Running, recreationally and competitively, has
increased in popularity in recent years. Although
several early investigations have studied the ground
reaction forces (GRF) during this basic form of
locomotion there is still much to be learned. There
are several reasons why the study of GRF during gait
is important beyond providing insight into the basic
mechanism of running. Many lower extremity
injuries have been associated with “overuse
phenomena” resulting from the repeated impact
loading of the foot. If the etiology of these injuries
is to be fully understood it is clearly important to
define the input conditions experience by the
musculoskeletal system each time the foot strikes the
ground during the gait cycle. Key variables often
associated with overuse running injuries such as
medial tibial stress syndrome include peak vertical
GRF (Fv), vertical loading rate (Gv), and vertical
center of gravity acceleration (acg).The purpose of
this experiment is to examine the influence of speed
and mass on vertical ground reaction forces. It is
hypothesized that as speed increases there will be an
increase in vertical ground reaction force. It is also
hypothesized that as mass increases vertical ground
reaction forces will increase.
During the data collection one male (age: 100,
height: 1.9 m, mass: 122.73 kg) and one female (age:
100, height: 1.53 m, mass: 59.9 kg). Each participant
was required to travel across the force plate at three
different speeds for three successful trials per speed.
During each trial it was imperative that the
participant landed on the force plate with their entire
foot. The male participant traveled across the force
plate at 1.5 m/s, 3.0 m/s, and 5.0 m/s while the female
participant crossed the force plate at speeds of 1.4
m/s, 2.8 m/s and 4.5 m/s. To record participant speed,
one researcher timed the participant as the traveled
over a 2 meter area leading up to the front edge of the
force plate. Speed was calculated as distance/time or
(2 m)/(time recorded (s)). Was all data was
calculated, researchers estimated the participants
peak vertical GRF (N), normalized peak vertical
GRF (BWs), the time to peak vertical GRF (s),
loading rate (BW/s), and final the acceleration
experienced at the center of mass of the participant
in g’s.
After analyzing the data is was found that males had
an average vertical force of 1482.65 N, 2225.68 N,
and 2660.48 N for the walking jogging and running
trials, while women experienced 579.89 N, 1121.89
N, 1175.01 N. Furthermore, males experienced an
average loading rate of 8.16 BW/s, 12.84 BW/s,
92.07 BW/s for the walking jogging and running
trials, while women experienced 7.88 BW/s, 17.61
BW/s, and 19.70 BW/s.