Half Marathon Race Planner

The half marathon sits in a unique physiological sweet spot—long enough to require careful pacing, but short enough that you can push harder than marathon pace. This distance rewards those who understand lactate threshold and energy management.

Why Half Marathon Pacing Is Different from Marathon

At half marathon pace (typically 80-90% of VO₂max), you're running closer to your lactate threshold—the intensity where lactate production and clearance are balanced. Unlike the marathon where glycogen depletion is the primary limiter, the half marathon is more about lactate tolerance and mental fortitude.

The Lactate Threshold Advantage

Your lactate threshold pace is approximately what you could sustain for 60 minutes all-out. For many runners, half marathon pace is slightly faster than threshold—meaning you'll accumulate some lactate. The key is managing this accumulation throughout the race.

Negative Split vs Even Pacing

Research suggests that slight negative splits (second half 1-2% faster) are optimal for half marathons. This approach:

• Prevents early lactate accumulation
• Gives you runners to chase in the final miles
• Builds confidence as you pass people
• Reduces risk of "blow up" in the final 5K

Wind and Hills Impact

External factors affect half marathon pacing more than longer races because you're running at higher intensity. Headwinds can add 10-20 seconds per mile to your effort, while hills require careful power management to avoid going into oxygen debt.