.37 ± 2.07 | |
Transverse plane | Ankle | -23.58 ± 1.05a | -26.82 ± 1.90 | -26.29 ± 1.06 | -26.73 ± 0.55 |
Knee | 12.13 ± 2.19a | 15.95 ± 1.62 | 15.44 ± 1.52 | 15.88 ± 0.99 | |
Hip | 15.34 ± 1.53 | 16.91 ± 1.56d | 14.69 ± 0.95 | 14.72 ± 0.99 | |
asignificant difference between EW jog and EW run; | bsignificant difference between IEW jog and IEW run; | csignificant difference between EW jog and IEW jog; | dsignificant difference between EW run and IEW run. |
Table 2: Peak angle during the stance phase in three dimensions (Mean ± SD).
Joints (Degree) | EW (n=11) | IEW (n=11) | ||
Jog | Run | Jog | Run | |
Ankle | -10.95 ± 2.15c | -9.97 ± 0.85d | -14.34 ± 2.31b | -13.63 ± 0.72 |
Knee | 18.72 ± 5.87 | 24.06 ± 3.42 | 23.39 ± 2.22 | 26.34 ± 1.47 |
Hip | 27.54 ± 2.84a | 35.99 ± 2.96d | 27.61 ± 3.92 | 29.09 ± 4.10 |
asignificant difference between EW jog and EW run; | bsignificant difference between IEW jog and IEW run; | csignificant difference between EW jog and IEW jog; | dsignificant difference between EW run and IEW run. |
Table 3: Joint angle at heel-strike in the sagittal plane (Mean±SD).
One defect of most studies that analyze high-heeled gait biomechanics is ignoring the possible importance of experience wearing high heels12. This study divided subjects into groups of regular and occasional wearers to explore the effects of high-heeled shoe wearing experience on lower-limb kinematics and GRF during moderate high-heeled jogging and running.
EW and IEW showed comparable jogging/running speeds. Compared with EW, IEW adopted a higher stride frequency and a shorter stride length, which might be a strategy to maintain body balance15,16. The longer stride length of EW is probably associated with larger knee extension during push-off, which also increases the knee ROM in the sagittal plane. Similarly, EW exhibited a larger hip flexion-extension ROM, with increased peak flexion. This could contribute to lowering the center of mass, enhancing body stability17. However, the reduced ROM of the hip and knee of EW in the frontal and transverse planes could be explained as an adaptation after the long-term use of high heels to control joints from excessive motion. The more flexible ankle, with a larger ROM in the sagittal plane of IEW, serves as a less effective lever for the application of muscle force to the ground. This is a potential factor of muscle fatigue, due to the greater required muscle work to achieve a similar amount of output during the propulsive period18.
The larger hip flexion has been reported to be a compensatory mechanism to attenuate the GRF to prevent injury7,19. In this study, EW exhibited larger hip peak flexion, while IEW showed larger knee peak flexion. Increased knee flexion may lead to excessive knee extensor moment20 and rectus femoris activity7,21, both of which are causes of knee overload22,23. Previous studies also reported that the higher quadricep forces induced by increased knee flexion increase proximal anterior tibial shear force, which is a major factor of anterior cruciate ligament strain24,25. Similarly, larger peak adduction of IEW during running may increase the medial compartment loads on the knee26,27 and contribute to the development of knee osteoarthritis1,23. Coupled with the plantar-flexed position, the larger peak inversion of IEW put them at high risk of lateral ankle sprain28. One possible explanation for the decreased inversion of EW is the increased pronator activity caused by the long-term effect of high-heel use15,16.
The higher impact force and loading rate during running have been considered potential factors of lower-limb injuries29,30. There was no significant difference in impact force observed between EW and IEW during jogging and running. However, the loading rate of EW was prominently higher during running, which was largely due to the faster transient of the force. It has been widely documented that the impact force with a rapid increasing rate would create a robust shockwave at the heel-strike event, which is then transmitted up to the lower-limb joints31, probably causing soft-tissue injury and eventually leading to degenerative joint disorders32. Another key finding is that EW showed a higher peak GRF than IEW, which could contribute to increase ankle plantar flexor and pronator moments15,16, reducing ankle instability during the propulsion period. However, the higher peak GRF also indicates higher plantar pressure on the metatarsal area. This may induce a deformity of the first metatarsophalangeal joint33,34.
The results are dependent on a number of critical steps in the protocol. First, turning off the incandescent lights and adjusting the optimal camera strobe intensity are required to ensure the accuracy of optical 3D marker tracking. Second, camera calibration within the capture volume is important for further optimizing the motion capture accuracy. Third, locations of passive retro-reflective markers on the skin should be carefully determined and marked before attaching the markers so that the mark can be re-attached to the same location in the case of the marker moving/falling. Fourth, calibrating the force platform to the zero level before starting each dynamic trial is necessary to ensure the accuracy of the force data recording. Studies that explicate subjects’ wearing experiences could provide specific information on injury reduction in targeted population. In addition to this, another advantage of this protocol presents in the data post-processing. Although the professional biomechanics analysis software is a premier tool for data management, it has its limits in terms of the graphic representation of the data. This study used an alternative to plot the data (see the Table of Materials). There are also limitations to this study. First, the small sample size of 11 experienced subjects and 11 inexperienced subjects may influence the statistics, resulting in non-significant differences. Second, the heel-strike event on the force platform (first frame) can be monitored in the view pane according to the instant when the force vector arises; however, the subsequent heel-strike on the ground (end frame) can only be estimated subjectively by the researchers according to the instant when there is no superior-inferior displacement of the right heel marker. The selection of this frame may vary depending on different researchers. The absence of parameters such as joint moment and joint work, which could further explain lower-limb mechanisms, is another limitation of this study.
In conclusion, regular and occasional high-heels wearers adopt different biomechanical adaptations while jogging and running. The results of this study suggest that further studies evaluating the biomechanics of high-heeled gait should carefully take into account individual wearing experience.
The authors have nothing to disclose.
This study is sponsored by the National Natural Science Foundation of China (81301600), K. C. Wong Magna Fund in Ningbo University, National Social Science Foundation of China (16BTY085), the Zhejiang Social Science Program “Zhi Jiang youth project” (16ZJQN021YB), Loctek Ergonomic Technology Corp, and Anta Sports Products Limited.
Motion Tracking Cameras | Oxford Metrics Ltd., Oxford, UK | MX cameras | n= 8 |
Vicon Nexus | Oxford Metrics Ltd., Oxford, UK | Version 1.4.116 | Proprietary tracking software (PlugInGait template) |
Dongle | Oxford Metrics Ltd., Oxford, UK | – | – |
MX Ultranet HD | Oxford Metrics Ltd., Oxford, UK | – | – |
Vicon Datastation ADC | Oxford Metrics Ltd., Oxford, UK | – | External ADC |
Passive Retro-reflective Marker | Oxford Metrics Ltd., Oxford, UK | – | n=16; Diametre=14 mm |
Force Platform Amplifier | Kistler, Switzerland | 5165A | n=1 |
Force Platform | Kistler, Switzerland | 9287C | n=1 |
T-Frame | Oxford Metrics Ltd., Oxford, UK | – | – |
Double Adhesive Tape | Oxford Metrics Ltd., Oxford, UK | – | For fixing markers to skin |
moderate high-heeled shoe | Daphne, Hong Kong | 13085015 | Heel height: 4.5cm; Size:37EURO |
Microsoft Excel | Microsoft Corporation, United States | Version 2010 | For low pass filtering data and calculations; Add-in:Butterworth.xla |
Origin | OriginLab Corporation, United States | Version 9.0 | Plot GRF-time curve |
Stata | Stata Corp, College station, TX | Version 12.0 | Statistical analysis |