For the first time, scientists demonstrate that the best time of day to exercise varies on one’s sex and training goals.
When should I fit in my regular workout routine? The majority of the time, the response is influenced by our family’s schedule, our employment hours, and possibly even if we are “larks” or “night owls.” However, during the last ten years, researchers have discovered that this question is considerably more important than these limitations. This is because new research indicates that the time of day (Exercise Time Of Day, ETOD) might affect how beneficial exercise is.
Now, randomized controlled research indicates that ETOD impacts exercise efficacy, and it also demonstrates that these effects vary across exercise kinds and between women and men. The findings have been recently published in the journal Frontiers in Physiology.
Principal investigator Dr. Paul J Arciero, a professor at the Health and Human Physiological Sciences Department of Skidmore College in Saratoga Springs, NY, USA, said: “Here we show for the first time that for women, exercise during the morning reduces belly fat and blood pressure, whereas evening exercise in women increases upper body muscular strength, power, and endurance, and improves overall mood and nutritional satiety.”
“We also show that for men, evening exercise lowers blood pressure, the risk of heart disease, and feelings of fatigue, and burns more fat, compared to morning exercise.”
New 12-week-long ‘multimodal’ training program
The researchers enlisted the help of 30 women and 26 men. They were all between the ages of 25 and 55, healthy, physically active, nonsmokers, and of normal weight. They were trained by coaches for 12 weeks, using the RISE program originally designed by Arciero et al.: either 60min of resistance (R) training, sprint interval (I) training, stretching (S) training, or endurance (E) training, depending on the day of the week. Rest days were Wednesdays, Saturdays, and Sundays. The participants followed a carefully developed diet plan that included 1.1-1.8g of protein per kg body weight each day.
Importantly, female and male participants were randomly assigned to one of two regimens: solely morning exercise (60 minutes between 06:30 and 08:30) or evening training (between 18:00 and 20:00). Those allocated to morning exercise ate breakfast immediately after exercise, and three more meals at four-hour intervals. Those allocated to nighttime exercise ate three meals at four-hour intervals before training, followed by another after.
At the start and end of the trial, participants were comprehensively assessed for their aerobic power, muscular endurance, flexibility, balance, upper and lower body strength and power, and jumping ability. Only 16% of the 56 enrolled participants dropped out over the course of the 12-week trial, exclusively because they were unable to adhere to this nutrition and exercise schedule.
Besides changes in the participants’ physical and metabolic parameters such as blood pressure, arterial stiffness, respiratory exchange ratio, and the bodily distribution and percentage of fat over the trial, the researchers also measured changes in relevant blood biomarkers, for example, insulin, total and ‘good’ HDL cholesterol, C-reactive protein, and IL-6. They also administered questionnaires to the participants, to quantify changes in mood and feelings of food satiety.
Clear overall benefits of the program
The researchers show that all participants improved in overall health and performance over the course of the trial, irrespective of their allocation to morning or evening exercise.
“Our study clearly demonstrates the benefits of both morning and evening multimodal (RISE) exercise to improve cardiometabolic and mood health, as well as physical performance outcomes in women and men,” said Arciero.
But crucially, they also show that ETOD determines the strength of improvements in physical performance, body composition, cardiometabolic health, and mood.
For example, all female participants reduced their total body fat, abdominal and hip fat, and blood pressure over the trial, but these improvements were greater in morning-exercising women. Only evening-exercising men showed a decrease in their ratio of total to HDL cholesterol, blood pressure, respiratory exchange ratio, and carbohydrate oxidation, as fat became the preferred fuel source.
Different ETOD recommendations for women and men
“Based on our findings, women interested in reducing belly fat and blood pressure, while at the same time increasing leg muscle power should consider exercising in the morning. However, women interested in gaining upper body muscle strength, power, and endurance, as well as improving overall mood state and food intake, evening exercise is the preferred choice,” said Arciero.
“Conversely, evening exercise is ideal for men interested in improving heart and metabolic health, as well as emotional wellbeing.”
Second author Stephen J Ives, an associate professor at Skidmore College concluded: “We have shown that ETOD should be an important consideration for anyone, women, and men, given its effects on the strength of physiological outcomes of exercise. But regardless of ETOD, regular exercise is essential for our health.”
Reference: “Morning Exercise Reduces Abdominal Fat and Blood Pressure in Women; Evening Exercise Increases Muscular Performance in Women and Lowers Blood Pressure in Men” by Paul J. Arciero1, Stephen J. Ives, Alex E. Mohr, Nathaniel Robinson, Daniela Escudero, Jake Robinson, Kayla Rose, Olivia Minicucci, Gabriel O’Brien, Kathryn Curran, Vincent J. Miller, Feng He, Chelsea Norton, Maia Paul, Caitlin Sheridan, Sheriden Beard, Jessica Centore, Monique Dudar, Katy Ehnstrom, Dakembay Hoyte, Heather Mak and Aaliyah Yarde, 31 May 2022, Frontiers in Physiology.
The study was funded by Isagenix International, LLC.