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SVTPerformance's Chain of Restaurants
Road Side Pub
Bench press advantage, long vs short arms?
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<blockquote data-quote="VerySneaky" data-source="post: 12633126" data-attributes="member: 109959"><p>This.</p><p></p><p></p><p>Almost. That is a very basic understanding. The forearm is colinear with the direction of the force, so it doesn't see the torque, but your forearm affects the lift by way of mechanical "work". </p><p></p><p>As a mechanical engineer that powerlifted in highschool I'll highlight some maths. </p><p></p><p>Let's take the following free body diagram, (it's colored green, because Hulk):</p><p>[ATTACH=full]416901[/ATTACH]</p><p></p><p>We can assume the following: </p><p>Left and right arm provide equal lifting strength, so the forces are equal. F<span style="font-size: 9px">R</span>=F<span style="font-size: 9px">L</span>.</p><p>H is the distance from the lifter's chest to the bar at the starting position (just taken it from the rack). </p><p>D is the length between the elbow and shoulder, this also assumes that your hands are positioned so your forearms are perpindicular to the bar. Widening your "stance" will change your load.</p><p>F<span style="font-size: 9px">G</span> is the force of gravity, or weight, that must be overcome is centered on the bar, in this case 400lbf, or 200lbf per arm.</p><p></p><p>We know the following equations from the work-energy theorem:</p><p>Work is the product of work and distance or torque and angular velocity, or W=F*d, also W=T*(angle if perpendicular to F).</p><p><a href="http://en.wikipedia.org/wiki/Work_(physics" target="_blank">http://en.wikipedia.org/wiki/Work_(physics</a>)</p><p></p><p>To complete a rep, you are required to do greater than 200*H ft-lbf of kinetic energy, or work. Considering a midget, H will be less than that of someone that is 6'-6", obviously. Therefor, less energy is spent to complete one rep. </p><p>To quantify, if the bar only has to travel 18" vice 24-30", it'll be 600ft-lbf for said midget, or 1000ft-lbf. </p><p></p><p>Torque also comes into play when you're thinking of strength. The length of your humerus (D) is your lever arm. Force is multiplied by this distance to create torque on your shoulder that your pecs, delts, etc. will have to overcome.</p></blockquote><p></p>
[QUOTE="VerySneaky, post: 12633126, member: 109959"] This. Almost. That is a very basic understanding. The forearm is colinear with the direction of the force, so it doesn't see the torque, but your forearm affects the lift by way of mechanical "work". As a mechanical engineer that powerlifted in highschool I'll highlight some maths. Let's take the following free body diagram, (it's colored green, because Hulk): [ATTACH=full]416901[/ATTACH] We can assume the following: Left and right arm provide equal lifting strength, so the forces are equal. F[SIZE="1"]R[/SIZE]=F[SIZE="1"]L[/SIZE]. H is the distance from the lifter's chest to the bar at the starting position (just taken it from the rack). D is the length between the elbow and shoulder, this also assumes that your hands are positioned so your forearms are perpindicular to the bar. Widening your "stance" will change your load. F[SIZE="1"]G[/SIZE] is the force of gravity, or weight, that must be overcome is centered on the bar, in this case 400lbf, or 200lbf per arm. We know the following equations from the work-energy theorem: Work is the product of work and distance or torque and angular velocity, or W=F*d, also W=T*(angle if perpendicular to F). [url]http://en.wikipedia.org/wiki/Work_(physics[/url]) To complete a rep, you are required to do greater than 200*H ft-lbf of kinetic energy, or work. Considering a midget, H will be less than that of someone that is 6'-6", obviously. Therefor, less energy is spent to complete one rep. To quantify, if the bar only has to travel 18" vice 24-30", it'll be 600ft-lbf for said midget, or 1000ft-lbf. Torque also comes into play when you're thinking of strength. The length of your humerus (D) is your lever arm. Force is multiplied by this distance to create torque on your shoulder that your pecs, delts, etc. will have to overcome. [/QUOTE]
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Bench press advantage, long vs short arms?
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