---
name: hypertrophy-training
description: Evidence-based muscle hypertrophy training, nutrition, exercise selection, periodization, recovery, supplements, and progress tracking. Use when Codex needs to build strength-training programs, set volume or RIR targets, choose exercises, troubleshoot plateaus, calculate macros/TDEE, or answer bodybuilding and muscle-growth questions.
---

# Evidence-Based Hypertrophy Training Guide

This skill provides a comprehensive overview of scientifically-backed principles for maximum muscle hypertrophy. All information is based on meta-analyses and systematic reviews from 2010 onwards, with emphasis on established findings from key researchers in the field.

> **Terminology:** For definitions of terms like RIR, RPE, MEV/MAV/MRV, and other abbreviations, see `references/glossary.md`.

---

## 1. Basic Principles of Hypertrophy

### 1.1 Mechanical Tension - Primary Driver

**Key Finding (Schoenfeld et al., 2017; Wackerhage et al., 2019):**
- Mechanical tension is the primary stimulus for molecular mechanisms of hypertrophy
- Acute hormonal responses, metabolic stress, cell swelling ("pump") **do not significantly contribute** to hypertrophy
- Sarcoplasmic hypertrophy as a standalone phenomenon **lacks strong scientific support**

### 1.2 Volume Landmarks (Renaissance Periodization)

For detailed volume recommendations by muscle group, see [volume-landmarks.md](references/volume-landmarks.md).

**Quick Reference:**
- **MEV:** 6-10 sets/muscle/week (minimum for growth)
- **MAV:** 12-20 sets/muscle/week (optimal for most)
- **MRV:** 20-26+ sets/muscle/week (maximum recoverable)

> **Note:** Individual variation is ±50%. Start conservatively and adjust based on progress.

### 1.3 Optimal Per-Session Volume

**Maximum per muscle per workout: 6-8 hard sets** (Krieger, 2010 [PMID: 20300012]; Schoenfeld et al., 2017 dose-response [PMID: 27433992])

**Why 6-8 sets specifically?**
- Meta-analyses show diminishing returns above ~10 sets/session
- 6-8 sets = optimal stimulus vs. recovery ratio
- Higher volumes are better split across multiple sessions (increased frequency)

---

## 2. Training Variables

### 2.1 Training Frequency

**Schoenfeld et al. (2016) meta-analysis:**
- For hypertrophy: frequency has minimal impact when volume is matched
- For strength: higher frequency has clear benefit
- **Practical recommendation: 2x per week per muscle** (optimal for most)

### 2.2 Rep Range

**Key Finding (Schoenfeld et al., 2017):**
- **5-30+ reps** produces comparable hypertrophy when training close to failure
- Higher loads (>75% 1RM) more effective for strength
- Lower loads require more sets to reach complete failure

**Practical rep range distribution:**

| Rep Range | Use Case | Why |
|-----------|----------|-----|
| 5-8 | Strength + hypertrophy, compound movements | High mechanical tension, efficient for nervous system |
| 8-12 | "Sweet spot" for hypertrophy | Balance between tension and metabolic stress, practical volume |
| 12-20 | Isolation, metabolic stress | Lower joint stress, good for pump and technique |
| 20-30 | BFR training, high fatigue | Effective only with BFR or for very experienced |

### 2.3 Proximity to Failure (RIR - Reps in Reserve)

**Recommendations:**
- **0-3 RIR** for most sets
- Training to complete failure not necessary, but effective
- **1-2 RIR** = optimal balance of stimulus vs. recovery
- Advanced lifters may need closer proximity to failure

### 2.4 Tempo / Time Under Tension

**Research findings:**
- Slow eccentric phase (4s) → greater 1RM improvement and hypertrophy
- **Recommendation: 2-8 seconds total rep duration**
- Controlled movement > fast or extremely slow

### 2.5 Rest Periods

- **2-3+ minutes** for compound movements (maximize strength)
- **60-90 seconds** for isolation (maintain volume)
- **Rule: Rest enough to complete prescribed volume**

---

## 3. Periodization

### 3.1 Periodization Models

| Model | Description | Best For |
|-------|-------------|----------|
| **Linear** | Progressive load increase, volume decrease | Beginners |
| **DUP** (Daily Undulating) | Different intensities each workout | Intermediate+ |
| **Block** | 3-6 week blocks with different focus | Advanced |
| **Autoregulation** | RPE/RIR-based management | All levels |

**Meta-analysis DUP vs LP:**
- DUP slightly better for strength (ES = 0.24)
- For hypertrophy: comparable

### 3.2 Mesocycle Structure

```
Week 1: Accumulation (lower intensity, higher volume)
Week 2: Accumulation (moderate intensity)
Week 3: Accumulation (higher intensity)
Week 4: Intensification (lower volume, higher loads)
Week 5: Deload (50% volume, 60-70% intensity)
```

### 3.3 Deload Protocols

For detailed deload protocols see [periodization.md](references/periodization.md#deload-protocols).

**Quick Overview:**
- Volume deload: 50% volume, full intensity
- Frequency: Every 4-6 weeks

**When to deload:**
- Systematically per plan
- With accumulating fatigue
- With stagnation 2+ weeks

---

## 4. Exercises and Exercise Selection

### 4.1 Lengthened Partials (Milo Wolf Research)

**Key Finding (Wolf et al., 2023 [DOI: 10.47206/ijsc.v3i1.182]; Kassiano et al., 2023 [PMID: 37015016]):**
- Training at stretched position may provide additional hypertrophic stimulus
- Lengthened partials = bottom 50-70% ROM
- **Practical suggestion:** Consider including lengthened partial training for some exercises. The optimal proportion is not yet established—current research compares full ROM vs partial ROM, not optimal ratios for mixed programming.

**Application examples:**

| Muscle | Exercises Emphasizing Stretch |
|--------|-------------------------------|
| Biceps | Preacher curl (bottom half), incline curl |
| Triceps | Overhead extension, skull crushers |
| Chest | DB fly (stop before peak), cable crossover low |
| Back | Pullovers, seated row with stretch emphasis |
| Quads | Leg extension (bottom half), sissy squat |
| Hamstrings | Seated leg curl (better than lying), RDL |
| Calves | Standing calf raise - deep stretch |

### 4.2 Stimulus-to-Fatigue Ratio (SFR)

**High SFR exercises (prefer):**
- Machine exercises with good resistance curve
- Cable exercises
- Exercises at stretched position

**Low SFR exercises (limit):**
- Heavy deadlifts (high systemic fatigue)
- Barbell rows (spinal erector fatigue)
- Leg press with extreme ROM

---

## 5. Nutrition for Hypertrophy

For complete nutritional protocols see [nutrition.md](references/nutrition.md).

### Quick Overview

**Protein:** 1.6-2.2 g/kg body weight daily
**Caloric surplus:** +200-500 kcal (depending on training status)
**Distribution:** 4-6 protein doses daily, 0.4-0.55 g/kg per dose
**Pre-sleep:** Casein or blended protein (30-40g)

---

## 6. Supplementation

For complete tier-based overview see [supplements.md](references/supplements.md).

### Quick Overview

**Tier 1 (Recommended):** Creatine 3-5g/day, Caffeine 3-6mg/kg, Protein as needed
**Tier 2 (Consider):** Beta-alanine, Citrulline, Vitamin D (if deficient)
**Not Recommended:** Turkesterone, Ecdysterone, most "testosterone boosters"

---

## 7. Recovery

### 7.1 Sleep

**Recommendation: 7-9 hours of quality sleep**

| Factor | Impact on Hypertrophy |
|--------|----------------------|
| <6 hours sleep | -60% testosterone, ↓ MPS |
| Consistent timing | Better circadian rhythm |
| Room temperature | 18-20°C optimal |

### 7.2 Cold Water Immersion (CWI)

**WARNING: CWI may IMPAIR hypertrophy!**
- Roberts et al. (2015): Significantly lower hypertrophy with CWI
- Mechanism: Blunts inflammatory response needed for adaptation
- **Recommendation: Avoid CWI after strength training (min 4-6 hours)**

### 7.3 Active Recovery

- Light cardio (60-65% HRmax, 20-30 min)
- Mobility work
- Foam rolling (acute relief, doesn't affect hypertrophy)

---

## 8. Advanced Techniques

| Technique | Description | When to Use |
|-----------|-------------|-------------|
| **Drop sets** | Set to failure → -20-25% weight → continue | 1-2x per workout, isolation |
| **Rest-pause** | Set to failure → 15-20s → 4-6 reps | Effective accumulation |
| **Myo-reps** | 12-15 activation set → mini-sets 4-6 reps | Time-efficient |
| **Giant sets** | 3+ exercises without rest | Metabolic stress |
| **Forced negatives** | Assistance in concentric, solo eccentric | Sparingly, high load |

---

## 9. Training Splits

### Overview

| Split | Frequency | Best For |
|-------|-----------|----------|
| **Full Body** | 3x/week | Beginners, time-constrained |
| **Upper/Lower** | 4x/week | Intermediate |
| **PPL** | 6x/week | Intermediate-Advanced |
| **Arnold** | 6x/week | Advanced bodybuilders |
| **Bro Split** | 5-6x/week | Enhanced athletes |

### Recommended Structure by Level

**Beginner (0-2 years):**
- Split: Full Body 3x/week
- Volume: 10-12 sets/muscle/week
- RIR: 3-4 (learning technique)
- Progression: Linear (every workout)

**Intermediate (2-5 years):**
- Split: Upper/Lower or PPL
- Volume: 12-20 sets/muscle/week
- RIR: 3→1 during mesocycle
- Progression: Weekly or bi-weekly

**Advanced (5+ years):**
- Split: PPL, PHAT, or specialization
- Volume: 16-26+ sets/muscle/week
- RIR: 2-0, intensification techniques
- Progression: Block periodization

---

## 10. Weak Point Training

### Strategies for Lagging Body Parts

1. **Prioritization:** Train weak part first in workout
2. **Frequency:** Increase to 3x/week
3. **Volume:** Add 2-4 extra sets
4. **Exercise selection:** Exercises emphasizing stretch for that muscle
5. **Mind-muscle connection:** Slower tempo, visualization

---

## 11. High vs Low Responders

> **Important:** Individual response to training varies significantly (up to ±50% in hypertrophy outcomes). The volume landmarks, rep ranges, and other recommendations in this guide represent averages. Track your own progress and adjust accordingly.

### Distinguishing Factors

| Factor | High Responders |
|--------|-----------------|
| Ribosomal biogenesis | Higher |
| Satellite cells | Greater proliferation |
| Androgen receptors | Higher content |
| IGF-1 expression | Elevated |

### Strategies for Low Responders

- Increase frequency (3-4x/week per muscle)
- Higher volume (20-30 sets/muscle/week)
- Vary stimuli (different rep ranges, exercises)
- Optimize recovery (protein 2.0+ g/kg, sleep 8+h)
- Patience - progress is slower but still possible

---

## Reference Files

For detailed information see files in `references/`:

### When to Use Which File

| Situation | Read File |
|-----------|-----------|
| Creating training plan | `programs.md` → `periodization.md` → `exercises.md` |
| Stagnation / plateau | `periodization.md` (deload) → `techniques.md` |
| Exercise selection for muscle group | `exercises.md` |
| Nutrition / macro questions | `nutrition.md` |
| Supplement evaluation | `supplements.md` |
| Recovery / fatigue / overtraining | `recovery.md` |
| Understanding why something works | `mechanisms.md` |
| Female-specific questions | `female-training.md` |
| Age-specific training (youth, masters, seniors) | `age-specific-training.md` |
| Injury / pain | `injury-prevention.md` → `exercises.md` (substitutions) |
| Progress tracking | `progress-tracking.md` |
| Motivation / adherence / mental strategies | `psychology.md` |
| Logging / tracking workouts | `sample-logs.md` → `progress-tracking.md` |

### Troubleshooting Decision Tree

```
Problem?
├── Not stagnating, but want to optimize
│   └── Read: periodization.md → techniques.md
├── Strength stagnation
│   └── Read: periodization.md (deload) → programs.md
├── Hypertrophy stagnation
│   └── Read: mechanisms.md → exercises.md (lengthened partials)
├── Fatigue / poor recovery
│   └── Read: recovery.md → nutrition.md
├── Injury / pain
│   └── Read: injury-prevention.md → exercises.md (substitutions)
├── Nutrition questions
│   └── Read: nutrition.md → supplements.md
├── Female-specific questions
│   └── Read: female-training.md
├── Age-specific questions (youth, masters, seniors)
│   └── Read: age-specific-training.md
├── Progress tracking
│   └── Read: progress-tracking.md
├── Cardio / conditioning questions
│   └── Read: cardio-interference.md → recovery.md
└── Motivation / adherence / mental blocks
    └── Read: psychology.md
```

### Reference Files

- `mechanisms.md` - Hypertrophy mechanisms (mTOR, MPS, satellite cells)
- `muscle-imbalances.md` - Bilateral asymmetries, postural issues, correction protocols
- `nutrition.md` - Detailed nutritional protocols, DIAAS, timing
- `periodization.md` - Periodization models (LP, DUP, Block)
- `supplements.md` - Complete tier-based supplement overview
- `recovery.md` - Recovery strategies, sleep, CWI warning, hormonal optimization
- `cardio-interference.md` - Cardio integration, AMPK-mTOR, interference minimization
- `techniques.md` - Advanced techniques (drop sets, myo-reps, BFR)
- `programs.md` - Sample programs by level
- `exercises.md` - Exercise database, SFR, substitutions
- `female-training.md` - Female-specific training considerations
- `injury-prevention.md` - Injury prevention and management
- `progress-tracking.md` - Progress tracking, metrics, apps
- `age-specific-training.md` - Training adjustments by age group (youth, masters, seniors)
- `psychology.md` - Training psychology, motivation, adherence, habit formation
- `glossary.md` - Quick reference for training, physiology, and nutrition terms
- `sample-logs.md` - Example training logs for different phases and levels
- `volume-landmarks.md` - Detailed volume landmarks (MEV/MAV/MRV) by muscle group
- `meal-plans.md` - Konkrétní příklady jídelníčků pro bulk/cut/recomp

### Quick Navigation by Topic

| If you need... | Start with | Then see |
|----------------|------------|----------|
| Build a plan from scratch | `programs.md` | `periodization.md` → `exercises.md` |
| Optimize nutrition | `nutrition.md` | `supplements.md` |
| Break through plateau | `periodization.md` | `techniques.md` → `recovery.md` |
| Understand the science | `mechanisms.md` | `glossary.md` |
| Train with injury | `injury-prevention.md` | `exercises.md` (substitutions) |
| Prepare for competition | `programs.md` (competition prep) | `nutrition.md` (cutting) |
| Optimize hormones naturally | `recovery.md` (hormonal section) | `nutrition.md` |
| Body recomposition | `nutrition.md` (recomp section) | `programs.md` |
| Konkrétní jídelníčky | `meal-plans.md` | `nutrition.md` |

### Plan Creation Workflow

When creating a complete training program:

```
1. Gather info → Age, goals, experience, schedule, equipment
2. Read `programs.md` → Select appropriate split
3. Read `exercises.md` → Choose exercises per muscle
4. Read `periodization.md` → Structure mesocycles
5. Read `nutrition.md` → Set macros and timing
6. Optional: `calculators.py` → TDEE, protein, volume
```

---

## Calculators

The `scripts/calculators.py` script provides common training calculations:

| Command | Description | Example |
|---------|-------------|---------|
| `tdee` | TDEE calculation (Mifflin-St Jeor) | `python3 scripts/calculators.py tdee 80 180 30 m moderate` |
| `macros` | Macronutrient targets by goal | `python3 scripts/calculators.py macros 80 2500 bulk` |
| `1rm` | Estimate 1RM from submaximal lift | `python3 scripts/calculators.py 1rm 100 8` |
| `protein` | Protein needs by status | `python3 scripts/calculators.py protein 80 bulk intermediate` |
| `weekly-volume` | Volume assessment vs landmarks | `python3 scripts/calculators.py weekly-volume 6 2` |
| `volume` | Training volume metrics | `python3 scripts/calculators.py volume 4 10 80` |
| `rir` | RIR to %1RM conversion | `python3 scripts/calculators.py rir 2` |

**Usage:**
```bash
python3 scripts/calculators.py <command> [args]
```

---

## Key Researchers

- **Brad Schoenfeld** (Lehman College) - Hypertrophy, volume, mechanisms
- **Stuart Phillips** (McMaster) - Protein, mechanical tension
- **Eric Helms** (AUT) - RIR/RPE, natural bodybuilding
- **Mike Israetel** (RP Strength) - Volume landmarks
- **Milo Wolf** (Updated 2025) - Lengthened partials research, multi-site trials
- **James Krieger** (Weightology) - Meta-analyses
- **Michael Zourdos** (FAU) - DUP, autoregulation

---

## Sources

1. Schoenfeld BJ et al. (2017). Strength and hypertrophy adaptations. J Strength Cond Res. PMID: 28834797
2. Schoenfeld BJ et al. (2016). Effects of resistance training frequency. Sports Med. PMID: 27102172
3. Morton RW et al. (2018). Protein supplementation meta-analysis. Br J Sports Med. PMID: 28698222
4. Wolf M et al. (2023). Partial vs full ROM resistance training: A systematic review and meta-analysis. Int J Strength Cond. DOI: 10.47206/ijsc.v3i1.182
5. Roberts LA et al. (2015). Cold water immersion and muscle hypertrophy. J Physiol. PMID: 26174323
6. Schoenfeld BJ et al. (2010-2022). Multiple meta-analyses on hypertrophy mechanisms.
7. Roig M et al. (2009). The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis. Br J Sports Med. PMID: 18981046
8. Wackerhage H et al. (2019). Molecular mechanisms of muscle hypertrophy. Eur J Sport Sci. PMID: 30741116
9. Kassiano W et al. (2023). Greater gastrocnemius muscle hypertrophy after partial ROM training at long muscle lengths. J Strength Cond Res. PMID: 37015016
10. Kassiano W et al. (2023). Which ROMs lead to Rome? Systematic review of ROM effects on hypertrophy. J Strength Cond Res. PMID: 36662126
11. Krieger JW (2010). Single vs. multiple sets of resistance exercise for muscle hypertrophy: A meta-analysis. J Strength Cond Res. PMID: 20300012
12. Da Silva JJ et al. (2023). Effects of eccentric vs concentric resistance training on strength and hypertrophy. J Strength Cond Res. PMID: 36989393
13. Zourdos MC et al. (2016). DUP vs traditional periodization for strength gains. J Strength Cond Res. PMID: 26398700
14. Grgic J et al. (2018). Effects of training frequency for muscular strength: A systematic review and meta-analysis. Sports Med. PMID: 29470825
15. Wolf M et al. (2025). Lengthened partial ROM resistance training is equally effective as full ROM training. PeerJ. PMID: 39959841
16. Wolf M et al. (2024). The effects of lengthened-partial range of motion resistance training of the limbs on arm and thigh muscle cross-sectional area: a multi-site cluster trial (preprint). SportRxiv. DOI: 10.51224/SRXIV.485
17. Pelland JC et al. (2025). The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains. Sports Med. PMID: 41343037
18. Piñero A et al. (2024). Throwing cold water on muscle growth: A systematic review with meta-analysis of the effects of postexercise cold water immersion on resistance training-induced hypertrophy. Eur J Sport Sci. 24(2):177-189. PMID: 38621735
19. Does Muscle Length Influence Regional Hypertrophy? A Systematic Review and Meta-Analysis. Int J Sports Med. PMID: 40570881

> **Note:** All citations are verifiable via PubMed or DOI.