When is the best time to exercise?

Exercise is a foundational pillar of optimal health and disease prevention, and something is always better than nothing. There are many ways in which you can maximize your results. Early morning exercise may aid weight loss. A study published in July 2019 in the journal Obesity assessed the relationship between the timing of exercise and the ability to maintain weight loss. The study included 375 participants from the National Weight Control Registry who engaged in moderate to vigorous intensity physical activity (MVPA) at least two days a week, and who had successfully maintained their weight loss. At least 50% of their workout sessions occurred during the same time, either morning, afternoon or evening. Overall, 68% maintained a consistent workout schedule, and those who did also exercised more — 4.8 days per week compared to 4.4 days per week among those whose schedules were less consistent. The duration of their exercise was also longer. The median duration for those with consistent schedules was 350 minutes per week, compared to 285 minutes per week among those with less consistent schedules. Among those who kept a consistent workout schedule, 48% exercised first thing in the morning, suggesting the timing of their exercise might be a contributing factor to successful weight management. There were no significant differences in performance levels between the different times, highlighting that consistency is really the key issue. Reasons to exercise in the morning. There are many reasons to exercise first thing in the morning. For starters, doing it first means it’ll definitely get done, whereas afternoon or evening plans can easily get dashed by unexpected events or social invitations, or sheer fatigue and lack of motivation after a long day. If you’re in the habit of using time restricted eating, exercising before your first meal of the day will also allow you to take advantage of fasted exercise, which has a number of metabolic benefits. Exercising while in a fasted state essentially forces your body to shed fat, as your body's fat burning processes are controlled by your sympathetic nervous system and is activated by exercise and lack of food. The combination of fasting and exercise also maximizes the impact of adenosine monophosphate-activated protein kinase (AMPK), which not only forces the breakdown of fat and glycogen for energy but also plays an integral role in autophagy — the process by which your body cleans out damaged cellular parts. Benefits of fasted exercise. As noted in one 2012 study, “aerobic training in a fasted state lowers body weight and body fat percentage,” while “fed aerobic training decreases only body weight.” Exercise and fasting together also yields acute oxidative stress which, benefits your muscle. Exercise and fasting yield acute oxidative stress, which keeps your muscles' mitochondria, neuro-motors, and fibers intact. Hence, exercise and fasting help counteract all the main determinants of muscle aging. The study also points out that, combined, exercise and fasting “trigger a mechanism that recycles and rejuvenates your brain and muscle tissues." The mechanism is the triggering of genes and growth factors such as brain-derived neurotropic factor (BDNF) and myogenic regulatory factors (MRFs). BDNF controls neurogenesis, signaling your brain stem cells to convert into new neurons, while MRFs are instrumental in muscle development and regeneration. In other words, fasted exercise may actually help keep your brain, neuro-motors and muscle fibers biologically young. Fasted exercise boosts stem cell regeneration. Fasting also helps boost the generation of new stem cells — cells that can be used to heal and regenerate your tissues. This occurs during the refeeding phase; at which time your body starts rebuilding and replacing all those damaged cells that were cleared out during the fasting phase. Regeneration can be further boosted by doing strength training the morning of the day when you're planning to break your fast. The reason for this is because during fasting, your growth hormone level skyrockets, rising as much as 300% for a five-day fast. Fasting can be likened to getting a growth hormone injection and a stem cell transplant, and by incorporating strength training at the right time, just before refeeding, you optimize all these regenerative benefits. Fasted exercise improves insulin sensitivity. Fasted exercise is also a potent prevention strategy for Type 2 diabetes. In one 2010 study, those who exercised fasted increased their levels of GLUT4 — a muscle protein that plays a pivotal role in insulin sensitivity by transporting glucose into the cell — by 28%, compared to those who had a carbohydrate rich meal before training, or controls (who did not train). This despite eating a hypercaloric diet (receiving 30% more calories than required for health; half of which was from fat). According to the authors: “This study shows that fasted training is more potent than fed training to facilitate adaptations in muscle and to improve whole-body glucose tolerance and insulin sensitivity during hyper-caloric fat-rich diet.” Will evening exercise disrupt your sleep? For all of the reasons discussed above, exercising first thing in the morning is likely an ideal choice. Exercise also tends to have an invigorating effect, which can propel you through the day when done early, and could backfire if done too late in the evening. Since exercise increases in your adrenaline level, heart rate and body temperature, it could make it difficult to fall asleep. Evening exercise does work well for some people and, again, consistency is the most important component for success. A study published in 2011, found that when people exercised vigorously for 35 minutes right before bed they slept just as well as on nights when they didn't exercise. A poll by the National Sleep Foundation found that 83% of people said they slept better when they exercised (even within four hours of bedtime) than when they did not. Just 3% of late-day exercises said their sleep quality was worse when they exercised than when they did not. Interestingly, of those who exercised more than four hours before bedtime, 73% reported their daily routine allowed for adequate sleep, whereas only 65% of those who exercised within four hours of bedtime felt they had enough time in the day to get the sleep they needed. The National Sleep Foundation concluded that exercise is good for sleep, regardless of the time of day it's performed, noting: "While some believe exercising near bedtime can adversely affect sleep and sleep quality, no major differences were found between the data for individuals who say they have done vigorous or moderate activity within four hours of bedtime compared to their counterparts (those who did vigorous or moderate activity more than four hours before bedtime) … [T]he conclusion can be drawn that exercise, or physical activity in general, is generally good for sleep, regardless of the time of day the activity is performed." Time of exercise influences your circadian rhythm. Indeed, there's a case to be made for exercise at virtually any time of day, including in the afternoon. Research published in February 2019 in the Journal of Physiology confirmed that exercise can cause a shift in your circadian rhythm, and that the magnitude and direction of that shift depends on the time you exercise. Ninety-nine participants of varying ages performed one hour of moderate intensity exercise on a treadmill for three consecutive days at one of eight time slots during the day and night: 1 a.m., 4 a.m., 7 a.m., 10 a.m., 1 p.m., 4 p.m., 7 p.m. or 10 p.m. Exercising at either 7 a.m., 1 p.m. and 4 p.m., will shift your body clock to an earlier time. As a result, you might find it easier to go to bed earlier when you’ve exercised at these times. Going to sleep earlier will also facilitate getting up earlier the next morning. When exercising at 7 p.m. and 10 p.m., you shift your body clock to a later time, which might be helpful if you need peak performance later the following day. As reported by Neuroscience News: “These findings suggest exercise could counter the effects of jet lag, shift work, and other disruptions to the body’s internal clock helping individuals adjust to shifted schedules.” Interestingly, the most robust circadian advancements occurred when exercising in the afternoon more so than exercising in the morning. As noted by the authors: As you can see, you can find support for exercise at just about any time of day. The question is, what are you trying to achieve? Weight loss may be more easily maintained by working out first thing in the morning. Add in fasting, and you can boost things like stem cell regeneration and insulin sensitivity. Meanwhile, afternoon or evening exercise may be helpful if you’re working shifts or traveling, by helping you reset your circadian clock. **Knowing the variables involved, and how you can influence your health through the timing of your exercise, you can use it as a targeted tool to help you achieve your health aims. Do you often skip a much-needed workout session because there’s not enough time to squeeze it in your busy schedule? This is one of the many excuses people come up with when they fail to get enough exercise — but don’t let it deter you from achieving your fitness goals. Source: mercola, 9/20/19.