Pulling your phone out mid-set to check whether that was your last rep, or mid-run to see your pace, breaks whatever rhythm you had going. A lock screen widget that already has the number on it means you never have to. iOS Live Activities exist for exactly this: a live card that sits on your lock screen and in the Dynamic Island for the length of your session, updated from the same tracking engine that's writing your workout log.

What actually lands on the card

The card is not one generic template, it is built differently depending on what you're doing. A cardio session shows distance, pace, heart rate, and calories burned. A strength session shows the current exercise name, completed sets against total sets, and the working target for that set (weight, rep range). Heart rate shows up on the strength card too, pulled from the Watch, but calories do not, that field is intentionally left blank on strength sessions for now. Neither card tries to cram the other type's fields in. If you're lifting, you get lifting numbers; if you're running, you get running numbers, the same distance and pace figures that feed your actual session log.

The strength card updates when you do something, not on a clock

Strength has no background timer driving it. Complete a set, and the card updates. Move to the next exercise, and the exercise name and set counts update with it. There's no polling loop deciding when to refresh, the update is pushed the moment your action changes what's true.

The cardio card deliberately doesn't chase every reading

Cardio works differently, because GPS and heart rate stream continuously rather than changing in discrete steps like a completed set does. A background timer checks in every couple of seconds, but it doesn't push a fresh number to the widget every time it checks. The card only actually updates once a metric has moved by enough to be worth showing: distance needs to move by at least 10 meters, pace by at least 5 seconds per kilometer, heart rate by at least 2 beats per minute, calories by at least 5. Below those thresholds, the check happens but nothing changes on screen. The effect is a card that feels alive without flickering a new digit every couple of seconds for changes too small to mean anything.

Your watch gets its own card, not a shrunk version of the phone's

Tap the workout card in your Apple Watch's Smart Stack and it opens the workout on the watch itself, not the iPhone. The watch card is a genuinely separate, compact layout: the Zirv mark, a live elapsed timer, and one metric row, distance and heart rate for a run, set progress and heart rate for a lift, plus a "tap to confirm" hint on a session Zirv auto-detected but hasn't started tracking yet. This requires iOS 18 and watchOS 11. On older versions, there's currently no Live Activity fallback at all, not a stripped-down card, just none, since the watch card support raises the whole widget's minimum OS version and there isn't a way around that in how Apple's widget framework works.

Starting a card without touching your phone

If Zirv auto-detects that you've started moving like you're running while your phone is locked in your pocket, it can't request a new Live Activity directly, iOS blocks that from a backgrounded app. Instead it asks Apple's push service to start one for you. That doesn't always land instantly, push delivery isn't guaranteed, so the card can occasionally be running late or missing entirely for a stretch of your run. Zirv checks for a missing card the next time you bring the app to the foreground and starts one locally if the push never showed up, so a delayed or dropped push costs you a temporarily blank lock screen, not the whole session's live tracking.

The honest limits

This is an iOS-only feature built on ActivityKit, there is nothing equivalent on web or Android. It also needs iOS 18 for the full experience with the Watch card; anything older gets nothing rather than a reduced version. And strength calories are a genuine gap right now, not a design choice you'd notice unless you went looking for the number and it wasn't there.

The takeaway

A workout tracker earns the "glanceable" label by deciding, carefully, what's worth showing and when it's worth updating. Strength updates the instant something real happens, no clock involved. Cardio updates constantly enough to feel live but is gated so a jittery GPS reading doesn't turn your lock screen into noise. And the watch gets a card built for a watch, not a squeezed-down phone screen. None of it replaces opening the app, it just means you don't have to, mid-set or mid-run, just to see where you stand.