Are smartwatches any good for interval training?

Good enough that the wrist deserves a trial, with limits worth testing for before you commit. Give it one week of real sessions and watch what happens when you edit a preset, whether the round number is readable mid-set, and what the battery graph does on training days. For running and pool work the wrist often wins outright; for gym intervals the phone usually stays the better tool.

Why does it take so long to sync a custom timer to a watch?

Because the connection between phone and watch was designed for notifications, settings and small activity records, and an interval session is a bigger object to move through it: per-round times, exercise names, cues, all at once. Some watch apps also rebuild their copy of the session when it lands. Changing one round later means sending the whole thing again.

Should I run an EMOM on my watch or my phone?

On the phone, unless the EMOM happens on a run. The format asks a timer for a reliable minute boundary plus a running count of which minute you are in, and the phone can deliver both to your ears as well as your eyes, which matters when the minute turns while your hands are full. The watch version works on paper, and in practice EMOM is the format most likely to send its owner back to the stopwatch, as it did in the thread that opened this article.

Will an interval timer drain my watch battery?

Noticeably, and by more than the listings suggest. A timer keeps the screen and the vibration motor busy for the full session, while the fitness trackers in the same watch assume short bursts of work. If the watch currently reaches bedtime with charge to spare, an hour of intervals changes that arithmetic, so charge before training or budget for the trade.

Watch vs phone: where wrist timing falls apart

August 2026, a kettlebell forum, a thread about EMOM programming. Among the debate over structure came one answer to the obvious question, what do you time it with: “I just keep it simple and start a stopwatch. When the minute ticks over, I do the sequence.” The person owns a flagship multisport watch. GPS, structured workouts, an interval mode somewhere in the menus; the hardware on that wrist cost more than most phones, and the timing still falls to a stopwatch and a minute boundary.

The answer collected agreements, because it is familiar. Watches have carried interval modes for years, and their owners keep ending up at the stopwatch, the wrist’s version of the phone’s clock-app problem. The rest of this piece is about why that keeps happening: what breaks between the phone and the wrist, and what the wrist is still genuinely good at. (The wall-mounted half of this decision has its own piece; this one is about the screen you are already wearing.)

The trip the workout has to make

The thing that has to move is small: ten rounds, 0:35 work, 0:25 rest, a warning before the last bell, maybe a name. On a phone you build that once, in an editor made for the job. A watch timer has to receive the structure from somewhere — the whole session, four numbers deep — and the somewhere is almost always the phone app.

Reviews of watch timers collect around this joint. A one-star from September: “it takes forever to sync the custom timers.” A three-star from August: “it just spins and spins. I have to completely shut down my Apple Watch.” App names withheld; the pattern repeats across the category. Read enough of these and the details line up: a transfer that ends in a spinner, a watch restart as the home remedy, and every edit to the session repeating the whole transfer. In those reviews the session itself stays intact on the phone, and what breaks is the handoff to the wrist.

Close to the eye, hard to read

By the distance measure, the wrist wins outright: no other screen you own sits that close to your eyes. Interval state still loses there, because state compresses badly. A plain clock face reads fine at forty millimetres; the line an interval timer has to show, “Round 6, rest, 0:23, swings next”, needs more room than that. One review from September puts it flat: “the watch app doesn’t Mirro for quick glance at info.”

Mid-set, other forces join in. The wrist you would glance at is holding a lockout, the hands are chalked, and reading the face means rotating the forearm under load to catch the light. The number you check ten times a session has to be big enough to read through that; the case for readable state at a distance has been made here before. A phone propped where you train answers that question from where you stand, and your arms can stay on the bar.

The battery bill

Outside navigation, few things tax a watch battery the way a timer does. The display wants to stay lit for the whole session, because wake-on-rotate misses the glance taken with the arm pinned. A vibration fires at every transition, heart-rate sensing runs alongside, and on some watches so does the music. An hour of that takes a real slice out of the daily charge, the same charge the rest of your day draws on.

Where the wrist wins anyway

On a run, the argument flips. The phone rides in a belt or stays home, the wrist is already there, and a tap at each transition works when the eyes are on the road. Haptics-only timing covers the quiet cases, a lunch break between meetings or a hotel room, anywhere beeps would be rude. Some watches are built for water. Take the phone into the pool and you are fishing it out afterward.

For those sessions the wrist earns its place. The demands to make before real training moves there:

Sync speed. A preset should cross from the phone to the watch faster than you could type it. If finishing takes a watch restart, the stopwatch is the faster way to set up.
The face at wrist scale. Phase, round count, time left, each sized for an arm under load. Odd numbers must arrive as typed: 35/25 stays 35/25, with no snapping to the watch’s built-in ladder.
Standalone running. Once the session is on the wrist, the phone should be able to stay home. A watch timer that quits when the phone is out of range depends on the phone for more than setup.
Timekeeping on low power. Battery-saving modes that stretch a second to save screen defeat the point of a timer, and why timers run long applies to wrists as much as to phones. Thirty minutes of intervals should finish at thirty minutes, on either device.

The pattern the forum found

The setup behind that answer is ordinary. The session lives on the phone: named presets one tap from running, the screen off and the phone pocketed on do-not-disturb, cues that carry over the music from the speaker. Moving the whole setup between phones is a solved problem. The watch returns to its actual duties and clocks your laps, your weather and the time of day. In that setup nothing has to travel between devices at all.

Where Intertakt stands

Intertakt is a phone app and ships as one; there is no watch companion, and this article is most of the explanation. The session sits where it was built, so the handoff problems above stay out of the picture. The screen puts the round number first with color carrying work against rest, voice cues play over the music, and presets open by name. The core timer is free, and no account stands in front of any of it.

The Android build is in review at Google Play; the waitlist sends one email when it ships.

Until a watch clears all four checks, the forum’s stopwatch crowd has it right: interval timing belongs on the phone.