Early bird or night owl? Are you exercising at the right time of day for your sex?

7 June 2022

What Is The Best Time Of Day To Exercise: Early Bird Or Night Owl? Are You Exercising At The Right Time Of Day For Your Sex?

When it comes to maximising fat loss and optimising your fitness gains, the best time of day to exercise may differ depending on your sex, according to a new study published in the Frontiers of Physiology by Dr Paul Aciero and colleagues.

Twenty-seven women and twenty men aged 25–55 years completed the 12-week study. They were all regular exercisers, participating in more than 30 minutes of exercise 4 days per week. They were also lean, with a BMI of less than 25, and their weight had been stable for at least 6 months prior to the beginning of the study.

The participants were randomly assigned to one of two groups: Group 1 performed an exercise programme comprising resistance, interval, and endurance training, and stretching in the morning (6-8 am). Group two performed the same exercise programme in the evening (18.30-20.30 pm).

The results of the study showed that women who exercised in the morning had a greater reduction in total body fat (-5% vs – 2%), abdominal fat (−10% vs −3%) and blood pressure (−10% vs −3%) in comparison to women who exercised in the evening. They also achieved a greater increase in lower body muscular power (13% vs 4%).

Women exercising in the evening achieved significantly greater gains in upper body muscle strength (16% vs 9%), power (37% vs 8%), and endurance (40% vs 25%). They also had a tendency to experience improved mood and greater satiety.

With regard to men, those exercise exercising in the evening experienced a significantly greater reduction in systolic blood pressure (−12% vs −3%) and feelings of fatigue (−55% vs 0%). They also experienced an increase in fat oxidation (6% vs 1%) compared to those exercising in the morning. Interestingly, unlike women, men demonstrated no difference in physical performance based on whether they exercised early or late in the day.

The authors concluded that these findings provide support for women to exercise in the morning to optimise fat loss, lower blood pressure, and increase lower body muscular power. While exercise in the evening may provide greater improvements in upper body muscular performance, and possibly mood enhancement.
For exercise-trained men, evening exercise may better to reduce blood pressure and fatigue, as well as to maximally stimulate fat oxidation.

In Closing….
According to the results of this study, it seems that women and men respond differently to exercising at different times of the day. Therefore, it would seem reasonable to schedule your training sessions to occur at the most productive time according to your sex to optimise your results, particularly if you’re a woman. However, don’t panic if the only time available to you to exercise does not coincide with the ‘optimal’ time identified in this study. As interesting and informative as the results of are, it is a relatively small study, having just 27 women and 20 men complete it, and at just 12 weeks in duration, is relatively short. Would the results be different over a longer period or perhaps with participants younger than 25 years and older than 55 years? These questions are bound to be answered by subsequent studies in the fullness of time.
However, as exercise will always provide you with a host of benefits, regardless of the time you perform it, the most important thing is that you do it, rather than when you do it.

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