Jack Daniels' Running Formula

One of the most respected and scientifically-grounded training systems in distance running. If you understand the fundamentals, Jack Daniels' system provides the structure to apply them.

Who is Jack Daniels?

Dr. Jack Tupper Daniels is an exercise physiologist and legendary running coach:

Olympic modern pentathlete (1956, 1960)
Coach of multiple Olympic runners
PhD in exercise physiology from University of Wisconsin-Madison
Developed the VDOT system based on extensive research
Author of Daniels' Running Formula (first published 1998, multiple editions)[1]
Named "World's Best Running Coach" by Runner's World magazine

Why trust this system:

Based on decades of peer-reviewed research and practical coaching experience
Used by elite and recreational runners worldwide
Scientifically validated training paces grounded in exercise physiology
Flexible and adaptable to individual needs

The VDOT System

What is VDOT?

VDOT is a measure of your current running fitness.

Derived from race performances
Represents your VO2 max adjusted for running economy
One number that determines all your training paces
Updates as you improve

Think of it as your "running fitness score."

How It Works:

Run a race or time trial (any distance from 1500m to marathon)
Look up your time in VDOT tables
VDOT gives you specific training paces for E, M, T, I, and R workouts
Train at those paces
Race faster
Recalculate VDOT with new race time
Repeat

Example:

Run a 10K in 42:00 (6:46/mile pace)
VDOT tables say this = VDOT 52
VDOT 52 gives you training paces:
- Easy: 8:02-8:47/mile
- Marathon: 7:00/mile
- Threshold: 6:37/mile
- Interval: 6:10/mile
- Repetition: 5:44/mile

Where to Find VDOT:

In this guide: VDOT and Pace Tables - race equivalencies and training paces for VDOT 30 to 85, computed from the published Daniels-Gilbert formulas and verified. You do not need to leave this repo.
Book: Daniels' Running Formula (includes the full official tables)
Online calculators: Many free VDOT calculators available

The Caveat Nobody Puts Next to the Table

VDOT equivalence tells you what you are capable of, not what you will run.

The tables assume you have done the training specific to the distance you are looking up. Read across from your 5K to the marathon column and you get the marathon you could run if your aerobic base and long-run endurance matched your speed. If they do not, that number is fiction.

A worked example, from the author of this guide. My 5K PR of 16:40 solves to VDOT 61.6. Read across, and VDOT 61.6 predicts a marathon of 2:39:46. My actual marathon PR is 2:55:13 - a VDOT of 55.

The table was not wrong. It was telling me what a 61.6 with a marathon-ready base would run. I had the speed and not the base, so I collected the 5K time and left fifteen minutes of the marathon on Boylston Street.

Read the equivalency in the direction that flatters you least. Predicting a marathon from a 5K is optimistic - it assumes endurance you may not have built. Predicting a 5K from a marathon is conservative and much more reliable. When the two disagree, the longer race is telling you the truth about your base.

See About the Author for the full VDOT ladder.

The Five Training Paces

Jack Daniels defines five specific training intensities, each serving a distinct purpose:

1. E Pace (Easy)

Purpose: Build aerobic capacity and endurance

Characteristics:

Comfortable, conversational pace
59-74% of VO2 max
Can sustain for hours
Most of your weekly mileage

When to use:

Easy runs (recovery and base building)
Warm-ups and cool-downs
Long runs (though some use M pace)

Typical pace: 60-90 seconds per mile slower than 5K race pace

Volume:

Up to 150 minutes or 25% of weekly mileage per single run
70-80% of total weekly mileage at E pace

Example (VDOT 52): 8:02-8:47/mile

2. M Pace (Marathon)

Purpose: Practice goal marathon pace, build endurance

Characteristics:

Sustainable for 2+ hours
~80% of VO2 max
Should feel controlled, not hard
Slightly faster than easy pace

When to use:

Marathon-specific training
Portions of long runs
Marathon race pace practice

Typical pace: 20-30 seconds per mile slower than threshold pace

Volume:

Up to 110 minutes or 15-18% of weekly mileage
Primarily in marathon-specific phases

Example (VDOT 52): 7:00/mile

Note: For non-marathoners, this pace is less important. Long runs should be at E pace.

3. T Pace (Threshold/Tempo)

Purpose: Improve lactate threshold

Characteristics:

"Comfortably hard" effort
~88% of VO2 max
Pace you could sustain for ~60 minutes
Breathing is deep but rhythmic

When to use:

Tempo runs
Cruise intervals
Most important workout for 10K to half marathon training

Typical pace: Current 10K race pace (or slightly faster than half marathon pace)

Volume:

Up to 60 minutes total at T pace per week
Usually broken into 20-40 minute segments
10% of weekly mileage at T pace (max)

Example workouts:

20-40 minutes continuous at T pace
3 x 2 miles at T pace with 1 min recovery
2 x 3 miles at T pace with 90 sec recovery

Example (VDOT 52): 6:37/mile

4. I Pace (Interval)

Purpose: Improve VO2 max

Characteristics:

Hard effort
~98-100% of VO2 max
Intervals lasting 3-5 minutes
Equal or slightly shorter recovery

When to use:

VO2 max workouts
Building speed endurance
Race-specific for 5K runners

Typical pace: Current 5K race pace or slightly faster

Volume:

Total time at I pace: 5-8% of weekly mileage (maximum)
Usually 8-10 minutes total for lower mileage runners
Up to 30 minutes total for high-mileage runners
Never more than 10K worth of I pace in one session

Example workouts:

5 x 1000m at I pace with 400m recovery
6 x 800m at I pace with 2-3 min recovery
4 x 1200m at I pace with 400m-600m recovery

Recovery: Should be able to repeat the interval at same pace

Example (VDOT 52): 6:10/mile

5. R Pace (Repetition)

Purpose: Improve speed, running economy, and neuromuscular power

Characteristics:

Fast but not all-out
Faster than I pace
Short repeats (200m-800m)
Full recovery between reps

When to use:

Speed work
Running economy development
Final sharpening before races
Less important for marathoners

Typical pace: Mile to 3K race pace

Volume:

Total distance: 5-8% of weekly mileage (combined with I pace)
Usually 1-3 miles total per session
Less volume than I pace

Example workouts:

8-12 x 400m at R pace with 400m jog recovery
6-8 x 200m at R pace with full recovery
Hill repeats: 8-10 x 60-90 seconds hard

Recovery: Near-complete recovery (heart rate returns to Zone 2)

Example (VDOT 52): 5:44/mile for 400m repeats

Training Phases

Jack Daniels organizes training into distinct phases:

Phase I: Base Building (Foundation)

Duration: 6-12 weeks

Focus: Build aerobic capacity and mileage

Workouts:

Mostly E pace running
One long run per week
Gradual mileage increase
No intensity work (or minimal T pace for experienced runners)

Goal: Establish foundation for harder training

Phase II: Early Quality

Duration: 6-8 weeks

Focus: Introduce threshold work

Workouts:

Continue E pace running (70-80% of mileage)
Add 1 T pace workout per week
Maintain long run
Optional: Some R pace for economy

Goal: Develop lactate threshold

Phase III: Transition to Quality

Duration: 4-6 weeks

Focus: Add VO2 max work

Workouts:

Maintain E pace base
Continue 1 T pace workout per week
Add 1 I pace workout every 7-10 days
Alternate T and I workouts

Goal: Build VO2 max while maintaining threshold

Phase IV: Race-Specific

Duration: 4-8 weeks

Focus: Prepare for goal race

For 5K-10K:

Emphasis on I pace and R pace
Some T pace maintained
Race pace practice

For Half Marathon:

Emphasis on T pace and tempo work
Some I pace for sharpness
Half marathon pace practice in long runs

For Marathon:

Emphasis on M pace and long runs
Some T pace for threshold
Marathon pace portions in long runs

Phase V: Taper

Duration: 1-3 weeks (depending on race distance)

Focus: Rest and sharpen

Workouts:

Reduce volume 30-50%
Maintain some intensity (short tempo, few intervals)
Stay sharp without accumulating fatigue

Sample Training Week

Intermediate Runner - Half Marathon Training (VDOT 50, 40 miles/week)

Phase III - Quality Phase:

Monday: Easy 6 miles at E pace (8:23-9:10/mile)
Tuesday: Tempo - 2 mile warmup + 3x2 miles at T pace (6:53/mile) with 1 min recovery + 1 mile cooldown = 10 miles total
Wednesday: Easy 5 miles at E pace
Thursday: Easy 6 miles at E pace
Friday: Rest or easy 3 miles
Saturday: Long run 10 miles at E pace with last 3 miles at M pace (7:18/mile)
Sunday: Easy 4-5 miles at E pace or rest

Total: 40 miles

70% at E pace
15% at T pace
10% at M pace
5% warmup/cooldown

Advanced Runner - 10K Training (VDOT 60, 60 miles/week)

Phase IV - Race-Specific:

Monday: Easy 8 miles at E pace (7:15-7:57/mile)
Tuesday: Intervals - 3 mile warmup + 6x1000m at I pace (5:23/mile) with 400m jog + 2 mile cooldown = 11 miles
Wednesday: Easy 6 miles at E pace
Thursday: Easy 8 miles at E pace
Friday: Easy 6 miles at E pace + 6x100m strides
Saturday: Tempo - 2 mile warmup + 5 miles at T pace (5:46/mile) + 2 mile cooldown = 9 miles
Sunday: Long run 12 miles at E pace

Total: 60 miles

75% at E pace
15% at T/I pace
10% warmup/cooldown/strides

Key Principles of Daniels' System

1. Quality Over Quantity on Hard Days

Hard workouts should be at correct pace, not faster
Faster than prescribed = wrong workout
Save energy for next hard session

2. Adequate Recovery

Easy days truly easy
Never do quality workouts on consecutive days
Respect the hard/easy principle

3. Specificity

Training should match goal race demands
5K training different from marathon training
Adjust phase emphasis based on goal

4. Progressive Overload

Gradual mileage increases
Build quality work over time
Don't rush the phases

5. Listen to Your Body

VDOT gives guidelines, not commandments
Adjust for conditions (heat, altitude, fatigue)
If workout isn't happening, back off

Limitations and Considerations

What Daniels System Does Well:

Provides clear, specific training paces
Based on current fitness (VDOT)
Scientifically validated
Applicable to all levels
Flexible and customizable

What It Doesn't Cover:

Specific weekly schedules (provides templates, not day-by-day plans)
Strength training details
Nutrition guidance
Recovery protocols
Highly detailed periodization

Adjustments You May Need:

Age:

Older runners may need more recovery between quality sessions
Reduce quality frequency, not intensity

Experience:

Beginners should spend longer in base phase
Advanced runners can handle more quality volume

Individual Response:

Some runners handle more I pace better
Others respond better to T pace
Experiment within the framework

Using VDOT Effectively

Best Practices:

Use recent race times - VDOT should reflect current fitness
Update regularly - After key races or time trials
Be conservative - When between VDOTs, use the lower one
Account for conditions - Hot/hilly races may underestimate VDOT
Time trials work - Don't need a race to establish VDOT

Common Mistakes:

Using goal times instead of current times - VDOT must reflect current fitness
Training at too high a VDOT - Ego-driven, leads to poor workouts
Never updating VDOT - As you improve, paces should too
Ignoring effort level - If prescribed pace feels wrong, adjust

Resources

The Book:

Daniels' Running Formula (3rd Edition, 2014)

Comprehensive VDOT tables
Detailed workout examples
Race-specific training plans
Essential reading for serious runners

Online Resources:

VDOT Calculator websites (many free options)
Running forums with Daniels plans
Coaching services using Daniels system

Key Takeaways

VDOT determines your training paces - Based on current race performance
Five paces serve specific purposes - E, M, T, I, R each target different systems
Easy running is the foundation - 70-80% of mileage at E pace
Quality work is specific and limited - Don't exceed recommended volumes
Progressive phases build fitness - Base → Quality → Race-specific
Adjust for individual needs - Use as framework, not rigid prescription
Update regularly - Recalculate VDOT after key races

Remember: Jack Daniels' system gives you the "what" and "how fast" for training. Combined with the fundamentals you've learned, you have everything you need to train effectively.

References

[1] Daniels, J. (2013). Daniels' Running Formula (3rd ed.). Human Kinetics. - The definitive guide to the VDOT system and scientifically-based training.

[2] Daniels, J., & Gilbert, J. (1979). "Oxygen Power: Performance Tables for Distance Runners." Tafnews Press. - Original research establishing the VDOT methodology.

[3] Wikipedia: Jack Daniels (coach) - Biography and overview of contributions to running science.

Next: McMillan Running