What's Better: Working Out in the Morning or Evening?

“Five a.m. Monday, Wednesday, and Friday.” I raised my eyebrows. Sure, my new client  seemed motivated to get her butt into gear, but that’s an early morning for anyone, trainers included.

She promised she’d be there, no matter what. Monday rolled around, and I got a sleepy email explaining that she’d be 10 minutes late. Wednesday, the tardiness increased to a full 30 minutes. Friday, a total no-show. With thinly disguised annoyance—hey, it was 5 a.m. and I was awake for no reason—I suggested we swapped early morning workouts for a less ambitious time.

There’s a reason 24 Hour Fitness is one of the biggest gym franchises in the United States—busy work and family schedules sometimes call for fitting in a workout at an ungodly hour. But depending on the time of day that you get your sweat on, you can get some really different results.

So when’s the ultimate, best time to get the most out of your workout? There’s a definitive answer, but as with everything it more so depends on your body and your goals.

The case for evening workouts

Scientifically, your body will perform best in the early evening. Body temperatures are highest from 5 p.m. to 8 p.m., thanks to our natural circadian rhythm. Even though researchers are unsure why circadian rhythm influences performance, there’s a pretty clear correlation between the two.

When researchers compare volunteers who do tests on stationary bikes from 6:30 a.m. to 9:30 a.m. versus those who train in the evening during the body’s highest temps, the morning spinners reached exhaustion much more quickly, nearly 20 percent faster than their evening counterparts. So if you’re trying to PR on your bench press or mile time, schedule your gym time for early evening.

If you want to burn a few more calories during your workout, pencil in an evening sweat session. Even though the body performs best in the evening—it’s less likely to reach exhaustion—it becomes less efficient, meaning it uses more energy and consumes more oxygen to complete exercises. More energy used means more calories burned, so if your goal is to torch calories, shoot for an after-work workout.

The case for morning workouts

To rev your metabolism throughout the day, set your alarm. Even though it’s harder to get your heart rate up earlier in the day, research has proven that a morning workout completed on an empty stomach elevates the metabolism for the rest of the day, burns more fat, and can even increase lean muscle mass.  

Morning workouts can set you up for healthier choices throughout the day. If you begin your day thinking about how to best care for your body, it’s at the forefront of your consciousness for the rest of the day. You’re probably less likely to grab a bagel for breakfast after powering through a workout, which sets you up for healthier choices throughout your day. In a study from Brigham Young University, researchers found that women who exercised in the morning were less likely to respond to images of unhealthy food than those who had done zero morning exercise. 

So when's the right time?

Remember, it doesn't matter how efficient your workout is if you skip it every day because it's at an inconvenient time. Once we switched my “early-bird” client’s workouts to the evening, she showed up on time and ready to witness the fitness. If you’re not a morning person, newsflash: You are not going to wake up early in order to get your butt kicked. It ain’t gonna happen! And if you have a stressful job that often has you on your feet, odds are by the end of the day you’re not going to feel very strong and therefore your workouts might suffer.

Bottom line:

It’s way more important to actually get your session in, rather than schedule it at a time that doesn’t feel good to your body or convenient to your life.

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