Does Time of Day Impact Muscle and Metabolic Responses to Resistance Exercise?

Is it better to lift weights in the morning or at night?

Overview

• What did they test? The researchers tested the effects of exercising in the morning between 6:00 and 10:00 am and the evening between 4:00 and 8:00 pm on muscle thickness, strength, and markers of metabolism in inactive young adults. 
• What did they find?  This study showed that resistance training time of day had no impact on muscle strength, muscle thickness, insulin sensitivity, or glucose levels after 6 weeks of training among inactive adults.
• What does it mean for you? Resistance training is one of the most beneficial habits that we can build for our long-term health and well-being. This study suggests that the timing of training doesn’t matter, so it is best to exercise when it is convenient for you.

What’s the Problem?

People who engage in regular resistance exercise for just 60 minutes per week have a 27% lower risk of death from any cause than those who don’t 1. Resistance exercise training can improve metabolic health, body composition, bone mass, cognitive health, and more 2.

It has been hypothesized that circadian rhythms may play a role in resistance exercise responses and that there may be advantages to either training in the morning or in the afternoon/evening 3. Acutely, strength tends to be higher in the evening vs. the morning 4. There is also evidence that evening exercise has a more favorable effect on blood glucose response 5.

However, research in this field is limited, and there is a need for studies examining the impact of time of resistance training on performance and health outcomes. 

Purpose

It is currently unclear if the time of day has an impact on chronic resistance training adaptations. The purpose of this study is to compare the effects of performing resistance training in the morning between 6:00 and 10:00 am compared to in the evening between 4:00 and 8:00 pm on muscle growth and metabolic health responses to a resistance exercise program. 

Hypothesis

The authors did not present a hypothesis for this experiment.

What Did They Test and How?

Participants