Easy Run Pace: How Slow Is Slow Enough?
Most runners run their easy days too fast — and it quietly destroys their training. Learn what easy run pace actually means, how to calculate it from your VDOT, and why slowing down makes you faster.
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Running Training Blog
Science-backed guides on periodization, training load, and race preparation.
Interval Training for Runners: How to Run I Pace Sessions Correctly
Interval training at I pace is the fastest way to raise your VO2max — but most runners do it wrong. Learn what interval training is, how to set your I pace, and how to structure sessions that actually work.
Tempo Run vs Threshold Run: Are They the Same Thing?
Tempo runs and threshold runs are used interchangeably — but they're not identical. Learn the difference, why it matters for your training, and how to run each one correctly.
Science of Race Training
How to Do a Long Run: Pace, Distance, and the Mistake That Ruins It
The long run is the cornerstone of distance training — and the workout most runners get wrong. Learn the right pace, how far to go, how to fuel, and why running it too fast undermines the entire purpose.
Science of Race Training
Heart Rate Zones for Running: Why Your Watch Is Probably Wrong
Heart rate zones are useful — but the formulas most watches use to calculate them are notoriously inaccurate. Here's how running HR zones actually work, where they go wrong, and how to use VDOT pace zones as a more reliable intensity guide.
Adaptive Training
12-Week Half Marathon Training Plan: Science-Backed Structure with VDOT Paces
A 12-week half marathon training plan built on Jack Daniels' VDOT system. Includes phase-by-phase structure, sample training weeks, and exact paces for every workout — calibrated to your current fitness, not a generic goal time.
Adaptive Training
16-Week Marathon Training Plan: Science-Backed Structure with VDOT Paces
A 16-week marathon training plan built on Jack Daniels' VDOT system and periodization principles. Includes phase-by-phase structure, sample training weeks, and exact paces for every workout type.
Science of Race Training
Pfitzinger vs Daniels: Which Marathon Training System Is Right for You?
Pfitzinger and Daniels are the two most respected science-based marathon training systems. They share the same physiological foundations but differ sharply on volume, intensity distribution, and who they work best for.
Adaptive Training
The Running Taper Guide: Why You Feel Worse Before You Race Better
Taper is the final phase of marathon preparation — and the most misunderstood. Learn why your legs feel heavy, why fitness isn't disappearing, and exactly how to taper without sabotaging your race.
Adaptive Training
Running Periodization Explained: How to Structure Your Training for Race Day
Periodization is the framework that turns individual workouts into a coherent race preparation strategy. Learn how the four phases work, why they matter, and why most runners skip the one that matters most.
Science of Race Training
What is Lactate Threshold Running? How to Find and Train Your LT Pace
Lactate threshold is the most trainable fitness variable in distance running. Learn what it actually is, how to estimate yours without a lab, and the three session types that raise it fastest.
Adaptive Training
Adaptive Running Plans: What They Are and Why They Outperform Static Training
Most marathon plans are written for a runner who doesn't exist. Adaptive training plans respond to what's actually happening in your body each week. Here's the difference, and why it matters for intermediate runners.
Science of Race Training
Jack Daniels Running Formula Explained: The Science Behind Training Paces
Jack Daniels' running formula is the most rigorously tested training system in endurance sport. Here's how it works, what the five training intensities do, and why it beats every generic plan.
Science of Race Training
VO2max vs VDOT: What Your Garmin Watch Isn't Telling You
Your watch gives you a VO2max estimate. Jack Daniels built VDOT to replace it. Here's why the two numbers differ, which one actually controls your training paces, and what to do when your watch gets it wrong.
Adaptive Training
Why Your Marathon Training Plan Isn't Working (It's Not Your Fault)
If you've followed a marathon training plan and still underperformed, hit the wall, or ended up injured, the plan is more likely to blame than you are. Here's the structural reason why most training plans fail intermediate runners.
Science of Race Training
CTL, ATL, and TSB Explained: The Training Load Metrics Behind Adaptive Running Plans
CTL, ATL, and TSB are the three numbers that tell you whether you're getting fitter, overtrained, or ready to race. Here's how they work and why they matter for marathon runners.
Science of Race Training
What is VDOT? How to Find Your Running Training Paces in 5 Minutes
VDOT is the most practical measure of aerobic fitness for runners. Learn how Jack Daniels' formula translates your race time into exact training paces for every workout type.