Methods and Material
To discover the changes that occur from the different shod and loading conditions we have pulled in several female and male volunteers. The volunteers had to walk a distance of 10 meters in the UNC biomechanics laboratory per trial. In the middle of the walkway are 2 AMTI force plates. Each volunteer had to walk at a pace of 1.5 meters per second +/-5%. To make sure that the volunteers were walking the distance in the correct amount of time we used a timing system with two gates. The timing gates were set at the start of the distance and at end of the distance. When the volunteers walked past the first timing gate it would start recording data, when the volunteer walked past the second timing system it would stop recording data.
There are 4 different conditions that we had the volunteers walk in. One of the conditions was to wear running shoes without a backpack, and the second condition was to walk while wearing running shoes and a backpack that weighed 15% of the volunteer’s body weight. The last conditions were walking barefoot unloaded and also barefoot loaded. To make sure that the volunteers were not getting used to the tests, the condition’s order was randomized.
Dependent measures included the step time (the amount of time it takes in between one step), peak vertical Ground Reaction Force (VGRF) , loading rate (the slope of the vertical GRF versus time graph), peak braking GRF (the highest amount of force that is being applied opposite to the direction of travel when the heal hits the ground), Peak propulsive GRF (the highest amount of force that being applied when the ball of your foot is pushing off the ground) and the step length (the distance from the first foot hitting the ground to the second foot hitting the ground) were measured all taken in to account. The step time is measured in seconds while the step length is measured in meters.
The Peak VGRFis found by finding the most amount of force applied in the first peak in the vertical force section of data provided by the force plates. The peak propulsive GRF is found by finding the highest point in the highest point in the last peak of the data.
Step time= 2nd intial contact- 1st initial contact
Loading rate= (Peak VGRF-0)/(time of first initial contact-time of peak VGRF)
There are 4 different conditions that we had the volunteers walk in. One of the conditions was to wear running shoes without a backpack, and the second condition was to walk while wearing running shoes and a backpack that weighed 15% of the volunteer’s body weight. The last conditions were walking barefoot unloaded and also barefoot loaded. To make sure that the volunteers were not getting used to the tests, the condition’s order was randomized.
Dependent measures included the step time (the amount of time it takes in between one step), peak vertical Ground Reaction Force (VGRF) , loading rate (the slope of the vertical GRF versus time graph), peak braking GRF (the highest amount of force that is being applied opposite to the direction of travel when the heal hits the ground), Peak propulsive GRF (the highest amount of force that being applied when the ball of your foot is pushing off the ground) and the step length (the distance from the first foot hitting the ground to the second foot hitting the ground) were measured all taken in to account. The step time is measured in seconds while the step length is measured in meters.
The Peak VGRFis found by finding the most amount of force applied in the first peak in the vertical force section of data provided by the force plates. The peak propulsive GRF is found by finding the highest point in the highest point in the last peak of the data.
Step time= 2nd intial contact- 1st initial contact
Loading rate= (Peak VGRF-0)/(time of first initial contact-time of peak VGRF)