Joubert Dustin P, Guerra Nicholas A, Jones Eric J, Knowles Erica G, Piper Aaron D
Department of Kinesiology and Health Science, Stephen F. Austin State University, Nacogdoches, TX, USA.
Int J Exerc Sci. 2020 May 1;13(4):427-437. doi: 10.70252/DBRF4451. eCollection 2020.
Running economy (RE) is defined as the oxygen consumption (VO) or caloric unit cost required to move at a specific velocity and is an important performance marker. Ground contact time (GCT) has been associated with RE; however, it has not been established how GCT imbalances between feet impact RE.
Determine the relationship between cadence, GCT, and GCT imbalances and RE.
11 NCAA Division I distance runners (7 male) completed a graded exercise test on a treadmill to determine lactate threshold (LT) and VOmax. Body composition was also assessed via DEXA. Subjects ran with a heart rate monitor capable of measuring cadence, GCT, and GCT balance between feet. VO and respiratory exchange ratio were recorded over the last minute of the 5-minute stages. RE expressed as caloric unit cost (kcal·kg·km) was calculated for the stage determined to be just below the LT (prior to > 4mmol/L) and was correlated with cadence, GCT, and GCT imbalance by Pearson correlations.
Pearson correlations between RE and the running dynamics measures were as follows: cadence ( = -.444, = .171), GCT ( = .492, = .125), GCT Imbalance ( = .808, < .005). An independent t-test revealed greater ( = .023) leg lean mass imbalances in runners with larger GCT imbalances compared to runners with smaller GCT imbalances.
GCT imbalances are strongly related to impaired RE. Future research should determine how to improve GCT imbalances and if doing so improves RE.
跑步经济性（RE）被定义为以特定速度移动所需的耗氧量（VO）或热量单位成本，是一项重要的运动表现指标。地面接触时间（GCT）与跑步经济性相关；然而，双脚之间的GCT失衡如何影响跑步经济性尚未明确。
确定步频、GCT以及GCT失衡与跑步经济性之间的关系。
11名美国大学体育协会（NCAA）一级联赛长跑运动员（7名男性）在跑步机上完成了分级运动测试，以确定乳酸阈值（LT）和最大摄氧量（VOmax）。还通过双能X线吸收法（DEXA）评估了身体成分。受试者佩戴能够测量步频、GCT以及双脚之间GCT平衡的心率监测器跑步。在5分钟阶段的最后一分钟记录VO和呼吸交换率。将被确定为刚好低于LT（在>4mmol/L之前）的阶段的跑步经济性表示为热量单位成本（kcal·kg·km），并通过Pearson相关性分析将其与步频、GCT和GCT失衡相关联。
跑步经济性与跑步动力学指标之间的Pearson相关性如下：步频（=-0.444，=0.171），GCT（=0.492，=0.125），GCT失衡（=0.808，<0.005）。独立t检验显示，与GCT失衡较小的跑步者相比，GCT失衡较大的跑步者腿部瘦体重失衡更大（=0.023）。
GCT失衡与受损的跑步经济性密切相关。未来的研究应确定如何改善GCT失衡，以及这样做是否能改善跑步经济性。
