The treadmill is a fine machine. Kayla Bonkowski has used one. It raises the heart rate, burns calories, and requires nothing of you except that you keep moving. That is also, more or less, its limitation.
A barbell asks more. Not just physically — though that part is obvious — but in the way it forces you to commit to a movement, learn it over months and years, and accept that some days it goes badly and some days it goes well and neither one means much about you as a person. That relationship is different from anything a piece of cardio equipment offers.
Kayla Bonkowski started lifting seriously when she came into CrossFit in 2021. The barbell was one of the first things that humbled her. A deadlift that looked straightforward on video felt like a foreign language when she tried it herself. A clean felt impossible for weeks and then, suddenly, clicked. That process — the failing, the drilling, the tiny adjustment that changes everything — is something you do not get from a treadmill, no matter how steep you set the incline.
What the Barbell Actually Trains
The obvious answer is muscle. Barbells are efficient at building strength, and compound lifts like squats, deadlifts, and presses do that in ways that machines and bodyweight movements struggle to match at scale. But that is the smaller part of it.
What a barbell also trains is patience with your own progress. Kayla Bonkowski has written about this before in the context of CrossFit competitions — the way that repeated exposure to difficulty builds a kind of composure that transfers to the rest of your life. The barbell is one of the clearest teachers of that lesson. Your back squat goes up slowly, then it plateaus, then it goes up again. You cannot rush it. You cannot talk it into moving faster. You have to do the work and wait.
A treadmill does not require that patience. You set the speed and you run. There is nothing wrong with that, but there is also nothing there that pushes back. The barbell pushes back every session.
The Skill Component
Barbell movements are technical. The snatch is considered one of the most complex athletic movements in existence. The clean and jerk is not far behind. Even a deadlift, which looks simple, has layers — how you set your back, where you initiate the pull, how you control the descent. Getting those things right takes months. Getting them consistently right takes years.
Kayla Bonkowski has been working on her Olympic lifts since she started training in Macomb, Michigan, and she will tell you that she is still learning. That is not a complaint. It is one of the things she values most about training with a barbell — there is always more to understand, always a reason to show up and pay attention.
A treadmill does not have that depth. You get better at running on it by running on it. The ceiling is high if you are training for distance or speed, but the skill component is narrow compared to what a barbell demands.
This Is Not an Argument Against Cardio
Kayla Bonkowski is not writing this as an argument that treadmills are useless or that cardio is a waste of time. Aerobic capacity matters enormously in CrossFit, and in life. Running, rowing, and cycling all build something real. The point is not that one is better than the other — the point is that they are not interchangeable.
People who spend their entire fitness practice on cardio equipment often miss out on the specific kind of growth that comes from learning to lift heavy things well. And people who lift without ever training their aerobic system are leaving something important on the table. The best training programs include both, but they understand that each one develops a different part of the athlete.
The barbell develops something you do not get anywhere else. Kayla Bonkowski keeps coming back to it for that reason — and also because, on the days when everything goes right, there is nothing quite like it.