This study investigated the biomechanical characteristics of the lower extremity kinematic variables between the initial and terminal phase of 5 km treadmill running. The lower-limb kinematic data of 10 runners were collected using a three-dimensional motion capture system on a treadmill at the initial phase (0.5 km) and the terminal phase (5 km), respectively.
Running is beneficial for physical health, but it is also accompanied by many injuries. However, the main factors leading to running injury remain unexplained. This study investigated the effects of long running distance on lower-limb kinematic variables and the lower limb kinematic difference of between the initial (IR) and terminal phase (TR) of 5 km running was compared. Ten amateur runners ran on a treadmill at the speed of 10 km/h. Dynamic kinematic data was collected at the phase of IR (0.5 km) and TR (5 km), respectively. The peak angle, peak angular velocities, and range of motion were recorded in this experiment. The main results demonstrated the following: ankle eversion and knee abduction were increased at TR; ROMs of ankle and knee were increased in the frontal plane at TR than IR; a larger peak angular velocity of ankle dorsiflexion and hip interrotation were found in TR compared to IR. These changes during the long distance running may provide some specific details for exploring potential reasons of running injuries.
Running is the most popular sport around the world. There are a large number of individuals that run and this number increases substantially every year1. It has been suggested that participation in regular exercise including running can promote health, reduce the risk of cardiovascular diseases and thus improve life expectancy2,3,4. Despite the significant health benefits of running, the incidence of running injuries has increased from 25% to 83% over the years5,6. There are some risks associated with running, especially to the lower extremities, which are mainly focused on musculoskeletal injuries7. The majority of common running-related injuries are related to patellofemoral pain, ankle sprain, tibial stress fractures, and plantar fasciitis8. Running injuries can be induced by many factors, such as incorrect foot striking patterns, incorrect shoe selection, and other individual biomechanical factors9. For instance, running with a heel-strike pattern can lead to greater pronation, and is accompanied by larger plantar pressure on the medial side of foot, which may lead a higher risk for Achilles tendinopathy and patellofemoral pain10. In addition, running with a greater knee internal rotation has been previously reported to be associated with the iliotibial band syndrome for female runners11, especially when running long distances.
Parameters of kinetics, kinematics, and time-space components can provide a precise analysis of gait biomechanics, and is currently considered to be an important parameter for clinical gait analysis12. Lower vertical ground reaction forces and larger impact accelerations are recoded after long-distance running13,14. Higher hip excursion and smaller knee flexions have also been found along with fatigued muscles15, and the increased stride frequency can result in reduced stride lengths13,16.
However, changes in biomechanical features of lower limbs at the phase of initial and terminal running have not been fully analyzed, since most studies measured biomechanical variation after running. Additionally, only a few studies use standard laboratory techniques to assess the effects of long-distance running on gait biomechanical changes in amateur runners. The main factors leading to running injuries are still unclear. Therefore, in order to reveal the underlying reasons for lower extremity injuries caused by long distance running, this study aims to compare the biomechanical changes of the lower extremity between the IR and TR phases in treadmill 5 km running in amateur runners.
Written informed consent was obtained from subjects and the testing procedures were approved by the university ethics committee. All participants were informed of the requirements and process of the trial.
1. Laboratory preparation
Figure 1: Test site layout. Cameras capture lower-limb motion while the subjects run on the treadmill. Please click here to view a larger version of this figure.
2. Subject preparation
3. Static calibration
4. Dynamic trials
5. Post-processing
6. Data analysis
7. Statistical analysis
The results showed that no differences in the peak angle of the ankle and hip were observed in the sagittal plane. Compared with IR, the peak angles of the ankle and the knee in the frontal plane were significantly increased at TR. A larger internal hip angle was found in TR as contrasted to IR. However, TR presented a smaller peak angle in hip abduction, ankle interrotation, and knee interrotation than IR (Figure 2).
In the sagittal plane, the ROMs of the ankle and the knee were significantly increased in IR when compared to TR. In the frontal plane, hip ROM was significantly decreased in TR compared to IR, whereas the ROMs of the ankle and the knee was increased in TR than IR. In the transverse plane, knee ROM was found to be significantly lower in the TR compared to the IR running, but no differences were found in the ROMs of the ankle and the hip (Figure 3).
Changes in peak angular velocity between IR and TR were also assessed. In the sagittal plane, there was no significant difference in the peak angular velocity of the hip and knee joints throughout the experiment. A larger peak angular velocity of ankle dorsiflexion was noted in TR. In the stance phase, the smaller peak angular velocity of hip abduction and knee abduction velocity were revealed at TR. The peak angular velocity of hip interrotation increased at TR. There was no significant difference in ankle eversion, knee and ankle interrotation velocity throughout the running.
Figure 2. Peak angle for ankle, knee, and hip in sagittal (A), frontal(B), and transverse planes(C) during one gait cycle (IR N=10; TR: N=10). Significant differences between the IR and TR are denoted with an asterisk (*). Please click here to view a larger version of this figure.
Figure 3. Changes in Joint ROM during the gait cycle IR- vs.TR (mean values). * Statistical significance. Please click here to view a larger version of this figure.
Peak angular velocity (deg/s) | IR Mean±SD |
TR Mean±SD |
p-value |
Hip flexion | 182.58±38.38 | 130.00±47.80 | 0.075 |
Knee flexion | 221.88±22.90 | 266.00±26.36 | 0.07 |
Ankle dorsiflexion | 326.11±20.49 | 344.85±43.76 | 0.046* |
Hip abduction | 256.06±47.31 | 245.54±38.17 | 0.000* |
Knee abduction | 128.65±17.04 | 96.14±15.50 | 0.041* |
Ankle Eversion | 235.43±41.68 | 232.95±11.60 | 0.915 |
Hip int. rotation | 195.92±7.85 | 302.32±29.14 | 0.012* |
Knee int. rotation | 353.83±66.05 | 355.26±39.74 | 0.912 |
Ankle int. rotation | 135.01±42.77 | 146.85±23.60 | 0.664 |
Table 1. Comparisons of knee, hip and ankle peak angular velocity before and after running. Significant differences between the IR and TR are denoted with an asterisk (*).
This study compared the effect of long distance running on the biomechanical characteristics of the lower extremity in amateur runners. It was found that the peak angle of ankle eversion and knee abduction increased after 5 km running, which is consistent with a previous study17. Studies have shown that excessive ankle eversion and eversion velocity are important factors that increase the risk of ankle injuries18,19. It is not surprising that the knee ROM increased at TR of 5 km running because studies have shown that knee kinematics are affected by long-distance running15,17.
Similarly, the knee rotation angle range is reduced in the transverse plane. One of the reasons can be explained because the runner did not experience fatigue at TR20. Compared with IR, the hip interrotation peak angle was larger in TR. Previous studies indicated that an increased angle of hip interrotation can lead to stress fractures of the tibia21. It was also reported that hip interrotation angular velocity was associated with muscle injury22,23. In this study, the angular velocity of the hip interrotation was greater at TR. Hip instability is considered as an important mechanism for lower limb injury24.
The results presented here are dependent on many procedures during the experiment. Firstly, lights must be switched off and other possible reflective objects must be removed. It is important to ensure that capture volume is entirely free from objects that may cause unwanted reflections. Secondly, it is vital to select the desired parameters in the Tools Capture pane for capturing a trial. Thirdly, before starting the test, the treadmill must be placed in the center of the test zone. Also, there are other potential limitations in this study. Only 10 amateur runners were recruited for this experiment. A further limitation of this study could relate to the running distance. Future studies should focus on the effect of different distances with different running shoes on muscle activities and joint moments.
The results of this study indicate that different levels of injury risk may exist for IR and TR of 5 km running. Runners should arrange running training plans scientifically, strengthen balance abilities prior to and during training, and choose running shoes with cushioning functions to reduce the injury risks of ankle and knee joint.
The authors have nothing to disclose.
This study sponsored by the National Natural Science Foundation of China (81772423), K. C. Wong Magna Fund in Ningbo University, and the National Key R&D Program of China (2018YFF0300903).
14 mm Diameter Passive Retro-reflective Marker | Oxford Metrics Ltd., Oxford, UK | n=22 | |
Double Adhesive Tape | Oxford Metrics Ltd., Oxford, UK | For fixing markers to skin | |
Heart Rate | Garmin, HRM3-SS, China | Detection of fatigue state | |
Motion Tracking Cameras | Oxford Metrics Ltd., Oxford, UK | n= 8 | |
T-Frame | Oxford Metrics Ltd., Oxford, UK | – | |
Treadmill | Smart Run,China | Subject run on the treadmill for all the process. | |
Valid Dongle | Oxford Metrics Ltd., Oxford, UK | Vicon Nexus 1.4.116 | |
Vicon Datastation ADC | Oxford Metrics Ltd., Oxford, UK | – |