Scientists from Skidmore College in New York, Arizona State University, and California State University, Chico, studied 30 men and 26 women between the ages of 25 and 55 who were defined as “very active” (performing more than 30 minutes of structured physical activity 4 days a week for more than 3 years).

Over 12 weeks, the researchers analyzed the effects of a varied training program – consisting of stretching, resistance exercise, interval sprints and endurance training – with the same relative training volume. .

Participants did one of four different exercise routines one day per week for a total of four workouts per week.

One group exercised for an hour between 6:30 a.m. and 8:30 a.m., while the other group followed the same exercise routines, but between 6 p.m. and 8 p.m.

The researchers found that, in women, morning exercise reduced abdominal fat and blood pressure, while evening exercise improved muscle performance.

In the male cohort, evening exercise increased fat oxidation and reduced systolic blood pressure and fatigue.

The study concluded that the time of day that subjects exercised “may be important in optimizing exercise-induced health and performance outcomes in physically active individuals and may be independent of ‘macronutrient intake’.

“Morning exercise in women improves total and abdominal fat loss, reduces blood pressure, and increases lower-body muscle power,” the study states. “Evening exercise dramatically increases upper body muscle strength, power, and endurance, and improves overall mood.”

For men, strength increased after morning and evening exercise, but evening exercise provided additional benefits with “lower systolic blood pressure and fatigue and boosts fat oxidation compared to early morning exercise.

Megan Johnson McCullough is a National Academy of Sports Medicine trainer, professional bodybuilder, and owner of Every BODY’s Fit in Oceanside, CA..

McCullough told Healthline that both sleep and hormones play an important role in optimal workout times.

“Women’s and men’s sleep patterns are different, which contributes to the gender difference in results that exercise can produce,” McCullough said. “There may be evidence that depending on the time of day and the type of exercise performed, cardio or strength training, there is an optimal choice for women and men to exercise. The differences in sleep cycles are correlated with differences in physical performance.

McCullough told Healthline that hormone production and sleep are interrelated. Women spend more time in deep sleep and less time in the lightest sleep phase, compared to men.

“Therefore, it has been suggested that women are more alert and awake in the morning than men,” McCullough said. “This notion may be linked to the fact that women burn more fat when they exercise in the morning, in part due to their ability to perform better when the body is more alert during the morning hours. Men can be more alert and the body is better prepared in the evening to exercise because you have to wake up during the day and be more alert to exercise later in the day or in the evening.

“Research has also shown that cortisol levels are highest in the morning, so there may be a link to burning more fat in the morning if there is more stress-induced fat. Men may take advantage of that and do cardio in the morning to literally ‘burn off’ their stress. It would also reduce blood pressure if either gender were to do cardio in the morning,” McCullough told Healthline. “Cortisol levels higher inhibit muscle growth, therefore, strength training at night might be more beneficial. The opposite would be true for women who might get up in the morning when testosterone levels are higher (for them) and there is strength to lift more weight.

DJ Mazzoni, a certified strength and conditioning specialist who is also the medical examiner for Illuminate Labs, told Healthline that many other factors contribute to when someone is best to train.

“What time of day someone performs best in the gym is too individual an answer to provide recommendations by gender,” Mazzoni said. “People of either sex prefer to train at different times of the day.”

“I’ve found that people do better in the gym when they go at a time that best fits their schedule and they enjoy it,” Mazzoni told Healthline. “Some people prefer to train after a long day at work to relieve stress, while others prefer to train at dawn. Training when you really want to train is likely to improve your performance and your results over training on a set schedule because you think it’s a healthier option.

“I generally recommend avoiding workouts within 3 hours of sleep, as it can disrupt sleep,” Mazzoni said. “People tend to prefer cardio exercises in the morning because they’re not ‘weighted down’ by food. Many people prefer to lift weights after a meal (and after digestion) because it improves power and performance.

Jake Dickson is a certified personal trainer and contributing editor to the BarBend bodybuilding website. He said it’s not clear why men and women reacted so differently when it came to exercise.

“However, nighttime exercise is good for men looking to improve their cardiovascular and metabolic health as well as their emotional well-being. Improved metabolic health reduces the risk of obesity, type 2 diabetes, cardiovascular disease and stroke,” explained Dickson.

Kent Probst, personal trainer, movement therapist and bodybuilder, told Healthline that the American College of Sports Medicine guidelines for exercise testing and prescription (11th edition, 2022) are the same for men and women. women.

“There is not enough published scientific evidence to make exercise testing and prescribing recommendations gender-specific,” Probst told Healthline.

But Probst said the time of day does indeed matter to anyone working out.

“[With] resistance training, thereour body temperature peaks between 4:00 p.m. and 6:00 p.m., and this is believed to be the reason why flexibility, speed, and strength peak during this time. Therefore, the optimal time for resistance training is between 4 p.m. and 6 p.m. to begin maximizing strength and muscle.

“[For] cardiovascular exercise, muscular endurance, and endurance peak between early and mid-morning, which means that’s the best time for cardiovascular exercise,” Probst said. “[For] sport-specific exercises, as mental acuity peaks around the middle of the day, sport-specific exercises should be performed during this time.