April 28, 20232 yr https://www.mlb.com/news/miguel-cabrera-gets-treatment-for-back-injury-c259639274 Edited April 28, 20232 yr by FourEyesShottenhoffer
April 28, 20232 yr 37 minutes ago, ptatc said: No. The torque isn't as stressful as sitting for the disc to resistthe force. As high as 35 percent of lumbar disk herniations in elite professional athletes occur in baseball players, because the axial rotation of the spine during hitting and pitching is considerably higher than it is in other sports…. For some comparison, according to a 2012 study done by Dr. Glenn Fleisig and colleagues at the American Sports Medicine Institute in Birmingham, Ala., baseball hitters get an average of 46 degrees of trunk rotation. Pitchers get 55 degrees, while a tennis forehand produces just 30 degrees of rotation.“ https://www.mlb.com/news/miguel-cabrera-gets-treatment-for-back-injury-c259639274
April 28, 20232 yr 13 minutes ago, FourEyesShottenhoffer said: How do explain this then? Baseball players sitting at a significantly higher rate? “Major League Baseball (MLB) players demonstrated a significantly higher RTP rate than those of other sports, and conversely, National Football League (NFL) athletes had a lower RTP rate“ “It has been postulated that the repetitive torque-producing motions of a baseball player may have negative implications after a disk injury….Ninety-seven percent of baseball athletes successfully returned to play at an average of 6.6 months after diagnosis.” https://pubmed.ncbi.nlm.nih.gov/22229920/ Sure. It does put the stress on it. No doubt. However as force in general the sitting shear force is still greater on the disc as opposed to rotational forces.
April 28, 20232 yr Just now, ptatc said: Sure. It does put the stress on it. No doubt. However as force in general the sitting shear force is still greater on the disc as opposed to rotational forces. As high as 35 percent of lumbar disk herniations in elite professional athletes occur in baseball players, because the axial rotation of the spine during hitting and pitching is considerably higher than it is in other sports…. For some comparison, according to a 2012 study done by Dr. Glenn Fleisig and colleagues at the American Sports Medicine Institute in Birmingham, Ala., baseball hitters get an average of 46 degrees of trunk rotation. Pitchers get 55 degrees, while a tennis forehand produces just 30 degrees of rotation.“ https://www.mlb.com/news/miguel-cabrera-gets-treatment-for-back-injury-c259639274
April 28, 20232 yr Just now, FourEyesShottenhoffer said: As high as 35 percent of lumbar disk herniations in elite professional athletes occur in baseball players, because the axial rotation of the spine during hitting and pitching is considerably higher than it is in other sports…. For some comparison, according to a 2012 study done by Dr. Glenn Fleisig and colleagues at the American Sports Medicine Institute in Birmingham, Ala., baseball hitters get an average of 46 degrees of trunk rotation. Pitchers get 55 degrees, while a tennis forehand produces just 30 degrees of rotation.“ https://www.mlb.com/news/miguel-cabrera-gets-treatment-for-back-injury-c259639274 Again of course it puts force on it just not as much as sitting and shear forces. Glen has done much more recent research than 2012.
April 28, 20232 yr 1 minute ago, ptatc said: Again of course it puts force on it just not as much as sitting and shear forces. Glen has done much more recent research than 2012. You mean like the shear force that results from torque movement??
April 28, 20232 yr 3 minutes ago, FourEyesShottenhoffer said: You mean like the shear force that results from torque movement??
April 28, 20232 yr 10 minutes ago, FourEyesShottenhoffer said: You mean like the shear force that results from torque movement?? Shear forces and torque forces are in different directions. Torque by definition is twisting. Shear is sliding.
April 28, 20232 yr 2 minutes ago, ptatc said: Shear forces and torque forces are in different directions. Torque by definition is twisting. Shear is sliding. Torsion results in shear force that is just a plain fact, as the graphic I posted demonstrates. Not even up for debate. If you are twisting your back, then the surfaces are sliding against each other in a parallel motion which is the definition of shear force
April 28, 20232 yr 6 minutes ago, FourEyesShottenhoffer said: Torsion results in shear force that is just a plain fact, as the graphic I posted demonstrates. Not even up for debate. If you are twisting your back, then the surfaces are sliding against each other in a parallel motion which is the definition of shear force Sure it is. The only reason there is a shear force with the torsion in your picture is the fact that there is a pin in the joint that move independent from the ridgid lever. The shear is between the two independent surfaces. In a solid structure you won't have the torsion and shear unless it breaks and there are two independant pieces. Regardles of that scenario The structure of a disc is such that the collagen is crossed in both lateral directions so it I more able to resist forces in those direction.
April 28, 20232 yr Maybe this will help. I’m guessing you didn’t study much physics in your field, but either way you are just plain wrong: “A moment that causes twisting is called a twisting or torsional moment. Torsion produces shear stresses inside the material. A beam in torsion will fail in shear; the twisting action causes the molecules to be slid apart sideways (for example, a pole with a sign hanging off one side).”
April 28, 20232 yr 1 minute ago, ptatc said: Sure it is. The only reason there is a shear force with the torsion in your picture is the fact that there is a pin in the joint that move independent from the ridgid lever. The shear is between the two independent surfaces. In a solid structure you won't have the torsion and shear unless it breaks and there are two independant pieces. Regardles of that scenario The structure of a disc is such that the collagen is crossed in both lateral directions so it I more able to resist forces in those direction. Well your argument is essentially that something that results in shear force does not have the same impact as shear force. If that seems reasonable to you that is your business I guess
April 28, 20232 yr 2 minutes ago, FourEyesShottenhoffer said: Well your argument is essentially that something that results in shear force does not have the same impact as shear force. If that seems reasonable to you that is your business I guess No a straight torque does not produce a shear force in a solid object. So my argument is that they are 2 separate directions for a force in a single structure.
April 28, 20232 yr 3 minutes ago, ptatc said: In a solid structure you won't have the torsion and shear unless it breaks and there are two independant pieces. False. The shear force is still acting on the molecules of the object whether the force is sufficient to break it or not. There is always shear force as a result of torsion regardless, the last I checked the spine is not a solid object. Twisting results in parallel motion of the various objects of the spine which by definition is shear force.
April 28, 20232 yr 53 minutes ago, FourEyesShottenhoffer said: False. The shear force is still acting on the molecules of the object whether the force is sufficient to break it or not. There is always shear force as a result of torsion regardless, the last I checked the spine is not a solid object. Twisting results in parallel motion of the various objects of the spine which by definition is shear force. So does this make you pro-Yoan or anti-Yoan? You have to pick. It's the rule.
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