ABSTRACT
Foot core system comprises active subsystem, passive subsystem and neural subsystem, which complement each other and provide different function for foot. Insufficient foot function (weak muscle strength, hypoesthesia of foot) is an important cause of foot injury, and aging, obesity and abnormal foot type are also possible factors of foot injury. At present, special foot strength enhancement methods, minimalist shoes training, and even the means of muscle/brain stimulation, can strengthen the intrinsic muscle strength of foot, improve the stability of the foot, increase the plantar sensory inputs, thereby enhance the core system, raise the foot function performance, and prevent sports injury.
ABSTRACT
Objective To compare the influence of two fatigue protocols on kinematics of lower extremities as well as time/frequency-domain characteristics of impact force during human landing.Methods A total of 15 trained male athletes (sprint/jumping events) were selected and their kinematics in sagittal/frontal plane and time/frequency-domain characteristics of ground reaction force (GRF) under pre-and post-fatigue conditions with two fatigue protocols (constant speed running,shuttle running + vertical jumping) were collected by the Vicon motion capture system and Kistler 3 D force plates.Results (1) Both fatigue protocols showed a significant decrease in the angle of hip and knee joints on the sagittal plane,and an increase in the flexion range of motion (ROM).The running + jumping fatigue protocol showed a significant increase in the flexion ROM of ankle joint,the maximum flexion angular velocity of knee joint (P＜0.05),the abduction ROM of hip joint and the maximum abduction an gular velocity of hip and knee joints (P ＜ 0.05).(2) No significant differences were found in time/frequency-domain characteristics of impact force between pre-and post-tests for both fatigue protocols.The running and running + jumping fatigue protocols showed lower amplitude spectra of the GRF in the frequency domain at 3.51,8.20 Hz and 1.17,3.51,7.03 Hz,respectively (P＜0.05).Conclusions Both fatigue protocols can induce a more flexed landing posture of lower extremities under the impact of landing,and the running + jumping fatigue protocol shows a better effect with shorter intervention time,which indicates such fatigue protocol has more ad vantages from the perspective of experimental methodology.The research findings can provide further references for studying force characteristics after fatigue.
ABSTRACT
Objective To compare the influence of two fatigue protocols on kinematics of lower extremities as well as time/frequency-domain characteristics of impact force during human landing. Methods A total of 15 trained male athletes (sprint/jumping events) were selected and their kinematics in sagittal/frontal plane and time/frequency-domain characteristics of ground reaction force (GRF) under pre- and post-fatigue conditions with two fatigue protocols (constant speed running, shuttle running + vertical jumping) were collected by the Vicon motion capture system and Kistler 3D force plates. Results (1) Both fatigue protocols showed a significant decrease in the angle of hip and knee joints on the sagittal plane, and an increase in the flexion range of motion (ROM). The running + jumping fatigue protocol showed a significant increase in the flexion ROM of ankle joint, the maximum flexion angular velocity of knee joint (P<0.05), the abduction ROM of hip joint and the maximum abduction angular velocity of hip and knee joints (P<0.05). (2) No significant differences were found in time/frequency-domain characteristics of impact force between pre- and post-tests for both fatigue protocols. The running and running + jumping fatigue protocols showed lower amplitude spectra of the GRF in the frequency domain at 3.51, 8.20 Hz and 1.17, 3.51, 7.03 Hz, respectively (P<0.05). Conclusions Both fatigue protocols can induce a more flexed landing posture of lower extremities under the impact of landing, and the running + jumping fatigue protocol shows a better effect with shorter intervention time, which indicates such fatigue protocol has more advantages from the perspective of experimental methodology. The research findings can provide further references for studying force characteristics after fatigue.