#218 What Happens Inside Your Body During Low Intensity Training? | With elite coach Brant Stachel

The Marathon Podcast is now proudly sponsored by Saysky Copenhagen. Use code TMP15 for 15% off at saysky.com.Get 20% off a Strava annual subscription with code KRISTIANSave on FlexBeam using code WARWICKRUNS or this link: https://rechargehealthas.sjv.io/55GAPbKristian welcomes back coach Brant Stachel for his third appearance on the podcast, this time to answer a question sparked by his own wife: why does low intensity training actually work?Brant and Kristian dig into the physiology behind easy running, from mitochondrial density and capillary growth to the honest caveat that a lot of the exact science still isn't fully settled. They discuss why low intensity training has become such a hot topic in the sport, what elite programs seem to be finding through trial and error even without perfect research to back it up, and how to actually judge whether your easy runs are truly easy. The conversation closes with practical advice on using the talk test, ignoring your watch, and getting past the ego hit of running slow on Strava. Kristian then shares a full recap of his own training week, including a look ahead to Puma Project 3 athletes racing Berlin.In this episode:- Why Brant's wife inspired this episode's big question- The physiology behind low intensity training, explained simply- Mitochondrial density, capillary growth, and what the research actually shows- Why elite training groups keep coming back to low intensity work- What "easy" is actually supposed to feel like- Using the talk test instead of your watch- Getting past the ego hit of slow paces on Strava- Kristian's own training week recap- A preview of Puma Project 3 athletes racing the Berlin MarathonTimestamps00:00 Welcome and the question that sparked this episode02:10 Announcing the podcast's sponsorship with Saysky Copenhagen04:51 Welcoming Brant Stachel back for his third appearance08:10 The alphabet soup of training zones and paces20:22 An honest look at what the research actually shows25:03 The capillary system explained through a father's advice39:36 Why zone two became such a hyped up trend46:55 Ditching heart rate and pace altogether for a season51:30 What easy is actually supposed to feel like52:07 Using the talk test to judge your effort55:21 Getting past the ego hit of slow Strava times56:11 Wrapping up and planning a future episode on hard training57:39 Kristian's own training week recap begins1:02:33 A breakdown of his easy runs and average heart rate1:08:19 Looking ahead to Puma Project 3 athletes racing Berlin1:13:01 Closing thoughts and thank you for listeningBrant on Instagram: https://www.instagram.com/brant_stachel/Brant on YouTube: https://www.youtube.com/channel/UC4Nd1yg5n94puosXxjeL5FQStart your free Musicbed trial: https://fm.pxf.io/kristianwarwickFull episodes + the Boston 2025 documentary: https://www.youtube.com/@WarwickrunsFollow my training journey on Instagram: @warwick.runsMusic from Musicbed: MB01XPYH8ZYENVAMB0133EV2TCQFZY