Comparison

Interval Flow vs Muscles

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Interval Flow

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Have you wanted to set the same timers over and over again but find it tedious and cumbersome? We did too so we built Interval Flow! With Interval Flow, you can easily set multiple timers that will ring one after the other, guiding you seamlessly through your activities. Transition effortlessly from one activity to another, whether it's your breathing exercises, stretching sessions, or any other tasks you have in mind. Interval Flow let's you create multiple programs tailored to your specific needs and preferences (watchOS 10+). With just a few taps on your Apple Watch, you can effortlessly switch between programs and enjoy a seamless flow of activities, staying focused and productive. Interval Flow ensures that your Apple Watch becomes a smart partner, helping you stay on track without any distractions. So, the question is, why settle for a standard timer when you can elevate your Apple Watch experience with Interval Flow? It's a game-changer for anyone who values their time and wants to make the most of every minute.

About

Muscles

This app offers a streamlined and intuitive way to log your exercise sessions. Easily track your progress with visual analytics and motivational graphs. Its beautiful interface makes fitness tracking enjoyable for all levels.

Highlights
  • Effortless workout logging
  • Customizable exercise tracking
  • Progress visualization with graphs
  • Insightful analytics and statistics
  • Beautiful and minimalist interface
  • Dashboard widgets for quick insights
Features
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Introducing Muscles: Your Ultimate Workout Companion Muscles is a sleek and intuitive mobile application designed to revolutionize how you track and view your workouts. With its user-friendly interface and powerful features, Muscles makes it effortless to monitor your fitness journey and achieve your goals with ease. Simplicity Redefined: Say goodbye to complicated workout tracking apps cluttered with unnecessary features. Muscles offers a minimalist and streamlined interface, ensuring that tracking your workouts is as simple as a few taps. Whether you're a seasoned gym enthusiast or just starting your fitness journey, Muscle's intuitive design makes it accessible to users of all levels. Effortless Tracking: With Muscles, tracking your workouts has never been easier. Simply select your exercise (or create one), enter reps for each set, and voila! Muscles automatically logs your sessions, allowing you to focus on what matters most - your workout. View Progress at a Glance: Stay motivated and track your progress effortlessly with Muscle’s comprehensive analytics. Visualize your workout history and monitor your improvements over time for each exercise. Muscles provides insightful graphs and statistics, allowing you to see how far you’ve come and where you’re headed on your fitness journey. With the dashboard widgets, you’ll get more insight in areas of interest. Beautiful Interface: Who said tracking workouts couldn’t be visually stunning? Muscles combines functionality with aesthetics, offering a beautifully designed interface that enhances your user experience. From vibrant color theming to smooth animations, every aspect of Muscles is crafted to delight your senses and make your fitness journey enjoyable. With Muscles, achieving your fitness goals has never been more convenient or enjoyable. Download Muscles now and take the first step towards a healthier, happier you!

Screenshots

Muscles4 screens

Verdict

The call

The clearest difference is device support: Interval Flow at 3 against Muscles's 1. Interval Flow also leads on iOS requirement (15.6 vs 17.0). On price, update cadence, ads and in-app purchases 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Interval Flow sells 1 one-off in-app purchase and Muscles sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Interval Flow ships an update every 2 weeks, Muscles fortnightly. The most recent releases landed on September 8, 2026 and June 1, 2026 respectively.

Scorecard2 real differences · 8 level
Interval Flow versus Muscles: the parameters behind the verdict, then further details
ParameterInterval FlowMuscles
PriceFreeFree
Rating—5.0 (3 ratings) — better
Positive reviews—100.0% of reviews
Number of ratings—3 — better
Update frequencyEvery 2 weeks — betterFortnightly
AdsNoNo
In-app purchasesYesYes
Monetization—Free with in-app purchases
DevicesiPhone, iPod, Apple Watch — betteriPhone
Requires iOS15.6 — better17.0
Further details — not scored
Size8 MB2 MB
Age rating4+4+
DeveloperTegyaanNathan Armstrong

In-app purchases

1 purchases

Interval Flow

One-time1
  • Multiple Programs$3.99
1 purchases

Muscles

One-time1
  • Full Access$4.99

Questions

Is Interval Flow free?
Interval Flow is free to download, with in-app purchases available.
Is Muscles free?
Muscles is free to download, with in-app purchases available.
Do Interval Flow or Muscles have ads?
Neither Interval Flow nor Muscles shows ads.
Which is updated more often, Interval Flow or Muscles?
Interval Flow ships an update every 2 weeks, and Muscles fortnightly. Most recently, Interval Flow was updated on September 8, 2026 and Muscles on June 1, 2026.

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