How Circadian Rhythms Shape Strength, Recovery, and Health with Dr. Karen Esser #829
Barbell Shrugged
Doug Larson
4.7 • 2.8K Ratings
🗓️ 31 December 2025
⏱️ 51 minutes
🧾️ Download transcript
Summary
In this episode, Dr. Karen Esser Professor and Chair of the Department of Physiology and Aging at the University of Florida joins the crew to break down one of the most overlooked performance variables in human physiology: circadian timing. After a career spent studying muscle adaptation, Dr. Esser shifted her research toward the molecular clocks inside our tissues, uncovering how every cell in the body keeps its own time. She explains how these clocks govern fuel storage, protein repair, metabolic readiness, and ultimately the way muscle responds to training. The team digs into what these clocks do, how they synchronize, and why misalignment affects everything from daily performance to long-term health.
The conversation dives deep into time-of-day effects on strength, endurance, and adaptation. Dr. Esser highlights that humans are consistently stronger and more explosive in the afternoon, a pattern reflected in Olympic records and decades of performance data. But her lab's animal research reveals something game changing: consistent morning training can shift the internal clock system, allowing morning athletes to achieve equal or even better adaptations after several weeks, despite using lower absolute training loads. She also explains how travel, jet lag, and mistimed eating disrupt organ specific clocks, reducing performance and creating metabolic consequences similar to pre-diabetes. The crew tests these ideas against real world training habits, coaching experience, and what happens when athletes switch from evening to early morning training.
Finally, Dr. Esser unpacks the broader health implications of circadian disruption from increased risk of metabolic disease and cardiovascular dysfunction to higher rates of depression and cancer in chronically misaligned shift workers. She outlines simple, actionable strategies: anchor your sleep and training times, keep eating within a roughly 10 hour window, avoid late night calories, and arrive early when competing across time zones. The conversation closes with practical takeaways for athletes, coaches, and everyday lifters who want to maximize adaptation, improve metabolic health, and align their biology with the rhythms built into every cell.
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| 0:00.0 | Shrug family this week on Barbell Shrug. Dr. Karen Esser is on the podcast and we have a phenomenal |
| 0:07.1 | conversation today about circadian rhythms and muscle tissue. Bananas had no idea this existed. |
| 0:16.8 | Absolutely mind-boggling how connected our body is to the sun and the spinning of this big rock |
| 0:25.8 | we all live on. And there's very few things that I hear in the strain conditioning world or performance |
| 0:32.1 | or health that catches my attention like talking to her today. Legitimately, it's so many things move at the speed of technology, and nobody ever just |
| 0:42.5 | stops and go, well, wait a second, maybe we're still connected to this nature thing. |
| 0:49.0 | It's the most important thing, but we just, we love to just move so fast without going, uh, maybe the sun's important. |
| 0:58.1 | Maybe the time of the day. Maybe how our body interacts with night and day and the sun. And, |
| 1:05.3 | ah, this is awesome. She's the coolest, mind-blowing stuff. And very, very happy we got to meet her. As always, get over to Rapid HealthRepport.com. As we're Dan Gardner and Dr. Andy Galpin doing a free lap, lifestyle performance analysis, and you can access that at Rapid Health Report.com. Friends, let's get into the show. Welcome to Bartle Shrug. I'm Anders Warner, Doug Larson, Coach Travis, Smash, Dr. Karen Esser. |
| 1:27.8 | We're going to be talking about all kinds of cool stuff, but none as important as the Jordan story you were about to tell us on super freak athletes because we just talked for 10 minutes about Chicago sports and how important they are to us. |
| 1:41.1 | Take it away. |
| 1:42.1 | All right. |
| 1:42.6 | So I was a, so I had a student working in my lab many years ago, |
| 1:47.8 | and it turned out she taught swim class in the summer, some of the parks or whatever. And |
| 1:52.8 | she had two of Michael Jordan's kids in her class. And the one thing that she noted with them, |
| 1:59.7 | so they were teaching them. I don't know whether it was breaststroke or backstroke, but one of those strokes. |
| 2:03.9 | And so they do that on the ground before they go into the water. |
| 2:07.5 | And the one thing she noted is his kids had it like that, you know, so the rest of the kids were kind of their arms were flailing in different directions and that kind of thing. |
| 2:16.4 | But his kids, as soon as she sort of walked through what you're supposed to do, the, you know, |
| 2:21.5 | sort of the coordination and the fact that, you know, they just would visualize it and then |
| 2:26.5 | the body did what it was supposed to do was just off the charts. And so the genetics were |
| 2:32.2 | absolutely there. Yeah. |
... |
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