Gymnast Crossing: A Rule of Thumb...

"In the absence of any other proof, the thumb alone would convince me of God's existence."

-Sir Isaac Newton

A favorite scene from the movie, 2001: A Space Odyssey:

Accompanied by one of the most famous transitions in cinematic history.

Opposable thumbs is one of those dramatic differences that distinguishes us from other primates and animals:

Humans are the only animals on earth with fully opposable thumbs. Primates have good power grips (grasping tree limbs for swinging and rocks for throwing), but lack the level of opposition that would give them a good pincher grip, or fine motor skills. Most primates' thumbs will only oppose to their index fingers, making a two-digit pincher grasp their best hope for peeling that banana.

So what distinguishes male gymnasts from female gymnasts when it comes to swinging bars? Well, aside from their ape-like manners, in essence, men: Thumbs wrapped around the pipe. Women: Thumbs on top of the rail, cupped next to the fingers.

This has to do mostly with the different circumference of the men's high bar pipe (2.8 cm diameter) to the women's uneven bar rails (4 cm in diameter).

Further difference is that the men's horizontal bar is made of steel with a fiberglass core while the women's is hollow, made of a fiberglass composite with a birch laminate-coating.

But it's really the circumference size difference that distinguishes the men swinging with thumbs wrapped opposite to the fingers and the women (and girls) keeping their fingers and thumbs cupped together.

Most WAG (women's artistic gymnastics) coaches will encourage/reinforce the female gymnast's natural proclivity to swing bars with thumb and fingers together on top of the rail. Even though there isn't a thumb war over the issue, not all coaches feel that female gymnasts must swing bars with thumbs by fingers:

Neil Resnick (Head coach at Boise State) says when he first walked into Tom's gym, he knew that Tom was a serious, knowledgeable bars coach because one of the things he noticed was how many men's bars Tom had available in his gym for girls/women's gymnastics.

Until the women's uneven bars equipment evolves further into being more like the men's bar, most female gymnasts will- and should- swing with their thumbs and fingers together. But if any can swing with the thumb wrapped under, more power to them:

Our thumbs, however, are finely tuned machines. They're longer, more maneuverable, and better controlled than our primate friends' thumbs. Though there are no muscles in the human thumb, it is controlled by five hand muscles and three major nerves. Twenty five percent of the brain's motor power is devoted to the hand, while a generous four percent of the brain's power is devoted to thumb control (so now we know that hitchhikers and film critics really do think before they act).

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The thumb is our most powerful digit - it's definitely "thumbody special." Not only has it impacted our lives, arguably more than any other evolutionary element, but it is the most powerful communicator of all of our digits. Without the thumb, there may be no written communication, no paintings, no sculpture, no music, no electronics...no industry.

There are moments where female gymnasts will want to take advantage of having opposable thumbs and wrap them opposite the fingers: Usually on front giants (in undergrip) and commonly on pirouetting skills.

As coach comment #7 points out:

IMO thumbs slip out to the side while ascending on the kip, hooked/wrapped/under during the compression/support phase, allows for an easier cast and helps keep the arms from bending. It allows the heel of the hand to securely rest slightly forward of the dead center top of the rail vs. slightly back from dead center top. Thumbs next to fingers is like trying to kick up to a handstand on the sled section of a spingboard with your finger pointing uphill vs kicking to handstand with fingers pointing downhill.

With the thumb working in opposition to the action of the fingers, you have better guidance command of support/handstand positions. Watch any competent bar swinger doing a handstand pirouette and you will see the thumb wrapped opposite the fingers. Instinctive sense will tell the gymnast that to do otherwise runs the risk of the palm slipping off the bar.

But in the case of a mere cast to handstand, not all gymnasts will move the thumbs out (control the handstand) and back in (for swing element); some probably find it more trouble than it's worth. However, I sometimes see gymnasts overcast their handstands and fall off the bar. Repeatedly. Without having the thumbs wrapped around, there is no grip strength/control to fight and prevent this from happening once you start to go over.

It's not uncommon to have gymnasts who never even think about what their thumbs are doing- they just act on instinct and what feels naturally right But sometimes our natural feelings and inclinations are out of habit, and might be "wrong".

Near the beginning of summer, Coach Amy and I encouraged the girls to think about what their thumbs are doing, and to play with moments of opportunity where they can switch thumbs around and back together with the fingers again, while doing kips to cast handstands.

Next time you are watching a bar worker (especially during high level skills), watch what their hands do. It can be quite fascinating.

UCLA gymnast Aisha Gerber moves her thumbs around the bar after the glide and prior to the cast handstand:

Just as many gymnasts seem to not move their thumbs around at all for a mere kip-cast-handstand.

Mattie Larson curiously has her left hand with fingers and thumb cupped together over the bar and her right hand with thumb wrapped around during a glide-kip-cast. She moves it out of the way during her double-leg toe-drop and then just as quickly brings it back around as her toes shoot off the bar. Meanwhile her left grip remains steadfast with fingers and thumb together:

In this clip, UCLA standout Vanessa Zamaripa is constantly moving her thumbs out of the way for swing elements, then wrapping them back around- left and right thumbs not always in conjunction with one another:

How many gymnasts are even aware of what their thumbs are doing?

Here is an example of someone (an Oklahoma gymnast) who feels comfortable going against the common grain and doing the unorthodox:

However, take note of the thumb tape. Swinging giants on the women's bar like this can put friction on the thumbs.

As I wrote here:

If I heard them right, Neil Resnick and Tom Forster favor thumbs around for any gymnast who is comfortable with it. Most girls, however, cannot swing like that (I think Tom's gym has at least one young level 5-6ish gymnast who I saw swinging giants with thumbs around the bar a year ago).

Without even coaching it, your general female bar worker will move thumbs in and out, dependent upon certain skills. Some will have thumbs around during cast handstands; others simply won't. If you had to balance a handstand on a single rail, regardless of circumference size, I think you're better off wrapping your thumbs around the bar to grip and control.

I'd say more common is seeing thumbs around during pirouetting and blind change actions (you have better command and control of the handstand position by taking advantage of having opposable thumbs)- and definitely during front giants.

It ultimately comes down to personal preference. Research your own experience and then do what works for you.

Thumbs around or not around the bar? In the final analysis, borrowing from Bruce Lee:

Research your own experience
Absorb what is useful
Discard what isn't
And add what is specifically your own

You can't (or rather, "shouldn't") reject something until you've fully investigated it. Don't do things simply because you're told to do it; understand why. Always question, investigate, examine. Periodically, revisit and Reexamine.

Not all wisdom has to be conventional wisdom; and in nature, there are always those exceptions to the conventional rules by those who live outside the norms.

As a general rule of thumb when swinging women's uneven bars: Thumbs by the fingers in overgrip when swinging. If the gymnast actually swings better with the thumb around, then by all means, break "the rule".

And don't simply do something because you're used to doing it a certain way; but do it that way because it is the right and correct way for you to do it. Remember: Not all habits are good habits. Adapt and evolve.

Okay, monkeys...let's get back to swinging and evolving!

Hope this post gets a thumbs up from readers!