# musclebuild.ing

> Free hypertrophy program builder. Arrange exercises by muscle group, equipment and training days, with visible effort and progression.

Agent guide: https://musclebuild.ing/agents/
Portable CLI: https://musclebuild.ing/tools/itrain-cli.tgz
CLI usage: node scripts/itrain.mjs validate program.json --json
CLI sharing: node scripts/itrain.mjs share program.json --domain musclebuild.ing --agent claude --json
Schema: https://musclebuild.ing/api/training/schema
OpenAPI: https://musclebuild.ing/api/training/openapi.json
POST /api/training/programs accepts {title,program,source:"agent"} and returns share_url.
Return only a real share_url returned by the service. Never invent tokens.
Program format: legacy ProgramV1, v,u,m,c,weeks; rows ex,mode,sets,reps,load,pct,rpe,rest.
Default full programs: four weeks, explicit progression, complete prescriptions.
Legacy /app/<STATE>, /program/<STATE>, /p/<STATE> and /#/p/<STATE> continue to work.
Short /workout/<token> links load immutable snapshots.
If no tool access, return complete JSON and direct the user to /agents/ for import.

## Starter programs
- [2-Day Full Body Hypertrophy](https://musclebuild.ing/programs/two-day-full-body-hypertrophy/index.md)
- [3-Day Full Body Hypertrophy](https://musclebuild.ing/programs/full-body-hypertrophy-3-day/index.md)
- [3-Day Push Pull Legs](https://musclebuild.ing/programs/push-pull-legs-3-day/index.md)
- [4-Day Upper Lower Hypertrophy](https://musclebuild.ing/programs/upper-lower-hypertrophy-4-day/index.md)
- [5-Day Body Part Split](https://musclebuild.ing/programs/five-day-body-part-split/index.md)
- [6-Day Push Pull Legs](https://musclebuild.ing/programs/push-pull-legs-6-day/index.md)
- [Arm Focus Upper Lower](https://musclebuild.ing/programs/arm-focus-upper-lower/index.md)
- [Dumbbell Home Upper Lower](https://musclebuild.ing/programs/dumbbell-home-upper-lower/index.md)
- [Four Week Upper Lower Muscle Building](https://musclebuild.ing/programs/four-week-musclebuild-foundation/index.md)

## Guides
- [Best Rep Range for Hypertrophy: Heavy vs Light](https://musclebuild.ing/blog/best-rep-range-for-hypertrophy/index.md): The best rep range for muscle growth, what low-load and high-load research shows, and how to mix heavy, moderate and light sets in your split.
- [Push Pull Legs Split: 3-Day and 6-Day Plans](https://musclebuild.ing/blog/push-pull-legs-split/index.md): How the push pull legs split works, 3-day vs 6-day PPL, the best exercises, sets and reps for each day, and a sample week you can run now.
- [How Many Sets per Muscle per Week to Build Muscle](https://musclebuild.ing/blog/sets-per-muscle-per-week/index.md): How many sets per muscle group per week build the most muscle, what the dose-response research shows, and how to spread sets across your split.

## All pages (markdown)
- [Build muscle, your way.](https://musclebuild.ing/index.md)
- [Create a program with your AI assistant](https://musclebuild.ing/agents/index.md)
- [Training guides](https://musclebuild.ing/blog/index.md)
- [Best Rep Range for Hypertrophy: Heavy vs Light](https://musclebuild.ing/blog/best-rep-range-for-hypertrophy/index.md)
- [Push Pull Legs Split: 3-Day and 6-Day Plans](https://musclebuild.ing/blog/push-pull-legs-split/index.md)
- [How Many Sets per Muscle per Week to Build Muscle](https://musclebuild.ing/blog/sets-per-muscle-per-week/index.md)
- [Questions about musclebuild.ing](https://musclebuild.ing/faq/index.md)
- [Privacy](https://musclebuild.ing/privacy/index.md)
- [Free muscle building programs](https://musclebuild.ing/programs/index.md)
- [Arm Focus Upper Lower](https://musclebuild.ing/programs/arm-focus-upper-lower/index.md)
- [Dumbbell Home Upper Lower](https://musclebuild.ing/programs/dumbbell-home-upper-lower/index.md)
- [5-Day Body Part Split](https://musclebuild.ing/programs/five-day-body-part-split/index.md)
- [Four Week Upper Lower Muscle Building](https://musclebuild.ing/programs/four-week-musclebuild-foundation/index.md)
- [3-Day Full Body Hypertrophy](https://musclebuild.ing/programs/full-body-hypertrophy-3-day/index.md)
- [3-Day Push Pull Legs](https://musclebuild.ing/programs/push-pull-legs-3-day/index.md)
- [6-Day Push Pull Legs](https://musclebuild.ing/programs/push-pull-legs-6-day/index.md)
- [2-Day Full Body Hypertrophy](https://musclebuild.ing/programs/two-day-full-body-hypertrophy/index.md)
- [4-Day Upper Lower Hypertrophy](https://musclebuild.ing/programs/upper-lower-hypertrophy-4-day/index.md)
- [Terms](https://musclebuild.ing/terms/index.md)