Can an AI-powered fitness app outperform a human trainer?

An AI trainer can tell me to jump, but it doesn’t matter how high.

It was a realization I had when I tried FitnessAI, an iPhone-only fitness app that uses artificial intelligence. FitnessAI produces personalized workout routines based on information you enter, such as height, weight, gender, and equipment available at your home or gym. But relying only on technology has its limits in honing the human body.

I compared Fitness AI to the Future app, which virtually connects you to a personal trainer. With Future, I wasn’t just answering myself or entering numbers into an app. I was dealing with a real person who had real expectations. And with my lizard brain as a brother, I wanted to show him that I could push myself harder.

It shows the key differences between training with machines and humans. FitnessAI says the app aims to slowly ease people into new routines, meaning it won’t throw you into a new workout methodology. This is because it cannot understand and summarize who you are as a person, nor register your specific needs or nuances. It can take a few weeks for the app to start varying workouts in more unique ways as it crunches numbers, collects data, and recognizes patterns.

The AI-ification of everything is upon us. Since the launch of ChatGPT, the world has been fascinated by the great language models. From generating poems and resumes to computer code, ChatGPT rummage through online data and form human-like sentences, making old-fashioned Google searches seem mundane by comparison.

As ChatGPT has become the fastest growing consumer product in history, there has been a surge of companies integrating more AI into their operations. A Google search for “Fitness AI apps” will net you at least 20, including Fitbod, Freeletics, and AI Gym. According to one estimate, the global digital fitness industry will reach $26.5 billion by 2026.

There’s a reason I haven’t turned to ChatGPT for a training program. Sure, I can add specific metrics to a ChatGPT prompt, but it’s essentially “autocomplete on steroidsand will produce a response predicting what the next best word should be. And when I told ChatGPT to create a routine around my supposedly sprained ankle, he recommended standing and weight-bearing exercises, which could make an injury worse. FitnessAI doesn’t it does not have a built-in chatbot, although that will soon change.

Testing artificial intelligence in fitness

Launched in 2019, FitnessAI relies on machine learning algorithms to optimize sets, reps, and weight for each workout. The app has an intuitive interface. Each workout features a 3D anatomical model of the human body, showing the undulations of each muscle group, how to perform each workout, and which muscles are targeted. After completing the exercise, you can tell FitnessAI if you’ve been using higher or lower weights, and the app will use that data to adjust for future workouts.

My first session focused on shoulders and abs. I started with five sets of barbell shoulder presses (five reps each), then progressed to dumbbell shoulder presses. Due to fatigue, doing two shoulder press exercises in a row didn’t feel entirely efficient. After a lateral dumbbell raise, I transitioned into a weighted decline crunch followed by some standard crunches. It was anything but a grueling workout. Sure, I could have moved on and added more workouts, but for testing purposes, I kept it as-is.

The next day he focused solely on his biceps. Just like my previous session, there wasn’t much variation. (Of course, there’s only so much you can do with bicep exercises.) Going from a dumbbell curl to a barbell curl felt repetitive. If it were immediately followed by a hammer curl, which targets the long head of the bicep, it would allow you to target different muscles. After five different biceps exercises, my arms got hit.

On chest day, I ran into the same problem, with FitnessAI recommending two workouts that largely target the same muscle groups: an incline bench press followed by an incline dumbbell press. I also didn’t see the point in starting with a bench press and ending with a Smith machine bench press. I was surprised that FitnessAI didn’t consider something like a cable chest fly, which allows for a greater range of motion.

At $15 per month, FitnessAI might be on the pricey side when you compare it to numerous other fitness apps on the market. However, I see it as a powerful training tool that can log your activity and show you exactly how to perform the exercises. The app can vary your workouts, improve efficiency, and help you gradually reach progressive overload, which may reduce the chance of injury. It takes time to get the most out of it, so don’t expect a massive change in your routine right from the start. It also won’t recommend a different workout style unless you specifically indicate it in the settings. But doing so requires some basic research on your part. Overall, FitnessAI seems better suited for more experienced gym-goers.

FitnessAI has confirmed that it will integrate a ChatGPT-like chatbot using deep learning AI into the app later this year. He’ll be able to “shape your preferences, provide feedback on your workouts, and get answers to questions about everything from nutrition to fitness,” said Justin Bingham, chief technical officer at FitnessAI.

And while you might be able to have a conversation with a future version of FitnessAI, it still might not motivate you as much when replying to a real person.

To know more: Could your future training partner be a robot?

Comparing my AI trainer to a real one

When I first started with the personal training app Future, I was in contact with Brett Carroll, a trainer based in Florida. He asked me if I wanted to continue with my five by five workout routine (five five-rep exercises near my maximum weight limit). I deferred to him, saying I had been doing this routine for a while and not seeing the results I wanted. Instead, he opted for a block routine, breaking my workouts between lower and upper body days. And workouts wouldn’t focus solely on weight training. He integrated a lot of stretching and movement exercises that I had overlooked.

The workouts Carroll created were some of the toughest gym workouts I’ve ever had.

I think of Future as an asynchronous personal training. It’s not like Carroll is there on a video call the whole time I’m at the gym. She creates workouts for me, and the app automatically plays videos on how to perform specific exercises and stretches. It also has bells for start and finish times and provides advice on how to do the exercises correctly. I can also go into the app and enter the changes I’ve made to the weights. Carroll can then adjust accordingly.

My first upper body day was tough, forcing me to cycle through multiple muscle groups with short rest periods. By the end of the hour, my shirt was noticeably soaked.

After a day’s break, I returned to the gym to do a lower-body workout, focusing on fun-looking lateral walks and Cossack squats, where you lean your body into a side-to-side lunge. After a few bodyweight squats, I grabbed two 30-pound dumbbells and did Bulgarian squats, a balance-squat variation that focuses on one leg at a time. From there, I was to immediately jump into “tied with a stick,” a movement where I jumped sideways from one leg to the other. The combination of lifting plus explosive movements left me frayed. And that was just the first complex.

The second complex of one-legged barbell deadlifts (while holding a 45-pound barbell) and 30-pound dumbbell step-ups had me questioning my years in the gym. Had I really made any progress? These relatively simple exercises with lower weights were draining me. Typically, I can perform a regular barbell squat with 275 pounds of weight on my shoulders. Even though I was only supposed to take 30-second breaks, I found myself needing more than a minute to compose myself.

That first leg day left me feeling so depleted that I skipped the next day’s workout. Thankfully, Carroll was able to adjust my routine accordingly to help me recover.

Speaking of recovery, Carroll recommended supplements. I could also tell him about my diet and macro goals. This is something companies may limit with AI fitness apps due to liability issues. When I asked ChatGPT which supplements I should take, she recommended whey protein, creatine, fish oil pills, and multivitamins. Her macro recommendations seemed off based on my body type and weight-loss goals: She suggested 360 to 540 grams of carbs, compared to the recommended 170 to 200 grams of carbs from online macro calculators.

At $199 per month, Future is significantly more expensive than FitnessAI, and even more expensive than many gym memberships. (For the purposes of this article, Future has granted me a trial membership.) But given that personal training sessions at the gym can range from $50 to $150 or more each, a month of fully curated workouts through Future isn’t a bad deal.

Human over machine

It’s early days for AI in the health and wellness space. Eventually, FitnessAI, and likely other fitness apps, will integrate AI chatbots so you can ask questions and have them answer them. Until then, you’ll be relying on apps that can, at best, crunch some data and put together a decent routine.

I had no particular qualms about using FitnessAI. If you’re on a budget, I’d recommend it to someone who already has gym experience and would like to record their workouts on their phone. (Admittedly, many apps do this for free.) There are numerous workouts in the app, so even the most discerning gym-goer will find something new to try. With FitnessAI, it’s up to you to maximize your workouts and you’ll need to contact outside sources about diet, supplements, stretches, and cardio.

Bottom line: AI-powered software and algorithms cannot generate a workout routine for you based on your thoughts and desires, and may not be accurate in accommodating injuries.

But everyone is different. Some may prefer logging numbers into an app and not having to deal with the pressure of reporting to a person. In my case, getting real feedback from a real coach is what kept me motivated, a sobering realization of my own social conditioning. Either way, when it comes to gym gains, I choose to trust a human over a machine.

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Editor’s note: CNET uses an AI engine to help create some stories. For more, see this post.