Research On The Relationship Between Core Stability And Countermovement Jump And The Biomechanics

ObjectiveCountermovement Jump?CMJ?is one of the most frequent and foundational movement.Core stability?CS?plays an important role during taking off of CMJ.But former studies found inconsistent results for the relationship between core stability and CMJ,and deemed that the choice of CS measurements or training methods affected the experiment results.In the present study,we assessed CS with 5 aspects?Core Strength,Core Endurance,Core Flexibility,Core Control and Core Function?to represent CS comprehensively.The aim was to probe the relationship between CS and CMJ,and to discuss the biomechanics of the effect of CS on CMJ through kinematic and kinetic analysis.MethodsTwenty active college students were recruited from a local university in America,and all of them had habit of doing exercise regularly and have no injury in lower limb and back in the past 2 years.We collected kinematic and kinetic data synchronously with Vicon Motion System and AMTI platform during CMJ by participants.Trunk flexion and extension range of motion?TFE?;dominant limb single leg stance time test?DLS?;dominant limb single leg hop distance test?DLH?;and trunk extensor endurance test?EE?;timed sit-up test?SU?and trunk strength?TS?were employed to assess CS comprehensively.Pearson correlation coefficient was employed to detect the correlation between CMJ related measurements and CS related measurements.Kinematic and kinetic data of CMJ taking off was divided into 2 groups according to CS related measurements,and One-way ANOVA was used to detect the difference between high score group and low score group.Multiple Linear Regression was conducted to determine which independent variables in CS related measurements were significant predictors of CMJ performance.ResultsResearch 1 found that 5 trunk strength measurements(E₆₀?A₆₀?A₉₀?A₁₂₀?T₁₂₀)correlated with TFE significantly.9 Trunk strength measurements(E₆₀?F₆₀?F₁₂₀?A₆₀?T₆₀?A₉₀?T₉₀?A₁₂₀?T₁₂₀)correlated with DLH significantly.Multiple Linear Regression analysis showed that trunk extensor moment could be predicted with TFE,trunk flexor moment could be predicted with DLH.Research 2 found that DLH and CMJ height without arm swing?H_N?shared 45.3%variance.DLH and CMJ height with arm swing?H_A?shared 46.5%variance.The difference(D_FE)between trunk flexion?TF?and extension?TE?range of motion and the difference(D_AN)between H_A and H_N significantly shared 34.0%variance.DLH correlated with peak moment of hip?P<0.05?and ankle?P<0.01?during CMJ with arm swing significantly,and correlated with peak moment of hip?P<0.01?and knee?P<0.05?during CMJ without arm swing significantly.TE correlated with the peak power of hip?P<0.05?and ankle?P<0.05?during CMJ with arm swing significantly,and correlated with the peak power of hip?P<0.01?and ankle?P<0.05?during CMJ without arm swing significantly.The one way ANOVA got the familiar results.Research 3 found that significant correlations?P<0.05?were detected between all trunk strength measurements and CMJ height.Trunk isokinetic strength in 180°/s(F₁₈₀)and Trunk isometric strength in 120°(T₁₂₀)shared 68.0%variance with CMJ height with arm swing,T₁₂₀ shared 57.0%variance with CMJ height without arm swing.F₁₈₀ correlated with peak moment of hip?P<0.01?and ankle?P<0.05?during CMJ with arm swing significantly,and correlated with peak moment of hip?P<0.05?and ankle?P<0.01?during CMJ without arm swing significantly.T₁₂₀ correlated with peak moment of hip?P<0.05?and ankle?P<0.01?during CMJ with arm swing significantly,and correlated with peak moment of hip?P<0.01?and ankle?P<0.05?during CMJ without arm swing significantly.Conclusions1 Trunk strength and DLH had significant correlation.Excessive TFE may decrease trunk extensor strength.The coaches,athletes and recreational players should deal with the relationship between core strength and core flexibility and conduct core stability training according to sport event.2 DLH was a good predictor for CMJ height with and without arm swing,and the same point of DLH and CMJ was the kinetic characteristic of hip and ankle.The difference between trunk flexion and extension range of motion(D_FE)was a good predictor for the difference between CMJ height with and without arm swing(D_AN).Comparing with trunk flexion range of motion?TF?,trunk extension range of motion?TE?had closer relationship with CMJ.The coaches,athletes and recreational players should consider the specificity of CS as an important factor to improve CMJ performance.3 F₁₈₀ and T₁₂₀ were good predictors for CMJ height with arm swing?H_A?,and T₁₂₀was a good predictor for CMJ height without arm swing?H_N?,F₁₈₀ could improve work capacity of hip and knee to benefit CMJ height.T₁₂₀20 could improve work capacity of hip and ankle to benefit CMJ height.The velocity and posture of motion should be considered to improve the efficiency of core strength training.