Kinematics: The Pursuit of Perfection

What is Kinematics

Kinematics is a method used in Biomechanics to study the motion of bodies with respect to time, displacement, velocity of the movement, either in a straight line or in a rotary direction. When associated to Kinetics - the forces associated with motion such as ground reaction forces, friction, air resistance, kinematics is a very power tool to understand athletic performance in a quantitative way.

While 3D kinematics (video 1) can be a very expensive and time consuming method, 2D kinematics can be as powerful as the previous when done right (video 2).

Video 1- 3D Kinematics of skating on a slide board. Force plates integrated. 52 body markers. EMG of 7 muscles of lower leg

Video 2 -2D Kinematics of skating. Range of motion. Coordination. Center of mass. Power. Velocity/acceleration. Reaction time

Infinite possibilities

If you don’t know about Biomechanics and Biomechanical Principles, you will probably find Kinematics very limited and hard. That is why several coaches undervalue Kinematics analysis and give up using Kinematics on a regular basis.

Kinematics is the best way to identify technique faults and make effective changes to improve the athlete’s technique. Even if you have years of experience on the sport and the best coaches’ eye that you can possibly imagine, there is nothing better than having a proper video recorded with a fast camera, with a good resolution, which you can pause, slow down, move back and forth and apply some sophisticated filters and tracking algorithms to help you see the hidden details and quantify the movement.

Here some example of analysis that can be done using Kinematics:

1- Qualitative analysis: body posture, base of support, position of joints, feet and hands

2- Measure of angular and linear joint position, speed and accelerations

3- Center of Gravity position and stability

4- Distance traveled by the center of gravity or by a specific body part

5- External force, external torque and power

6- Mechanical efficiency

7- Moment of inertia and angular momentum

8- Contact time and impulse

9- Potential or Kinetic energy

10- Coordination and timing intra and inter segments

11- Movement Asymmetries (check next blog post)

Correcting technique

If you know Basics Biomechancs and how each principle works, technique defaults can be detected and effectively improved.

The physics of the movement and formula will never change, independent of the sport or individual characteristics.

However, the right correction and intervention can be different for each athlete, depending or his/her strength, power, mobility, body proportions, and other athletic factors.

For example, the ideal body position and joint angle will depend on how long your trunk is with respect to your thigh and lower leg. It will also depend on hip, knee and ankle. mobility and strength of the main muscle groups involved in the action.

Center of Gravity position will also change with different body type and therefore, its ideal position will be slight different for each athlete.