GymAdapt: the right sets, twice a week, heavier over time
Choose "Build muscle" and GymAdapt builds a split that hits each muscle about twice a week, in the 8 to 12 rep range, then raises your weights as you beat your targets. Free to start; code TRYFREE01 gives a month of Pro free. How many sets per week? →
Building muscle isn't mysterious. The research points to a few things that matter most: doing enough hard sets for each muscle every week, training each muscle more than once a week, eating enough protein, and gradually lifting more. A good app handles the training part so you can focus on showing up.
What builds muscle (and what an app should do)
| What matters | The evidence | What the app should do |
|---|---|---|
| Weekly hard sets | More sets per muscle per week means more growth; around 10+ beats fewer than 5 | Plan enough sets for every muscle |
| Frequency | Training a muscle twice a week beats once, for the same work | Use a split that repeats each muscle |
| Progression | Adding load or reps over time both work | Raise your targets when you beat them |
| Protein | About 1.6 g per kg of body weight a day is where benefits level off | Remind you; it can't eat for you |
The best apps to build muscle
1. GymAdapt (our app)
Free: An AI-built plan for your goal, days, equipment and injuries; unlimited workouts; a video for every lift; full logging; 3 new AI plans and 5 coach messages a week; the first 30 days of adaptive weights.
Paid: Pro is $4.99/month or $24.99/year (7-day free trial), or $79.99 once for lifetime. It keeps adaptive weights on after day 30 and removes the weekly AI limits. Code TRYFREE01 gives a month of Pro free.
2. Alpha Progression
Free: Logging, manual plans and videos.
Paid: Pro $12.99/month or $79.99/year.
3. Fitbod
Free: A 7-day free trial.
Paid: $15.99/month or $95.99/year.
4. Boostcamp
Free: Most programs and logging.
Paid: Pro about $59.99/year.
5. Hevy
Free: Up to 4 routines and 3 months of charts.
Paid: Pro $2.99/month or $23.99/year.
A simple muscle-building week
- 3 days: full body each session.
- 4 days: upper, lower, upper, lower.
- 5 to 6 days: push, pull, legs, repeated.
- Every session: 2 to 4 hard sets per exercise, most sets 6 to 12 reps, stopping one to three reps short of failure.
- Every week: beat last week by a rep or a little weight on most lifts.
The best split is the one you will keep doing. Total weekly sets matter more than how they are arranged.
GymAdapt is free to start. Want Pro free for a month?
The free version gives you an AI-built plan and unlimited workouts. Code TRYFREE01 adds a full month of Pro: weights that adjust from what you log and unlimited coach chats.
Redeem the free month → Opens the App Store with the code filled in. iPhone only. After the month it's $4.99/mo unless you cancel in Settings, and the free version stays yours either way.Questions people ask
What is the best workout app to build muscle?
GymAdapt handles the split, weekly sets and progression for you, with a free tier (our app, iPhone only). Alpha Progression and Fitbod are strong paid options; Boostcamp has free programs.
How many sets a week to build muscle?
Around 10 or more hard sets per muscle per week works better than fewer than 5. Start near 10 and add sets only if you recover well.
How often should I train each muscle?
About twice a week. A full-body, upper/lower or push/pull/legs split all do this.
Do I need to lift heavy to build muscle?
No. Light and heavy weights build similar muscle when sets are taken close to failure. Heavier weights build more strength.
How much protein do I need?
About 1.6 g per kg of body weight per day (around 0.7 g per pound) covers most people. More than that adds little for muscle.
A coach, not just a counter, free to start
GymAdapt builds your plan and raises your weights from what you log. Free to start; code TRYFREE01 adds a month of Pro.
Get GymAdapt on the App Store → Free to start. Pro is $4.99 a month or $24.99 a year (7-day free trial), or $79.99 once for lifetime. iPhone only. In English, Spanish, Portuguese, French, German and Japanese.Sources
- Schoenfeld et al. 2017: weekly sets and muscle growth (meta-analysis)
- Schoenfeld et al. 2016: training frequency and muscle growth (meta-analysis)
- Morton et al. 2018: protein supplementation and muscle (meta-analysis)
- Plotkin et al. 2022, PeerJ: progressing load vs repetitions
- SensAI: Fitbod review 2026 ($15.99/mo, $95.99/yr)
- SensAI: Juggernaut AI vs RP Hypertrophy vs Alpha Progression (Oct 2026)
