Sub 3:15 Marathon Training Plan
Sub-3:15 requires running 4:37/km for 42.2 kilometres. That demands not just fitness but precise pacing discipline, excellent fuelling execution, and a training block that has built genuine aerobic power at threshold. This 20-week plan is the most demanding of the marathon series. It includes higher weekly mileage, more complex session structures, and race-specific work that begins earlier in the build than the sub-4 or sub-3:30 plans. It is designed for experienced runners who know how to train hard and recover properly.
Who This Plan Is For
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Experienced marathon runners with a current PB in the 3:20–3:30 range seeking a significant breakthrough
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Runners with a half marathon time of 1:30 or faster
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Athletes already running 50+ miles per week who need structure and specificity, not more mileage
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Runners who can commit to six sessions per week including double run days
Entry Requirements
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Half marathon time of 1:32 or faster within the past 4 months
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Current weekly mileage of 45–55 miles consistently over at least 8 weeks
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Experience with threshold intervals and long runs at goal pace
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No significant injury issues in the past 6 months
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Strong understanding of training zones and the ability to execute prescribed effort levels accurately
Plan Specifications
Weekly Training Hours 9-12 hours per week at peak.
The plan includes 6 sessions per week, including one double day. Recovery is non-negotiable.
Plan Length 20 weeks, including a 3-week taper
Delivery Platform TrainingPeaks (structured workouts with targets)
Sport Running
Key Sessions Included
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Long runs building to 38 kilometres, several of which include extensive marathon-pace sections
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VO2 max intervals - 5 × 1km to 6 × 1200m at 5K race effort with full recovery
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Threshold tempo runs - 35–50 minutes of continuous threshold running
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Double days in peak weeks - an easy morning run followed by a quality afternoon session
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Race-pace long runs in weeks 12–16 with the majority of the run at goal marathon pace
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Lactate clearance strides and neuromuscular activation work on easy days
What You Get
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Full 20-week structured plan in TrainingPeaks with session notes, pace and HR targets
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Detailed zone calibration guidance based on recent race performances
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Race-simulation long runs with pre-planned fuelling protocols built into session notes
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Performance management guidance - how to read CTL, ATL, and TSB through peak and taper
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Race week schedule including final sharpening sessions and competition-day routine
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PDF guide: advanced race execution strategy, pacing for a sub-3:15 course, fuel and hydration timing
How It Works - TrainingPeaks Delivery
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After purchase, you will receive an email with a link to connect the plan to your TrainingPeaks account. If you don't already have a TrainingPeaks account, you can create one for free - the free tier is sufficient for this plan.
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Once connected, every session will appear in your TrainingPeaks calendar on the correct day, with structured workout targets including pace zones, heart rate zones, duration, and session notes.
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Sessions sync automatically to Garmin, Wahoo, Apple Watch, and most other GPS devices via the TrainingPeaks app. You train to the targets on your device - no need to memorise sessions or carry notes.
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The plan starts from the date you choose at setup. If you have a specific race date, set that in TrainingPeaks and the plan will align automatically.
Coaching Instead?
If you'd like a coach to adapt this plan to your life, review your sessions, and support you through to race day, Essentials Coaching starts at £80/month for the first three months. Your training plan purchase price of £45 will be deducted from your first month's coaching fee if you upgrade within 30 days of purchase.
DISCLAIMER
This training plan is designed for general educational purposes and is not a substitute for personalised medical or coaching advice.
Before beginning any new training programme, consult a qualified medical professional, particularly if you have any pre-existing health conditions, injuries, or concerns. The targets and progressions within this plan are guides - if at any point training causes pain, illness, or excessive fatigue, rest and seek appropriate advice.
By purchasing this plan, you accept responsibility for how you apply it to your own training.
Barbour Performance Systems accepts no liability for injury or illness arising from the use of this plan.