Ground Contact Time (GCT) is the amount of time the foot spends on the ground in each stride cycle, defined by time from foot strike to toe-off. It is a widely used metric for both athletic and clinical populations, as it relates to load while the foot is on the ground.
GCT and running performance - Ground contact time is related to both running efficiency and maximal running speeds in elite distance runners, with differences between genders and distance specialties.
Chapman, Robert F, Laymon, Abigail S, Wilhite, Daniel P, Mckenzie, James M, Tanner, David A, & Stager, Joel M. (2012). Ground Contact Time as an Indicator of Metabolic Cost in Elite Distance Runners. Medicine and Science in Sports and Exercise, 44(5), 917–925. https://doi.org/10.1249/mss.0b013e3182400520
Ground contact time and injury prevention - An increased cadence (which decreases GCT) decreases average and instantaneous vertical load, along with vertical ground reaction forces. In turn, these decreased forces manipulate running parameters that may prevent plantar fasciopathy, patellofemoral pain, achilles tendinopathy, and tibial stress fractures.
Adams, Douglas, Pozzi, Federico, Willy, Richard W, Carrol, Anthony, & Zeni, Joseph. (2018). ALTERING CADENCE OR VERTICAL OSCILLATION DURING RUNNING: EFFECTS ON RUNNING RELATED INJURY FACTORS. International Journal of Sports Physical Therapy, 13(4), 633–642. https://doi.org/10.26603/ijspt20180633