You get woken up by a little tone because an app on your phone tells you it’s the correct moment in your predetermined sleep cycle. Then you fire up the app to check your heart rate and how many calories your workout burned yesterday, and whether your fitness regimen is on track for the day to begin training again. Next you login to your food tracker app to see if you overate last night and if your workout will let you cheat a little bit for lunch or keep your intake to a healthy minimum. Eventually, you’re out the door for your early run. Wearable tech increasingly provides health nuts a wealth of data and direction. With Jawbone, FitBit, Apple Watch, and smartphones making it easier for people ditch gyms, where does that leave the personal trainer?

Health and wellness tech could be a $5 billion business this year alone, with FitBit’s IPO valuing the company at a rotund $4 billion. As fads go, this one seems to be sticking. Most of this tech is seductively simple, requiring only that you punch in basic details catered to your own preferences. The gym you may safely leave to the showoffs.

But, wouldn’t you know, personal trainers say they have another few reps left in them. Chris Piegza, the training manager of DavidBartonGym Limelight in Manhattan, told me flat-out that wearables are junk without someone to help interpret their data. “Simply knowing certain numbers is not enough,” he said. “Knowing how to apply and filter through the seemingly limitless information is crucial. This is where a personal trainer comes in.”

And he’s right. Take for instance the health apps on the Apple Watch. To use the watch’s workout app, users let it know they’re ready for an outdoor walk, run, or cycle workout and then set unique goals for it to calculate and report back to you. This is partly based on the app’s initial setup that encourages you to try and achieve three broad daily fitness goals: to stand up for at least one minute of every hour, to set and achieve a calorie burn amount, and to do at least 30 minutes of daily activity at or above a brisk walk.

You provide the app information (age, sex, weight, height) and personal activity levels based on questions like “Typically, how active are you?” You can also set the watch to send reminders to stand up or to get active. If you reach certain goals, you even get little rewards in the form of icons on the app on your phone. Incentives!

Wearable tech may collect real-time data based on miles run or calories burned, but then what? Knowing the distance you ran isn’t the same as knowing when to run, what other exercises to do in tandem, how to avoid injury, or anything meaningful. The data may motivate you; otherwise, it’s really just trivia.

“Algorithmically, apps and technology can certainly compute ideal conditions and settings based on the information they are given,” Piegza said. “It’s a personal trainer, however, that humanely and humanly can synthesize such information and present even more perfect programming to the person training.”

The analogy to work from, perhaps, is the difference between learning the rules to a sport and buying the equipment — versus getting coached in it. “It’s only through professional instruction and feedback that the real results occur,” Piegza said. Granted, some people don’t want the pressure of a personal trainer butting into their simple workouts — nobody needs a trainer to clock his/her morning two-mile jog — and having someone to guide you to the next task once you’ve mastered the old one is irreplaceable.

It’s not as if personal trainers shun technology for some strict, analog-only, Rocky IV-style training sessions. “I encourage wearable technology,” Piegza said. “In the past I’ve used a heart rate monitor and now either a FitBit or an Apple Watch.” He’s also a fan of more thorough computer-based programs. “For diet, I recommend apps like MyPlate, wherein either myself or a client tracks calories and nutritional content throughout the day, and balances it against a estimate of calories burned.”

As it stands, wearable tech would only really make people think they could be their own personal trainers. Meanwhile, personal trainers who want to adapt will embrace new tech. Piegza said, personal trainers “are the spokespeople, whether professionally or inadvertently, for technology that perfectly measures everything they have always preached.”