In this episode of Science & Chill, I talk with Dr. Karyn Esser, the associate program director at the Institute of Myology at the University of Florida.

Dr. Esser is an expert in the area of biological rhythms, also known as circadian rhythms. In particular, her group focuses on how circadian rhythms function in skeletal muscle and respond to things like exercise, feeding, and light.

In this episode, we talk about why humans (and plants and animals) have circadian rhythms in the first place, the importance of sleep and exercise for maintaining circadian rhythms, and much more. Dr. Esser also answers some bonus questions at the end!

I hope you enjoy this episode. If you do, please leave a 5-star rating, share it with friends and family, or write a review!

If you have any questions or comments about the podcast, send them to scienceandchillpodcast@gmail.com.

Links:

Great video on Dr. Esser and Circadian Rhythms: https://youtu.be/QZWllk38iSE

Dr. Esser's bio: https://physiology.med.ufl.edu/faculty/karyn-esser-phd/

Dr. Esser's publications: https://pubmed.ncbi.nlm.nih.gov/?cmd=search&term=esser+ka

Follow Dr. Esser on Twitter: @kaesser

Follow Science & Chill on Twitter: @ScienceChill

Subscribe on iTunes

SHOW NOTES:

Check out this great video on Dr. Karyn Esser from the University of Florida

https://youtu.be/QZWllk38iSE

Dr. Karyn Esser’s scientific publications: https://pubmed.ncbi.nlm.nih.gov/?cmd=search&term=esser+ka

Relevant publications:

  1. Harfmann BD, Schroder EA, Esser KA. Circadian rhythms, the molecular clock, and skeletal muscle. J Biol Rhythms. 2015;30(2):84–94.
  2. Riley LA, Esser KA. The Role of the Molecular Clock in Skeletal Muscle and What It Is Teaching Us About Muscle-Bone Crosstalk. Curr Osteoporos Rep. 2017;15(3):222–230.
  3. Wolff CA, Esser KA. Exercise Timing and Circadian Rhythms. Curr Opin Physiol. 2019;10:64–69.
  4. Hodge BA, Zhang X, Gutierrez-Monreal MA, et al. MYOD1 functions as a clock amplifier as well as a critical co-factor for downstream circadian gene expression in muscle. Elife. 2019.

In this episode we talk about:

7:30: The utility of Twitter for scientists: how Dr. Esser uses Twitter to solve problems in her lab, and why she encourages her students and trainees to use Twitter for academic reasons.

  • You can follow Dr. Esser on Twitter here: @kaesser

13:17: Dr. Essers introduction into science. She didn’t always “want” to be a scientist -- instead starting as a math major and was interested in band and athletics (she wanted to be a conductor at a young age).

  • Her 7th grade laboratory class taught her a lot about the fundamentals of science
  • She started as a chemistry major at Wake Forest, and in one class was able to take a trip to the Galapagos Islands. This trip shaped a lot of her thinking about evolutionary approaches to science.

19:00: Our mutual experience working in cardiac rehabilitation

22:30: Working with an exercise program at the University of Nevada Las Vegas (UNLV)

30:30: 2017 Nobel Prize in Physiology and/or Medicine. The prize was awarded to Jeffrey C. Hall, Michael Rosbash, and Michael W. Young “for their discoveries of molecular mechanisms controlling the circadian rhythm.”

Nobel Society press release: https://www.nobelprize.org/prizes/medicine/2017/press-release/

36:00: The SCN is no longer considered the “master clock” controlling our circadian rhythms.

  • We have clocks throughout the body that dictate their own rhythm

38:15: What time of day and when we are exposed to cues like exercise, light, and food play a crucial role in “setting the clock” for our cells

  • We can “misalign” clocks by sending cues at the wrong times of day or traveling time zones
  • “Social jetlag”

40:00: Circadian clocks in skeletal muscles and how they respond to exercise

  • Clocks are sensitive to temperature

42:00: Chronic diseases and aging affect our circadian clocks

44:20: Consequences of circadian misalignment

  • Shift workers have higher risks for cardiovascular disease and metabolic problems
  • Increased insulin resistance, blood pressure

48:00 Time-restricted feeding

50:00: Circadian timing of drugs and medicine

50:45: How circadian rhythms apply to exercise and performance

51:00: Therapeutic uses for circadian rhythms

  • Timing exercise to improve sleep outcomes and metabolic health
  • Small molecules with clocks effects that might hold the potential for drug development

53:20: Why exercise is a good thing...REGARDLESS of when you do it

  • We recently had a Twitter conversation about this issue on a recent paper about how exercise timing might influence insulin sensitivity

55:00: Some studies proposing to study the effects of circadian rhythms on training adaptations might not actually be studying circadian rhythms

PAPER: Effect of time-of-day specific strength training on muscular hypertrophy in men

CONCLUSIONS: “The magnitude of muscular hypertrophy did not statistically differ between the morning and afternoon training times. From a practical point of view, strength training in the morning and afternoon hours can be similarly efficient when aiming for muscle hypertrophy over a shorter period of time (

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