Session Time Budgeting & Timeline Predictions

How to allocate time within sessions and predict results based on user commitments. Status: Research Complete

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Part 1: Session Time Budgeting

Session Time Breakdown

Session Duration	Warmup	Main Workout	Cooldown	Effective Training Time
30 min	5 min	20 min	5 min	20 min
45 min	5 min	35 min	5 min	35 min
60 min	8 min	44 min	8 min	44 min
75 min	10 min	55 min	10 min	55 min
90 min	10 min	70 min	10 min	70 min

Sources: ISSA, Harvard Health

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Exercise Count by Session Duration

Based on rest periods and set duration research:

Session Duration	Compounds	Accessories	Isolation	Total Exercises	Total Sets
30 min	2	1	0-1	3-4	9-12
45 min	2-3	1-2	1	4-6	14-18
60 min	3	2	2	6-7	18-22
75 min	3-4	2-3	2	7-9	22-27
90 min	4	3	2-3	9-10	27-32

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Time Per Exercise Calculation

Compound Exercises (with 2-3 min rest)

Per Set Time:
- Execution: 30-45 sec (8-12 reps at 3-4 sec tempo)
- Rest: 120-180 sec

Total per 4-set compound:
- Sets: 4 × 40 sec = 160 sec (~2.7 min)
- Rest: 3 × 150 sec = 450 sec (~7.5 min)
- Total: ~10 min per compound exercise

Accessory Exercises (with 90 sec rest)

Per Set Time:
- Execution: 40-50 sec (10-12 reps)
- Rest: 90 sec

Total per 3-set accessory:
- Sets: 3 × 45 sec = 135 sec (~2.3 min)
- Rest: 2 × 90 sec = 180 sec (3 min)
- Total: ~5.5 min per accessory exercise

Isolation Exercises (with 60 sec rest)

Per Set Time:
- Execution: 40-60 sec (12-15 reps)
- Rest: 60 sec

Total per 3-set isolation:
- Sets: 3 × 50 sec = 150 sec (2.5 min)
- Rest: 2 × 60 sec = 120 sec (2 min)
- Total: ~4.5 min per isolation exercise

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Session Builder Formula

interface SessionTimeConfig {
  totalMinutes: number;
  warmupMinutes: number;
  cooldownMinutes: number;
}

interface ExerciseAllocation {
  compounds: number;
  accessories: number;
  isolation: number;
  totalSets: number;
}

function calculateExerciseAllocation(config: SessionTimeConfig): ExerciseAllocation {
  const effectiveTime = config.totalMinutes - config.warmupMinutes - config.cooldownMinutes;

  // Time constants (in minutes)
  const COMPOUND_TIME = 10;    // 4 sets, 2-3 min rest
  const ACCESSORY_TIME = 5.5;  // 3 sets, 90 sec rest
  const ISOLATION_TIME = 4.5;  // 3 sets, 60 sec rest

  // Allocation strategy: 60% compounds, 25% accessories, 15% isolation
  let compounds = 0;
  let accessories = 0;
  let isolation = 0;
  let remainingTime = effectiveTime;

  // Minimum 2 compounds for any session
  compounds = Math.min(Math.floor(remainingTime * 0.6 / COMPOUND_TIME), 4);
  compounds = Math.max(compounds, 2); // At least 2
  remainingTime -= compounds * COMPOUND_TIME;

  // Accessories
  accessories = Math.min(Math.floor(remainingTime * 0.6 / ACCESSORY_TIME), 3);
  remainingTime -= accessories * ACCESSORY_TIME;

  // Isolation with remaining time
  isolation = Math.min(Math.floor(remainingTime / ISOLATION_TIME), 3);

  return {
    compounds,
    accessories,
    isolation,
    totalSets: (compounds * 4) + (accessories * 3) + (isolation * 3),
  };
}

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Volume Distribution by Session Duration

Duration	Sets/Session	Sessions/Week (4-day)	Weekly Sets	Weekly Sets/Muscle (U/L)
30 min	9-12	4	36-48	9-12
45 min	14-18	4	56-72	14-18
60 min	18-22	4	72-88	18-22
75 min	22-27	4	88-108	22-27
90 min	27-32	4	108-128	27-32

Note: For body recomp, optimal range is 12-20 sets/muscle/week. Sessions of 45-60 min hit this perfectly.

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Part 2: Ideal vs Adjusted Plan System

The Core Concept

┌─────────────────────────────────────────────────────────┐
│                    IDEAL PLAN                           │
│  • Optimal frequency (4 days/week)                      │
│  • Optimal duration (60 min)                            │
│  • Optimal volume (14-16 sets/muscle/week)              │
│  • Expected timeline: 12-16 weeks                       │
└─────────────────────────────────────────────────────────┘
                          │
                          ▼
┌─────────────────────────────────────────────────────────┐
│               USER ADJUSTS PLAN                         │
│  • "I can only do 3 days/week"                          │
│  • "I only have 45 minutes"                             │
│  • "I want to skip leg day" (not recommended!)          │
└─────────────────────────────────────────────────────────┘
                          │
                          ▼
┌─────────────────────────────────────────────────────────┐
│              RECALCULATED PREDICTION                    │
│  • Adjusted volume: 10-12 sets/muscle/week              │
│  • Progress rate: 70% of optimal                        │
│  • New timeline: 18-22 weeks                            │
│  • Trade-off explanation shown                          │
└─────────────────────────────────────────────────────────┘

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Progress Rate Research

Muscle Gain Rates (Natural, Optimal Conditions)

Experience Level	Monthly Gain	Weekly Gain	% Body Weight/Month
Beginner	2-4 lbs	0.5-1 lb	1-1.5%
Intermediate	1-2 lbs	0.25-0.5 lb	0.5-1%
Advanced	0.25-0.5 lb	0.06-0.12 lb	0.25-0.5%

Sources: Precision Nutrition, Men's Health

Fat Loss Rates (For Muscle Retention)

Approach	Weekly Loss	Monthly Loss	Muscle Retention
Optimal (slow)	0.5-0.7% BW	2-3% BW	Excellent
Moderate	0.7-1% BW	3-4% BW	Good
Aggressive	1-1.5% BW	4-6% BW	Fair (risk of loss)
Too fast	>1.5% BW	>6% BW	Poor (muscle loss likely)

Research Finding: Athletes aiming to gain lean body mass during weight loss should aim for weekly body weight loss of 0.7% (PubMed).

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Volume-Progress Relationship

Research shows a dose-response relationship between volume and results:

Weekly Sets/Muscle	Progress Rate	Notes
<4 sets	~40%	Below minimum effective dose
4-9 sets	~60-70%	Minimum effective
10-12 sets	~80-85%	Good results
12-20 sets	100%	Optimal range
20+ sets	100-105%	Diminishing returns, recovery concerns

Sources: Stronger by Science, SportRxiv Meta-Analysis

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Frequency-Progress Relationship

Frequency	Impact on Progress	Notes
1x/week per muscle	~70%	Suboptimal MPS utilization
2x/week per muscle	100%	Optimal for most
3x/week per muscle	~100-105%	Slight edge for beginners

Key Finding: When volume is equated, frequency has minimal impact. The real issue with low frequency is fitting enough volume into single sessions.

Sources: PubMed Meta-Analysis, Stronger by Science

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Timeline Prediction Algorithm

interface UserProfile {
  experienceLevel: 'beginner' | 'intermediate' | 'advanced' | 'returning';
  currentBodyFat: number;      // percentage
  targetBodyFat: number;       // percentage
  currentWeight: number;       // lbs
  targetWeight: number;        // lbs (optional, often same for recomp)
}

interface PlanCommitment {
  daysPerWeek: number;         // 2-6
  minutesPerSession: number;   // 30-90
  weeklyCardioMinutes: number; // 0-180
  nutritionAdherence: 'poor' | 'fair' | 'good' | 'excellent';
  sleepHours: number;          // 5-9
}

interface TimelinePrediction {
  optimalWeeks: number;
  adjustedWeeks: number;
  progressRate: number;        // 0-100%
  weeklyFatLoss: number;       // lbs
  weeklyMuscleGain: number;    // lbs
  tradeoffs: string[];
}

function predictTimeline(
  profile: UserProfile,
  ideal: PlanCommitment,
  adjusted: PlanCommitment
): TimelinePrediction {

  // Base rates for optimal conditions
  const baseMuscleGain = getBaseMuscleGain(profile.experienceLevel); // lbs/week
  const baseFatLoss = profile.currentWeight * 0.007;                 // 0.7% BW/week

  // Calculate progress modifiers
  const volumeModifier = calculateVolumeModifier(adjusted);
  const frequencyModifier = calculateFrequencyModifier(adjusted.daysPerWeek);
  const nutritionModifier = getNutritionModifier(adjusted.nutritionAdherence);
  const sleepModifier = getSleepModifier(adjusted.sleepHours);

  // Combined progress rate
  const progressRate = Math.min(
    volumeModifier * frequencyModifier * nutritionModifier * sleepModifier,
    1.0 // Cap at 100%
  );

  // Adjusted rates
  const adjustedMuscleGain = baseMuscleGain * progressRate;
  const adjustedFatLoss = baseFatLoss * progressRate;

  // Calculate timelines
  const fatToLose = calculateFatToLose(profile);
  const optimalWeeks = Math.ceil(fatToLose / baseFatLoss);
  const adjustedWeeks = Math.ceil(fatToLose / adjustedFatLoss);

  // Identify trade-offs
  const tradeoffs = identifyTradeoffs(ideal, adjusted);

  return {
    optimalWeeks,
    adjustedWeeks,
    progressRate: Math.round(progressRate * 100),
    weeklyFatLoss: adjustedFatLoss,
    weeklyMuscleGain: adjustedMuscleGain,
    tradeoffs,
  };
}

function calculateVolumeModifier(commitment: PlanCommitment): number {
  const allocation = calculateExerciseAllocation({
    totalMinutes: commitment.minutesPerSession,
    warmupMinutes: commitment.minutesPerSession <= 45 ? 5 : 8,
    cooldownMinutes: commitment.minutesPerSession <= 45 ? 5 : 8,
  });

  // Weekly sets estimate (assuming Upper/Lower split)
  const weeklySets = allocation.totalSets * commitment.daysPerWeek;
  const setsPerMuscle = weeklySets / 2; // Rough estimate for U/L

  // Volume-progress curve
  if (setsPerMuscle < 4) return 0.4;
  if (setsPerMuscle < 10) return 0.6 + (setsPerMuscle - 4) * 0.033;
  if (setsPerMuscle < 12) return 0.8 + (setsPerMuscle - 10) * 0.025;
  if (setsPerMuscle <= 20) return 1.0;
  return 1.0; // Diminishing returns beyond 20
}

function calculateFrequencyModifier(daysPerWeek: number): number {
  // Based on muscle frequency (2x/week optimal)
  if (daysPerWeek <= 2) return 0.7;  // 1x/muscle/week
  if (daysPerWeek <= 4) return 1.0;  // 2x/muscle/week
  return 1.0;                         // 2-3x/muscle/week
}

function getNutritionModifier(adherence: string): number {
  const modifiers = {
    poor: 0.5,
    fair: 0.7,
    good: 0.9,
    excellent: 1.0,
  };
  return modifiers[adherence] || 0.7;
}

function getSleepModifier(hours: number): number {
  if (hours < 6) return 0.6;
  if (hours < 7) return 0.8;
  if (hours <= 9) return 1.0;
  return 0.95; // Oversleeping slightly negative
}

---

Progress Rate Calculation Examples

Example 1: Optimal Commitment

User: Intermediate, 180 lbs, 20% BF → 15% BF goal

Commitment:
- 4 days/week (2x/muscle)
- 60 min sessions (18-22 sets)
- Good nutrition
- 7.5 hours sleep

Calculation:
- Volume modifier: 1.0 (14-16 sets/muscle/week)
- Frequency modifier: 1.0 (2x/muscle)
- Nutrition modifier: 0.9
- Sleep modifier: 1.0
- Progress rate: 90%

Timeline:
- Fat to lose: ~9 lbs
- Weekly loss: 1.26 lbs × 0.9 = 1.13 lbs
- Optimal timeline: 8 weeks
- Adjusted timeline: 8 weeks (minimal difference)

Example 2: Reduced Commitment

User: Same profile

Commitment:
- 3 days/week (1.5x/muscle)
- 45 min sessions (14-18 sets)
- Fair nutrition
- 6 hours sleep

Calculation:
- Volume modifier: 0.85 (10-12 sets/muscle/week)
- Frequency modifier: 0.85 (between 1x and 2x)
- Nutrition modifier: 0.7
- Sleep modifier: 0.8
- Progress rate: 40% (0.85 × 0.85 × 0.7 × 0.8)

Timeline:
- Fat to lose: ~9 lbs
- Weekly loss: 1.26 lbs × 0.4 = 0.5 lbs
- Optimal timeline: 8 weeks
- Adjusted timeline: 18 weeks

Trade-offs shown:
- "Reducing to 3 days/week decreases weekly volume by ~25%"
- "45-minute sessions limit exercise variety"
- "Sleep under 7 hours impairs recovery and fat loss"
- "Nutrition adherence is the biggest factor - improving this alone adds 20%"

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UI Concept: Timeline Slider

┌─────────────────────────────────────────────────────────────────┐
│                     YOUR RECOMP TIMELINE                        │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  OPTIMAL PLAN                          YOUR PLAN                │
│  ────────────                          ─────────                │
│  4 days/week                           3 days/week              │
│  60 min sessions                       45 min sessions          │
│  16 sets/muscle/week                   11 sets/muscle/week      │
│                                                                 │
│  ┌─────────────────────────────────────────────────────────┐   │
│  │ TIMELINE COMPARISON                                      │   │
│  │                                                          │   │
│  │ Optimal:  ████████░░░░░░░░░░░░░░ 12 weeks               │   │
│  │ Your Plan: ████████████████████░░░░░░░░░ 18 weeks       │   │
│  │                                                          │   │
│  │ Progress Rate: 67%                                       │   │
│  └─────────────────────────────────────────────────────────┘   │
│                                                                 │
│  💡 WHAT'S IMPACTING YOUR TIMELINE:                            │
│                                                                 │
│  ┌────────────────────────────────────────────────────────┐    │
│  │ Training Volume      ████████░░  -15%                  │    │
│  │ Training Frequency   ███████░░░  -20%                  │    │
│  │ Nutrition           ██████░░░░  -30%  ← Biggest factor │    │
│  │ Sleep               ████████░░  -20%                   │    │
│  └────────────────────────────────────────────────────────┘    │
│                                                                 │
│  [Adjust My Plan]              [Continue with Current Plan]     │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

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Key Trade-off Messages

Adjustment	Impact	Message
4→3 days/week	-15-20% progress	"Training 3 days instead of 4 reduces muscle stimulus. Consider longer sessions to compensate."
4→2 days/week	-30-40% progress	"Training only 2 days significantly limits results. Each muscle only gets trained once per week."
60→45 min	-10-15% progress	"Shorter sessions mean fewer exercises. Focus on compounds to maximize efficiency."
60→30 min	-25-35% progress	"30-minute sessions are maintenance-level. Results will be slow but steady."
Good→Fair nutrition	-20% progress	"Nutrition is the #1 factor. Hitting protein targets alone can recover most of this."
7→6 hrs sleep	-20% progress	"Sleep deprivation impairs fat loss and muscle recovery. Consider this non-negotiable."
Skip cardio	-5-10% progress	"Cardio accelerates fat loss but isn't essential. Prioritize lifting first."

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Integration with Plan Generation

3-Option Plan Presentation

When generating plans, present 3 options:

Option	Name	Description
Peak	Maximum Results	Optimal frequency, duration, and volume. Fastest timeline.
Optimized	Balanced	Slightly reduced commitment with 85-90% results.
Sustainable	Lifestyle Fit	Minimum effective dose. Slower but maintainable.

interface PlanOption {
  id: 'peak' | 'optimized' | 'sustainable';
  name: string;
  frequency: number;
  sessionDuration: number;
  weeklyVolume: number;
  progressRate: number;
  estimatedWeeks: number;
  tradeoffs: string[];
}

function generatePlanOptions(profile: UserProfile, constraints: UserConstraints): PlanOption[] {
  return [
    {
      id: 'peak',
      name: 'Peak Performance',
      frequency: 4,
      sessionDuration: 60,
      weeklyVolume: 16,
      progressRate: 100,
      estimatedWeeks: calculateTimeline(profile, 1.0),
      tradeoffs: [],
    },
    {
      id: 'optimized',
      name: 'Optimized Balance',
      frequency: Math.min(constraints.maxDays, 4),
      sessionDuration: Math.min(constraints.maxDuration, 55),
      weeklyVolume: 13,
      progressRate: 85,
      estimatedWeeks: calculateTimeline(profile, 0.85),
      tradeoffs: ['Slightly longer timeline for better work-life balance'],
    },
    {
      id: 'sustainable',
      name: 'Sustainable Progress',
      frequency: Math.min(constraints.maxDays, 3),
      sessionDuration: Math.min(constraints.maxDuration, 45),
      weeklyVolume: 10,
      progressRate: 65,
      estimatedWeeks: calculateTimeline(profile, 0.65),
      tradeoffs: [
        'Longer timeline but highly maintainable',
        'Focus on compound movements',
        'Perfect for busy schedules',
      ],
    },
  ];
}

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Sources

• ISSA - Warmup and Cooldown
• Harvard Health - Exercise Warmup
• Precision Nutrition - Rates of Fat Loss and Muscle Gain
• Men's Health - Muscle Gain per Month
• PubMed - Weight Loss Rate for Athletes
• Stronger by Science - Volume and Diminishing Returns
• SportRxiv - Volume Meta-Analysis
• PubMed - Training Frequency Meta-Analysis
• Stronger by Science - Frequency

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Related Documents

• 02-ten-pillars.md - Volume, frequency, intensity research
• 03-body-recomposition.md - Recomp timeline and nutrition
• 06-implementation.md - Algorithm integration

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Last Updated: 2025-12-08