The Waterbag Stability Method: A Simple Fix That Changes Everything
All Triphasic Principles and Methods
I want to walk you through something that honestly surprised me when I first saw it.
The idea actually came from a conversation with speed coach Chris Korfist Slow guys Speed School. He mentioned that he had seen athletes run with a water bag—just one rep—and it seemed to clean up running mechanics without any coaching.
No cues. No drills. Just… fixed.
At first, that sounds a little too good to be true, right? So we decided to test it.
What we started noticing
We began tracking athletes more closely, especially using the 1080 Sprint machine, which allows us to measure power output in each leg during sprinting.
Instead of just looking at running form, we asked a better question:
👉 Where is the performance breakdown actually happening?
What we found was pretty clear:
- Some athletes had a 10% or greater power deficit in one leg
- In more extreme cases, it was much higher
One athlete stood out immediately. She had been competing at a national team level with a broken bone in her foot for nearly three years. She never got it fixed because she didn’t want to miss her opportunity.
When we tested her, the numbers confirmed what we expected:
👉 She had a 30–40% power deficit in one leg during sprinting.
The experiment
So we tried something simple.
We handed her a water bag.
No complicated setup. Just:
- Hold the bag
- Run 10–15 meters
That’s it.
Then we brought her right back to the 1080 and retested her.
What happened next was the shocking part
In less than 5–6 seconds, that power deficit was essentially gone.
Not improved. Not slightly better.
👉 Gone.
What’s actually happening?
After a lot of testing and looking at the data, here’s what we believe is going on:
When an athlete has pain or a previous injury, the body creates compensation patterns. The brain protects the area by changing how you move.
Over time, those patterns become automatic.
What the water bag does is introduce instability and unpredictability. That forces the brain to:
- Override those compensation patterns
- Reorganize movement in real time
- Reactivate key muscular systems
Specifically, it turns on what we call:
- The lateral sling
- The spiral sling
These systems are critical for:
- Running efficiency
- Stability
- Force transfer through the body
And they are a major factor in ACL injury prevention.
Why this matters more than you think
Here’s something most people overlook:
👉 If you have a shoulder injury, it doesn’t just affect your shoulder.
It can shut down the entire chain—from the shoulder, through the core, all the way down into the leg.
That means your slings aren’t working properly.
And when your slings aren’t working:
- Your stability drops
- Your power leaks
- Your injury risk goes up
What’s incredible is that a 5–10 second water bag run can turn that system back on.
What we’ve seen over time
After a couple years of testing, this method has been consistent across different situations:
- Power deficits on the 1080 → improved
- Force plate imbalances → improved
- Balance issues during rehab → improved
- Running mechanics → cleaned up
Even simple movements like skipping with the water bag can help.
And the best part?
👉 It’s ridiculously simple.
How to use it
You don’t need a complicated program.
Just:
- Pick up the water bag
- Run, skip, or jog for 10–15 meters
- That’s it
I usually implement it at the very beginning of a session.
You don’t even need a warm-up beforehand—in fact, this often improves the quality of the warm-up and can even reduce how long it takes.
Why I use it (and why I don’t overuse it)
People ask me if I’m a big fan of water bag training overall.
Honestly? Not really.
Most of the time, it slows things down too much for my liking.
But for this specific purpose?
👉 It’s incredibly effective.
If an athlete has a sling issue, I’ll use:
- 1–2 reps max
- Then we move on
That’s all it takes.
The real takeaway
If you can:
- Increase power output
- Improve stability
- Reduce injury risk (especially ACL)
All in about 10 seconds at the start of a workout…
Why wouldn’t you use it?
For less than $60, you can get a couple water bags and use this with an entire team.
As a coach, this is one of those tools that’s:
👉 Simple
👉 Fast
👉 Effective
And it solves a problem most people don’t even realize they have.
