The Difference Of Balance Abilities Between Sub-elite And Elite Sprint-trained Track Cyclists

Objective:The aim of this study was to explore the effects of muscle strength, proprioception, vestibular function and central nervous system on the sprint-trained track cyclists'balance, so as to provide theoretical and applying basis for making great achievement for cyclists.Subjects:The subjects were divided into 3 groups,amounted to 25 persons, the control group had 10 persons,the sub-elite sprint- trained track cyclists had 8 persons and the elite sprint-trained track cyclists had 7 persons.The average age for the control group(20.6±0.8 years)and the sub-elite cyclists(19.8±1.0years) in comparison with the elite sprint-trained track cyclists(25.4±2.6years)showed marked difference (P<0.05).The training time for the sub-elite cyclists(4.5±1.7years) in comparison with the elite cyclists(9.9±1.8years) showed marked difference (P<0.05) too. Heigh and weight among the three groups had no significant difference (P>0.05).All subjects were volunteer for the test and had no eyes diseases, nerve system disease and orthopaedics disease,all subjects eyesight were equal and superior to 5.0.Methods:1 Dynamic balance and vestibular function test: Biodex dynamic balance system was used to acquire balance index with eyes opened and closed for 30 seconds, the difficulty coefficient of dynamic balance test was from 7 to 7,simultaneously tested Elcetromyogram (EMG) of right tibialis anterior and gastrocnemius and observed iEMG and MF changes.2 Muscle strength test:BiodexⅢAP isokinetic system(con/con 60°/s×5)was used to test dorsiflexion and plantar flexion muscle strength in the ankle joint, flexor and extensor muscle strength in the knee joint and in the trunk for three groups.3,Proprioception test:BiodexⅢAP isokinetic system was used to test proprioception of the knee joint which range was from 90°to 45°(deg 180°/s) for three groups.4,Central nervous system test: The cyclists'right hands were predominant, they were required to keep quiet and eyes closed for 3 minutes before test, followed to recall 1 kilometer in track cycling which they had won the best event in recent years for one minutes and four seconds, and at last recovered for 3 minutes, the training time added up to 2 weeks, 30 minutes per training,once per day.Bio-logic was used to test cyclists'central nervous system,following above the procedure.Results:1 Dynamic balance abilities were correlation with muscle strength and proprioception and vestibular function2 Dynamic balance abilities and vestibular function 1) Dynamic balance abilities With Eyes opened and closed, dynamic balance index of the sub-elite cyclists and the elite cyclists in comparison with the control group were significant difference(P<0.01).Dynamic balance index of the elite cyclists were lower than the sub-elite cyclists(P<0.05).2) Vestibular functionWith eyes opened,there were no significant difference in integration electromyography(iEMG) and median frequence(MF) of tibialis anterior between the sub-elite cyclists and the control group(P>0.05).iEMG and MF showed significant differ- ence between the elite cyclists and the control group (P<0.05).iEMG and MF of tibialis anterior showed no significant difference between the elite cyclists and the sub-elite cyclists either(P>0.05).But iEMG and MF of gastrocnemius showed no significant difference among the elite cyclists and the sub-elite cyclists and the control group (P>0.05).With eyes closed,iEMG and MF of tibialis anterior showed significant difference among the elite cyclists and the sub-elite cyclists and the control group(P<0.05).iEMG of gastrocnemius showed significant difference(P<0.01)between the sub-elite cyclists and the control group,but MF of gastrocnemius didn't (P>0.05),however iEMG and MF of gastrocnemius all showed signify cant difference between the elite cyclists and the control group(P<0.05 or P<0.01).iEMG of gastrocnemius showed significant difference(P<0.01) between the elite cyclists and the sub-elite cyclists,but MF of gastrocnemius didn't(P>0.05).3 Muscle strengthMuscle strength in the ankle and knee and trunk:The sub-elite cyclists and the elite cyclists in comparison with the control group had significant difference( P<0.05) .There was no significant difference between the sub-elite and the elite cyclists(P>0.05).4 ProprioceptionThe sub-elite cyclists and the elite cyclists in comparison with the control group differed significantly in proprioception of the knee (P<0.01).There was significant difference in proprioception of the knee joint between the sub-elite cyclists and the elite cyclists(P>0.05).5 Central nervous system1)During quiet,the absolute power of FP1 vs FP2,F3 vs F4,C3 vs C4 P3 vs P4,F7 vs F8,T3 vs T4,T5 vs T6,O1 vs O2 in the sub-elite cyclists showed no difference(P>0.05)and the absolute power of FP1 vs FP2,F3 vs F4,C3 vs C4,P3 vs P4,F7 vs F8,T3 vs T4,T5 vs T6,O1 vs O2 in the elite cyclists either(P>0.05).The absolute power of the right brain showed no difference (P>0.05)between the sub-elite cyclists and the elite cyclists,the absolute power of the left brain either(P>0.05).2)During recalling,the absolute power of FP1 vs FP2,P3 vs P4,O1 vs O2 in the sub-elite cyclists showed significant difference (P>0.05)and the rest didn't(P>0.05),but the absolute power of FP1 vs FP2,F3 vs F4,C3 vs C4,P3 vs P4,F7 vs F8,T3 vs T4,T5 vs T6,O1 vs O2 in the elite cyclists showed no difference(P>0.05).The absolute power of FP1,P3,P4,O1 and O2 between the sub-elite cyclists and the elite cyclists showed significant differentce (P<0.01 or P<0.05)and the rest didn't(P>0.05).P3 vs O1,P4 vs O2αindex of EEG in the sub-elite cyclists showed no difference between quiet and recalling,but P3 vs O1,P4 vs O2αindex in the elite cyclists showed significant difference(P<0.01). 3) During quiet,activation coefficient of parietalis cortex and occipitalis between the sub-elite cyclists and the elite cyclists showed no difference (P>0.05).But during recalling, activation coefficient in parietalis cortex and occipitalis between the sub-elite cyclists and the elite cyclists showed difference (P<0.05).Conclusions:1 Balance abilities were marked correlation with dorsiflexion and plantar flexion muscle strength in the ankle,extensor muscle strength in the knee, flexor and extensor muscle strength in the trunk, proprioception, vestibular function and the central nervous system.2 Balance among the control group and the sub-elite sprint-trained track cyclists and the elite sprint- trained track cyclists showed significant difference, the elite cyclists > the sub-elite cyclists > the control group.3 Muscle strength in the ankle, knee and trunk was one of the reasons that caused balance difference between the control group and the sprint-trained track cyclists, but muscle strength was not major reason that caused balance difference between the sub-elite sprint-trained track cyclists and the elite sprint-trained track cyclists.4 The reasons those caused significant difference among the elite cyclists proprioception,the sub-elite cyclist -s proprioception and the control group proprioception were proprioceptor threshold decrease and synaptic sensitization.5 The vestibular function showed significant difference between the sprint-trained track cyclists and the control group(P<0.01 or P<0.05),it suggested that track sprint-trained could improve the vestibular function. The significant difference in vestibular function between the elite sprint-trained track cyclists and the sub-elite sprint-trained track cyclists were caused by training time and content.6 Central nervous system function was one of the reasons that caused the difference of balance abilities between sub-elite and elite sprint-trained track cyclists.