It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too.

Dec 10, 17 18:15

Post #1 of 100 (5581 views)

I've googled "angular momentum and swimming" and it's out there. http://theraceclub.com/...tems-of-the-swimmer/

Same with angular momentum and running. And cycling. There is some information and I think there could be more if we really want to understand energy conservation and why people do better with higher/lower stroke, stride and cadence in relationship to their mass/weight.

Angular or rotational momentum conserves energy/velocity through movement in the direction you want to go.

Arms and legs in the "recovery" phase of swimming, running and cycling help us move forward. It's not just the pull or push off that propels us in the cycle of moving forward.

It's also reasonable that a bigger, more massive arm or leg "recovering" in the direction that you want to go is an advantage. A less massive arm or leg would need a higher stroke/stride or cadence to be as fast.

Not taking advantage of angular momentum by moving your arm/leg slowly during the recovery phase with the emphasis on the pull or push off to increase length is a loser. Moving the arm/leg more quickly and efficiently through the "recovery" phase helps makes us faster and the bigger that arm/leg is the better.

So what to do. If you are not massive your friends are higher rates and lift. If you are massive you have the advantage over a smaller person, especially when gravity is negligible, if you can match their stroke/cadence rate (which you probably won't have to do while swimming/cycling because of your mass).

It's not just about length/height. It seems like mass and rotational momentum are crucial too because we have the desire/agency to make our mass and turn over work for us.

Bees fly. Hummingbirds fly. Big birds flap less. Penguins swim.

Indoor Triathlete - I thought I was right, until I realized I was wrong.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [IT] [ In reply to ]

Dec 10, 17 18:19

Post #2 of 100 (5567 views)

Here we go again...
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Howard's_Therom_P3482781/?search_string=the%20churner#p3482781

AndyF
bike geek

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [IT] [ In reply to ]

Dec 10, 17 18:26

Post #3 of 100 (5561 views)

Angular momentum has been discussed quite a lot on this forum as it relates to wheel performance. There is a lot of misunderstanding regarding the effects of angular momentum with respect to wheels.

I am not sure I understand what you are saying about the angular momentum of massive arms or legs during the recovery phases of swimming, cycling or running. Are you saying that during the recovery phase of a swim strong, somehow the mass of the arm moving forward will somehow be beneficial? Same thing for the mass of a leg moving forward off the ground during running? What about cycling - what are you proposing?

If my descriptions above are what you mean, it is not correct. First, IF we assume that these motions are circular, which they aren't, the effects of momentum during recovery would be perfectly cancelled by the momentum effects during the drive. Also, the effects are the opposite of what you seem to be saying. If you are floating in zero G and you move your leg or your hand in front of you, your body would move correspondingly backwards.

Edit - While Gary Hall Sr. certainly knows a lot about swimming fast, he seems to not know a lot about physics.

-------------
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www.VeloVetta.com
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Last edited by: RowToTri: Dec 10, 17 18:35

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [AndyF] [ In reply to ]

Dec 10, 17 18:58

Post #4 of 100 (5522 views)

AndyF wrote:

Here we go again...
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Howard's_Therom_P3482781/?search_string=the%20churner#p3482781

That's a blast from the past. That guy was a right kook - riding with water in his tires because it makes them more stable. Wonder how that's going to work when (not if) we're all going to tubeless :-)

Citizen of the world, former drunkard. Resident Traumatic Brain Injury advocate.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [AndyF] [ In reply to ]

Dec 10, 17 19:00

Post #5 of 100 (5519 views)

AndyF wrote:

Here we go again...
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Howard's_Therom_P3482781/?search_string=the%20churner#p3482781

Awesome,

I love the old "moment of inertia discussions" Remeber Nimble?

I still have an old set of 650c flys which are actually pretty nice wheels. Super light and for sure the fastest wheels out there at 90 degrees yaw ;-)

Maurice

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [RowToTri] [ In reply to ]

Dec 10, 17 19:59

Post #6 of 100 (5459 views)

Try this exercise

Stand with both feet on the ground and lift your body weight off the ground standing up to balancing on your left ball of foot, with the right foot just above it dorsiflexed (parallel to the ground).

Now do the same thing instead drive your right knee forward so your right femur ends parallel to the ground.

Which "push off" mode felt easier.

Now do the same thing but instead do option one and try to convert that into a forward motion step. Now do option 2 and convert that into a forward motion step. Which one is easier?

I could get into drawing free body physics diagrams on this, but I THINK what the OP is suggesting is that the swing of the recovery side assists in the push off side. This makes sense if I draw a static free body diagram on the mass of the leg and component of gravity associated with that swinging leg helping the push of leg on the other side. You'll see some "windmillers" in swimming and it's almost like driving the recovery arm fast, forces the hip rotation and the pull on the other side and doing that "fast" (Janet Evans example). For 110 m high hurdlers, clearing the hurdle has everything to do with driving the recovery leg forward with a snap and crunching the upper body forward with a lean and crunch. Hurdlers from what i recall, don't even worry about the push of leg other than the orientation in the air and clearing the hurdle low and quickly snapping it down into recovery and next stride.

This is probably an extreme example of how the recovery leg drive really helps the push of side, but it kind of makes the point that the OP is getting at.

Last edited by: devashish_paul: Dec 11, 17 6:16

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [devashish_paul] [ In reply to ]

Dec 10, 17 20:13

Post #7 of 100 (5434 views)

Hmm... I do not understand your exercises that you are asking me to do. How can I stand on my left leg, then drive my right knee forward until my left femur is parrallel to the ground, unless I fall on my face? I'm missing something.

While you are driving one leg forward, it does create a force that your propulsive leg must push against, but this will serve to slow you down. There's nothing you can do about it, it's just the way the kinematics works. But your propulsive leg is moving backwards relative to your center of mass which works to move you forward. So the oscillating nature of the momentum of your legs relative to your body will essentially cancel. With every stride cycle your leg moves forward with respect to your body the same distance that it moves backwards.

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
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Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [RowToTri] [ In reply to ]

Dec 10, 17 20:22

Post #8 of 100 (5419 views)

In running, what driving the leg forwards does is shift your CoM forward, but conservation of momentum means that CoM should remain at a constant velocity absent any other forces acting on it. that means that your pushing leg is shifted backwards, which adds to the propulsive force on the ground.

None of that means that having more mass in your legs is advantageous though, since that energy to drive the leg forward has to come from somewhere.

swimming has no solid anchor point, so aggressively throwing your arms forward doesn't really do anything for propulsion.

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Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [JasoninHalifax] [ In reply to ]

Dec 10, 17 20:29

Post #9 of 100 (5405 views)

Driving knee forward to get proper body position to apply your power to the ground and avoid extraneous movements I get... Totally buy it.

In his blog post, Gary Hall Sr. is arguing that by throwing your arm forward quickly, your arm will have forward momentum. As your arm reaches the extent of its reach and enters the water that momentum has to go somewhere and that where it goes is into the mass of your body through the skeletal connection.

What he misses though is that to get that forward momentum, it had to "take it" from your body. So there is no net gain.

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [devashish_paul] [ In reply to ]

Dec 10, 17 20:33

Post #10 of 100 (5400 views)

Of course in hurdling you need to drive the leg forward. Having said that Steve Magness (Science of running)...

Has looked at recovery phase and (his opinion) is that it is passive, IE brace someone on a treadmill who is paralyzed from the waist down and they will be able to walk.

He also analyzed a recent 10km world championships and determined that stride frequency and length are highly variable and independent of speed/height/overall both within the context of sustained output (middle of the race) and kick (last 400-800m)

In swimming turnover or perhaps correct speed of recovery is likely driven more by what happens underwater than what we can see or assume above.

Maurice

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [RowToTri] [ In reply to ]

Dec 10, 17 20:34

Post #11 of 100 (5400 views)

Gary Hall doesn't physics....

Neither does the op.

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Last edited by: JasoninHalifax: Dec 10, 17 20:50

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [JasoninHalifax] [ In reply to ]

Dec 11, 17 0:55

Post #12 of 100 (5334 views)

JasoninHalifax wrote:

Gary Hall doesn't physics....

Neither does the op.

This.

The first post is a minefield of confused and inaccurate application of misunderstood physics applied to a problem that seems rather undefined! At best the ideas are badly explained. But much more likely they are ill-conceived.

Edit: The title alone is confused. How can angular momentum and mass be undervalued? Do you value density, inertia, kinetic energy.....? These are physics terms, not assets. It's not so much that it's wrong, as it is meaningless.

Last edited by: Ai_1: Dec 11, 17 1:15

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [Ai_1] [ In reply to ]

Dec 11, 17 4:19

Post #13 of 100 (5229 views)

Ai_1 wrote:

JasoninHalifax wrote:

Gary Hall doesn't physics....

Neither does the op.

This.

The first post is a minefield of confused and inaccurate application of misunderstood physics applied to a problem that seems rather undefined! At best the ideas are badly explained. But much more likely they are ill-conceived.

Edit: The title alone is confused. How can angular momentum and mass be undervalued? Do you value density, inertia, kinetic energy.....? These are physics terms, not assets. It's not so much that it's wrong, as it is meaningless.

Translating from pseudo-scientific nonsense to what I think is his theory, I think what IT is getting at is that running technique, swimming technique, etc should be different based on a person's mass due to differences in angular momentup of their limbs. The problem (well, one of the many problems) is that the contributions of angular momentum to forward propulsion are so small that they are best ignored. For an example, imagine a kid on a swing set, and how much the kid has to pump their legs and torso to get moving if they don't get a push from an outside helper. it's a lot of work to create motion from CoM shifts alone, and that's swinging two legs through a much larger range of motion than you would do whilst running.

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Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [JasoninHalifax] [ In reply to ]

FindinFreestyle

Dec 11, 17 4:54

Post #14 of 100 (5185 views)

JasoninHalifax wrote:

Gary Hall doesn't physics....

He doesn't swimming either, other than being very good at it himself.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [FindinFreestyle] [ In reply to ]

Dec 11, 17 5:08

Post #15 of 100 (5162 views)

I dunno, I've read some stuff by him in the past that makes sense, some things I don't like, and having never attended one of his camps (nor can I afford to) I really don't know about his ability to instruct. I don't really consider him a coach though, and I'm not totally sold on the idea of technique-based swim camps, at least not for people past a certain level of proficiency. Training camps are a whole different thing, but I think those are best done by coaches who know you and what your training has looked like.

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Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [mauricemaher] [ In reply to ]

Dec 11, 17 5:10

Post #16 of 100 (5159 views)

mauricemaher wrote:

AndyF wrote:

Here we go again...
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Howard's_Therom_P3482781/?search_string=the%20churner#p3482781

Awesome,

I love the old "moment of inertia discussions" Remeber Nimble?

I still have an old set of 650c flys which are actually pretty nice wheels. Super light and for sure the fastest wheels out there at 90 degrees yaw ;-)

Maurice

I liked the Nimbles. Buddy of mine had a set of the trispokes and they were pretty nice riding wheels. I wouldn't give up my Specialized trispokes for them though.

Swimming Workout of the Day:

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2020 National Masters Champion - M50-54 - 50m Butterfly

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [Ai_1] [ In reply to ]

Dec 11, 17 6:03

Post #17 of 100 (5120 views)

Ai_1 wrote:

Edit: The title alone is confused. How can angular momentum and mass be undervalued? Do you value density, inertia, kinetic energy.....? These are physics terms, not assets. It's not so much that it's wrong, as it is meaningless.

He pretty clearly means they're not discussed with the depth or frequency that we discuss other physics-based attributes like aerodynamics or rolling resistance.

I'm not defending the rest of the post.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [RowToTri] [ In reply to ]

Dec 11, 17 6:22

Post #18 of 100 (5098 views)

RowToTri wrote:

Hmm... I do not understand your exercises that you are asking me to do. How can I stand on my left leg, then drive my right knee forward until my left femur is parrallel to the ground, unless I fall on my face? I'm missing something.

While you are driving one leg forward, it does create a force that your propulsive leg must push against, but this will serve to slow you down. There's nothing you can do about it, it's just the way the kinematics works. But your propulsive leg is moving backwards relative to your center of mass which works to move you forward. So the oscillating nature of the momentum of your legs relative to your body will essentially cancel. With every stride cycle your leg moves forward with respect to your body the same distance that it moves backwards.

Sorry, I fixed my post. It should have been "right femur" parallel to ground.

In any case if you draw a free body diagram of the center of mass of the right leg when it is parallel to the ground you will see there is a horizontal component of the gravitation force (mg sin theta) where m is the mass of the leg and theta is the angle created between a vertical line from the hip to the ground and the other line from the point on the ground under your hip to the point in space that is the center of mass of your leg. This forward force component of your leg will pull your body forward a bit and will assist the push off leg. This is why track coaches tell you to drive you knees forward on recovery. That's the basic free body diagram physics behind it.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [devashish_paul] [ In reply to ]

Dec 11, 17 6:27

Post #19 of 100 (5089 views)

devashish_paul wrote:

RowToTri wrote:

Hmm... I do not understand your exercises that you are asking me to do. How can I stand on my left leg, then drive my right knee forward until my left femur is parrallel to the ground, unless I fall on my face? I'm missing something.

While you are driving one leg forward, it does create a force that your propulsive leg must push against, but this will serve to slow you down. There's nothing you can do about it, it's just the way the kinematics works. But your propulsive leg is moving backwards relative to your center of mass which works to move you forward. So the oscillating nature of the momentum of your legs relative to your body will essentially cancel. With every stride cycle your leg moves forward with respect to your body the same distance that it moves backwards.

Sorry, I fixed my post. It should have been "right femur" parallel to ground.

In any case if you draw a free body diagram of the center of mass of the right leg when it is parallel to the ground you will see there is a horizontal component of the gravitation force (mg sin theta) where m is the mass of the leg and theta is the angle created between a vertical line from the hip to the ground and the other line from the point on the ground under your hip to the point in space that is the center of mass of your leg. This forward force component of your leg will pull your body forward a bit and will assist the push off leg. This is why track coaches tell you to drive you knees forward on recovery. That's the basic free body diagram physics behind it.

can you quantify the effect that "driving" the leg forward has on the person's velocity purely from the CoM shift?

I suspect that although driving the leg forward is good from a sprinting perspective, the CoM shift is a very minor component.

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Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [trail] [ In reply to ]

Dec 11, 17 6:27

Post #20 of 100 (5088 views)

trail wrote:

Ai_1 wrote:

Edit: The title alone is confused. How can angular momentum and mass be undervalued? Do you value density, inertia, kinetic energy.....? These are physics terms, not assets. It's not so much that it's wrong, as it is meaningless.

He pretty clearly means they're not discussed with the depth or frequency that we discuss other physics-based attributes like aerodynamics or rolling resistance.

I'm not defending the rest of the post.

I actually read it a bit differently and thought he meant that higher mass and angular momentum are specifically positive, as opposed to being under-discussed. Your interpretation is probably closer to what he's saying, I'm not sure an that's my point. I like to be sure.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [devashish_paul] [ In reply to ]

Dec 11, 17 6:35

Post #21 of 100 (5078 views)

The shift of the CoM of the leg can certainly be helpful in attaining the appropriate forward lean as you describe nicely. But there is no forward propulsion from the angular momentum of the recovering leg.

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [AndyF] [ In reply to ]

Dec 11, 17 8:07

Post #22 of 100 (5029 views)

AndyF wrote:

Here we go again...
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Howard's_Therom_P3482781/?search_string=the%20churner#p3482781

AndyF, I actually saw that thread before posting mine. Don't know quite what he was getting at though because I'm not him.

What I am trying to understand is what I see. There are good reasons that some swimmers are at 90+ strokes per minute and others not. Some cyclists at 90+ cadence and others below that. Same with running.

It seems like mass and rate (angular momentum) have a relationship in nature. It's not a one size fits all world.

Indoor Triathlete - I thought I was right, until I realized I was wrong.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [RowToTri] [ In reply to ]

Dec 11, 17 8:21

Post #23 of 100 (5013 views)

RowToTri wrote:

I am not sure I understand what you are saying about the angular momentum of massive arms or legs during the recovery phases of swimming, cycling or running. Are you saying that during the recovery phase of a swim strong, somehow the mass of the arm moving forward will somehow be beneficial? Same thing for the mass of a leg moving forward off the ground during running? What about cycling - what are you proposing?

If my descriptions above are what you mean, it is not correct. First, IF we assume that these motions are circular, which they aren't, the effects of momentum during recovery would be perfectly cancelled by the momentum effects during the drive. Also, the effects are the opposite of what you seem to be saying. If you are floating in zero G and you move your leg or your hand in front of you, your body would move correspondingly backwards.

Edit - While Gary Hall Sr. certainly knows a lot about swimming fast, he seems to not know a lot about physics.

Yes, you understand what I am suggesting. Same across all three sports. The movement forward is also important.

I don't know about zero G; yet, we are not in zero G. Even small birds in the air have to more quickly re-anchor on that air by a flapping their wings faster than larger birds who can glide longer in between.

What I observe is that smaller massed athletes (not necessarily short - yet there is a relationship between mass/height) tend to have higher turnovers in the water, bike and run.

Larger mass athletes tend to have slower turn over and do quite well.

I think angular velocity or rotational velocity helps both.

In basketball, different sized players succeed in different ways. It's the large massive player that can play at the speed of a smaller massed player who is a beast to stop. So I'm not saying all massive people are slow rotationally, just suggesting they don't have to be fast given their mass.

Indoor Triathlete - I thought I was right, until I realized I was wrong.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [devashish_paul] [ In reply to ]

Dec 11, 17 8:28

Post #24 of 100 (5007 views)

devashish_paul wrote:

Try this exercise

Stand with both feet on the ground and lift your body weight off the ground standing up to balancing on your left ball of foot, with the right foot just above it dorsiflexed (parallel to the ground).

Now do the same thing instead drive your right knee forward so your right femur ends parallel to the ground.

Which "push off" mode felt easier.

Now do the same thing but instead do option one and try to convert that into a forward motion step. Now do option 2 and convert that into a forward motion step. Which one is easier?

I could get into drawing free body physics diagrams on this, but I THINK what the OP is suggesting is that the swing of the recovery side assists in the push off side. This makes sense if I draw a static free body diagram on the mass of the leg and component of gravity associated with that swinging leg helping the push of leg on the other side. You'll see some "windmillers" in swimming and it's almost like driving the recovery arm fast, forces the hip rotation and the pull on the other side and doing that "fast" (Janet Evans example). For 110 m high hurdlers, clearing the hurdle has everything to do with driving the recovery leg forward with a snap and crunching the upper body forward with a lean and crunch. Hurdlers from what i recall, don't even worry about the push of leg other than the orientation in the air and clearing the hurdle low and quickly snapping it down into recovery and next stride.

This is probably an extreme example of how the recovery leg drive really helps the push of side, but it kind of makes the point that the OP is getting at.

Exactly Dev.

We also see it in cycling too with say a Chris Froome spinning away while more massive riders (not necessarily tall riders) have a much lower RPM. And, both can have a good result given their mass. And, energy systems.

Indoor Triathlete - I thought I was right, until I realized I was wrong.

Re: It seems like mass and angular momentum are under valued on ST. No doubt it impacts crank length too. [JasoninHalifax] [ In reply to ]

Dec 11, 17 8:32

Post #25 of 100 (4997 views)

JasoninHalifax wrote:

swimming has no solid anchor point, so aggressively throwing your arms forward doesn't really do anything for propulsion.

Exactly, one doesn't have to have a solid anchor point for the throwing of an arm or leg forward to help.

If one is running on a muddy surface, focusing on the push off in the mud may not help as much as engaging in some leg lift and pulling those legs through quickly.

Indoor Triathlete - I thought I was right, until I realized I was wrong.

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