Ergonomics & paddle shaft circumference

Had a training session yesterday conducted by a PT. Subject: Ergonimics 101. His contention was that the human hand has it’s strongest grip on a cylinder about the size of a soda can. Claimed that it could be measured with a device at their therapy center.

My contention is that the greatest grip strength is with the thumb and forefinger just barely touching. Coincidentally, around an object just about the size of a kayak or canoe paddle.

Anecdotal evidence:

My favorite shaft x-section is that of an AT Exception paddle.

Overly fat and round shafts cause me to have forearm pain.

While Greenland Paddle shafts are often greater in circumference than Euros, the GP grip using the base of the blade makes up for grip lost on the shaft.

Baseball bats are not the same diameter over their length.

Hammers have handles designed for the index-to-thumb touch (ITTT).

His major argument was that screwdriver handles are now larger in dia than they once were. OK, I’ll give him that. But I hold to my theory on shaft size.


Screw drivers

– Last Updated: Mar-22-06 2:51 PM EST –

The use of a screw driver requires a turning/rotating force. A wider handle increases the lever being rotated.

In a paddle, the force isn't being applied by rotating the paddle shaft. You are pulling on the blade. You really don't need to grip the paddle very tightly.

Measuring what?

– Last Updated: Mar-22-06 3:15 PM EST –

The ability to crush the can or to have it pulled out of the fingers? Two different things, certainly.

I could easily imagine the soda can is about the optimal size for crushing.


It depends
I think it depends on the size of the object that you typically grip. Are you a small shaft, large shaft, or beer can size person?

Just regular
Thank you very much…

Consider the diameter of the high bar in gymnastics. About the same size as a standard paddle shaft I would guess. And certainly something it’s important to be able to hang on to. A beer-can-diameter high bar wouldn’t work very well at all.

Need to understand what the ergo guy was really trying to say.


Your hanging off a cliff for dear life…

– Last Updated: Mar-22-06 6:57 PM EST –

Would you rather be holding onto a bar which is soda can diameter or paddle shaft diameter ???

Thought about it .... now I think my grip would be strongest if someone were trying to pull my last two cans of Guiness out of my hands.

I think
that grip strength is probably more a function of the size of the hand, rather than the size of the thing that you are gripping.

crushing force vs gripping
I think in this case we are discussing two different things.

  1. Maximum crushing force.
  2. Maintained grip for an extended time period under tension.

    While maximum crushing force is produced on the larger diameter object, gripping an object for an extended time period is more a case of the fingers locking in position and would rarely require them to hold more than the persons body weight. Gripping a larger cylinder under tension bends the wrist further back and subjects the wrist to increased load which may then become the limiting factor in how long the grip can be maintained.

    As already pointed out by njkayaker the screwdriver handle is used to create torque which is another matter entirely.

    BTW: grip force is totally irrelevant with paddling as you don’t need to grip the paddle tightly. The comfort of the grip is what matters and most people find a smaller shaft more comfortable.

same with me
I’m studying ergonomics.