Explaining: Dr. Jack Daniels’ Interval and Rep Paces (I-Pace & R-Pace)

Intervals and rep work are two of the most misunderstood parts of distance training. A lot of runners hear terms like VO2 max, I-Pace, R-Pace, intervals, and reps, but never get a clear explanation of what each one is actually doing or how they should fit into a training plan. In this video, I break down interval training versus repetition training, what each one targets physiologically, and how to use both without turning every hard session into an all-out race. We get into the difference between building aerobic capacity and building efficiency, why VO2 max work is not just a number on your watch, and how Jack Daniels’ I-Pace and R-Pace concepts actually work in practice. I also explain the key mistakes runners make with these sessions, including racing intervals, taking the wrong recovery, stacking too much intensity, and repeating the same workouts without real progression. At the end, I share practical examples of interval and rep workouts I use with athletes across a wide range of levels, from Boston qualifiers to high-performance runners, and explain how these sessions fit into a training week alongside easy running, tempo work, and long runs. If you want to better understand when to use VO2 max work, when to use repetition work, and how to make both more effective, this will help clear it up. Happy Training! ➡️ Watch my “Running: Explained” Series: https://www.youtube.com/playlist?list=PLXSHy1fG_CEMUOxJD_2cYeSJZmUIdIDro ➡️ Sign Up For My Newsletter And Get My Next YouTube Video Early: https://brantstachel.activehosted.com/f/30 ⸻ Relevant Links 🚨 FREE TOOLS I CREATED FOR RUNNERS 🚨 https://www.runfastandfree.com/free-tools ⚠️ TAKE THE MARATHON READINESS QUIZ NOW ⚠️ https://marathon-readiness-quiz.scoreapp.com Get coached by Brant Stachel https://teamrunrun.com/coach/brant-stachel-kingston-ontario-running-coach/ Mental Performance Coaching with Brant Stachel: https://calendly.com/cepadminteam/15-minute-intake-call-clone?month=2026-01 Get my Book, “Fast and Free”: https://a.co/d/00twBZ6d Learn More about Team RunRun: https://teamrunrun.com/ Fuel Your Training (Affiliate Link): https://fuelgoods.com/?ref=Brant ⸻ Follow Brant Stachel Fast & Free Performance Coaching https://www.youtube.com/@UC4Nd1yg5n94puosXxjeL5FQ https://www.instagram.com/fastandfreecoaching https://www.instagram.com/brant_stachel https://www.tiktok.com/@BrantStachel https://www.strava.com/athletes/12318637 https://www.facebook.com/FastandFreeWithBrant https://www.twitter.com/BrantStachel https://www.LinkedIn.com/Brant-Stachel Visit My Website: http://runfastandfree.com ⸻ Listen to the Fast and Free Podcast on Your Favourite Podcast Platform: Spotify: https://open.spotify.com/show/2jI6TBvBPYihSf9FhQFZAv Apple Podcasts: https://podcasts.apple.com/us/podcast/the-fast-and-free-podcast/id1867807916 Chapters: 00:00 - Understanding Intervals and VO2 Max Workouts 03:00 - The Physiology Behind Interval and Rep Training 06:07 - Common Mistakes in Interval Training 08:48 - Effective Workout Strategies for Runners 11:53 - Wrapping Up: Key Takeaways for Runners #vo2max #runningworkout #runningtips #runningcoach #distancerunning