The Best (and Worst) Fitness Devices I Tested in 2025.
2025 was an interesting year for fitness device reviews. Three companies unveiled devices that could compete with Whoop, and one definitely came closer to the mark than the others. One running watch impressed me with its accuracy, one device was so inaccurate that it forced me to dig deeper to find the cause, and two devices impressed me with how well they solved a real problem that no other device had even attempted. Read on to discover the winners in my highly subjective award categories.
Most Accurate: Garmin Forerunner 570
This year, the Garmin Forerunner 570 and 970 were new devices . Overall, I was mixed about the improvements over previous models, like the 265. But I do want to highlight the heart rate sensor on the 570, which was so accurate that it confused me.
The thing is, previous Garmin watches, like the Forerunner 265 , had a pretty good heart rate monitor. I’d put them in the same league as most Coros watches, just above the Apple Watch, and overall they’re as good or even better than most other high-end devices.
But Garmin has equipped the Forerunner 570 with its best heart rate monitor yet. This same sensor, the Elevate 5 version, is also used in the Garmin Forerunner 970, Venu 3 and 4, and Fenix 8. I wasn’t prepared for how much better it would be. I test all my devices with an electrical chest strap heart rate monitor , which is considered the gold standard in this regard, and a good wrist-based monitor shows only slight deviations between the heart rate graph obtained with a chest strap and the graph obtained with a chest strap. But the 570 sometimes showed exactly the same data. The graph below shows what I expect from a good sensor (top) and what I got from the 570 (bottom). Yes, there are two lines in the bottom graph.
At first, I thought I’d made a mistake and somehow mixed up the data from the chest strap and wrist strap, perhaps by uploading the same file twice—they were that close. But after further testing, and zooming in to see the rare, subtle differences between the two lines, I confirmed that the 570 sensor really is that accurate. Damn, Garmin. I’m impressed.
Coolest concept (that actually works): Core 2 temperature sensor.
Summer heat is a challenge for every runner in hot climates. Hot runs are not only uncomfortable, but they literally slow you down, increasing the risk of heatstroke. If you can adapt your body to the heat, you’ll be able to better tolerate it and make your summer workouts much more bearable and productive. You don’t need a special gadget to train in the heat, but there’s a lot of guesswork involved, and it can be difficult to know if you’re training enough (or too much) in the heat.
The Core 2 sensor promised to solve this problem, and it did a great job. You can read about my experience here . You attach the device to a chest heart rate monitor, and it measures your body temperature in two ways: a temperature sensor detects skin temperature, and a heat flux sensor, combined with a heart rate algorithm, provides an approximate estimate of your core body temperature. Based on this data, the device can tell you when you’re hot enough for your workout to be considered beneficial in heat conditions, and warn you when you’re getting too hot and need to take a break.
The biggest drawback was that I only got workout data if I wore a chest heart rate monitor during every hot-weather workout, which I wasn’t always comfortable doing. But once I got through the spring and early summer and reached 100% heat adaptation, I realized I didn’t really need the device.
I found this device incredibly useful, especially because it could transmit my temperature data to my Garmin watch during runs. I could also record my sauna visits in the device’s app (without taking the device into the sauna) and see how well I was adapting to the heat. The data I received from the app seemed accurate, and as a result, I probably had my most productive and enjoyable summer of running.
Second place: DFC
The Data Fitness Connector is a small box that plugs into the cables on the back of your Peloton exercise bike (only the original model , not the Bike+). Ordering this device from a crowdfunding site with few reviews seemed a bit risky, and unfortunately, it only displays power data, not speed or distance. But it works! You can read my review here .
I took the plunge and purchased the DFC because I’d canceled my Peloton subscription but still wanted to use the bike and sync workouts with my fitness watch. The DFC delivered on all its promises: it transmitted power data via Bluetooth, allowing my watch or phone to capture it and record it in my workouts. My Garmin watch was able to estimate my FTP and recommend power-based workouts, and there were no additional costs. (The price of $125 is less than a three-month Peloton All-Access subscription.) I highly recommend the DFC to any original bike owner who wants to ditch their Peloton subscription.
Best Upgrade and Best Overall: Coros Pace 4
Coros running watches are slightly inferior to Garmin watches in terms of functionality, but the price more than makes up for it. I’ve consistently found the Coros Pace line (Pace 3, Pace Pro, and Pace 4) to be reliable, accurate, and easy to use. The Pace 3, in particular, has long been one of my favorite budget watches, despite a few minor flaws.
But later this year, Coros introduced the Pace 4. With new features and a couple of extras added in a December software update , it’s undoubtedly the best fitness watch for the money, and I consider it the best fitness watch of 2025.
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You can read my review here to learn more about why I think so. In terms of improved features, the Pace 4 surpasses the Pace 3 by adding an AMOLED screen, longer battery life, and a new button and microphone. The latter two unlock two features that have significantly improved my runs and workouts: voice tags, which let me quickly take location notes during a hike or trail run, and voice-activated workout logs, which prompt me to record a 60-second voice memo immediately after completing a workout.
These notes are copied and attached to the workout in the Coros app, providing me with information I likely would n’t bother adding later. Then, the December software update added a key feature that had left Coros lagging behind Garmin and other watches: the ability to control media playback from your phone. The interface isn’t as user-friendly as I’d like, but it’s there , and it’s a huge plus.
Second place: charging features on the Pixel Watch 4.
The next best upgrade for 2025 will be the Pixel Watch 4. You can read my review here , where I found the improvements to be mixed. (Dual-band GPS? Great! Brighter screen? Well, not quite.) But the biggest improvement, in my opinion, is the super-fast charging.
It took me just half an hour to almost fully charge the watch—specifically, I went from 3% to 97% in 31 minutes. No other smartwatch charges this quickly. The Pixel Watch 4 also comes with a new magnetic charging dock, which is much more convenient than the stand on the back of the watch used in previous versions.
The Best Whoop Alternative: Amazfit Helio Strap.
This summer, competition suddenly emerged: rumors swirled that three different device makers (Garmin, Polar, and Amazfit) were working on screenless fitness trackers that could compete with Whoop . All three companies released their promised or purported devices over the following months, and I tested them all.
The Garmin device turned out to be a $170 sleep tracker; not bad, I suppose , but not what many of us were hoping for. The $200 Polar device is more similar to the Whoop, at least in terms of hardware. It’s a welcome addition to the market, as Whoop has dominated this category for too long, but I must admit I wasn’t particularly interested in it .
To my surprise, the Amazfit Helio Strap was the winner. For $99, it performs all the functions of the Polar device, but (in my experience) it’s more reliable and costs half as much. Needless to say, it significantly outperforms the Garmin sleep tracker in these regards. You can read my review of the Amazfit Helio Strap here .
None of these devices even attempt to compete with Whoop’s paid app in terms of software functionality, which is unsurprising—Whoops is essentially a software company that provides a cool gadget in addition to its app, while other companies in this segment are hardware makers who believe their app isn’t important if you’re happy with a physical device. I think this is a fair assessment of the market: these new products are designed for people who like the idea of a screenless tracker but don’t want to pay for an app like Whoop’s. I expect Amazfit will have many satisfied customers.
Biggest Disappointment: Powerbeats Pro 2
The idea of putting a heart rate sensor in your ears is intriguing, and I’m really sad it wasn’t implemented in the Powerbeats Pro 2. But the company that bet on this technology this year—Beats—simply failed to implement it well enough.
As I discovered through extensive testing ( here , and then in more detail in my review here ), the heart rate sensor doesn’t adhere well to the skin unless your ears are a certain shape and size. Changing the silicone ear tips doesn’t change the heart rate sensor’s fit (or at least not enough to solve the problem), so for some people, heart rate data is unusable or unreliable.
Based on the limited data I have, people with larger ears receive fairly good data, while those with smaller ears may have more problems. I suspect these issues are more common in women than in men, but Beats hasn’t provided me with any data to confirm or refute this hypothesis.
In September, a software update was released that slightly improved the heart rate algorithm and added a warning feature to alert users if the earbuds are not sitting properly, which could affect heart rate readings. This is a good start, as otherwise you wouldn’t even know if you were getting inaccurate readings. But if you’re the type for whom adjusting the fit doesn’t provide useful data, you’re wasting $250 on a device that doesn’t actually fit you. On the other hand, these are good earbuds for the gym, even with the heart rate feature disabled.