What Are Yasso 800s?

Yasso 800s is a famous marathon workout created by Bart Yasso, former Chief Running Officer at Runner's World. The concept is brilliantly simple:

Your 800m time in minutes:seconds predicts your marathon time in hours:minutes.

The Formula

The Workout

Standard Protocol

• Warmup: 1-2 miles easy
• Intervals: 10 × 800m at goal pace
• Recovery: 400m jog (same time as 800m)
• Cooldown: 1-2 miles easy

Building Up

Start with fewer reps and build over your training cycle:

• Week 1-4: 4-5 × 800m
• Week 5-8: 6-7 × 800m
• Week 9-12: 8-10 × 800m

Does It Actually Work?

The Good ✅

• Easy to remember and calculate
• Motivating benchmark workout
• Good speed/endurance combination
• Works well for many runners

The Limitations ❌

• Not scientifically validated
• Doesn't account for course/weather
• Better predictor for 3:00-4:30 marathoners
• Individual variation is significant

Why It (Mostly) Works

The 800m interval hits multiple energy systems:

• Aerobic capacity
• Lactate tolerance
• Running economy
• Mental toughness

These are all crucial for marathon success.

Sample Workout for 4:00 Marathon Goal

Warmup: 1.5 miles easy
────────────────────────
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
800m @ 4:00 | 400m jog
────────────────────────
Cooldown: 1 mile easy
Total: ~8 miles with quality

Pro Tips

1. Don't obsess over the prediction — use it as one data point
2. Run on a track for accurate measurement
3. Stay consistent — all 10 reps should be similar pace
4. Recovery matters — jog, don't walk
5. Do it once every 2-3 weeks during marathon buildup

Alternative Predictors

Remember: Yasso 800s are a tool, not a guarantee. Use them alongside other workouts for the full picture!