RELATIONSHIP BETWEEN VERTICAL GROUND REACTION FORCE AND SPEED DURING WALKING, SLOW JOGGING, AND RUNNING

Objective. To obtain descriptive information between vertical ground r eaction 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 G RF descriptor variables for male subjects running at speeds from 3 to 6 m s(-1), but very little descriptive data exists for slower or faste r running, nor have previous studies reported GRF descriptors separate ly for female subjects. Methods. GRF-time histories were recorded for 13 male and 10 female recreational athletes during walking and slow jo gging at speeds between 1.5 and 3.0 m s(-1), and running at speeds bet ween 3.5 and 6.0 m s(-1). Vertical GRF-time data for trials with speed s within 0.2 m s(-1) of the prescribed speed were analysed to determin e thrust maximum GRF (F-z) and loading rate (G(z)). Results. In both m ale and female subjects, F-z increased linearly during walking and run ning from 1.2 BW to approximately 2.5 BW at 6.0 m s(-1), remaining con stant du ring forward lean sprinting at higher speeds. F-z was linearl y correlated to G(z), the latter ranging from 8 to 30 BW s(-1) over th is speed range. Slow jogging was associated with a > 50% higher F-z an d G(z) 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 ado pted a higher, less fixed centre of gravity during slow jogging. Relev ance These results suggest that vertical GRF norms can be established for male and female subjects alike, and that slow or fast running with a lower, fixed centre of gravity decreases impact forces. Copyright ( C) 1996 Published by Elsevier Science Ltd.