By Nicole Nguyen

Like nearly 80% of U.S. adults, I made a fitness resolution last January. I stuck with it for a few months. Then, life -- work deadlines, bad sleep, parenting demands -- got in the way.

A new crop of AI coaches promise the kind of personalization, expertise and encouragement that would come from a personal trainer, without the high price tag. I was intrigued. Could a robot fix my very human issues?

I have been testing fitness bots from Fitbit, Peloton and Apple for months and learned that the best kind of coach -- AI or otherwise -- is one who will watch and listen.

Problem 1: Bending to a busy life

I wanted to start with my biggest issue: lack of time.

Fitbit's new Personal Health Coach, a fitness and wellness chatbot powered by Google's Gemini, can create a workout regimen based on your specific plans and limitations.

I typed in my goals (training for an 11-mile swim relay), equipment (dumbbells) and time constraints (many), then the coach programmed three custom 30-minute workouts for my week. It can adjust the number or length of the sessions at any time.

Each workout came with easy-to-follow video demonstrations, specified the number of sets and weight for the move and included short context about how the session helps with my aspirations.

When I couldn't stick to the plan, the coach rolled with all of my excuses. Traveling? It came up with standing exercises to do at the airport. No time? It suggested a 30-second posture-improving exercise. I liked that the coach always nudged me toward movement.

Fitbit's coach has the same flaws other AI assistants do, including hallucinations. It confirmed adjustments that were never made. Once, confused from a long chat discussing multiple moves, it set a high weight for the wrong exercise. That could have been dangerous.

A Fitbit spokeswoman said that the team is actively improving Personal Health Coach. The experimental feature is available to Android Fitbit Premium subscribers ($10 a month) with compatible devices, and will expand to iOS users soon, the spokeswoman said.

Problem 2: Am I doing this right?

I've heard it repeatedly from experts: The greatest risk of working out alone is bad form, leading to inefficient movement, slacking off and higher chance of injury.

So I set the Fitbit coach aside for something that could watch me move. Peloton's latest cardio machines have new Peloton IQ movement-tracking cameras in their screens. For certain classes, the camera can count reps, assess your form and recommend heavier or lighter weights.

A green light indicates the computer-vision model is activated, and the AI coach is watching. From standing bicep curls to seated crunches, my motions were tracked inside a yellow box on screen. When my reps showed full range of motion, the system rewarded me with a satisfying "bloop."

I got a more alarming "bleep" during dumbbell thrusters: "Go deeper so your thighs are closer to parallel."

The AI regularly kept me in check. For a push up: "Lower your hips." For a tired bicep curl: "Avoid swinging your body for momentum." For an overhead press with meager 6-pound dumbbells: "You did a lot of reps. Do you want to increase your weight?"

I've tried similar tech built in to the Tonal smart cable machine and phone-based Tempo Move. Peloton's implementation is best.

The form correction did, in fact, correct my form. The rep counting kept me accountable. I wanted to work for each "bloop." I just wish it could analyze more types of movement, such as pilates and yoga. Peloton currently gives form feedback for more than 60 popular strength-training moves, and a spokeswoman said the company would continue to build out support, possibly in other fitness areas.

If you want Peloton IQ, you can't just buy the camera. (Peloton discontinued its Guide smart TV accessory.) You have to buy an entirely new bike, treadmill or row machine, starting at $2,695, plus a $50-a-month subscription.

My actions on camera don't go to the company's servers. Instead, movement is processed on the device and then discarded immediately. However, as someone who often covers cyber hacks, I swivel the lens out of sight after my workout.

Problem 3: Losing my mojo

For those of us who work out alone, jogging on the sidewalk or pumping iron in the living room, Apple's AI-powered Workout Buddy aims to keep you motivated.

You need a compatible Apple Watch and an Apple Intelligence-enabled iPhone nearby, plus AirPods or other Bluetooth headphones to hear the coaching. I've used in-ear audio feedback before in apps like Nike Run Club. Apple's version is different because the voices, crafted from the company's in-house trainers, sound so real.

My 5-mile run kicked off with a cheery "All right, way to make time to work out!" The AI also dropped a fun stat -- I've done at least six workouts a week for the past month -- before ending with a "You've got this."

It was perhaps my slowest jog ever, but Buddy still said, "Way to crush that run!" and marked a milestone: "You've just hit 50 miles this year." The messaging is basic, but sometimes basic affirmation is what I need to keep putting my running shoes back on.

The best bot

My ideal digital fitness platform would combine all of the above: Fitbit's personalization and flexibility, Peloton's accountability and Apple's motivation. That perfect mix doesn't exist yet, but workout apps have only just begun to embrace AI.

For now, the new Peloton AI is the best bot-powered system of the bunch, if you can stomach the economics. Existing Peloton Bike+ owners probably don't need to upgrade, but it is a good option if you're looking for a new setup.

After all the bot talk, I wanted input from my human trainer on the fitness app Ladder, Sasha Hanway. Her diagnosis?

The best tech boost would be...stashing my phone at night. "Instead of scrolling, can you go to bed 45 minutes earlier, so you're able to get up and train in the morning less tired?"

Now, if a bot could bring me a preworkout coffee at 5:30 a.m., that would be AI worth waiting for.

Write to Nicole Nguyen at nicole.nguyen@wsj.com

(END) Dow Jones Newswires

January 04, 2026 08:00 ET (13:00 GMT)

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