# Positions of Max Load a human would exert on horizontal rods of such a system by positioning leverage & bodyweight?

My mechanical & civil engineering usage is gone as the last time I did that was in Freshman year & my major went in another direction, but I've tried to be as thorough as possible using a prior question.
PS: If this has to go to Physics SE, please let me know or move it.

Based on this question I posted on DIY:
What kind of Extruded Aluminum sections to replace main wooden frame on this DIY project?,

I received a very detailed & interesting answer here from Ben Welborn pointing out various factors around angles, lengths loads, torque, Center of Gravity/ Mass etc.
I still have to completely digest the math/ calculations, which I'll have to do with my uncle.

That question was centered around the vertical sections, whereas he did help with determining some of the detailed loading parameters.

Here, I am curious to find "In what position would a human be exerting Max Load on the horizontal rods, and what would that load be?"

Constraints:
Human body weight: 200 lbs for simplicity. No added plates, dumbbells, barbells etc.
Rods are 36-40" wide and 1-2" in Diameter if that helps.

Position types:

• No aerials & similar momentum; i.e. Handclap pull-ups.
• Static positions as shown or what you guys can think of,
• Dynamic positions/ movements; Hanging V-up, i.e. Straight vertical Hang and full leg sit up from the waist, but in steady control (I guess the 90 degree L-position would be max leverage), NO Crossfit style momentum.
• No purposefully destructive positions/ movements as suggested in one comment;
• The worst case scenario I believe would be to have Žydrūnas Savickas at the top of your structure (or at the midspan between two supports), resting his feet on the wall, grabbing one of the rungs and then trying to do a 524kg deadlift.

Please do not constrain yourself to only the given examples of what people are able to do, but I'm sharing examples to kick start things. Positions vary in being 1 or 2 handed/ legged, both on same or different horizontal rods.

Which of these or other positions/ leverage you might think of would be position of Max Load?

• The worst case scenario I believe would be to have Žydrūnas Savickas at the top of your structure (or at the midspan between two supports), resting his feet on the wall, grabbing one of the rungs and then trying to do a 524kg deadlift.
– Wasabi
Jun 26, 2016 at 16:38
• Ok let's take a 200 lb as human weight and body weight only as a constraint. Positioning then Jun 26, 2016 at 16:45
• "Body weight only" is an unrealistic constraint. In the "flag" positions, you have to multiply body weight by the factor (distance of the body center of mass from the pole) / ( distance between the two supports on the pole). Taking the CM = 36 inches (as in your picture) the hand separation could be as small as 3 inches with an overlapping grip, so a 200lb person could theoretically apply more than 1 ton of force to the pole with each arm or leg, if his or her limbs were strong enough to do that. Jun 26, 2016 at 22:51
• @alephzero please share some realistic positions using body only (not additional barbells or kettle bells or Dumbbells) and the max loads based on creativity & difficulty of positioning. Please see the link for how calculations were done & share answers. Jun 27, 2016 at 1:46
• I don't of any poledancer-like movements (wioth lots of momentum) that would be relvant here, but could be wrong. I would at least consider a muscle over (quick pullup followed by a dip) for a dynamic load. Or maybe handclap pullups if the OP is really strong ...
– mart
Jun 27, 2016 at 5:21

The load that exert an human supported on two rods depends chiefly on:

• The weight of the human.
• How apart from the rods he is (measured in the horitzontal direction).
• How close are the two rods that support him.

From the photographs you posted, those exerting a smaller load are those in which the person just hangs vertically from one or several bars.

The highest load that I can imagine would be a person in an horitzontal position holding to two contiguous rods with his feet (see picture), although I doubt if there exist a gymnast strong enough to suport himself in such a demanding position.

If somebody could stand this way, the horizontal load exerted to the rods would be about five times his weight (assuming that the gymnast has his centre of masses about his belly button - around 1 m above ground - and that rods are spaced about 20 cm).

• Interesting. How would one calculate that to be 5 x Bodyweight, assuming CoM/ CoG is at belly button. Can you share some formulae, calculation, details on this? Thanks. Jul 24, 2016 at 11:25
• You can just use the lever principle or take moments on the lower (or upper) rod. If W stands for weigh and H stands for horizontal load on each rod, W*1m=H*0.2m. Do you need a diagram for this?
– Pere
Jul 24, 2016 at 13:13
• This result could be improved by taking in account the combination of horizontal and vertical load on the same bar, but the this improvement would be little compared to the uncertainty of bar spacing, body weight and mass centre position.
– Pere
Jul 24, 2016 at 13:18