| Objective: Running economy(RE)is typically defined as the energy demand or oxygen uptake for a given velocity of submaximal running,ml/kg/min and kcal/kg/km are the common evaluation units.Running straight test on treadmill measures RE is a commonly used test method for evaluating athlete's endurance,and the test is also used for team ball games.However,it is unclear whether the running straight test can truly reflect the characteristics of the team ball project.The purpose of this study is to investigate the difference between the RE of running straight on treadmill and that of 20m-shuttle running,and to provide a scientific basis for testing the team ball project to select the RE test method.Methods: 18 male students of physical education from Shanghai University of Sport and their major is track and field(age:22.4 ± 2.4yrs,height:177.4 ± 7.5cm,weight:69.3 ± 8.2kg,training period: 4.6 ± 1.6yrs)volunteered to participate in one treadmill running graded test(8?10?12 and 14km/h)and one 20m-shuttle running graded test(6?8?10 and 12km/h),The portable gas metabolism system was used to measure the breathing gas during running,and collect blood lactate and RPE during testing.The RE was evaluated by measuring the average oxygen cost(Oc:ml/kg/min)for the last 1 min of each stage,and the energy cost(Ec: kcal/kg/m)calculated in combination with the respiratory quotient.Results: With the increase of running speed,the oxygen consumption and energy consumption of straight running and shuttle running are significantly increased(p<0.05).At the same running speed(8,10 and 12km/h),Oxygen consumption at 20m-shuttle running(34.0 ± 3.6 vs.32.5 ± 4.9ml/kg/min,p>0.05;47.9 ± 5.0 vs.37.9 ± 5.9ml/kg/min,p<0.05;54.9 ± 6.2 vs.42.0 ± 7.0 ml/kg/min,p<0.05)and energy consumption(1.204 ± 0.167 vs.1.004±0.099kcal/kg/km,p>0.05;1.173 ± 0.142 vs.1.137 ± 0.170kcal/kg/km,p<0.05;1.178 ± 0.124 vs.1.082 ± 0.200kcal/kg/km,p<0.05)were higher than the straight running.Compared with other indexes of straight running and shuttle running under the same running speed,there was only significant difference in blood lactic acid at 8km/h(p<0.05),and there was no significant difference in other indexes(p>0.05);except for respiratory quotient at 10km/h(p>0.05),all indicators were significantly different(p<0.05);at 12km/h,except for the respiratory quotient(p>0.05),all indicators were significantly different(p<0.05).Whether it is straight running or 20m-shuttle running,RE decreases with increasing speed(ie.higher oxygen consumption and energy consumption),and the difference between each two speeds is significant(p<0.05).In terms of other indicators,RE,mean heart rate,blood lactate,respiratory quotient,and RPE were significantly changed in the same test(except for respiratory quotient,blood lactate,and RPE of 6 vs.8 km/h,mean heart rate of 10 vs.12km/h)(p<0.05).According to the RE definition of the submaximal intensity and steady state two conditions,the oxygen consumption and energy consumption at 8 and 10 km/h were selected as the evaluation of the RE value of the group,which were 32.5 ± 4.9 ml/kg/min and 1.004 ± 0.099kcal/kg/km(8km/h straight running),37.9 ± 5.9ml/kg/min and 1.137 ± 0.170 kcal/kg/km(10km/h straight running),and 34.0 ± 3.6ml/kg/min and 1.204 ± 0.167 kcal/kg/km(8km/h shuttle running),47.9 ± 5.0ml/kg/min(10km/h shuttle running).Conclusion: At the same running speed,the RE of 20m-shuttle running is worse than that of treadmill running.The straight running assessment may overestimate the RE of the change of direction running.It is recommended to use the Cod-running assessment to test RE on team ball sports. |
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