Ben's Aerobic Base Builder

Workout - Ben's Aerobic Base Builder

• 10min @ 7'00''/km
• 16.0km @ 4'45''/km
• 5min @ 6'30''/km

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A breakdown of TRAINING FOR A HALF MARATHON PB | 20 MILE DOUBLE RUN DAY from Ben Is Running. Worth watching in full for context. The summary below covers the main takeaways so you can run this session.

Key points

• Double-run days (two runs in one day at conversational effort) let you build volume while keeping intensity low and heart rate controlled.
• Aim for an aerobic zone: heart rate 130 to 145 bpm (zone 2) to limit injury risk and avoid overtraining.
• Each run covers about 10 mi (16 km) at roughly 4:44 min/km (about 7:38 min/mi), holding a comfortable rhythm that builds the aerobic capacity you need for half-marathon speed.
• This approach works toward a ~70 min half-marathon (around 5:20 min/km pace) and fits into your week 2 to 3 times.

Workout example

1. Morning run. 10 mi (16 km) easy, HR 135 to 145 bpm, around 4:44 min/km.
2. Refuel with protein and carbs. Drink water.
3. Evening run. Another 10 mi (16 km) on the same route, same HR range and pace.
4. Day total: 20 mi (32 km) of aerobic running.

Practical tips

• Wear a heart-rate monitor to stay honest with pacing.
• Splitting the mileage across two sessions reduces stress on the body and lowers injury risk.
• After each run, eat protein and carbs within 30 minutes (scrambled eggs, avocado, bacon).
• Run the same course at the same effort. Adjust for conditions like rain if needed, but stay in zone 2.

Closing note Try a double-run day and set the distances and paces to your fitness in the Pacing app.

Watch the full Ben Is Running video for the detailed explanation.

References

• TRAINING FOR A HALF MARATHON PB | 20 MILE DOUBLE RUN DAY - YouTube (YouTube Video)