Zx: Heart Rate Zones Training

Name: Zx: Heart Rate Zones Training
Rating: 4.3 (70 reviews)
Author: OverSphere LLC

By: OverSphere LLC

Interval Timer & HIIT Trainer

Features & Capabilities

Zx is your personal heart-rate coach for interval training. Create custom interval workouts or download community workouts; official Zx workouts are updated regularly. Zx supports Apple Watch or any compatible Bluetooth heart rate monitor, and it integrates with the Health app to surface your heart-rate zones and training stats.

Key features include Guided Interval Training, Open Mode on Apple Watch, custom workout creation, and a library of community workouts to download and remix. Track daily, weekly, and monthly stats and plan future sessions to improve fat burn, VO2 max, and overall performance.

User Growth & Download Statistics

App Sports Analytics Data

By:

OverSphere LLC

Rating:

4.30

(70)

Version:

1.8 Last updated: 2026-01-10

Version code:

881358637

Creation date:

2019-12-22

Compatible devices:

Size:

50.81MB

URLs:

Website ,Privacy policy

Full description:

Source:

Apple Apps Store

Data ingested on:

2026-06-06

Compare stats and ranking:

Ranking

# 176,066 ▼ 298

Other rankings

#56 in effort keyword 3 ▼ 2

For Developers

Monetize with App Pass Boost with Extension Booster

Contact the developer

Chrome-Stats does not own this Apple app. Please use these information below to contact the Apple app developer.

Developed by:

OverSphere LLC

Apple Apps Store

https://apps.apple.com/us/app/zx-heart-rate-zones-training/id1457355997

Website:

https://www.oversphere.net

User Reviews

Overall sentiment is mixed. Some users praise the app’s concept, interval timing, and customization options, and even report health benefits. However, multiple reviewers consistently cite Apple Watch syncing problems (workouts not appearing, spinning, or failing to sync), issues with self-created workouts, and general stability glitches. Support quality and documentation are also cited as poor by several users. In short, the app has promising features, but recurring syncing, reliability, and support problems dominate the user experience.

Pros

Cons

Persistent Apple Watch synchronization issues: workouts not appearing on the watch, watch not syncing with the iPhone app, and occasional spinning.
App stability problems: crashes or shutdowns during editing and general glitches.
Poor support and outdated or placeholder documentation/website; slow or unhelpful responses.
Custom/self-created workouts frequently fail to sync or appear on the watch.

Recent reviews

I was looking for an interval timer for my own HIIT training that could also pair with my coros armband to show my heart rate. Paying $14 for this app seemed like a no-brainer when the cheapest watch I could find to show my heart rate was $180. Now I get to see my interval timer and heart rate in the one place. It works perfectly with my coros armband and make sure I stay in the zone during night intensity intervals (while not pushing too hard above my range). Thanks for making such an intuitive and affordable app with great functionality.

by Na*****, 2024-09-13

I’m not able to use the custom and community workouts after paying for this app because they don’t show up on my watch. 😕

by S.*****, 2024-06-26

App is promising. While running and cycling work fine, logging a swimming workout fails. It says "Please allow Zx to 'Write Workout Data' in Health and try again. By the way your support website is just a placeholder site. Might want to update that. In addition to the above bug, to be useful during swimming, the alerts would have to be different patterns for above and below zone, and they'd have to be constant. For example, short quick vibrations if below zone and long slow vibrates if above zone. The same kind of constant and differentiated alerts would be useful in other situations (e.g. watch under your sleeve or glove) but especially in swimming when it's not practical to look at the watch face during a lap.