Flex AI Workout Trainer & Log vs MuscleUp
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Flex AI Workout Trainer & Log
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.
- AI personal trainer
- Real-time form feedback
- Personalized workout plans
- Adaptive progression
- Strength tracking
- Community leaderboards
- Apple Watch integration
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Flex AI is the world’s first true AI personal trainer — built for lifters who want to train smarter, progress faster, and perfect their form. Whether you’re chasing size, strength, or consistency, Flex uses real-time AI to guide every rep, adjust your program, and keep you motivated through challenges, leaderboards, and streaks. - Your AI Coach, Every Rep Personalized workouts built automatically by AI personas that learn your goals, history, and preferences. Real-time form feedback powered by patented computer-vision AI — get instant corrections on squats, bench, deadlift, rows, and more. Adaptive progression and deloading backed by sports-science principles — no spreadsheets, no guesswork. - Train Smarter — See Results AI tracks your strength curve and increases weight when you’re ready. Visual progress graphs show PRs, volume, and recovery trends. Track sets, reps, and tempo with a tap — or automatically with Apple Watch. - Stay Motivated & Connected Join a global community of lifters. Compete on leaderboards, build streaks, and earn badges. Post progress photos, celebrate milestones, and share results. - Accessible to Everyone Free to start with all core features included. Upgrade anytime for advanced AI coaching and premium analytics. Designed for all experience levels — from beginners to pros. - Why Flex AI Real-time AI form feedback (patented) Adaptive, science-based programming Progress tracking & recovery insights Gamified streaks + leaderboards Apple Watch integration Built for hypertrophy & strength goals Start Training Smarter — Today Download Flex AI and experience personal training powered by real AI. Perfect your form. Unlock your best lift. Train smarter — free on iPhone + Apple Watch.
MuscleUp
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.
- Personalized workout plans
- Customizable for fitness level
- Real-time progress tracking
- Strength building monitoring
- Gym and home workout routines
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Take your fitness to the next level with MuscleUp! - Plan personalized workouts tailored to your fitness level. - Track progress and monitor your strength-building journey. - Perfect for gym or home training. Features You’ll Love: - Custom workout plans designed for all fitness goals. - Real-time progress tracking to celebrate your achievements. - Gym routines, home workouts, and more. Start your fitness journey today —download MuscleUp now!
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | Flex AI Workout Trainer & Log | MuscleUp |
|---|---|---|
| Price | Free | Free |
| Rating | 4.6 (2.4K ratings) | 4.8 (393 ratings) — better |
| Positive reviews | 69.0% of reviews — better | 50.0% of reviews |
| Number of ratings | 2.4K — better | 393 |
| Update frequency | Every 9 days — better | Every 10 days |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Freemium | Free with in-app purchases |
| Devices | iPhone, Apple Watch | iPhone, iPod |
| Requires iOS | 18.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 574 MB | 131 MB |
| Age rating | 17+ | 17+ |
| Developer | Flex Artificial Intelligence Inc. | DEEP FLOW SOFTWARE SERVICES |
Customer experience
Flex AI Workout Trainer & Log
MuscleUp
Bugs and requests
Flex AI Workout Trainer & Log
Reported bugs
3 issues- App crashes on iOS 16 update
- Inability to log workouts on previous days
- Inconsistent syncing between app and Apple Watch
Requested features
4 requests- Offline workout mode
- Ability to save and reuse custom workout plans
- Muscle group targeting and analytics
- Social features and community integration
MuscleUp
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Flex AI Workout Trainer & Log
- Premium Subscription Monthly$12.991 Month
- Premium Plus Monthly$29.991 Month
- Premium Plus Family Monthly$69.991 Month
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- Premium Yearly Subscription$79.991 Year
- Premium Plus Yearly7 Days trial$191.991 Year
- Premium Plus Family Yearly7 Days trial$499.991 Year
- 1 Month Free PremiumFree
- Lifetime Free PremiumFree
MuscleUp
- MuscleUp Premium 1 Week$6.997 Days
- MuscleUp Premium 1 Week3 Days trial$6.997 Days
- MUSLEUP PREMIUM7 Days trial$9.997 Days
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- MUSLEUP PREMIUM$9.997 Days
- MuscleUp Premium Yearly$39.991 Year
Questions
Is Flex AI Workout Trainer & Log free?
Is MuscleUp free?
Which has better reviews, Flex AI Workout Trainer & Log or MuscleUp?
Do Flex AI Workout Trainer & Log or MuscleUp have ads?
Which is updated more often, Flex AI Workout Trainer & Log or MuscleUp?
Other comparisons
