Elite coach explains: What actually happens to your body at low intensity training

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 KRISTIAN Save on FlexBeam using code WARWICKRUNS or this link: https://rechargehealthas.sjv.io/55GAPb Kristian 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 Marathon Timestamps 00:00 Welcome and the question that sparked this episode 02:10 Announcing the podcast's sponsorship with Saysky Copenhagen 04:51 Welcoming Brant Stachel back for his third appearance 08:10 The alphabet soup of training zones and paces 20:22 An honest look at what the research actually shows 25:03 The capillary system explained through a father's advice 39:36 Why zone two became such a hyped up trend 46:55 Ditching heart rate and pace altogether for a season 51:30 What easy is actually supposed to feel like 52:07 Using the talk test to judge your effort 55:21 Getting past the ego hit of slow Strava times 56:11 Wrapping up and planning a future episode on hard training 57:39 Kristian's own training week recap begins 1:02:33 A breakdown of his easy runs and average heart rate 1:08:19 Looking ahead to Puma Project 3 athletes racing Berlin 1:13:01 Closing thoughts and thank you for listening Brant on Instagram:   / brant_stachel   Brant on YouTube:    / @brantstachel   Start your free Musicbed trial: https://fm.pxf.io/kristianwarwick Full episodes + the Boston 2025 documentary:    / @warwickruns   Follow my training journey on Instagram: @warwick.runs Music from Musicbed: MB01XPYH8ZYENVAMB0133EV2TCQFZY