Validity of Running Economy Evaluation by Energy Unit

Objective:To verify the validity of three running economy evaluation units, RE across four submaximal speeds was tested on the track with a portable oxygen respiratory function analyzers.Methods:Ten middle-distance runners performed an incremental test to measure maximal oxygen uptake (O2max) and anaerobic threshold (AT) , then performed a constant load test that lasted 5¹0min with loads respectively at 70%, 80%, 90% and 105%AT.The RE with different units were calculated according to some steady respiratory indices.Result:The correlationships between three RE expressed by different units were very strong (P<0.01) ;with the increment of work loads, oxygen uptake per minute (ml/kg/min) increased significantly (P<0.05) and successively;oxygen uptake per distance (ml/kg/km) remained relative steady stage (P>0.05) , furthermore there was slight decrement in succession between 80%¹05%;energy consumption increased slightly among 70%⁹0%AT (P>0.05) , but experienced a sharp growth (P<0.05) between 90%¹05%AT;RER increased significantly between 80% and 90%AT (P<0.05) and between 90% and 105%AT (P<0.01) .Conclusion:Both time-oxygen uptake unit and distance-oxygen uptake unit neglect that energy yielded per liter of oxygen is dependent on the substrate metabolized, and can't evaluate RE effectively, the energy unit reflects the essential feature of RE, is a more valuable expression of RE.