I'd been deadlifting for about a year. Nothing heroic — I was pulling 80kg for sets of five — but consistently, twice a week. And every single session left me with that low, dull tightness across my lower back that hung around for a day or two and made putting on socks a small negotiation. I'd decided this was just what deadlifts felt like. That's the dangerous part: I'd normalised a warning sign.
I had done the homework, or thought I had. I'd watched the famous form videos. I'd read the long articles with the anatomical diagrams. I could recite 'neutral spine' and 'hip hinge' like a catechism. And I still couldn't tell what I, specifically, was doing wrong on my specific deadlift, because none of that content was looking at me.
Describing the problem out loud
I opened the Fix My Form: Setup, Execution, and the Mistake You Can't See prompt and just described what I do, the way I'd describe it to a friend. Bar over mid-foot, double-overhand grip, I try to keep a flat back but I feel it round somewhere in the upper-middle, and the lower back tightness shows up after. I gave it to GPT-4o because I wanted a fast, no-nonsense answer, and that's exactly the register it hit.
The 'likely root cause' section did something the videos never had: it diagnosed me. It guessed my hips were starting too high — turning the pull into a stiff-legged deadlift that loads the lower back — that I was losing upper-back tension at the setup, and that I wasn't driving through the floor. Three specific hypotheses about my pull, from a paragraph of my own rambling.
- The setup cue 'set your lats like you're tucking them into your back pockets' instantly changed how my upper back felt under the bar
- The breathing instruction — big breath and brace BEFORE the pull, exhale at the top — was something I'd been doing in a random order
- The mid-set self-check, 'the bar should drag up your shins; if it drifts away, your hips shot up too early,' gave me live feedback with no mirror
- The 'when to drop the weight' section gave me explicit permission to deload to 60kg and rebuild the pattern, which I needed to hear
The session that fixed a year of tightness
Next session I deloaded to 60kg like it told me to, swallowing a bit of ego, and ran through every cue. The one that rewired everything was 'push the floor away' — thinking about driving my feet down rather than yanking the bar up. The back tightness afterwards wasn't reduced. It was gone. I kept waiting for it the next day, the way you brace for a hangover. Nothing. I'd spent a year collecting information when what I needed was the right five words at the right moment.
The 'common mistakes' section read my mind
There's a section in the output called 'common mistakes for this lift,' and the format is what makes it land: for each error it tells you what it looks like, why it happens, and how to fix it. Reading the deadlift one was uncomfortably like reading a transcript of my last year. 'Hips rise before the bar — you're trying to lift with your back because your legs disengaged at the start.' Yep. 'Bar drifts away from the shins — you've lost lat tension.' Also yep. Generic form content lists mistakes in a vacuum. This connected each one to a cause and a correction, so I wasn't just told 'don't round your back' — the single least useful cue in all of strength training — I was told the mechanical reason it was happening and the one thing to do instead.
Why the cueing format matters
What makes this prompt different from a generic 'how to deadlift' answer is the structure. It separates setup from execution from breathing, and crucially it includes a self-check you can run inside a set, which is where form actually breaks down. A coach isn't valuable because they know more than the internet — they're valuable because they give you one cue at the exact moment you need it. This prompt is engineered to do that, and GPT-4o delivers it fast enough that I now run it before trying any new lift. The speed genuinely matters here: I'm often standing in the gym between sets with my phone, and a model that thinks for forty seconds is a model I'll close before it finishes. GPT-4o spits the cues out almost instantly, which is exactly the latency a between-sets tool needs.
One honest caveat, because the prompt is good but not magic: it's working off my description, so if I describe my form wrong, it diagnoses the wrong thing. The first time I ran my overhead press through it I said my 'lower back arched,' and it gave great cues for bracing — but the real culprit turned out to be that I was leaning back to clear my chin, which a video would've caught instantly. The prompt even flagged this: it noted that if the cues didn't fix it, the issue might be something only a camera or a coach could see. It knows its own blind spot, which is more than I can say for most fitness advice.
I've since used it for the goblet squat (knees caving) and the overhead press (the lean-back thing). When the form gremlin is a true technique problem, the root-cause diagnosis is the part that earns its keep. When it's a fault I can't accurately describe, the prompt is honest about handing me back to a video — and that honesty is exactly why I trust it on the lifts I can describe well, like the deadlift that started all this. Grab the Fix My Form: Setup, Execution, and the Mistake You Can't See prompt on Prompt Dock, describe your problem lift in plain English, and try the cues on your very next set. Sometimes you don't need more information. You need the right words, in the right order, at the right time.