Half Marathon Training 2025
Master 13.1 Miles with Science-Based Training
By Glen Meade
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January 20, 2025
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16 min read
The half marathon represents the perfect distance—challenging enough to demand respect, accessible enough for ambitious goals, and long enough to reward smart training. At 13.1 miles, it's where speed meets endurance, where tactical racing shines, and where personal bests feel achievable with the right preparation.
Having completed multiple Ironman 70.3 races and coached dozens of runners to half marathon success, I've learned that the 21K distance rewards those who balance aerobic development with targeted speed work. This guide provides everything you need to train smart, race tactically, and achieve your half marathon goals in 2025.
🎯 What You'll Achieve in 12 Weeks
- ✅ Complete your first half marathon with confidence
- ✅ Run negative splits using proven pacing strategies
- ✅ Develop the aerobic base for sustained 13.1-mile effort
- ✅ Master race-day fueling and hydration tactics
- ✅ Build speed with targeted tempo and interval training
- ✅ Prevent injury with smart progression and recovery
- ✅ Race tactically for optimal performance
- ✅ Set new personal records with confidence
📋 Complete Training Guide
🧠 Half Marathon Training Philosophy
⚡ The 80/20 Training Principle
Half marathon success follows the proven 80/20 rule: 80% of your training should be at an easy, conversational pace to build your aerobic base, while 20% consists of targeted speed work to develop lactate threshold and VO2 max power.
- • Builds mitochondrial density
- • Improves fat oxidation
- • Develops capillary networks
- • Allows high training volume
- • Raises lactate threshold
- • Improves running economy
- • Develops neuromuscular power
- • Practices race-specific pacing
🏃♂️ Aerobic Base Building
The foundation of half marathon success is a robust aerobic system. Easy miles at 65-75% max heart rate build the metabolic machinery needed for sustained effort.
- • Increased stroke volume
- • Enhanced oxygen delivery
- • Improved fat utilization
- • Greater mitochondrial capacity
⚡ Lactate Threshold Development
Tempo runs and threshold intervals improve your body's ability to clear lactate, allowing you to sustain faster paces for the 13.1-mile distance.
- • 15K-half marathon race pace
- • "Comfortably hard" effort
- • 85-90% max heart rate
- • 20-40 minute sustained efforts
🚀 Speed Development
Interval training at 5K-10K pace develops VO2 max and running economy, providing the speed reserve needed for strong finishing kicks.
- • 3-8 minute intervals
- • 90-95% max heart rate
- • Equal work-to-rest ratio
- • 5K-10K race pace efforts
📅 Complete 12-Week Half Marathon Plan
Phase 1: Base Building (Weeks 1-4)
Build your aerobic foundation with gradually increasing mileage. Focus on running all easy miles truly easy while establishing a consistent routine.
Week 1-2: Foundation
Week 3-4: Building
Phase 2: Build Phase (Weeks 5-8)
Introduce quality workouts while continuing to build mileage. Add tempo runs and interval training to develop lactate threshold and speed.
Week 5-6: Quality Introduction
Week 7-8: Peak Build
Phase 3: Peak & Taper (Weeks 9-12)
Peak fitness development followed by strategic taper. Practice race pace and prepare your body for optimal race day performance.
Week 9-10: Peak Training
Week 11-12: Taper & Race
🎯 Half Marathon Pace Strategies
📊 Optimal Pacing Strategy
Research shows the most effective half marathon pacing is slightly negative splits: run the first 10K conservatively, settle into goal pace for miles 7-10, then finish strong in the final 5K if you have energy remaining.
- • Miles 1-3: Goal pace + 10-15 seconds per mile
- • Miles 4-8: Settle into goal pace
- • Miles 9-11: Hold goal pace with focus
- • Miles 12-13.1: Gradually increase if feeling strong
🧮 Calculate Your Target Paces
Use our pace calculator to determine your optimal training and racing paces based on your current fitness level.
🥉 Sub-2:00 Half Marathon
🥈 Sub-1:45 Half Marathon
🥇 Sub-1:30 Half Marathon
💪 Essential Half Marathon Workouts
🏃♂️ Tempo Runs
The cornerstone of half marathon training. Tempo runs develop your lactate threshold—the pace you can sustain for roughly an hour of hard effort.
- • 20-minute tempo (after 2-mile warmup)
- • 3x8 minutes @ tempo pace (2-min recovery)
- • 30-40 minute sustained tempo
- • 2x15 minutes @ tempo (5-min recovery)
- • "Comfortably hard" effort level
- • 15K-half marathon race pace
- • 85-90% maximum heart rate
- • Controlled breathing pattern
⚡ Interval Training
Speed intervals develop VO2 max and running economy, providing the speed reserve needed for strong half marathon performance.
- • 6x800m @ 5K pace (400m recovery)
- • 5x1000m @ 10K pace (2-min recovery)
- • 4x1200m @ 10K pace (400m recovery)
- • 3x1600m @ 10K pace (3-min recovery)
- • Equal work-to-rest ratio
- • Focus on consistent splits
- • 90-95% maximum heart rate
- • Recovery should be active jogging
🎯 Race Pace Runs
Practice sustained efforts at goal half marathon pace to build confidence and teach your body the target rhythm.
- • Week 5: 3 miles @ HM pace
- • Week 7: 5 miles @ HM pace
- • Week 9: 6-7 miles @ HM pace
- • Week 11: 3x2 miles @ HM pace
- • Practice nutrition timing
- • Build pacing confidence
- • Develop race rhythm
- • Test gear and clothing
🏃♀️ Long Runs
Build the aerobic endurance needed to sustain race pace for 13.1 miles. Long runs are where you develop race-day confidence.
- • Weeks 1-4: 6-10 miles
- • Weeks 5-8: 10-14 miles
- • Weeks 9-10: 15-16 miles
- • Week 11: 10-12 miles (taper)
- • Progressive: Start easy, finish moderate
- • Split: Easy miles with HM pace segments
- • Simulator: Practice race day routine
- • Steady: Consistent moderate effort
🍌 Half Marathon Nutrition Strategy
⚡ Fueling Strategy Overview
The half marathon sits at the perfect distance where fueling becomes optional but beneficial. While your body can complete 13.1 miles on stored glycogen, strategic fueling can prevent late-race fade and improve performance.
- • Miles 1-6: Water only (if cool) or sports drink
- • Miles 7-9: 15-20g carbs if feeling energy dip
- • Miles 10-13.1: Focus on hydration and pushing pace
💧 Hydration Guidelines
- • Pre-race: 16-20oz fluid 2-3 hours before
- • Start line: 6-8oz 15-30 minutes before
- • During race: 3-6oz every 15-20 minutes
- • Total intake: 12-24oz for full race
- • Weather adjustment: Increase 25-50% in heat
🍯 Carb Fueling Options
- • Sports drinks: Gatorade, Powerade (easiest option)
- • Gels: GU, Hammer, Maurten (15-25g carbs)
- • Chews: Clif Bloks, Honey Stinger
- • Natural: Dates, banana pieces, honey
- • Timing: Mile 6-8 if planning to fuel
🥐 Pre-Race Meal Strategy
- • Moderate carb loading (not excessive)
- • Familiar foods only
- • Good hydration throughout day
- • 300-400 calories of carbs
- • Low fiber, moderate protein
- • Examples: Bagel with banana, oatmeal with honey
⚠️ Fueling Mistakes to Avoid
- • Over-fueling: More isn't always better for 13.1 miles
- • New products: Never try anything new on race day
- • Too much too late: Avoid heavy fueling after mile 9
- • Ignoring weather: Adjust strategy for temperature
- • Dehydration: Check urine color for hydration status
🏁 Race Day Execution
🎯 The Perfect Half Marathon Race Plan
Successful half marathon racing is about patience early, confidence in the middle, and strength at the finish. Here's your mile-by-mile execution strategy.
🚀 Start: Miles 1-3
- • Pace: Goal pace + 10-15 seconds/mile
- • Effort: Should feel easy and controlled
- • Position: Don't get caught up in the pack
- • Breathing: Relaxed, rhythmic pattern
- • Form: Stay relaxed, conserve energy
- • Fueling: Hydrate if warm, otherwise skip
💪 Build: Miles 4-8
- • Pace: Settle into goal pace
- • Effort: Comfortably hard, controlled
- • Focus: Find your rhythm and lock in
- • Mental: Stay present, positive self-talk
- • Fueling: Consider 15-20g carbs if needed
- • Check-in: How do legs and breathing feel?
🏆 Finish: Miles 9-13.1
- • Miles 9-11: Hold goal pace with focus
- • Mile 12: Time to assess - can you push?
- • Final 1.1: Give everything you have left
- • Mental: "I've trained for this moment"
- • Form: Stay tall, drive with arms
- • Kick: Sprint final 200m if possible
✅ Pre-Race Checklist
- □ Lay out all race gear
- □ Check weather forecast
- □ Eat familiar dinner
- □ Set multiple alarms
- □ Review race course map
- □ Visualize race execution
- □ Wake up 3-4 hours before start
- □ Eat pre-race meal
- □ Hydrate gradually
- □ Arrive 60-90 minutes early
- □ 15-minute dynamic warm-up
- □ Final bathroom visit
❓ Half Marathon Training FAQ
How long should I train for my first half marathon?
A 12-week training plan is ideal for most beginners with a base of running 3-4 times per week. If you're completely new to running, build a 4-6 week base phase first, running 20-30 minutes every other day. More experienced runners can use shorter 8-10 week plans focused on half marathon-specific fitness.
What pace should I run during training?
Follow the 80/20 rule: 80% of your miles should be at an easy, conversational pace (you should be able to talk in full sentences). The remaining 20% consists of tempo runs at half marathon pace and intervals at 5K-10K pace. Use our race pace calculator to determine your specific training zones.
Do I need to run longer than 13.1 miles in training?
Yes, running 14-16 miles in training builds the aerobic endurance and mental confidence needed for race day. Your longest runs should be done at an easy pace, 30-90 seconds per mile slower than your goal race pace. This teaches your body to run efficiently at distance without the stress of race pace.
How important is nutrition during a half marathon?
For most runners, the half marathon can be completed on stored glycogen without fueling. However, taking 15-20g of carbs between miles 6-8 can prevent late-race energy dips, especially if you're racing in warm weather or targeting an aggressive time. Practice your fueling strategy during long training runs.
What's the best pacing strategy for race day?
Run slightly negative splits: start 10-15 seconds per mile slower than goal pace for the first 3 miles, settle into goal pace for miles 4-10, then push the pace in the final 5K if you're feeling strong. This conservative start preserves energy for a strong finish and prevents the devastating effects of starting too fast.
How many days should I rest before race day?
Begin tapering 2 weeks before race day. In the final week, reduce your mileage by 50-70% while maintaining some intensity with short intervals or strides. Take 2 complete rest days before the race, or do easy 20-30 minute jogs with a few 20-second strides to keep your legs feeling fresh.
What should I do if I miss training runs due to illness or injury?
Missing 3-5 days won't significantly impact your fitness. Focus on returning gradually and don't try to make up missed mileage. If you miss more than 10-14 days of training, consider adjusting your goal time or postponing your race. It's better to arrive at the start line slightly undertrained than injured.
Can I run a half marathon without doing speed work?
Yes, you can complete a half marathon on easy running alone, but targeted speed work will significantly improve your time and racing experience. Tempo runs build the specific fitness needed to sustain half marathon pace, while intervals develop the speed reserve that makes race pace feel more comfortable.
🏁 Your Half Marathon Success Journey
The half marathon is the perfect distance to challenge yourself, build fitness, and experience the thrill of distance running. With 12 weeks of smart, progressive training, you'll develop the aerobic base, speed, and confidence needed to achieve your goals.
Remember: the key to half marathon success lies in patience during the early miles, confidence in your training during the middle portion, and the courage to push when it counts in the final 5K. Trust your preparation, execute your race plan, and enjoy the incredible accomplishment of completing 13.1 miles.
Your half marathon PR is waiting—now go train smart and make it happen!
📚 Related Training Guides
10K Training Plan 2025
8-week program to master the 10K distance with pace strategies and speed development.
Marathon Training Guide 2025
Complete 16-week training plan for conquering the full 26.2-mile distance.
Running Pace Training Guide
Master different training paces for improved performance and race execution.