Exercise AM vs PM
By Aparna Mele, MD
Who wins when it comes to maximizing the positive effects of exercise: the early bird or the night owl? Should we all rise at dawn to work out, or is it better to refresh our brains and bodies for the evening with an after-work exercise session? Earlier research has confirmed that exercise timing according to our circadian rhythm can optimize the health-promoting effects of exercise. Turns out, both can have major benefits!
Morning workouts could have the upper hand in this competition, because morning routines can nurture routine consistency. You wake up and get right to it, leaving less room to cop out of it. Once you’re up, you’re up and you have no excuse not to exercise and get your heart pumping for the day! Morning exercise can shift your circadian rhythms to keep your body most alert in the morning and more tired in the evening, facilitating falling asleep at a more reasonable hour. Did you know that exercising on an empty stomach, ie in a fasting state burns more fat than after a meal in the fed state. This is because your body utilizes more fat stores to fuel your routine when you haven’t yet eaten. Prior research has shown that an active cardio workup at sunrise burns 20% more fat and individuals ate 100 less calories in the day as well! Morning exercise can really increase productivity by boosting energy levels, making us more alert and focused, and fine-tuning logical thinking. The endorphins produced by exercising will boost your mood all day long and well beyond the workout, keeping you optimistic and positive and giving you a sense of accomplishment that can help you perform better at all the other things you do all day. There are some drawbacks to consider. Waking up hungry and then exercising could make you less motivated and more fatigued during your workout, but this could be combatted with a mini energy fueling meal/small high carb snack like a small banana. Most people have a busy morning starting their life and fitting in a workout could prove challenging, unless you wake up earlier than your usual, cutting into sleep. That said, if you consistently wake up earlier and exercise, you will train your body to sleep earlier and then ultimately still get your needed hours of restful sleep.
Evening workout people argue that the day fuels them, giving them the power they need to perform in the pm. In the afternoon, many people have sustained and increased energy to push themselves through a workout for a longer period of time. By being up and mobile and mentally alert for much of the day, your anaerobic capacity is 7% higher in the day, warming core temperatures and optimizing muscle function and strength, ie your muscles are more powered up to perform! This is important because core body temperature correlates with exercise performance. Additionally, most people will achieve higher muscle activation levels in the evening vs. the morning. That means they can use and fatigue more of their muscle fibers, making workouts more productive. Oxygen uptake kinetics also appear to be faster in the evening , so oxygenating through a workout is more effective than in the morning. Reaction time is quicker when we are alert and active so can benefit you during high intensity interval training and improve overall performance. Being more mentally alert can keep you focused better during your evening exercise routine. Evening workouts are a great way to allay the day’s stress and the endorphin surge with exercising can help you curtail negative emotions. It allows you to go to sleep relatively soon after training, while still giving you enough time for one or two good meals before bed so in other words, timing a workout in the evening allows you to optimally satisfy both the need for post-workout nutrition and the need for post-workout sleep, while also replacing bad evening habits such as excess snacking, alcohol intake, or even screen time. There are drawbacks, including messing with sleep if the endorphin surge after working out keeps you wired and unable to fall asleep. Some people get the munchies after an evening workup and have an insatiable appetite. Focus on a high protein meal with a small amount of carbs to replenish glycogen stores. Consistency can be compromised with evening workouts as sometimes after a long and tiring day, you end up rationalizing why not to work out afterwards.
In the end, which is better–AM or PM? In exercise, consistency is always key and it should be made a solid priority regardless of the day you have behind or ahead of you. So ultimately, the best time to work out each day is the SAME time each day. If you train at the same time of day every day, your body learns to predict when it will have physical demands put on it, thereby shifting your biochemistry to give you more energy and strength at that particular time. Once you discover that perfect workout time for you, stick with it and make it a healthy and long-term habit.
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