Lead Image Credit: Rob Thames via Tsunami Bar
Wobble, You Weeble, But Don't Fall Down
Exercise physiologist types have long debated the merits of instability training, postulating that lifting on an unstable surface or lifting an unstable load would lead to recruitment of more muscle and more muscle groups.
The idea has led to all kinds of innovations, whether they be actual inventions like the BOSU ball or newer techniques where the lifter hangs things off the bar (chains, kettlebells, laundry) to make it harder to lift without falling over on his face.
There was even one coach who recommended you squat while a second party nudges you to threaten your balance. Whether or not the second party had to be drunk and say, "You think you're better than me, huh?" over and over again while poking you wasn't addressed.
One of the newer inventions to take advantage of this principle is a weightlifting bar made of plastic. Because it's not as rigid as a cambium steel bar, it's prone to bend, wobble, and even oscillate a bit, and it threatens the stability of the lifter as he lifts and lowers the weight.
Furthermore, the bar provides significant resistance as the lifter tries to reverse the direction of the bar, owing to the necessary shift in momentum.
Some American sports scientists from Furman University decided to test whether these plastic bars actually had any merit. It turns out they did, leading to not only additional core muscle activation (as you would have guessed), but increased activation of the rectus femoris and vastus lateralis, too.
What They Did
The researchers recruited 10 male football players and asked them to perform squats using a conventional steel bar and the Tsunami bar, a plastic alternative to metal bars. (While the manufacturer provided the Tsunami bars, they didn't pay for the study.)
The lifters performed squats using 30% of their 1RM (the most weight they could lift for one rep). On one occasion they used the steel bar and on another, the plastic bar. Their muscle activity was measured through electrodes that had been placed on their skin.
What They Found
Every muscle involved in doing a squat was significantly more involved through use of the plastic bar. This was especially true for the core muscles (rectus abdominis and external obliques), but also for leg muscles (rectus femoris and vastus lateralis).
The researchers cautioned that any potential users of the plastic bar familiarize themselves with the bar to "limit any safety concerns," but nearly in the same breath they postulate that there might be limits to the increases in muscle activity as one gets "more accustomed to the flexible bar."
What This Means to You
One of the pioneers of "wobbly" training is T Nation contributor Dan John, who introduced the "slosh pipe" to the world back in 2007.
Constructed simply from a 4 or 6 inch diameter PVC pipe, capped at both ends and filled about two-thirds of the way with water, the slosh pipe oscillates like mad, causing an effect that's no doubt similar to that of the plastic bars used in the Furman University study.
Another innovator who makes use of this principle extensively is T Nation contributor Dr. Joel Seedman, whose "earthquake" style training uses straps by which he hangs kettlebells off of Olympic bars, among other things.
It's probably irrefutable that these methods work, but like any method, the body eventually adapts, ultimately relegating Tsunami bars and the like to just another training method to be used occasionally, for awhile, until it stops working.
- Hutchinson, Randolph Edward; Caterisano, Anthony, "Electromyographic and kinetic comparison of a flexible and steel barbell," Journal of Human Sport and Exercise, 2017, 12(2): 380-385.