# Flex AI Workout Trainer & Log vs MuscleUp

Flex AI Workout Trainer & Log and MuscleUp both sit at 4.6 stars, but that hides the real split: 69% of Flex AI Workout Trainer & Log's written reviews are positive against 50% of MuscleUp's. Flex AI Workout Trainer & Log also leads on ratings volume (2.4K vs 393). MuscleUp's advantage is iOS requirement (12.0 vs 18.0). On price, rating, update cadence and ads there is nothing between them.

Both are free to download. Flex AI Workout Trainer & Log sells 8 in-app purchases, starting at $12.99 per month and MuscleUp sells 5 in-app purchases, starting at $6.99 per 7 days. Whichever you choose, the download price is not the number that matters.

MuscleUp holds the better App Store score, 4.8 against 4.6. That said, the two scores are not equally well evidenced: Flex AI Workout Trainer & Log has 2.4K ratings behind it against 393, so its average is the more settled of the two. Written reviews complicate that: 69% of Flex AI Workout Trainer & Log's written reviews are positive against 50% of MuscleUp's, so the app with the better star average is not the one people write more warmly about.

Flex AI Workout Trainer & Log ships an update every 9 days, MuscleUp every 10 days. The most recent releases landed on October 29, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Flex AI Workout Trainer & Log | MuscleUp |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.6 (2.4K ratings)](https://appshunter.io/ios/app/flex-ai-workout-trainer-and-log/id1446354547/reviews) | **[4.8 (393 ratings)](https://appshunter.io/ios/app/muscleup-workout-planner/id6738424338/reviews)** |
| Number of ratings | **2.4K** | 393 |
| Positive reviews | **69.0% of reviews** | 50.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 9 days** | Every 10 days |
| Monetization | Freemium | Free with in-app purchases |
| Size | 574 MB | 131 MB |
| Requires iOS | 18.0 | **12.0** |
| Devices | iPhone, Apple Watch | iPhone, iPod |
| Age rating | 17+ | 17+ |
| Developer | [Flex Artificial Intelligence Inc.](https://appshunter.io/developer/1446354546) | [DEEP FLOW SOFTWARE SERVICES](https://appshunter.io/developer/1833881740) |

## What reviewers say

### Flex AI Workout Trainer & Log

[App page](https://appshunter.io/ios/app/flex-ai-workout-trainer-and-log/id1446354547)

This app uses AI to provide personalized workout plans and real-time form feedback for weightlifters. It tracks progress, offers adaptive progression, and includes motivational features like leaderboards and streaks. It's designed for all experience levels, from beginners to pros.

**Highlights:** AI personal trainer, Real-time form feedback, Personalized workout plans, Adaptive progression, Strength tracking, Community leaderboards, Apple Watch integration

**Features:** Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (8)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Subscription Monthly | $12.99 | per month |
| Premium Plus Monthly | $29.99 | per month |
| Premium Plus Family Monthly | $69.99 | per month |
| Premium Yearly Subscription | $79.99 | per year |
| Premium Plus Yearly | $191.99 | per year |
| Premium Plus Family Yearly | $499.99 | per year |
| 1 Month Free Premium | Free | one-time |
| Lifetime Free Premium | Free | one-time |

**What reviewers like**

- 🚀 Detailed workout tracking
- 👍 Customizable workouts
- 🔒 Comprehensive exercise library
- 💡 Helpful progress tracking
- 👍 Clean and intuitive interface

**What reviewers complain about**

- 🐛 Glitches and bugs
- 💰 Expensive premium subscription
- 🔒 Limited functionality without premium
- 🐛 Inconsistent rest timer
- 🐛 Workout data loss

**Reported bugs**

- App crashes on iOS 16 update
- Inability to log workouts on previous days
- Inconsistent syncing between app and Apple Watch

**Requested features**

- Offline workout mode
- Ability to save and reuse custom workout plans
- Muscle group targeting and analytics
- Social features and community integration


### MuscleUp

[App page](https://appshunter.io/ios/app/muscleup-workout-planner/id6738424338)

Create personalized workout plans for any fitness level and track your strength-building progress. Whether you train at the gym or at home, this app helps you achieve your fitness goals.

**Highlights:** Personalized workout plans, Customizable for fitness level, Real-time progress tracking, Strength building monitoring, Gym and home workout routines

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| MuscleUp Premium 1 Week | $6.99 | per 7 days |
| MuscleUp Premium 1 Week | $6.99 | per 7 days |
| MUSLEUP PREMIUM | $9.99 | per 7 days |
| MUSLEUP PREMIUM | $9.99 | per 7 days |
| MuscleUp Premium Yearly | $39.99 | per year |


## Frequently asked questions

### Is Flex AI Workout Trainer & Log free?

Flex AI Workout Trainer & Log is free to download, with in-app purchases available.

### Is MuscleUp free?

MuscleUp is free to download, with in-app purchases available.

### Which has better reviews, Flex AI Workout Trainer & Log or MuscleUp?

MuscleUp is rated higher. Flex AI Workout Trainer & Log averages 4.6 out of 5 from 2.4K ratings, while MuscleUp averages 4.8 from 393 ratings.

### Do Flex AI Workout Trainer & Log or MuscleUp have ads?

Neither Flex AI Workout Trainer & Log nor MuscleUp shows ads.

### Which is updated more often, Flex AI Workout Trainer & Log or MuscleUp?

Flex AI Workout Trainer & Log ships an update every 9 days, and MuscleUp every 10 days. Most recently, Flex AI Workout Trainer & Log was updated on October 29, 2026 and MuscleUp on October 30, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*