In a study published in Cell Metabolism, researchers from the University of Copenhagen sought to better understand the effects of exercise timing on muscle metabolic pathways and systemic energy homeostasis. What they discovered is that the effects of exercise may differ depending on our circadian rhythms (which are key to controlling metabolism) and the time of day it is performed. 

Researchers identified “distinct responses of metabolic oscillations that characterize exercise in either the early rest phase or the early active phase”...and found “the time of day is a critical factor to amplify the beneficial impact of exercise on both metabolic pathways within skeletal muscle and systemic energy homeostasis” in animal models. In other words, when mice performed exercise in the morning (dark/active phase) there was a metabolic response increase in muscle cells, while exercise performed in the evening (light/resting phase) increased overall systemic energy expenditure hours after exercise was completed. Specific gene programs and transcriptional responses were far stronger following morning exercise within the muscle, enhancing the utilization of carbohydrates and fats. Their findings show that this effect is controlled by a mechanism involving the HIF1-alpha protein, which also regulates our circadian rhythm. 

This discovery of these significant differences could help you determine the best time(s) of day that may be the most beneficial for your patients to exercise for targeted results based on their goals and current health status or disease state. For those with some sort of blood sugar dysregulation, such as type II diabetes, and/or metabolic dysfunction (e.g., obesity, metabolic syndrome) exercising in the morning may be more advantageous to support glucose and fat metabolism as it “exerts a robust metabolic response in skeletal muscle.” On the other hand, working out in the evening may also be helpful to increase total energy expenditure hours after exercising, thus increasing the total calorie deficit for the day. Perhaps, doing strength and resistance training that targets skeletal muscle in the morning and a lower impact cardiovascular workout or high-intensity interval training (HIIT) in the early evening may be a great way to receive the benefits of both! 

We all know that exercise requires additional nutritional support. It’s important to emphasize the need of replenishing the body with sufficient micro and macronutrients after any form of moderate to intense workout. The “exercise more, eat less” paradigm is shifting and more and more practitioners and consumers are realizing the importance of refueling and refeeding the body post-workout. A prolonged caloric deficit (from either over-exercising or under consuming or both) may actually lead to a slower metabolic rate and even thyroid dysfunction. 

Exercise alone is not sufficient to yield positive health outcomes. For optimal results, exercise should be paired with appropriate nutritional support for athletic performance and recovery. A great way to ensure patients are meeting their nutritional needs (on top of eating a well-balanced diet of protein, healthy fats, and fiber at every meal) is to suggest protein powder, branched-chain amino acids, and even full-spectrum amino acid supplementation as part of their post-workout regimen. Refueling with pea, whey (for those who are not sensitive to dairy), and/or hydrolyzed beef protein powders are superior options to protect muscle breakdown and support muscle protein synthesis and may also help regulate blood sugar levels, benefiting overall metabolic function. Greens and reds powders are also wonderful additions to the protein shakes and amino acids to boost micronutrient and antioxidant levels for post-exercise recovery.   

By Caitlin Higgins, MS, CNS, LDN