Does time of day affect the body’s response to exercise?

Anywhere during one’s fitness journey, this question will eventually come to mind. Whether you’re plotting your workouts within your work schedule or finding what works best for you, we’re here to find out how time affects your body’s response to exercise.

It’s quite well known that almost every aspect of our physiology and metabolism is dictated by the circadian clock,” says Gad Asher of the Department of Biomolecular Sciences at the Weizmann Institute of Science. A person’s circadian rhythm includes physical, mental, and behavioural changes that follow a 24-hour cycle in response tolight and darkness.

Senior author of another recent paper that has shown similar findings, out of the Center for Epigenetics and Metabolism at the University of California, Paolo Sassone-Corsi adds “Circadian rhythms dominate everything we do”. He goes on to say, “Previous studies from our lab have suggested that at least 50% of our metabolism is circadian, and 50% of the metabolites in our body oscillate based on the circadian cycle. It makes sense that exercise would be one of the things that’s impacted.”

Studies have shown that morning exercise initiates gene programs in the muscle cells, making them more effective and better capable of metabolising sugar and fat while evening exercise, on the other hand, increases whole body energy expenditure for an extended period of time.

So, there isn’t a better time to exercise as both have different effects in the body. So how might we be able to use these to our advantage?

Since morning exercise increases the ability of muscle cells to metabolise sugar and fat, plotting workouts in the morning would be beneficial for people who may be severely overweight or those who are type 2 diabetes.

Based on the research shown above, evening workouts were associated with increased energy expenditure, which affects how many calories we burn daily. But we may take such information lightly as it all depends on a person’s energy levels throughout the day, the amount of sleep they get, as well as food intake to fuel them for a workout.

There isn’t a best time for a workout. The different times of the day may have different effects to the muscles but best way to measure its effectivity is how much effort is put into a workout which means fuel and recovery will come into play.  

What matters most is finding the best workout regime that fits your schedule.

What’s the best time for you?

1. Saar Ezagouri, Ziv Zwighaft, Jonathan Sobel, Sébastien Baillieul, Stéphane Doutreleau, Benjamin Ladeuix, Marina Golik, Samuel Verges, Gad Asher. Physiological and Molecular Dissection of Daily Variance in Exercise Capacity. Cell Metabolism, 2019; DOI: 10.1016/j.cmet.2019.03.012
2. Shogo Sato, Astrid Linde Basse, Milena Schönke, Siwei Chen, Muntaha Samad, Ali Altıntaş, Rhianna C. Laker, Emilie Dalbram, Romain Barrès, Pierre Baldi, Jonas T. Treebak, Juleen R. Zierath, Paolo Sassone-Corsi. Time of Exercise Specifies the Impact on Muscle Metabolic Pathways and Systemic Energy Homeostasis. Cell Metabolism, 2019; DOI: 10.1016/j.cmet.2019.03.013