Ground Contact Time Imbalances Strongly Related to Impaired Running Economy.

Unlabelled: 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.

Purpose: Determine the relationship between cadence, GCT, and GCT imbalances and RE.

Methods: 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.

Results: 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.

Conclusion: GCT imbalances are strongly related to impaired RE. Future research should determine how to improve GCT imbalances and if doing so improves RE.