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Endurance

20-week half-iron distance training program

v1

A periodized 20-week triathlon program focusing on aerobic foundation, lactate threshold, and race specificity for 70.3 distance.

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triathlonendurancehalf-ironmantraining-plan

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FitnessGrid is an AI coach that plans your week and adapts as you go. Install 20-week half-iron distance training program and your coach will follow this protocol every week, learn from what you actually do, and adjust on the fly.

  • Your coach builds the week from this skill
  • Adapts to your actual progress, not a static template
  • Free to start — no credit card, ~60 seconds to set up

Procedure

  1. Initial Assessment and Setup

    • Call get_user_preferences to identify the user's current fitness level and target race date.
    • Call compute_hr_zones to establish Zone 2 (Aerobic) and Zone 4 (Threshold) parameters, which will guide the 80/20 intensity distribution.

  2. Phase 1: Base Phase (Weeks 1–8)

    • Initialize the first 8 weeks using create_week.
    • Volume Planning: Start Week 1 with approximately 3,900yd swimming, 2h 45m cycling, and 1h 45m running.
    • Progression: Apply the "10% Rule," increasing total weekly volume by no more than 10% each week.
    • Structure:
      • Mondays: Strength (High weight, 3–5 reps).
      • Tuesdays: Swim (Technique - focus on "Reach and Glide").
      • Wednesdays: Run (Zone 2 - focus on "Quiet Feet").
      • Thursdays: Bike (Aerobic - 85–95 RPM cadence).
      • Fridays: Swim (Endurance - sustained aerobic).
      • Saturdays: Long Bike/Brick (Aerobic endurance).
      • Sundays: Long Run (Zone 2 - time on feet).
    • Deload: Schedule Week 4 and Week 8 as recovery weeks. Reduce total volume by 25–60% while maintaining brief Zone 3/4 intervals.

  3. Phase 2: Build Phase (Weeks 9–14)

    • Shift focus to Lactate Threshold and "Sweet Spot" intervals.
    • Continue the 3:1 loading ratio (Weeks 9–11 load, Week 12 deload).
    • Increase the frequency of "Brick" workouts (bike-to-run transitions).
    • Monitor cumulative fatigue and ensure 80% of sessions remain at low intensity.

  4. Phase 3: Peak Phase (Weeks 15–20)

    • Increase volume toward the Week 17 peak (approx. 6,700yd swim, 5h 20m cycle, 3h 7m run).
    • Incorporate race-pace efforts in all three disciplines.
    • Taper: Initiate a 10-day taper starting in Week 19, significantly reducing volume to ensure freshness for race day in Week 20.

  5. Workout Generation

    • Use create_workout for specific sessions, embedding coaching cues:
      • Swim: "Reach and Glide" to reduce drag.
      • Bike: "Consistent Cadence" (85–95 RPM).
      • Run: "Quiet Feet" (170–180 bpm cadence).

  6. Ongoing Management

    • Every 4th week, use plan_week to generate the deload schedule.
    • Adjust volume if the user reports excessive fatigue or misses sessions, adhering to the 10% limit when resuming progression.

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