The best exercise routine, according to your muscle clocks with Professor Karyn Esser

Our bodies naturally follow a roughly 24-hour cycle, called our circadian rhythm. And every cell has a rhythm.As we get older, we tend to lose muscle, making us more prone to falls and less able to live independently. Though we can't stop aging, staying active helps keep our muscles strong and our bodies healthy for longer.Prof. Karyn Esser is a specialist in how the body's natural rhythms affect muscles. Today, she guides us through the latest research and shows that it's always possible to harness the power of your muscles to enhance your quality of life. She is a professor in the Department of Physiology and Aging at the University of Florida, where she’s also the co-director of the University of Florida Older Americans Independence Center.In today's episode of ZOE Science & Nutrition, Jonathan and Karyn explore the body's internal clocks and ask: why do our muscles have their own schedule, and is there an ideal time of day to exercise?If you want to uncover the right foods for your body, head to, and get 10% off your personalized nutrition program.Want ZOE Science & Nutrition’s top tips for better gut health? Download our FREE gut guide.Follow ZOE on Instagram.Timecodes00:00   Introduction00:18    Quickfire questions02:01    Why are muscles important, particularly as we get older?08:45   Why we all lose strength as we age11:07    What type of exercise do we need to maintain our muscle strength as we age?14:55    What is a circadian clock?19:25    Everything has a circadian rhythm21:32    Why do our muscles work on a 24-hour cycle?24:20    Humans are stronger in the afternoon30:24    Is there a best time to exercise?35:01    Can exercise before or after work help shift workers with jet lag?37:33    Is there a difference between men and women’s responses to circadian rhythms?  41:44    What are the effects of time-restricted eating on muscle mass?53:42    SummaryMentioned in today's episode:Defining the age-dependent and tissue-specific circadian transcriptome in male mice from Cell ReportsRelated studies: Timing is everything: Circadian clocks set the rhythm for vital functions in bacteria from the University of ChicagoEffects of resveratrol on in vitro circadian clock gene expression in young and older human adipose-derived progenitor cells in AgingAge is associated with dampened circadian patterns of rest and activity: The Study of Muscle, Mobility and Aging (SOMMA) in medRxivIs there a nutrition topic you’d like us to explore? Email us at

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The world’s top scientists explain the latest health, nutrition, and gut health research and translate it into practical advice to improve your health & weight. Join ZOE Science & Nutrition, on a journey of scientific discovery. Hosted by Jonathan Wolf.