Half Marathon Sub-1:45: A 16-Week Build of Threshold and Race Pace

The Sub-1:45 Barrier

A half marathon time of 1:45:00 corresponds to an average pace of 4:58 min/km. To break this line, your lactate threshold pace needs to fall around 4:35–4:40 min/km, with a VDOT of roughly 49–50. This plan assumes your current half marathon ability is about 1:50 (pace 5:13), and over 16 weeks we’re squeezing out 15 seconds per kilometer—in the advanced range, this is “difficult but reasonable.”

Why Threshold Dominates

At the 1:45 level, the limiting factor shifts from “insufficient aerobic volume” to “whether you can hold near-threshold intensity for 21 kilometers.” Therefore, the weekly training ratio should be: roughly 75–80% easy volume + 15% threshold + 5–10% VO2max. Threshold work is the engine, VO2max is the spark plug, and easy runs are the fuel tank—if any of the three falls out of balance, you’ll stall.

Core Workout Design

16-Week Periodization Highlights

• Weeks 1–5: Build volume (weekly 50→62K), threshold work centered on “cruise intervals,” long run 14→18K.
• Weeks 6–11: Threshold sessions extend to continuous 35–40-minute tempo; long run pushes to 22K with the final 8K @ 4:58. In week 9, do a 10K time trial as a checkpoint—you should land within 47:30.
• Weeks 12–14: Peak. Week 13 features a 19K simulation race: first 9K easy, final 10K @ 4:55.
• Weeks 15–16: Taper. Keep 1 short threshold session (2×2K) and 1 long run (12K including 4K @ HMP), and clear out the rest.

Training to “Hold On” at Race Pace

The key move for breaking 1:45 is to “stack the HMP segment behind fatigue.” For example, in a 22K long run, run the first 12K at 6:00 pace to build fatigue, then immediately switch to 4:58 for the final 10K. This simulates the muscular and psychological state after 11K of racing—far more meaningful than running 10K @ 4:58 when fresh. Those who can hold pace under this kind of fatigue won’t blow up at 16K on race day.

Advanced Fueling Strategy

Within 2 hours, glycogen stores are theoretically sufficient, but to sustain an intensity near threshold like 4:58, carbohydrate oxidation rates are high. It’s recommended to take in 30–40g of carbs per hour during the race: one gel at 7K and one at 14K. In the 2–3 days before the race, do a mild glycogen supercompensation (carbs at 65–70% of total calories, no need to binge).

Self-Check Signals

If your threshold pace drops more than 5 seconds/km for two consecutive sessions, your resting heart rate rises above 7 bpm, or the HMP segment feels unusually hard, these are early signs of overtraining—immediately insert 4–5 days of reduced volume.

Coach’s perspective: 1:45 isn’t about “running faster”—it’s about “enduring 20 more minutes at the uncomfortable threshold edge.” If your threshold sessions always feel “great,” then the intensity is wrong; you should want to stop at the end of every rep, yet still be able to go again on the next one.

Related Reading

• Half Marathon Sub-1:45 Training: Speed-Breakthrough Strategies for Intermediate Runners
• Half Marathon Sub-1:45: Lactate Threshold Training for Advanced Runners
• From 90 to 75 Minutes in the Half Marathon: A 60K Weekly Advanced Plan
• Half Marathon Sub-1:45 Training Plan: A Dual-Track Boost in Speed and Lactate Tolerance