Zone 2 Guardrail

Stay in your aerobic base zone without staring at your wrist. A buzz the moment your heart rate drifts too high - so you can train by feel, not by glancing.

Train in Zone 2 without watching your wrist.

Zone 2, your easy aerobic base zone, only works if you actually stay in it. Go too hard and you lose the fat-burning, endurance-building benefit. But constantly glancing at your heart rate breaks your rhythm and ruins the run, ride, or row.

Zone 2 Guardrail fixes that. Set your ceiling once, start a session, and put your wrist down. The moment your heart rate climbs above your Zone 2 cap, you get a firm haptic buzz, a clear "ease off" you can feel without looking. When you settle back into zone, a gentle tap confirms you're good. Train by feel; let the watch keep the line.

HOW IT WORKS • Set your Zone 2 ceiling: from your age automatically, your measured max heart rate, or a number you choose. • Tap Start and begin your workout. • Drift above the cap and a strong haptic alert fires on your wrist. • Still above? Lighter periodic nudges until you recover. • Back in zone? A gentle confirmation tap. • Finish to see your time in zone, time above, and percentage over the cap.

FEELS IT, EVEN IN SILENCE The wrist haptic always fires on a breach, whether or not sound is on. Optional audible beeps are there if you want them (turn them on in settings), but you never need to hear a thing to stay guarded.

SET YOUR CEILING YOUR WAY • Automatic from your age (read once from Health, fully adjustable). • From your own measured maximum heart rate. • Or set the exact bpm ceiling yourself. Choose what fraction of max defines your zone, then forget about it. Your setting sticks for next time.

BUILT FOR THE WATCH A focused, single-purpose tool with no feeds, no clutter, and no account. It runs right on your Apple Watch and saves your guarded session to the Health app so it sits alongside your other workouts.

TRY IT FREE Your first 5 guarded sessions are completely free. If it earns a place in your training, unlock unlimited sessions forever with a single one-time purchase. No subscription.

REQUIREMENTS Apple Watch running watchOS 10 or later. Heart rate is read from Health during your session; your date of birth is read once (optionally) to set a sensible default ceiling. Your data stays on your device and nothing is collected or transmitted.

Set the line. Feel the buzz. Stay in Zone 2.