Your best time to work out

When is the best time of day to work out? Some people think early morning, others like afternoon and there are people who love to workout late at night. So what is the correct answer to this question? As you can imagine, there is no one-size-fits-all approach to what time of day is best for a workout.

Unsurprisingly, there has been a fair amount of research on exercise and time of day, but most of the studies are limited and not without controversy. What we do know from a bio-science point of view is human hormones, core body temperature and metabolism are all influenced by our daily circadian rhythms which in turn effects physical performance and conditioning. With that said, it would make sense to look at our circadian rhythm for part of the answer on timing your workout.

What is circadian rhythm again? Our circadian rhythm is a set cycle of biological activity that occurs in our body in a 24-hour period. The most commonly understood aspect of this biological activity is our sleep-wake cycle. The specific part of our brain that manages our circadian rhythm is called the 'suprachiasmatic nucleus,' which is located in our hypothalamus and acts as our primary clock. This built-in clock, which has molecular oscillators, has been found in roughly 10 percent of our expressed genes affecting our nervous system, cardiovascular system and musculoskeletal systems including hormone production.

Many people think circadian rhythms only affect our sleep cycle. These cycles have a much broader influence on regulating our body temperature, blood pressure, mental acuity and metabolism. These complex 24-hour rhythms conform to daily cues such as sunlight, meals and other triggering factors. The time of day that we typically exercise can be one of those cues. Extensive research has been done on circadian rhythms and those studies show that we are born with a set circadian rhythm, but we can also reset them based upon our individual behaviors.

Studies done on athletes found their bodies had the ability to learn new patterns for better performance around time of day. For example, when an athlete trains in the morning, over time their bodies respond better to morning exercise. When they switched to evening exercise, their performance was not as good. So for a competitive athlete, it becomes important to understand their own circadian rhythms around their daily fluctuations in core body temperature, optimal metabolism and peak hormonal levels. A great example of this is found with regard to testosterone, which is highest first thing in the morning in most men. The same holds true in both men and women when it comes to cortisol levels, which are highest in the morning hours in part to get us up and moving.

Most of us do not put a whole lot of thought into the optimal time of day to exercise. For many of us, it comes down to when it's convenient or when we have time to squeeze in a quick run between busy life events. This approach to exercise and fitness can limit your overall progress and cause inconsistent workout schedules. So it's time to rethink how you set your body's clock to exercise for the best results.

The best way to optimize your workout is to understand when your body's natural rhythms are at their highest. This is a great idea and very doable, but wait there is the age old problem that your personal or career schedule will trump your peak performance time. Let's face it, most of us train or workout when time allows so rethinking your approach to exercise is needed.

The many studies out there have found that certain types of exercise work better at various times of the day. For example, weight training is best done between 2 p.m. and 8 p.m. Swimming is another example that is best done later in the evening for good results. Many running coaches will tell you early morning runs are best even though your core body temperature and flexibility are at its lowest in the a.m. Afternoons are great for intervals and short distance speed runs. But all the science in the world can't shake the reality that each of us have different lifestyles and schedules making it a challenge to apply the study data to your workout schedule.

The very best thing you can do is get a feel for your circadian rhythm. What feels best, do you get up early or are you a night owl? Do you function better after work or are you sluggish at the end of a long day?

Once you have an idea of what feels right, make your workout times a habit and your body's clock will adjust and become comfortable with a consistent exercise schedule. The old saying is you can make something a habit by repeating it for 21 days. I am not sure this really works, but it may be worth a try.

One final point regarding exercise performance and circadian rhythms is around food. It has been found that erratic eating patterns and poor food choices affect insulin production and processing. In turn, this can create metabolic disturbances and disrupt your circadian rhythm. Both issues can disrupt your workouts, drop performance and limit your ability to lose weight.

Bottom-line, tune into how you feel during key points in the day. Leverage your circadian rhythms by setting your exercise clock with a solid consistent schedule. Elite athletes already know that consistency will help them be stronger, faster with better recovery and overall improvements in endurance, body composition and muscle build. There is no reason you cannot apply the same principles to your fitness and workouts.

Judd Jones is a director for the Hagadone Corporation.