18-Week Flexible Half Marathon Training Plan
Mileage Guidelines:
Beginner: Lower end of ranges (15-35 miles/week peak)
Intermediate: Higher end of ranges (20-48 miles/week peak)
Pace Guidelines:
Easy: Conversational pace, can speak in full sentences
Tempo: Comfortably hard, sustainable for 45-60 minutes
Threshold: Hard but sustainable, 10K effort
Interval: 5K effort, hard breathing
10K Pace: Slightly faster than threshold
Strides: Relaxed fast running, 85-90% effort, 20-30 seconds
Key:
SOS = Something of Substance (quality workout)
XT = Cross-training (cycling, swimming, etc.)
Numbers represent mileage ranges (Beginner-Intermediate)
This evidence-based 18-week half marathon plan progresses through four distinct phases: Base Building (weeks 1-6) establishes your aerobic foundation with mostly easy running and basic speed work, Development (weeks 7-12) introduces structured quality sessions including intervals and tempo runs, Race Preparation (weeks 13-16) shifts focus to half marathon-specific training with goal pace practice, and finally a Taper (weeks 17-18) reduces volume while maintaining sharpness for race day.
Built on the proven 80/20 intensity distribution, the plan offers flexible mileage ranges that accommodate both beginners (12-32 miles/week peak) and intermediates (18-48 miles/week peak), ensuring you can adapt the training to your current fitness level and life circumstances.
Each week follows a consistent structure with 2-3 quality sessions (SOS workouts), progressive long runs, abundant easy running for recovery, and strategic rest days, synthesizing the best elements from Jack Daniels, Hansons Method, David Roche, and other leading methodologies into a practical, sustainable approach that builds both physical fitness and mental confidence for race day success.
Phase 1: Base Building (Weeks 1-6)
Focus: Aerobic development, movement patterns, gradual adaptation
Phase 2: Development (Weeks 7-12)
Focus: VO2max development, lactate threshold, increased quality
Phase 3: Race Preparation (Weeks 13-16)
Focus: Half marathon specificity and race pace confidence
Phase 4: Taper (Weeks 17-18)
Focus: Recovery while maintaining neuromuscular sharpness
