Biomechanics and Kinetics of Elbow Position in the Baseball Swing - PowerPoint Presentation

Slide1

Biomechanics and Kinetics of Elbow Position in the Baseball Swing

By: Samantha

Erosa

Slide2

Overview

Objective: Analyze two different swings:

‘regular’ elbow versus ‘chicken wing’ elbow

Disclaimer: My natural swing utilizes the ‘regular’ elbow position.

Which position produces the best results?

Analysis from three positions:

Elbow

Bat

ball

Elbow measured from highest position (after loading phase).

Equipment:

Sanyo High Speed Camera (240 frames/second)

Easton Softball Bat [33 inches(.838 m), 23 oz (.652 kg)]

11 inch softball [6.0oz (.17 kg)]

Slide3

Phases of the Swing

Stance Phase

Feet and hand position vary.

Balanced and weight evenly distributed.

Personal preference.

2. Loading Phase

Backward movement of shoulders and arms

Backward rotation of the spineBeginning of the timing step.The cocking of the hips.Cocking of the wrists

3. Launching PhaseContinuation of timing step.Opening of the hips.Forward rotation of spine.Pushing and pulling action of the arms and shoulders.Guiding action of the hands on the bat.

4. Follow-Through

After contact

Hips open completely toward pitcher.

Stiff front leg

Full Arm extension

Slide4

Muscles Involved

Stance Phase

Preparation of muscle usage.

2.

Loading Phase

Pectoralis major muscle,

trapezius

muscle, supraspinatus, and middle deltoid muscles. Lateral spine rotatorsBig muscles on thigh and buttocks. External hip rotators.

Flexor carpi radialis, flexor carpi ulnaris3. Launching PhaseExternal/internal hip rotators.

Pelvis muscles, forearm muscles

Quadriceps

Abdomen

Lateral spine rotators

Bicep/

Tricep

4. Follow-Through

Elbow extensors

Forearm

pronates

Forearm

supinates

Slide5

Significance of the Elbow

Common advice: “Keep your back elbow up!”

Elbow down: direction of force for the top hand is directed toward the pitcher.

Driving of the top hand puts the elbow directly in the ‘slot’ and results in a good driving position.

Like throwing a punch.

Elbow up: more elevated position to snap the bat head further back during the loading phase.

Goal is to achieve maximum torque during launching phase.

Greater source of error: causes hitters to drop their back shoulder instead of getting into a good driving position. Results in an ‘upper cut’ or ‘loopy’ swing.At contact, the hitter ideally wants the elbow as close to the body as possible. This position of the elbow allows for concentration of force and energy needed for ‘explosion’ of the swing. Lose massive amounts of energy and power with elbow away from the body. With elbow far from the body, the hitter loses energy which translates into weaker contact with the ball.

Slide6

Elbow Positions

Regular Elbow Position

Chicken Wing Elbow Position

Calculated Angle:

sin

-1

(.1739/.3164) = 33.34°

Calculated Angle: sin

-1 (.3582/.8248) =25.74°

Slide7

Regular Elbow position

Slide8

Elbow Velocity

Slide9

Elbow Acceleration

Slide10

Bat Velocity

Slide11

Bat Acceleration

Slide12

Ball Velocity

Blurry ball

Slide13

Ball Acceleration

At contact

Slide14

Calculations: Regular Elbow

Elbow:

Max velocity: 5.91 m/s

Max acceleration: 66.638 m/s

2

Bat- .838 m & .652 kg :Max velocity: 22.181 m/sKE= ½ mv2 = ½ (.652 kg)(22.181 m/s

2)2 = 160.39 Jρ= mv = (.652 kg)(22.181 m/s)= 14.46 kg*m/sMax acceleration: 161.171 m/s2F= ma= (.652 kg)(161.171 m/s

2)= 105.08 NBall- .17 kg :Max velocity: 28.257 m/sKE= ½ mv2 = ½ (.17 kg)(28.257 m/s)2 =67.87 Jρ= mv = (.17 kg)(28.257 m/s)= 4.8 kg*m/sMax acceleration: 415.051 m/s

2

F

= ma = (.17 kg)(415.051 m/s

2

)=

70.56 N

Slide15

Calculations: At Contact

Elbow:

velocity: 3.045 m/s

acceleration: 21.520 m/s

2

Bat- .838 m & .652 kg :velocity: 18.842 m/sKE= ½ mv2 = ½ (.652 kg)(18.842 m/s

2)2 = 115.74 Jρ= mv = (.652 kg)(18.842 m/s)= 12.28 kg*m/sacceleration: 133.874 m/s2F= ma= (.652 kg)(133.874 m/s

2)= 87.29 NBall- .17 kg :velocity: 17.055 m/sKE= ½ mv2 = ½ (.17 kg)(17.055 m/s)2 =24.72 Jρ= mv = (.17 kg)(17.055 m/s)= 2.9 kg*m/sacceleration: 415.051 m/s

2

F

= ma = (.17 kg)(415.051 m/s

2

)=

70.56 N

Slide16

Chicken Wing Elbow

Slide17

Elbow Velocity

Slide18

Elbow Acceleration

Slide19

Bat Velocity

Slide20

Bat Acceleration

Slide21

Ball Velocity

Slide22

Ball Acceleration

At contact

Slide23

Calculations: Chicken Wing Elbow

Elbow:

Max velocity: 7.097 m/s

Max acceleration: 48.203 m/s

2

Bat- .838 m & .652 kg :Max velocity: 23.081 m/sKE= ½ mv2 = ½ (.652 kg)(23.081 m/s

2)2 = 173.67 Jρ= mv = (.652 kg)(23.081 m/s)= 15.05 kg*m/sMax acceleration: 204.055 m/s2F= ma= (.652 kg)(204.055 m/s2

)= 133.04 NBall- .17 kg :Max velocity: 22.643 m/sKE= ½ mv2 = ½ (.17 kg)(22.643 m/s)2 =43.58 Jρ= mv = (.17 kg)(22.643 m/s)= 3.85 kg*m/sMax acceleration: 364.526 m/s

2

F

= ma = (.17 kg)(364.526 m/s

2

)=

61.97 N

Slide24

Calculations: At Contact

Elbow:

velocity: 3.642 m/s

acceleration: 13.740m/s

2

Bat- .838 m & .652 kg :velocity: 19.678 m/sKE= ½ mv2 = ½ (.652 kg)(19.678 m/s

2)2 = 126.23 Jρ= mv = (.652 kg)(19.678 m/s)= 12.83 kg*m/sacceleration: 162.120 m/s2F= ma= (.652 kg)(162.120 m/s2)=

105.70 NBall- .17 kg :velocity: 11.061 m/sKE= ½ mv2 = ½ (.17 kg)(11.061 m/s)2 =10.40 Jρ= mv = (.17 kg)(11.061 m/s)= 1.88 kg*m/sacceleration: 330.899 m/s2

F= ma = (.17 kg)(330.899 m/s

2

)=

56.25 N

Slide25

Comparison of Calculations

‘Regular’ Elbow Position

Elbow:

max velocity:

5.91 m/s

max acceleration:

66.638 m/s2Bat:

max velocity: 22.181 m/smax acceleration: 161.171 m/s2KE= 160.39 JF= 105.08 N

ρ= 14.46 kg*m/sBall:max velocity: 28.257 m/smax acceleration: 415.051 m/s2KE= 67.87 J

F=

70.56 N

ρ

=

4.8 kg*m/s

‘Chicken Wing’ Elbow PositionElbow:

max velocity:

7.097 m/s

max acceleration:

48.203 m/s

2

Bat:

max velocity:

23.081 m/s

max acceleration:

204.055 m/s

2

KE=

173.67 J

F=

133.04 N

ρ

=

15.05 kg*m/s

Ball:

max velocity:

22.643 m/s

max acceleration:

364.526 m/s

2

KE=

43.58 J

F=

61.97 N

ρ=

3.85 kg*m/s

***These quantities for elbow and bat position are reflective of the ideal contact location. It is at this position that the most force and energy transfer to the ball will occur.

Slide26

Comparison of Calculations- At Contact

‘Regular’ Elbow Position

Elbow:

velocity:

3.045 m/s

acceleration:

21.520 m/s2

Bat:velocity: 18.842 m/sacceleration: 133.874 m/s2KE= 115.74 JF= 87.29 N

ρ= 12.281 kg*m/sBall:velocity: 17.055 m/sacceleration: 415.051 m/s2KE= 24.72 J

F=

70.56 N

ρ

=

2.9 kg*m/s

‘Chicken Wing’ Elbow PositionElbow:

velocity:

3.642 m/s

acceleration:

13.740 m/s

2

Bat:

velocity:

19.678 m/s

acceleration:

162.120 m/s

2

KE=

126.23 J

F=

105.70 N

ρ

=

12.83 kg*m/s

Ball:

velocity:

11.061 m/s

acceleration:

330.899 m/s

2

KE=

10.40 J

F=

56.25N

ρ=

1.88 kg*m/s

As expected for the ‘chicken wing’ elbow, more force and energy is generated just before contact in comparison to the ‘regular’ elbow swing. However, due to the ‘upper cut’ less force and energy was transferred to the ball.

Slide27

Does Chicken Wing Provide Extra Torque?

Slide28

Regular Elbow Position

Slide29

Chicken Wing Elbow

Slide30

Torque: Pre-Contact

Regular Elbow Position:

Force=F= 87.29 N

Lever arm=r= .4841 m

Ƭ= r*F= (87.29 N)*(.4841)= 42.26 N*m

Assume that the force on the bat is perpendicular to the shoulder pivot point.

Center of mass of bat is roughly around 22 in (.588 m)

Chicken Wing Elbow Position:Force=F= 105.70 NLever arm=r= .4451 mƬ= r*F= (105.70 N)*(.4451)= 47.05 N*m

Slide31

Which hit would go farther?

(Hypothetically- constant acceleration, no wind resistance, ideal projectile motion )

Regular Elbow Position

Chicken Wing Elbow Position

Projected Angle:

Sin

-1

(.3377/1.912) = 10.17°-velocity: 17.055 m/sv

fy = viy + ay *t= 0=17.055*sin(10.17)- 9.8*t t =.307 so, 2*t =.614xf = vix *t= 17.055*cos(10.17)*.614= 10.31 m =33.8 ft-Driving position enabled solid contact- line drive.

Projected Angle:

sin

-1

(.6005/1.899) = 18.43°

velocity: 11.061 m/s

vfy = viy+ ay*t=0=11.061*sin(18.43)-9.8*t t =.357 so, 2*t = .714

x

f

=

v

ix

*t=11.061*

cos

(18.43)*.714= 7.49 m

=24.6 ft

-Dropped shoulder resulting in poor contact- pop up.

Slide32

Conclusions

The ‘chicken wing’ elbow position does in fact generate more force and kinetic energy. This position also creates more torque.

However

, this position results in a ‘loopy’ and ‘upper cutting’ bat path that makes contact less direct.

More likely to hit a pop up.

The ‘regular’ elbow position generates less force and kinetic energy but due to the driving bat path, is able to make solid contact with the ball and result in more energy transfer than the ‘chicken wing’ swing.

More likely to hit line drives. Further investigations:Study torque more closely. Difficult to view the motion with the limited perspective of the camera. Also, Logger Pro doesn’t have capabilities to determine exact angles or angular motion. Also will be interesting to analyze the lower body. Project was limited to the effects of the upper body in the swing but the energy originates from the lower half and is transferred into the upper body.

Slide33

Tips for Hitting

Keep the elbow below the shoulder position.

Provides greater driving mechanism as opposed to ‘upper cutting’ the ball and hitting a pop up.

Let the ball get deep for maximum energy transfer and force application.

Keep elbow as close to the body as possible.

If not, you will lose critical energy during the pivot portion of the swing which results in less torque.

Slide34

References

Van Such, Larry. "Developing Bat Speed and Power in the Baseball Swing: How To Swing The Bat For More Speed and Power."

Athletic Quickness

. Web. 14 Apr. 2012. <http://www.athleticquickness.com/bat_speed_power_baseballswi ng_4.asp>.

Mankin

, Jack. "

BatSpeed.com_Baseball and Softball Swing Hitting Mechanics." Bat Speed. Web. 14 Apr. 2012. <http://www.batspeed.com/tf09.html>.