When Is The Best Time To Workout? AM vs PM

Most gym goers have their preferences and set-in-stone ideas as to when is the best time to workout. Some swear that Training in the morning is the best way to start their day with a good workout, a small number squeeze in their workouts around lunchtime while most people feel training in the evening is best (after work in the late afternoon or at night.) The question remains however, when is the best time to train and does the time that you train make that much of a difference in terms of results? It’s a question my New York City personal training clients often ask. However, like so many questions related to human physiology, the answer isn’t as clear cut as we might like it to be as there are indeed times when most of us are, in theory, able to perform at our physical best but, (and it’s a big ‘but’), that all depends on your individual training habits and, (to a degree), your goals. The hard science leans towards late afternoon/early evening workouts being best for optimum Performance, but this may not be applicable to everyone. In this article we will take a look at the pros and cons of working out in the morning vs working out in the evening and hopefully it provides some insight into when would be the best training time for you.

When Is The Best Time To Workout- A Look At How Our Body Works

Like most creatures on Earth, our bodies are completely influenced by the rising and setting of the sun. Almost all of our bodily functions oscillate, (rise and fall), in what are termed circadian rhythms that repeat themselves every twenty four hours[1], thanks to part of our brain called the suprachiasmatic  nuclei and it’s bundle of circadian oscillator cells. An internal clock of sorts that resets itself every day using light as a point of reference for the time of the day. These ‘clocks’ synchronize our moods, hunger and energy levels in a cyclical pattern, something we all can all relate to in some form. For example, when you wake up you aren’t anywhere near as sharp as you would be if you had been awake for a few more hours, (regardless of how many cups of coffee you have!) It takes time for us to ‘warm up’ and the increase in our mental acuity continues up to the early evening, at which point our ability to concentrate begins to decline. This rise and fall pattern holds true not just for our mental capacities, and our motivation to train, but also for most of the components related to sports performance such as muscle strength, flexibility and short term power output. All of which can vary depending on the time of the day.[8]

When Is The Best Time To Workout- The Connection Between Muscle Strength, Performance & Body Temperature

One important change in our bodies over the course of the day that affects sports performance is body temperature. Your body temperature drops to its lowest point at or around 4 am and continues to rise until it peaks around 6 pm.[3] A fluctuation between 97.5 and 99.5 degrees Fahrenheit (that’s 36.5 to 37.5 degrees Celsius for those of us on the metric system), and these changes in temperature appear to have a significant impact on our ability to perform physical tasks.[4] Studies show a direct correlation between body temperature and nerve conduction. Making arousal levels and reaction times higher in the afternoon/evening compared to what they are in the morning.[5] Increases in body temperature may also lead to an increase in carbohydrate utilization as a primary fuel source over fats and also facilitate actin-myosin cross bridge mechanics, which allows muscles to generate more force.[6] This may partly explain why peak performances are postulated to usually occur in the early evenings at the time of the highest body temperatures.[7] (See also my article on Weight Loss and Food Timing) In keeping with the timeline of increasing body temperature, isometric grip strength appears to peak between 2 pm and 5 pm and the isometric strength of the arm muscles have been seen to peak in the early evening as well.[8, 9,10] Lower back strength is also higher in the evening than it is in the morning,[12] and our ability to perform brief, explosive movements also peaks in the later part of the day.[13,14,15] Plasma levels of testosterone, which plays an essential role in increasing muscle size and strength have been found to be significantly higher after evening training sessions, when compared to morning training sessions. And some studies have found greater strength increases from workouts performed at 8pm compared to those performed at 9 am.[16]

When Is The Best Time To Workout- Things To Consider When Training In The Morning

Given that increased body temperature has a significant effect on increasing exercise performance, it is highly recommended that you warm up thoroughly before training on mornings. One study found that by extending the warm up period before morning exercise sessions, participants were able to increase body temperature to levels comparable to that of afternoon exercise sessions and an increase in performance was observed, seemingly as a result.[18] However, while another study observed increases in exercise performance among cyclists who did extended warm ups, the average cycling times were still always better in the early evenings.[18] While body temperature is indeed linked to increased performance, the fact that warming your body to the same temperature as it would be during an afternoon training sessions does not equate to the same level of performance means that there are other factors involved.

Recent studies have found other performance related changes in our bodies, changes that occur independent of body temperature. Force produced during maximal voluntary contraction is higher in the evenings than it is on mornings, even when induced by electrical stimulation. Thus, it is thought that the increase in contraction force over the course of the day may be because of greater calcium release into the muscles and increased calcium sensitivity of contractile proteins and changes in myosin ATP activity. All of which increase over the course of the day, peaking in the afternoon/early evening. [19] Another change at the muscular level is an increased concentration of inorganic phosphate. Which reaches its highest values at 6pm and has a significant effect on the actin-myosin crossbridge process responsible for muscular contractions.[20]

There are some possible safety considerations as well for certain populations. The two main indicators of breathing rhythms, (forced expiratory volume and peak expiration flow), are at their lowest levels between the hours of 3 am and 8 am[21] and research shows that those who suffer from asthma have much greater breathing variations and can thus have very low levels slightly later in the morning.[22] Given that most asthma attacks occur at night or in the early morning, asthmatics are usually advised against high intensity exercise early in the morning.[22] The risk of suffering a coronary event is also three times higher in the morning compared to any other time of the day.[23] Since there is some connection between physical exertion and cardiac events, especially among those who are generally inactive and suddenly perform strenuous activities. (Note though that all the research evidence suggests that the risks of physical activity far outweigh the benefits for healthy subjects and the risk of an exercise-related cardiac event decreases with increasing amounts of physical activity.[23,25,26]) However, given the increase in risk earlier in the day, some recommend that individuals with pre-existing heart conditions not schedule their most intense exercise sessions in the morning [24] and include at least a 5 minute warm up and cool down session before and after training to further reduce the likelihood of myocardial infarction.[27,28,29]

Is Late Afternoon/Early Evening The Best Time To Workout?

From the aforementioned research cited thus far, it would certainly appear that training in the afternoon/early evening might be the best time to workout, but as with so many aspects of human physiology, it isn’t quite that simple and to date no study has been able to convulsively say that one time is universally better than another as a general recommendation.[8] Some argue that since most world records are broken by athletes competing in the early evening (between the so called magic hours), it is a strong implication that we should all train at that time but such observations must be looked at in the proper context. For example, most major sporting events are held in the early evening so as to cater to the demands of peak television broadcasts[30,31] so the fact that more records are broken at that time may be simply because there are more events at that time.[8] Timing of optimal performance also varies by activity. Since overheating has a significant negative impact on endurance type activities such as running, marathons and the like are usually scheduled earlier in the day when it is cooler- especially in summer and in warmer climates.[8] Marathons starting later in the day are often plagued by runners becoming ill and marked reductions in the performance of even the best in the field because of the higher temperatures.[32]

Individual Best Time Of Day Considerations

For non-endurance athletes, in trials done at different times of the day, cyclists, runners, swimmers, and weight throwers generally tend to perform better in the early evenings. [15,33] However there is also evidence that individuals with different sleeping patterns and diurnal preferences find it difficult to train in the afternoon to late evening times. Some of us simply prefer morning activity, (the ‘larks’), while at the other end of the spectrum, some would rather be active later in the day or at night, (the ‘owls’). Most of us however, fall somewhere in the middle and the aforementioned studies reflect the performance shifts of the general population, not those who identify themselves as being more of a morning person or more of a night person.[8]

Temperature and time of day may have an effect on performance but what is most important when scheduling a training program is the time of day the individual is able to train and the time when they feel most motivated to do so. True, there is some research that finds an increase in self-motivated exercise intensity among those training in the late afternoon/early evening[8] however all the intensity in the world is not worth much if you don’t make it to the gym in the first place!

We should also bear in mind that the increases in performance over the course of the day are far greater among advanced athletes than among sedentary individuals or for those just starting an exercise routine.[8] So for a beginner, the differences between training in the morning and training in the late afternoon/early evening would not be as pronounced.[34] For a beginner what would be more important would be to find a schedule that allows him or her to train regularly so as to build up to their fitness levels and worry about details like optimal performance later if it ever becomes relevant. Individuals over the age of 50 also appear to have a smaller change in body temperature over the course of the day and their performance does not increase as much as their younger counterparts over the course of the day.[15] Most individuals over 50 years old appear to also have a greater tendency towards ‘morningness’[34,35,36,37] Thus for those over 50, the best time to train would be the time when they are most motivated and inclined to do so.

When Is The Best Time To Workout? Anytime!

We like clear cut answers to often asked questions and in this case it’s important to not try to set in stone a specific time of day as the best time to train. We are by nature adaptive beings, who are constantly being shaped by our environment and so it should come as no surprise that we are able to condition ourselves to be at or close to our best in terms of performance at different times of the day.[8] Research shows that when individuals train only in the morning or only in the early evening (during the theoretical peak performance time), those who usually trained on mornings did better on physical performance tests given early in the day while those accustomed to training on evenings did better on performance tests when in the evenings.[8] Like light and timing of meals, exercise appears to have a powerful effect as well on synchronizing our internal clock[2] and so it makes sense to not be too hung up on any particular training time. What is important is that you try to train at or around the same times so your body can adapt to that time as a period requiring high levels of performance.

Training Recommendations for Fat Loss

On a personal note, I have trained both on morning and in the evenings for decades (I did my leg workouts on Sunday mornings and the rest of my body during the week at around 6:30 pm for over twenty years). Did I see any noticeable differences? It’s hard to say, I set all of my personal best lifts for legs in the morning when I trained them and my best lifts for upper body exercises in the evening when I trained them. That said, when I stopped training on Sunday mornings and switched to training legs later in the day there was no difference in my lifts and any increases in my personal best lifts now could be attributed to simple improvements over time.  On that note, over 95% of clients I have trained were in the late afternoon/early evening between the hours of 5 pm to 7:30 pm- but that is simply because most people find it easier to go to the gym right after work. There is indeed an increase in fat utilization as fuel during the earlier part of the day, and some swear that training on mornings makes a big difference in fat loss. However, over the course of 26 years, I personally never saw any difference in fat loss among the clients I had training in the mornings compared to those training in the afternoon/early evening. The only factor that made any difference in their rate of fat loss was how regular they were with their training and how strictly they adhered to their dietary program. The time that they trained made absolutely no difference in outcomes. The bottom line is that consistency is key to the success of any athletic endeavor and as long as you can find the time to train and keep on training, you’ll be successful. Now if you have an event that will require you to be at your very best at a specific time, it would make sense that you time your workouts to coincide with the time of the event several weeks beforehand.

Now the number one cited reason why most people don’t workout is lack of time and I highly recommend high intensity training modalities than call for intense training over a short period of time, (10-15 minutes) rather than marathon workouts lasting an hour or more for two reasons. Firstly, you’ll be more likely to fit in a 10 minute high intensity workout consistently at or around the same time than an hour long workout, and with higher intensity training, you train for no more than three times a week, further making it more likely for you to sustain the routine and reap the benefits that come from working out regularly.  Otherwise, even though research shows that the “ideal time” for most of us to exercise is in the late afternoon, we are so designed that your body will adapt to whatever time you regularly train. So be sure to train regularly whenever you can!

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References for When Is The Best Time To Train AM vs PM

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