Exercise Specification v1.5

Overview

The Exercise Specification defines how exercises are structured within Intrvl's Program Collection format. Version 1.6 adds set intent markers (warm-up and failure sets), while v1.5 introduced flexible exercise capabilities, hierarchical muscle group targeting, and advanced volume tracking.

Exercise Schema

Each exercise object defines a movement with its parameters:

{
  "name": "String (required)",
  "muscleGroups": "String, Array, or Object (optional)",
  "muscleGroup": "String (optional, legacy)",
  "capabilities": ["String"] (optional),
  "exerciseType": "String (optional, legacy)",
  "equipment": "String or Array (optional)",
  "defaultResistance": "String (optional)",
  "doublesVolume": Boolean (optional),
  "description": "String (optional)",
  "sets": [Set] (optional),
  "source": Object (optional)
}

Exercise Fields

Field	Type	Required	Description
name	String	Yes	Name of the exercise (e.g., "Bench Press", "Pull-up")
muscleGroups	String, Array, or Object	No	v1.5: Muscle group targeting. See Muscle Groups section.
muscleGroup	String	No	Legacy: Primary muscle group. Use muscleGroups for v1.5.
capabilities	Array<String>	No	v1.5: List of capabilities for combined exercise types.
exerciseType	String	No	Legacy: Type of exercise. Use capabilities for v1.5.
equipment	String or Array<String>	No	Required equipment (e.g., "Barbell", ["Dumbbell", "Bench"])
defaultResistance	String	No	Default resistance for banded exercises
doublesVolume	Boolean	No	When true, volume calculations are doubled (for bilateral exercises)
description	String	No	Brief description or coaching notes
sets	Array<Set>	No	Prescribed sets for this exercise

Capabilities (v1.5)

The capabilities array allows exercises to support combined metric types. This enables flexible exercise definitions that can track multiple metrics simultaneously.

Valid Capability Values

Value	Description
weight	Tracks external weight (barbell, dumbbell, machine)
reps	Counts repetitions
duration	Measures time (seconds/minutes)
distance	Measures distance (meters/yards)
band	Tracks resistance band usage
bodyweightVolume	v1.5: Calculates volume using user's body weight

Common Capability Combinations

Preset Name	Capabilities	Example Exercises	Volume Formula
Weighted	["weight", "reps"]	Bench Press, Squat	weight × reps
Loaded Carry	["weight", "distance"]	Farmer's Walk, Sled Push	weight × distance
Timed Loaded	["weight", "duration"]	Weighted Plank	weight × duration
Bodyweight Weighted	["weight", "reps", "bodyweightVolume"]	Weighted Pull-ups, Weighted Dips	(bodyweight + weight) × reps
Bodyweight	["reps", "bodyweightVolume"]	Push-ups, Pull-ups	bodyweight × reps
Shuttle Runs	["reps", "distance"]	Sprint intervals	—
Cardio	["distance", "duration"]	5K Run, Rowing	—
Timed	["duration"]	Plank, Wall Sit	—
Distance Only	["distance"]	Sprint	—
Banded	["band", "reps"]	Band Face Pulls, Band Rows	—
Banded Bodyweight	["band", "reps", "bodyweightVolume"]	Assisted Pull-ups	bodyweight × reps

Muscle Groups (v1.5)

Version 1.5 introduces hierarchical muscle group targeting for detailed tracking and analytics.

Format Options

Legacy (v1.0-v1.3): Single string or flat array

{
  "muscleGroup": "Legs"
}
// or
{
  "muscleGroups": ["Legs", "Core"]
}

v1.5 Hierarchical: Object with primary/secondary breakdown

{
  "muscleGroups": {
    "primary": {
      "Legs": ["Glutes", "Quads"],
      "Back": ["Lats", "Lower Back"]
    },
    "secondary": {
      "Core": ["Abs"],
      "Arms": ["Forearms"]
    }
  }
}

Parent Categories and Child Muscles

Parent	Children
Legs	Glutes, Quads, Hamstrings, Calves, Adductors, Abductors
Arms	Biceps, Triceps, Forearms
Chest	Upper Chest, Middle Chest, Lower Chest
Back	Lats, Traps, Rhomboids, Lower Back
Shoulders	Front Delts, Side Delts, Rear Delts
Core	Abs, Obliques

Set Schema

Each set object within an exercise defines the parameters for that set. All fields are optional, but you should include at least one field describing the set type.

{
  "reps": Number (optional),
  "duration": Number (optional),
  "durationUnit": "String (optional)",
  "distance": Number (optional),
  "distanceUnit": "String (optional)",
  "suggestedWeight": Number (optional),
  "resistance": "String (optional)",
  "bandWeight": Number (optional),
  "bandWeightUnit": "String (optional)",
  "isWarmUp": Boolean (optional, v1.6),
  "toFailure": Boolean (optional, v1.6)
}

Set Fields

Field	Type	Description
reps	Integer	Number of repetitions. Mutually exclusive with duration
duration	Integer	Duration value. Mutually exclusive with reps
durationUnit	String	Unit for duration: "seconds" (default) or "minutes"
distance	Number	Distance value for cardio/loaded carry exercises
distanceUnit	String	Unit for distance: "m" (default) or "yards"
suggestedWeight	Number	Suggested weight in kilograms
resistance	String	Resistance type: "bodyweight", "extra-light", "light", "medium", "heavy", "extra-heavy"
bandWeight	Number	Numeric band resistance
bandWeightUnit	String	Unit for band weight: "kg" (default) or "lbs"
isWarmUp	Boolean	v1.6: Mark as warm-up set. Default: false. Warm-up sets are excluded from effective volume.
toFailure	Boolean	v1.6: Mark as failure set. Default: false. Failure sets receive 1.5x volume multiplier.

Volume Calculation

When weight is present, volume is calculated using this priority:

1. weight × distance (loaded carries) — if both weight and distance > 0
2. (bodyweight + weight) × reps (weighted bodyweight) — if bodyweightVolume + weight + reps
3. weight × reps (traditional) — if both weight and reps > 0
4. bodyweight × reps (bodyweight or banded bodyweight) — if bodyweightVolume + reps only
5. weight × duration (timed loaded) — if both weight and duration > 0
6. 0 — (no volume for pure banded, distance-only, or timed-only)

Examples

Weighted Exercise

{
  "name": "Bench Press",
  "capabilities": ["weight", "reps"],
  "muscleGroups": {
    "primary": { "Chest": ["Middle Chest"] },
    "secondary": { "Arms": ["Triceps"], "Shoulders": ["Front Delts"] }
  },
  "equipment": ["Barbell", "Bench"],
  "sets": [
    { "reps": 8, "suggestedWeight": 60 },
    { "reps": 8, "suggestedWeight": 60 },
    { "reps": 6, "suggestedWeight": 65 }
  ]
}

Bodyweight with Volume Tracking

{
  "name": "Pull-ups",
  "capabilities": ["reps", "bodyweightVolume"],
  "muscleGroups": {
    "primary": { "Back": ["Lats"] },
    "secondary": { "Arms": ["Biceps"], "Shoulders": ["Rear Delts"] }
  },
  "equipment": ["Pull-up Bar"],
  "sets": [
    { "reps": 10, "resistance": "bodyweight" },
    { "reps": 8, "resistance": "bodyweight" },
    { "reps": 6, "resistance": "bodyweight" }
  ]
}

Loaded Carry (Weight + Distance)

{
  "name": "Farmer's Walk",
  "capabilities": ["weight", "distance"],
  "muscleGroups": {
    "primary": { "Back": ["Traps"], "Core": ["Abs", "Obliques"] },
    "secondary": { "Arms": ["Forearms"], "Legs": ["Calves"] }
  },
  "equipment": ["Dumbbells"],
  "sets": [
    { "suggestedWeight": 30, "distance": 50, "distanceUnit": "m" },
    { "suggestedWeight": 30, "distance": 50, "distanceUnit": "m" }
  ]
}

Timed Exercise

{
  "name": "Plank",
  "capabilities": ["duration"],
  "muscleGroups": {
    "primary": { "Core": ["Abs", "Obliques"] },
    "secondary": { "Shoulders": ["Front Delts"] }
  },
  "equipment": [],
  "sets": [
    { "duration": 30, "durationUnit": "seconds" },
    { "duration": 45, "durationUnit": "seconds" },
    { "duration": 60, "durationUnit": "seconds" }
  ]
}

Exercise Libraries

Exercise libraries are standalone files containing only exercises (no workouts). They use a slightly different root structure:

{
  "version": 1.6,
  "libraryName": "String (required)",
  "author": "String (optional)",
  "description": "String (optional)",
  "exercises": [
    { /* Exercise objects */ }
  ]
}

Exercise libraries are useful for:

• Building a comprehensive exercise database
• Sharing exercise definitions across multiple programs
• Creating standardized exercise libraries for coaches

Need Help?

Questions about exercise specifications or building exercise libraries? Get in touch: