If you follow sports tech, your inbox fills up fast. Most of what lands is minor patches dressed up as news. This cuts through all that with one weekly post covering every feature addition across the major brands, nothing else. Trivial bug fixes are excluded. Subscribe via RSS at the5krunner.com.
Hammerhead — Karoo — v1.636.2450 — 11 June 2026
the5krunner insight: A small release, with one addition that earns attention only if you train against HRV data.
The build adds the AI Endurance app to the Karoo Extension Library, putting real-time HRV analysis alongside AI coaching and training metrics on the head unit. The dashboard route editor now requires a deliberate press of the Edit button before a route can change, which stops accidental edits on web and mobile. The remaining changes are colour updates to CLIMBER and to workout zones, plus a fix for rides that were not syncing to AXS web.
- AI Endurance extension added to the Extension Library, for real-time HRV analysis and AI coaching and training metrics
- Route editor now requires the Edit button before any change, preventing accidental route edits on web and mobile
- CLIMBER colours on the dashboard updated
- Workout zone colours updated
Full release notes: Karoo
Amazfit — Balance 3 / Balance Ultra / Cheetah 2 Ultra / Helio Strap — June 2026
the5krunner insight: The notification change is the one to care about, and only if you pair an Amazfit watch with an iPhone in the EU.
iOS Notification Forwarding has reached the Amazfit Balance 3, Balance Ultra and Cheetah 2 Ultra in the EU, a result of Apple opening the iPhone notification system under the Digital Markets Act. Alerts stop behaving as read-only mirrors: you can reply to an iMessage, accept, decline or silence a call, and act on supported third-party app notifications from the wrist, with fuller notification content and per-app control over what forwards. The coverage note points to the other watches on the Zepp OS 6 track (Bip Max, Balance 2, T-Rex Ultra 2, T-Rex 3 Pro, T-Rex 3, Cheetah 2 Pro, Active 3 Premium and Active Max) as the likely next group, without committing to dates: one to watch. Separately, the Helio Strap firmware optimises the heart rate algorithm for accuracy and stops the strap creating a duplicate activity record when a watch is already tracking the session.
- iOS Notification Forwarding in the EU: reply, dismiss or act on alerts from the wrist, including iMessage replies and call handling (Balance 3, Balance Ultra, Cheetah 2 Ultra)
- Fuller notification content on the watch, with per-app control over what forwards (Balance 3, Balance Ultra, Cheetah 2 Ultra)
- Heart rate monitoring algorithm optimised for accuracy (Helio Strap only)
Full release notes: Amazfit product updates
No updates this week
Checked and nothing to report for the week ending 13 June 2026: Garmin, COROS, Suunto, Polar, Wahoo, Samsung and Huawei either had no release in the window or shipped beta, stability and bug fix updates only. Garmin posted a Tactix 8 beta and announced the Catalyst R1 racing radar, neither of which is a shipped firmware feature. Polar pushed a Flow app maintenance release. Samsung and Huawei shipped security and stability updates.
Previous edition: #2 Deep Dive Feature Files: Week Ending 6 June 2026
Frequently Asked Questions
What is new in the latest Hammerhead Karoo firmware update?
It adds the AI Endurance app to the Extension Library for real-time HRV analysis and AI coaching, and it changes the dashboard route editor so you must press Edit before altering a route. The remaining changes are colour updates to CLIMBER and to workout zones.
Does the Hammerhead Karoo work with AI Endurance?
Yes. AI Endurance is now in the Karoo Extension Library. Once downloaded and installed, it provides real-time HRV analysis and additional AI coaching and training metrics on the device.
Which Amazfit watches received iOS Notification Forwarding?
The Amazfit Balance 3, Balance Ultra and Cheetah 2 Ultra received it, and only in the EU. The feature follows Apple opening its iPhone notification system to third-party wearables under the Digital Markets Act.
Does the Amazfit Cheetah 2 Ultra let you reply to messages from the watch?
Yes, for iPhone users in the EU. With iOS Notification Forwarding you can reply to an iMessage, accept, decline or silence a call, and act on supported app alerts from the wrist, rather than only viewing them.
What is new in the latest Amazfit Helio Strap firmware update?
It optimises the heart rate monitoring algorithm for better accuracy and stops the strap creating a duplicate activity record when your watch is already tracking the same session.
Last Updated on 13 June 2026 by the5krunner
My favourite kit and nutrition
- Injinji – Runners protect your toes. Avoid discomfort and minor injury. Run more. run faster. I use them.
- Garmin 90-degree charging adapter — the small adapter that keeps your charging cable tidy at the stem. Essential for race day. I use one.
- Garmin charging puck — the fastest and most reliable way to top up your Garmin before a session. I use one.
- Ravemen FR300 — front light that mounts directly under your Garmin or Wahoo head unit. Keeps your bars clean and your beam pointed where it matters. I use one.
- Body Glide – The Blue anti-chafe stick that all swimmers and many runners use. I use it.
- Maurten — the race nutrition trusted by elite athletes. Gels and drink mix engineered to be easy on the stomach. I use them.
- Garmin Varia RTL515 — radar rear light that alerts you to vehicles approaching from behind. Pairs with your Edge or Garmin watch. I use this model.
- Favero Assioma Pro RS2 — the power meter pedals most serious cyclists end up choosing. Accurate, easy to move between bikes. I use this model.
Reader-Powered Content
This content is not sponsored. It’s mostly me behind the labour of love, which is this site, and I appreciate everyone who supports it.
Support the site: Follow (free, fewer ads) · Subscribe (paid, ad-free) · Buy Me A Coffee ❤️
All articles are written by real people, fact-checked, and verified for originality. See the Editorial Policy. FTC: Affiliate Disclosure — some links pay commission. As an Amazon Associate, I earn from qualifying purchases.
tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID
