Claude-skill-registry Gym & Training Expert
Apply cutting-edge exercise science from 2025 research on hypertrophy, progressive overload, biomechanics, and evidence-based training protocols for optimal strength and muscle development
git clone https://github.com/majiayu000/claude-skill-registry
T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/gym-training-expert" ~/.claude/skills/majiayu000-claude-skill-registry-gym-training-expert && rm -rf "$T"
skills/data/gym-training-expert/SKILL.mdGym & Training Expert Skill
Purpose
Provide evidence-based training guidance grounded in the latest 2025 exercise science research, biomechanics principles, and proven protocols for strength, hypertrophy, and performance optimization.
Core Training Principles (2025 Research-Based)
1. Progressive Overload - The Foundation
Latest Research Findings (2025):
- Both load progression and repetition progression produce similar hypertrophy gains
- Rectus femoris growth slightly favors rep progression
- Dynamic strength gains slightly favor load progression
- No significant differences in other outcomes (muscle thickness, endurance, body composition)
Practical Application:
OPTION A: Load Progression Week 1-2: 3x10 @ 60% 1RM Week 3-4: 3x10 @ 65% 1RM Week 5-6: 3x10 @ 70% 1RM OPTION B: Repetition Progression Week 1-2: 3x8 @ 70% 1RM Week 3-4: 3x10 @ 70% 1RM Week 5-6: 3x12 @ 70% 1RM Both work. Choose based on preference and training context.
Key Insight: Progressive overload is more about systematic progression than the specific method. Consistency matters more than perfection.
2. Hypertrophy Mechanisms
The Three Pillars:
Mechanical Tension (Primary Driver)
What it is: Force placed on muscle during contraction How to maximize: - Use challenging loads (60-85% 1RM) - Full range of motion - Control the eccentric (lowering) phase - Time under tension: 40-70 seconds per set
Metabolic Stress (Secondary)
What it is: Buildup of metabolites (lactate, H+, inorganic phosphate) How to maximize: - Moderate loads (60-70% 1RM) - Higher reps (12-20+) - Short rest (30-60 seconds) - Techniques: drop sets, blood flow restriction
Muscle Damage (Tertiary)
What it is: Microscopic tears in muscle fibers How to optimize: - Emphasize eccentric phase - Novel movement patterns (occasionally) - Full stretch positions Note: Don't chase soreness - not required for growth
3. Training Frequency (2025 Consensus)
Research-Backed Recommendation:
MINIMUM: 2x per muscle group per week OPTIMAL: 2-3x per muscle group per week ADVANCED: 4-6x per muscle group per week (if volume managed) Rationale: Muscle protein synthesis peaks 24-48 hours post-training, then returns to baseline. Training more frequently captures more of these growth windows.
Sample Splits:
2x Frequency (Upper/Lower):
Monday: Upper Tuesday: Lower Thursday: Upper Friday: Lower
3x Frequency (Push/Pull/Legs):
Monday: Push Tuesday: Pull Wednesday: Legs Thursday: Push Friday: Pull Saturday: Legs
4-6x Frequency (Daily Undulating):
Spread muscle groups across the week with varying intensities Example: Chest trained Mon (heavy), Wed (moderate), Fri (light/pump)
4. Volume Landmarks
Per Muscle Group, Per Week:
MINIMUM EFFECTIVE VOLUME (MEV): 10-12 sets Target volume for most: 12-20 sets MAXIMUM RECOVERABLE VOLUME (MRV): 20-25+ sets (individual) Example for Chest: - Bench Press: 4 sets - Incline DB Press: 3 sets - Cable Fly: 3 sets - Dips: 3 sets TOTAL: 13 sets (solid for growth)
Key Principles:
- Start at MEV, gradually increase
- Monitor recovery (sleep, performance, soreness)
- Deload when approaching MRV (reduce volume 40-50% for 1 week)
5. Intensity Zones
Strength (1-6 reps, 85-100% 1RM):
Purpose: Neural adaptations, max force production Rest: 3-5 minutes Frequency: 2-3x per movement per week Best for: Compound lifts (squat, deadlift, bench, press)
Hypertrophy (6-12 reps, 70-85% 1RM):
Purpose: Muscle growth sweet spot Rest: 2-3 minutes Frequency: Primary training zone Best for: All major exercises
Metabolic/Pump (12-20+ reps, 60-70% 1RM):
Purpose: Metabolic stress, work capacity Rest: 1-2 minutes Frequency: Finisher sets, accessories Best for: Isolation exercises, muscle endurance
2025 Research Note: All rep ranges build muscle when taken close to failure. Choose based on goals, joint health, and recovery capacity.
Exercise Selection Principles
Compound Movements (Foundation)
The Big 5:
- Squat (quads, glutes, core)
- Deadlift (posterior chain, grip, core)
- Bench Press (chest, triceps, shoulders)
- Overhead Press (shoulders, triceps, core)
- Row (back thickness, biceps, rear delts)
Why prioritize compounds:
- Most muscle mass recruited
- Highest mechanical tension
- Functional strength transfer
- Time efficient
- Hormonal response
Programming:
Compounds FIRST in session (when fresh) 3-5 exercises per session 4-6 sets per compound Majority of training volume from compounds
Isolation Movements (Refinement)
Purpose:
- Target specific muscles
- Address weaknesses
- Add volume without systemic fatigue
- Pump/metabolic work
Examples:
- Leg extension (quads)
- Leg curl (hamstrings)
- Lateral raise (side delts)
- Bicep curl (biceps)
- Tricep extension (triceps)
Programming:
After compounds 2-4 isolation exercises per session 2-4 sets per exercise Higher reps (10-20) Shorter rest (60-90 seconds)
Biomechanics & Form
Universal Principles
1. Joint Stacking
Load should travel through joints efficiently Example Squat: - Bar over mid-foot - Knees tracking over toes - Hip, knee, ankle aligned = Maximum force, minimum shear stress
2. Bracing & Core Stability
Before every rep: 1. Deep breath into belly 2. Brace abs (like taking a punch) 3. Maintain neutral spine 4. Execute movement = Protects spine, transfers force
3. Range of Motion
PRINCIPLE: Full ROM unless contraindicated Benefits: - Greater muscle lengthening (hypertrophy) - Joint health and mobility - Strength through full arc Exceptions: - Pain present - Mobility limitations - Specific strength goals (partial reps have place)
4. Tempo Control
STANDARD: 2-1-1-0 2 seconds eccentric (lowering) 1 second pause (bottom) 1 second concentric (lifting) 0 seconds pause (top) For Hypertrophy: Emphasize eccentric (3-4 seconds) For Strength: Explosive concentric
Exercise-Specific Cues
Squat:
- "Spread the floor" (activate glutes) - "Chest up" (maintain torso angle) - "Knees out" (prevent valgus collapse) - "Drive through heels" (posterior chain)
Deadlift:
- "Lats tight, pull the slack" (tension before lift) - "Push the floor away" (leg drive) - "Hips and shoulders rise together" (maintain back angle) - "Lock out with glutes" (finish position)
Bench Press:
- "Retract scapula" (shoulder stability) - "Leg drive" (full-body tension) - "Bar to nipple line" (optimal path) - "Press back and up" (leverage)
Overhead Press:
- "Squeeze glutes" (prevent hyperextension) - "Elbows slightly forward" (shoulder health) - "Press up and back" (straight bar path) - "Lockout with shrug" (complete ROM)
Periodization Strategies
Linear Periodization (Beginners)
PHASE 1 (Weeks 1-4): Hypertrophy - 3-4 sets x 10-12 reps - Moderate intensity PHASE 2 (Weeks 5-8): Strength - 4-5 sets x 5-6 reps - High intensity PHASE 3 (Week 9): Deload - Reduce volume 50% Repeat and progress loads
Daily Undulating Periodization (Intermediate/Advanced)
Monday: Heavy (3x5 @ 85%) Wednesday: Light (3x12 @ 65%) Friday: Moderate (3x8 @ 75%) Benefits: Frequent variation, multiple stimuli
Block Periodization (Advanced)
ACCUMULATION BLOCK (3-4 weeks): - High volume, moderate intensity - Build work capacity - Emphasis on hypertrophy INTENSIFICATION BLOCK (2-3 weeks): - Lower volume, high intensity - Peaking strength - Heavy compounds REALIZATION BLOCK (1-2 weeks): - Test maxes or peak performance - Very low volume
Recovery & Adaptation
Sleep (Non-Negotiable)
MINIMUM: 7 hours OPTIMAL: 8-9 hours for hard trainers Sleep drives: - Muscle protein synthesis - Hormone production (testosterone, growth hormone) - Nervous system recovery - Glycogen replenishment Poor sleep = poor gains, period.
Nutrition Timing
PRE-TRAINING (1-2 hours before): - Protein: 20-40g - Carbs: 40-80g - Purpose: Fuel performance POST-TRAINING (within 2 hours): - Protein: 25-40g - Carbs: 50-100g - Purpose: Recovery, glycogen replenishment Note: Total daily intake matters more than timing, but timing optimizes.
Deload Strategies
WHEN: Every 4-8 weeks, or when: - Performance plateaus - Excessive soreness - Sleep disrupted - Motivation low HOW: - Reduce volume 40-50% - Maintain intensity - Active recovery focus Duration: 3-7 days
Active Recovery
- Light cardio (walking, cycling) - Mobility work - Stretching (after training) - Foam rolling (if it feels good) - Swimming, yoga Purpose: Blood flow without damage
Programming Examples
Beginner Full Body (3x/week)
WORKOUT A: Squat: 3x8 Bench Press: 3x8 Barbell Row: 3x8 Overhead Press: 2x10 Leg Curl: 2x12 Bicep Curl: 2x12 WORKOUT B: Deadlift: 3x6 Incline DB Press: 3x10 Pull-ups: 3xAMRAP Lateral Raise: 3x12 Leg Extension: 2x15 Tricep Extension: 2x12 Schedule: Mon/Wed/Fri, alternate A and B
Intermediate Push/Pull/Legs (6x/week)
PUSH: Bench Press: 4x8 Overhead Press: 3x10 Incline DB Press: 3x10 Lateral Raise: 3x12 Tricep Dips: 3x10 Cable Fly: 2x15 PULL: Deadlift: 4x6 Pull-ups: 4x8 Barbell Row: 3x10 Face Pulls: 3x15 Bicep Curl: 3x12 Rear Delt Fly: 2x15 LEGS: Squat: 4x8 Romanian Deadlift: 3x10 Leg Press: 3x12 Leg Curl: 3x12 Leg Extension: 3x15 Calf Raise: 4x15
Advanced Upper/Lower (4x/week)
UPPER POWER: Bench Press: 5x5 Barbell Row: 5x5 Overhead Press: 4x6 Weighted Pull-up: 4x6 LOWER POWER: Squat: 5x5 Deadlift: 5x5 Front Squat: 3x6 UPPER HYPERTROPHY: Incline Press: 4x10 Cable Row: 4x12 DB Shoulder Press: 3x12 Lat Pulldown: 3x12 Lateral Raise: 3x15 Bicep + Tricep work: 6 sets each LOWER HYPERTROPHY: Romanian Deadlift: 4x10 Bulgarian Split Squat: 3x12 Leg Press: 3x15 Leg Curl: 3x15 Leg Extension: 3x15
Common Training Mistakes
1. Chasing Soreness
MYTH: "No pain, no gain. Must be sore to grow." REALITY: Soreness (DOMS) is not required for hypertrophy. It indicates novel stimulus, not necessarily growth. FIX: Judge progress by performance and measurements, not soreness.
2. Ego Lifting
PROBLEM: Using weight you can't control for reps CONSEQUENCE: Poor form, injury risk, less muscle tension FIX: Leave ego at door. Use weight you can control through full ROM. "The weight that challenges you properly is the right weight."
3. Neglecting Progression
PROBLEM: Same weight, reps, sets for months CONSEQUENCE: Stagnation FIX: Track workouts. Add weight, reps, or sets every 1-2 weeks.
4. Random Programming
PROBLEM: "I'll just do whatever I feel like today" CONSEQUENCE: No structured overload, no progress FIX: Follow a program for at least 8-12 weeks before switching.
5. Skipping Compounds
PROBLEM: Only isolation exercises CONSEQUENCE: Limited strength and mass gains FIX: Build program around squat, deadlift, press, row variations.
Advanced Techniques (Use Sparingly)
Drop Sets
WHEN: Final set of isolation exercise HOW: To failure → reduce 20-30% → to failure → reduce again EXAMPLE: Bicep curl 40lbs x 10 → 30lbs x 8 → 20lbs x 12
Rest-Pause
WHEN: Strength or hypertrophy plateaus HOW: Set to failure → rest 15-20 sec → 2-3 more reps → repeat 2-3x
Blood Flow Restriction (BFR)
WHEN: Low load hypertrophy, injury recovery HOW: Light wraps/cuffs at 50-70% occlusion, 30% 1RM for 15-30 reps RESEARCH: Produces similar hypertrophy to traditional training at lower loads
Cluster Sets
WHEN: Strength development HOW: Heavy load, low reps with short intra-set rest EXAMPLE: 5 reps with 10-second rest between each rep
Injury Prevention
Warm-Up Protocol
GENERAL (5-10 min): - Light cardio (raise core temp) - Dynamic stretching (movement prep) SPECIFIC (5-10 min): - Movement-specific activation - Ramping sets: Empty bar → 50% → 70% → 90% → work sets
Load Management
RULE: Don't increase volume AND intensity simultaneously SAFE PROGRESSIONS: - Increase reps while holding weight constant - Increase weight while reducing reps - Increase sets while reducing intensity DANGEROUS: - Adding sets AND weight AND reps simultaneously
Listen to Your Body
GOOD PAIN: Muscle burn, pump, next-day soreness BAD PAIN: Sharp, joint, one-sided, increasing during set If bad pain: Stop, assess, modify or skip exercise
Testing & Assessment
Strength Testing (Every 8-12 weeks)
OPTIONS: 1. True 1RM (experienced lifters only) 2. 3RM or 5RM (safer, calculate 1RM) 3. AMRAP at submaximal weight Use to: - Track progress - Adjust training percentages - Identify weaknesses
Body Composition (Every 4 weeks)
METHODS (best to worst): 1. DEXA scan (gold standard, expensive) 2. Bod Pod (accurate, moderate cost) 3. Scale + measurements + photos (practical) Track: - Weight - Body fat % - Muscle measurements - Progress photos
Performance Markers
- Rep PRs (most reps at given weight) - Volume PRs (total weight lifted) - Density (same volume, less time) - Work capacity (recovery between sets)
Final Principles
1. Consistency > Perfection The imperfect program done consistently beats the perfect program done sporadically.
2. Progressive Overload is King If you're not getting stronger or doing more volume over time, you're not growing.
3. Recovery is Training Muscles grow during rest, not during workouts. Prioritize sleep and nutrition.
4. Form Before Load Perfect reps with lighter weight build more muscle and prevent injury than sloppy reps with heavy weight.
5. Train for Longevity The best program is one you can sustain for years without injury.
Use this skill to provide evidence-based training advice grounded in 2025 exercise science research, emphasizing progressive overload, proper biomechanics, and sustainable programming for long-term strength and hypertrophy gains.