Motion Analysis Project

1151: Biomechanics Alex, Jenessa, Karlee, Clayton

BaseballThe aspect of baseball that our group looked at specifically was a batters swing

How to…Set up video camera and taping environment:

Ensure to have a dark background behind where the athlete will be performing their task

The camera should be feet away

The lights should be right under the camera

The cameras speed should be set to 300 Hertz

Preparing the athlete to be video taped doing a specific skill:

Have the athlete wear tight clothing that covers their body from the neck down

Place reflective markers on joints that are going to be looked at for data collection

Have them perform the skill to the best of their ability

Using SiliconCoach to measure and calculate linear kinematic or angular kinematic data:

In SiliconCoach you are able to measure many aspects of your performer from slide to slide such as…

Critical Angles Displacement Time Stamps

Measuring Critical Angles

These are examples of critical angle measurements. The angles we used were at the elbow, the knee, and the trunk. These were all done at the point of contact with the ball.

Why Are These Angles Critical?

Studies show that the velocity of the bat determines the hitting performance

The knee, elbow and trunk were the most important angles in the swing

Maximum angles from extending right before bat/ball contact means maximum velocity from momentum transfer on to the ball

Measuring Displacement

These are some examples of measuring displacement. The measurement were taken before the swing, at the point of contact, and after the follow through. Again, the points of interest were the elbow, the knee, and the hips/trunk.

Time Stamps

The following examples provided show the time stamps before the swing, at the point of contact, and after the follow through. These were the most important frames because they were the ones that we took our measurements from.

Findings…

A study evaluating average measurements of high caliber hitters showed that at the point of contact…

Right knee angle at 106 degrees

Right elbow angle at 131 degrees

Trunk flexion at -9 degrees

Why Are Their Differences Between Angles?

Extension right before contact allows for a greater bat swing velocity

This increases the transfer of momentum Poorer hitters tend to do a pulling motion on

the bat at first with a relatively bent elbow This decreases the speed of the bat end by

reducing movement derived from rotation

Findings & Analysis of Athlete

Angles at Joints

Study Athlete

Elbow Flexion(Relative Angle)

131±15° 142°

Knee Flexion(Relative Angle)

106±4° 129°

Trunk Flexion(Relative Angle)

-9° 158°or -22°

Areas of Improvement

For the most proficient swing at bat-ball contact this athlete should1. Increase elbow flexion of the right arm by approximately 10°2. Increase knee flexion of the right knee by approximately 25°3. Decrease trunk flexion by approximately 10°

How we did it all…

Yellow markers were set 1m apart Set up so the batter was against the blue backdrop in the gym Our athlete was 0.73m behind the yellow markers, 11.2m from the lights, and

11.5m from the camera The lights were in front of the camera and a tripod was used We placed markers on the knee, front (right) elbow, and hip. Our athlete was

wearing all black The camera was set to 300 fps ANALYZING…chose our best video Measured angles at the knee, trunk and elbow at the beginning, contact point

and follow through Set up the 1m scale and found the time stamps for the beginning, contact point

and follow through Measured knee, hip and elbow displacement from the beginning to contact, and

from contact to follow through

…

Ryan’s camera operations tutorial

Citations Inkster, B.; Murphy, A.; Bower, R.; Watsford, M., Medicine & Science in Sport & Exercise,

Jun2011, Vol. 43 Issue 6, p1050