Relationship between vertical ground reaction force and speed during walking, slow jogging, and running

Objective. To obtain descriptive information between vertical ground reaction force (GRF)-time histories and gait speed, running style, and gender. Design. GRF-time history measurements were obtained from male and female subjects during walking, slow jogging, jogging and running on an indoor platform. Background. Previous studies have established GRF descriptor variables for male subjects running at speeds from 3 to 6 m s−1, but very little descriptive data exists for slower or faster running, nor have previous studies reported GRF descriptors separately for female subjects. Methods. GRF-time histories were recorded for 13 male and 10 female recreational athletes during walking and slow jogging at speeds between 1.5 and 3.0 m s−1, and running at speeds between 3.5 and 6.0 m s−1. Vertical GRF-time data for trials with speeds within 0.2 m s−1 of the prescribed speed were analysed to determine thrust maximum GRF (FZ) and loading rate (GZ). Results. In both male and female subjects, FZ increased linearly during walking and running from 1.2 BW to approximately 2.5 BW at 6.0 m s−1 remaining constant during forward lean sprinting at higher speeds. FZ was linearly correlated to GZ, the latter ranging from 8 to 30 BW s−1 over this speed range. Slow jogging was associated with a > 50% higher FZ and GZ in comparison to walking or fast running. Conclusions. Similar GRF descriptor data and velocity relationships were obtained for male and female subjects. Impact forces were greatest when the subjects adopted a higher, less fixed centre of gravity during slow jogging.