Body Torques #3, #4 Shoulder Flexors/Extensors for Running Speed

BODY TORQUE #3

Faster running speed with help from the arms as they produce torques around the body. Torque #3 will come from the right arm. Since the right arm has been thrust in front of our athlete, we know then that a force, relatively speaking with regards to direction, will end up pulling the right shoulder forward. See Figure 1.

Figure 1. Right arm creates a pulling force on the body.

And if this were the only force acting on the body, the question then is, which direction, if any, will it cause our athlete’s upper body to turn?

Well in this case, and with respect to the spinal column, the force pulling on the right shoulder is displaced to the right of it. So we know that it has to rotate the body in one direction or the other.

And if we imagine this pulling force continuing in the same direction, forward, we can then see that it will produce a counterclockwise torque around the spinal column as seen by the direction of this arrow. See Figure 2.

Figure 2. Torque #3 creating counterclockwise torque around the spinal column.

The muscles responsible for this torque are primarily the shoulder flexors, or upper arm flexors, and their names are anterior deltoid, long head of the biceps, pectoralis major and coracobrachialis. See Figure 3.

Figure 3. Torque #3 Muscles are the Right Shoulder Flexors.

BODY TORQUE #4

The fourth torque involved in running will come from the left arm. Since the left arm has been thrust behind our athlete, we know then that a force, relatively speaking with regards to direction, will end up pulling the left shoulder backward. See Figure 4.

Figure 4. Left shoulder creates a pulling force on the body backward.

And if we imagine this pulling force continuing in the same direction we can then see that it will also produce a counterclockwise torque around the spinal column as seen by the direction of this arrow. See Figure 5.

Figure 5. Torque #4 creating counterclockwise torque around the spinal column.

The muscles responsible for this torque are primarily the shoulder extensors, or upper arm extensors, and their names are the posterior deltoid, the triceps, the teres major and the latissimus dorsi. See Figure 6.

Figure 6. Torque #4 Muscles are the Left Shoulder Extensors.

PURPOSE #1 OF THE ARMS

One of the purposes your arms serve when you run is to help you overcome gravity and make your body feel and act lighter. Because the lighter you are on your feet, the less weight you have to move and the less weight you have to move, the faster you will be able to run.

And your body does this by vectoring not only one arm forward and the other backward at the same time, but it also vectors both arms upward, at the same time, as seen in here in Figure 7.

Figure 7. Arms creating upward force to make you lighter in the air.

And this creates the necessary momentum in the vertical plane to make you feel lighter which is similar to what high jumpers do with their arms to help them jump higher.

Now momentum is mass times velocity and in this case, we are talking about the mass of each arm and the speed or velocity in which you are moving them.

So as an athlete, you have several opportunities to improve the momentum created by your arms to help you feel lighter and run faster.

One of them is you can add more mass or size to your shoulders and arms while maintaining the velocity in which you can swing them.

Another is you can work on improving the speed in which you swing your arms without adding any size to them.

And the last one is you can try to add both mass to your shoulders and arms as well as work on increasing the speed in which you swing them. See Figure 8.

Figure 8. How to increase the momentum in your arms.

This is why you may have noticed that many sprinters have really big arms because it helps them create more momentum in the vertical plane when they run, making them lighter in the air, and therefore making them faster.

PURPOSE #2 OF THE ARMS

Another purpose the arms play while running is that they are needed to help counterbalance one of the torques produced by your legs.

And you may have experienced their value with this if you had ever tried to run without moving them, such as running with your hands in your pockets while it was raining or for some other reason.

And if you did, you will have noticed that it is rather difficult, if not impossible, to get yourself up to full speed.

And again, this is because your arms are needed to counterbalance one of the two torques created by your legs. And to see which leg torque your arms side with, let’s do a quick review of the 4 torques we have learned about so far.

REVIEW TORQUES #1 – #4

Torque #1 from video #1 of this series, produced by the glutes/hams, quads and calves, was found to be a counterclockwise torque in this image.

Torque #2 from Video #2 of this series, produced by the hip flexors, was found to be a clockwise torque in this image.

And here in this video we just learned that both Torque #3 produced by the right shoulder flexors and torque #4 produced by the left shoulder extensors were both were found to be CCW torques in this image. Siee Figure 9.

Figure 9. Review of torques #1 – #4.

And since we learned in Video #2 of this series that all of the CW torques must be equal to all of the CCW torques we now have the following equation:

On CW side we only have torque #2 generated by the hip flexors on the left side of the body. And on the CCW side, we have the other three which include, Torque #1 generated the glutes/hams, quads and calves on the right side of the body, torque #3 from generated by the right shoulder flexors and torque #4 generated the left shoulder extensors. See Figure 10.

Figure 10. Clockwise torques equal counterclockwise torques.

So with this we can start to see a pattern developing where the hip flexors are working alone to counterbalance the torques produced by the rest of the body.

And there are several conclusions that we can draw from this such as how it may affect your running speed as well as where to target your training so that you can reach your true running speed potential.

But before we get in to those details, we will need to talk about the 5th and final torque produced by your body and that is the subject of our next video. See Figure 11.