# Vertical Jump Kinesiology

By | December 6, 2017

## Determine Hang Time Using Force Platform Capstone

This is a tutorial showing how to calculatethe time of flight using a force platform. So the primary work for thisworkbook is done within the calculator. The first set of calculations are toadd the forces between two force platforms. This workbook can also beconfigured for a single force platform. So, the first line is summing thenormal forces from two force platforms. This can be done either with a one axisor a two axis force platform. The next line here is testing to see if thenormal force for the sum of the force platforms is less than 5% of the initialvalue. This will make sure that the

timing will only take place when thenormal force drops below certain critical value. This value can bereduced further below 0.5 if desired. There is a certain amount of ring to forceplatforms so that sometimes there can be some variation in forces even when itssubject has left the surface. This value can be adjusted to make surethat you're getting the best values. The hang time is calculated by the number of data points under which the normal force is below a certain critical threshold and that'swhat the hang time level has done. I've configured this to report out in seconds. The weightof the subject can also be determined so

prior to the jump, the workbook records the sum of the forces, records the first value of that and then records this as the weight of the subject. The mass of the subject can be calculated bydividing by the acceleration due to gravity. The jump height is determined by takinghalf the hang time and putting it into the kinematic equations to determinehow high the subject has jumped. This does not take into account the changing center ofmass of the subject so any motion of the arms will really change the center ofmass of the subject. Within this workbook I have a simple displayhere which displays the hang time in

seconds, the jump height in meters, andthen also has the weight of the subject that's determined at the start of therun in Newtons, and in the mass of the subject to in kilograms. This workbookwill be linked to below this tutorial and the calculations will also be placed inthe comments for this tutorial.

### Knee pain jumpers knee

Jumpers knee.Jumpers the, also known as patellar tendinopathy, is a common injury affecting athletes whodo a lot of running and jumping. It is considered a repetitive stress injury and affects peoplewho play basketball, volleyball, soccer, and who engage in high jumping.Risk factors include overtraining and training on hard surfaces.Symptoms include pain at the insertion of the patellar tendon into the patella. Thediagnosis is made by history, physical examination, and imaging studies such as MRI and ultrasound.Often there is an area of cartilage irregularity where the patellar tendon inserts into thepatella.

Treatment includes modification of activity,ice, joint motion, stretching, strengthening, a patellofemoral race, and occasionally archsupports. Knee immobilization is contraindicated. More aggressive treatment includes sport specificphysical therapy, electric shock wave therapy, and more recently the use of platelet rich plasma and Tenex. Corticosteroids should never be used because they weaken tendon and cartilage.