Should one exercise / work out in the morning (soon after waking up) or in the evening?

Do what your body likes.

I like using the treadmill between 7:00 and 8:00 PM, which is a peculiar time. However, I can go faster and farther then because I feel energized and strong.

Exercising earlier in the day boosts metabolism for the rest of the day.
I have always done my walks/workouts before noon for optimal benefit early in the day.
Exercising before bed can often cause insomnia by boosting adrenalin.

The benefits remain the same regardless, other than what I have mentioned.

From a study measuring performance on cycling, jumping, and sprinting at different times of day:

The [maximal anaerobic power for cycling] and [jumping] were higher at 1400 and 1800 hours than at 0900 hours. The diff€erences between the morning and the afternoon reached 3% (P < 0.05†) for cycling and 5%±7% for jumping …P (< 0.01)†. The time-of-day eff€ect was significant for [flight time during jumping] (…P < 0.05)† but not for [ground contact time during jumping]. During the dash-run tests, the di€fferences almost reached significance for [maximal anaerobic velocity] between 0900 and 1800 hours (…P=ˆ0.0544)†. No significant variations were observed between 1400 and 1800 hours for cycling, jumping and running tests. A time-of-day eff€ect in the maximal anaerobic power of cycle and multi-jump tests existed.

From another study measuring aerobic and anaerobic performance during a cycling task Total work performed was 9.6% greater in the afternoon (mean +/- SE, 348.8 +/- 40.6 J.kg-1) compared to the morning (318.2 +/- 39.5 J.kg-1). The greater amount of work in the afternoon was associated with a 5.1% higher aerobic power and a 5.6% larger anaerobic contribution.

From another cycling task study: Time to exhaustion was 9% greater (p<0.01) in the PM (214±43 sec) than in the AM (196±38 sec). Peak VO2 was 7% higher (p<0.01) in the PM (3.34±1.00 1.min-1) in the AM (3.11±0.98 1.min-1). The aerobic system responded 6% faster (p=0.04) in the PM than in the AM: the time constant describing VO2 kinetics was 33.5±5.7 sec in the PM and 35.5±5.5 sec in the AM. However, there were no significant correlations (p≥0.20) between the AM-PM differences in time to exhaustion, time constant of the response, or peak VO2. The findings confirm previous reports of a time of day effect on time to exhaustion in high-intensity exercise. It was also concluded that there is a higher peak VO2 in the PM than in the AM. In addition, there is a time of day effect on VO2 kinetics, with the aerobic system responding faster in the PM than in the AM.

More here if you want them.

If you are trying to lose weight it might be more beneficial to work out in the morning if you can exercise with a high intensity, as studies have shown your metabolism will remain elevated (with a tail-off effect) throughout the day and as long as 36 hours after.

If you are exercising to stay healthy, put on muscle, tone up – then it probably doesn’t matter much except to you and doing what you like. The more you like the workout (and the time of it) the more you will do it!

I don’t have any scientific evidence unless you count psychology as a science :) .

For me it absolutely must be in the morning. If not, I have to go through the entire day, use up all of my energy and then go wear myself out in the gym, or running.

Getting up early already has psychological value as it is. You get a head start on things that have to be done that day. Throw in a workout and you will not only feel more accomplished and ready for the day, but you will feel quite refreshed as you take a hot shower, eat a healthy breakfast, and check your email having already completed your workout for the day.

It’s a no-brainer for me.

Whichever you prefer. it is best not to exercise within a couple of hours of going to bed, otherwise, it doesn’t really matter.

@marinelife – that’s interesting – I would have thought the exhaustion from the workout would make a person sleep better, but the chemical reaction in the body seems to work against that theory.

@digitalimpression

Yes, I totally agree! I HAVE to be out fairly early or I won’t go out at all.
If it’s after 11 it is likely I will nix the expedition and go to the bakery. lol

I workout at lunch time. Breaks up my day. It is nice and sunny.

@Coloma Exactly! Morning workouts mean you only have to fight the “I don’t wanna wake up” demon.

The evening idea provides you with so much more time to come up with an excuse not to exercise.

My routine is to wake up and “be regular”. Then after I am “empty” I feel better about all that moving and bending during exercises. Once I’ve eaten it’s very difficult to feel as comfortable about exercise. Try eating and doing a situp, or going for a run after you eat. To me it’s no fun. But when I exercise and then eat, I feel my body ripping into the food to find what it needs.

My vote is exercise on an empty stomach, as early as possible.

I find it more refreshing in the morning rather than the evening.

I personally find that having a regular routine of exercise every morning works out best, afterwards I am ready for anything the entire day. Evening exercise I found I tended to sit down to relax after the day and more often than not I could and usually find an excuse not to do it, telling myself, tomorrow.