Biomechanical Factors Affecting Endurance Running Economy

Objective:Based on previous research and theories related to running economy(RE),we chose RE as the dependent variable and the human lower extremity running biomechanics as the independent variables,such as the thigh angle,knee angle,and the ankle angle etc which can reflect the lower extremity performance.Based on the dependent variable RE,we have explored the performance characteristics of the independent variables and the relationship between independent variables and dependent variable.Design:In this study,based on the VO2max,we deceded three different test speed.After that,we got the dependent variable RE at the three different speeds of 12km/h,14km/h and 16km/h respectively.Meanwile,we got the surface electromyogram(sEMG) of the lower extremity muscles.And then,and we got the lower extremity kinematics and the kinetics varibles on the overgroud running at the same controled speed.Methods:Based on the 800m results and the VO2max,We have chose 7 highly homogeneous runners(age:21.43±0.53 years old;height:172.8±379cm; weight:63.66±3.82kg,and training period:4.57±0.98 years) as the Subjects.We processed the data by using the digital filters,normalization and cubic spline interpolation function;The statistics in this study included the Pearson rank correlation analysis,Spearman correlation analysis and the principal component anlysis.Conclusion:(1)By using the self-developed speed control system,we have effectively control the athlete running rhythm with the Photocells.So we have achieved the receivable test effects.(2)It is proper to test the RE of the 800m players under the running speed of 14 km/h.But,we also found if the runner was considered as economical under one running speed,it was possible that he maybe uneconomical under another speed.(3)With the increase of the running speed,the VO2 rose accordingly and the lower extremity kinematics also showed its own trend.The PAC (Principle analysis component) indicated that the synthetic factors of the kinematics can not expain the RE.(4)Though we have not found the Principle component and the kinetics varibles influenced the RE,we indeed found that the rank corraltion coefficient was the highest(r=0.64).Furthur research should be done to verify the possibility of the independent variables,such as maximum anterior-posterior ground reaction force,the maximum medial-lateral ground reaction force,the anterior-posterior impulse,and the medial-lateral implse etc,which may influence the RE.(5) The rank corraltion coefficient between the RE12 and the Principle components F2 which was influenced by the gastrocnemius,rectus femoris, vastus lateralis,and tibialis anterior was highly significant(r=-0.80, p=0.03).This further indicated that it was possible for us to understand the RE through SSC.