When Is The Best Time To Do Cardio?


Well-Known Member
4 Jul 2011
The best time for you to do your cardio exercise is when you feel it is the best time to do it, and stick to that time. There is no set time where you make the best gains to do cardio. It ranges for everyone.

Cardio In The Morning On An Empty Stomach?

First of all NO! Cardio in the morning is probably the most stupid idea I have ever heard. This isnt just my opinion but the most knowledgeable trainers and exercise experts agree that cardio in the morning on an empty stomach is not good for you body.
Well, you might ask, what if I want to burn fat? I have low glycogen stores in the morning and my energy levels are low because I dont have carbohydrates, so then I will tap into my fat stores right? This is TOTALLY wrong. The complete opposite happens.

Let me enlighten you. Fat burn doesnt occur during cardio exercise, but about two hours after. Instead your body will look at your tasty muscles for energy meaning. Bye bye muscles. This is a bodybuilders worst nightmare.

So unless your goal is to become scrawny and lose muscle then by all means do cardio in the morning. Its also common sense not to do it on an empty stomach.

You wont have a satisfactory amount of energy meaning decreases performance which = crappier results. And if you think about it, your body has just fasted for eight hours and it needs something to eat to refuel itself.

Not feeding your body and doing exercise is like going into war without any ammunition.

Dont Get Me Wrong

Yes, dont get me wrong, it isnt that doing cardio in the morning is bad, but doing it on an empty stomach is bad unless you want to lose muscle instead of fat.
So when you wake up at 5:00 A.M at least have something light to eat and wait at least 30-45 minutes before performing your cardio. Like I said earlier if youre a morning person and you feel best in the morning then keep doing it in the morning, just make sure you dont do it on an empty stomach.

Cardio Workout Right Before Weightlifting?

Again this is also a HUGE NO! Not unless you dont want good results from pumping iron, then I guess you're wasting your time in the gym if you go all out and perform cardio before your workouts.

But for a lot of people, especially women, they dont want to gain serious mass, so then if your weight workout is relatively low intensity and doesnt leave you feeling like you just got hit by a car, then by all means you can do cardio before your workout.

But for most of the guys, they want some serious mass, and let me tell you that the last few reps (Say the last 3-2 reps) where you struggle and sweat is where you stimulate your muscles to grow. But when you run before working out, an intense cardio workout totally or almost depletes your glycogen stores.

When weightlifting, you dont use as much of your glycogen stores, but you still need quite a bit (This might come as a surprise to some people but its true).

So if you have no glycogen stores which is your muscles source of energy and your pushing yourself to max, the energy wont be there to push those last few grueling reps meaning a way less effective workout.

Another reason why this is such a big NO is because during a hard cardio session, protein synthesis drops low and protein breakdown goes up. During a weight lifting session, protein synthesis either goes up a little or stays the same while protein breakdown goes up.

After your cardio session while protein synthesis drops (Meaning your bodys ability to build muscle), and you hit the weights, the result will be that your bodies ability to build muscle will be impaired because of your cardio training depending on how intense your cardio was.

So Let's Make Up A Situation:

Billy goes and does his intense cardio workout. After that his protein synthesis drops and muscle breakdown goes high.​

He goes weightlifting and instead of his protein synthesis being normal or slightly elevated, it is very low because of his cardio session. Plus his muscles are in a state of breakdown.​

So basically you dont want your bodys ability to build/repair muscle (Protein synthesis) to be impaired right after a weight workout.

Again, Dont Get Me Wrong

Yes, dont get me wrong again, what I just explained above is doing cardio right before your workout or even an hour before your workout. But it is all right if you do your cardio exercise then your weightlifting program after if you give yourself an adequate amount of time to recover and replenish your glycogen stores.
But in between you must have the proper nutrition to stop protein breakdown and increase muscle synthesis before you hit the weights. Plus you have to replenish your muscles glycogen stores.

Still though, your performance in the weight room may suffer even though you have given yourself enough rest and nutrition, so it is best if you do your weight lifting before anything else to make sure that you lift to your full potential.

Also if you do an intense cardio session and eat hamburgers and fries then 6 hours later do your cardio session, it just wont cut it. Another thing is if your cardio workout is relatively short and low/very low intensity then its all right to hit the weights right after.

Cardio Right After Weights?

Doing cardio right after weights is way better than doing it before weights. The reason being is that weight lifting doesnt deplete your glycogen stores as bad as it does in cardio workouts depending on how intense you go.

So you still will have some of your glycogen stores left meaning that you can still get an alright cardio session. But for a more effective cardio session right after a workout, I recommend waiting at least 2 hours even more (If you have the time to do this) before doing your cardio.

In between this time it is important you replenish your glycogen stores quickly, and stop protein breakdown as fast as possible. But if you dont have the time it is still alright to do it right after weights. Just be prepared to have a less effective cardio session.

For Best Results..

For best results in your cardio training, try to do schedule your sessions separate from your weightlifting program. So if you lift weights 4 times a week, then do running on the other three days that youre not lifting weights.

Just remember try to schedule your cardio session as far away as possible from your leg lifting schedule, because running on super sore tired legs basically sucks. Doing cardio on separate days than weight lifting ensures that you have the proper energy to perform your best in either your cardio or lifting session.

If you cannot then do your cardio after your workouts at least. You also have to do cardio after weights if you have 4-5 cardio sessions and are a serious weight lifter.

Remember you get the best gains when you have the most energy. Yea, if you did an all out run for 45 minutes do you think you could have a good leg workout?

Doing Cardio And Gaining Serious Mass? Is It Possible?

Yes it is possible, it can be done. A bodybuilder would cry at the idea of losing precious hard gained muscle. This is also one of those topics that also depends on your goals.

If a bodybuilder wants to gain serious mass and still maintain a balance in his cardiovascular system then it is totally possible to do it without losing muscle.

But if someone wants to gain serious mass and wants to be a professional marathon runner, then my answer is no since heavy training in the field of endurance, marathon running, and long distance running causes major muscle loss over time.

Just look at all the marathon athletes, they are scrawny not muscular. If you want to be well rounded (Meaning quite cardiovascular fit while still having decent muscle and strength), then your cardio program might cause slight/very slight muscle loss depending on how long, intense and how many times a week you do it.

But, your weight lifting program will cause you to gain more mass than is lost and you WILL get stronger. So there are basically two categories for this topic. Guys who want huge mass and dont want to lose it and guys who want some mass and strength but also want to be cardiovascular fit.

So for the guys who want to get big without losing muscle and just want to do enough cardio to stay balanced, well doing cardio three days a week for 30-45 minutes at 60-75% of your max heart rate is enough that you will maintain and get benefits for your cardio system and you also will NOT lose muscle.

So theres the good news for all the bodybuilders who get the crap scared out of them by cardio. Now for the people who want to be well rounded.

If you want to be pretty decently fit in the cardiovascular system and still be strong and have mass, then do cardio about 4-5 times a week from anywhere to 45-60 minutes at 60-85% of your max.

Remember the higher the intensity (heart rate), times exercised a week and length of exercise determines how much muscle you will lose. So if you run everyday for two hours then you lose lots of muscle over time.

For those of you who are still scared, I run 6 times a week for 1 hour and 15 minutes and I still made strength gains in the gym.

source: bodybuilding.com/fun/topicoftheweek34.htm


Well-Known Member
4 Jul 2011
To Retain Muscles,

HIIT (High intensity interval training)

HIIT combines the use of all out intervals and periods of lower intensity periods. Dont worry, if you are well fed and energized, these sessions last for only 30 minutes at the max, in that time you wont use up enough of your energy that you will have to tap into your muscle stores.

The Good Old Run

Run at most for 3 days a week for 30-45 minutes and you wont lose any muscle if your well fed and energized. Try running outside because on a treadmill, staring at a wall for 30+ minutes is kind of... It sucks.


New Member
8 Nov 2011
This is a great article but I have some questions. It seems the article is trying to retain muscle mass by not mixing cardio during weight training days.

What if your main goal is for pure fat loss (with the intent to gain muscle mass once the body fat percentage is lowered to almost single digits)?

Would mixing lighter cardio with weight training in the same days have beneficial or detrimental effects?


12 Nov 2011
Very great facts here man! I always thought myself that you should lift weights after some cardio. However now I know it is best to recover first. Thanks for this, very helpful. I am thinking of doing weight lifting a little because I have a broken ankle and can't do cardio much.


Active Member
5 Jun 2011
What if your main goal is for pure fat loss (with the intent to gain muscle mass once the body fat percentage is lowered to almost single digits)?

Would mixing lighter cardio with weight training in the same days have beneficial or detrimental effects?
Firstly, when weight loss is involved, you will lose some muscle together with the fat lost. With a calorie deficit diet, it is almost unavoidable that your body will use some lean muscles for energy. The thing is to reduce the amount of muscle lost as much as possible.

I would still include weight training but reduce the intensity by a notch. Cardio has to be intense and not too long. For me, 20-30mins of fast runs are effective to burn fat. Running fast and hard is much more effective to burn fat compared to slow and light runs.

I will not mix cardio and weight training on the same day. It is just not efficient IMHO. Another factor is that mentally u may not be strong enough to give your best after completing one component.
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New Member
21 Nov 2011
I don't mix cardio and weight training on the same day either. I prefer to focus my energy on one type of building at a time. I have a friend that runs on a treadmill with weights in their hands, but I don't see the benefits of that. She's lost weight steadily but hasn't really built any muscle or strength.


3 Nov 2011
There are really people who jog or do some cardio first thing in the morning and thinks it was just okay. Glad that I do not believe on it and would definitely consume something for breakfast first before doing any exercise. And I prefer working out late in the afternoon. ;)


New Member
13 Nov 2011
I can't do anything before I have breakfast- I'm totally useless then, so I can't imagine trying to get a run or some cardio in that early. That said, perhaps the best time to do cardio is the time when you will actually do it! If the morning is when you can fit it in, that's better than avoiding a workout altogether.


New Member
29 Nov 2011
I think that the best time to cardio is whenever YOU are most likely to do it. I do it at lunch because I need to mental break and to recharge my batteries. If I leave it until the evening I am drained and drag my butt through it. If I plan it for the morning I am crabby...I am not a morning person. So, schedule it for when it works best and when you are most likely not to excuse yourself from it completely.


New Member
18 Nov 2011
I think it's up to you to choose the best time. I know sometimes experts say to not workout before bed. I find that I sleep the best after I have done a great workout. It doesn't keep me up. I have tried to do the morning thing, before getting everyone else up. It doesn't really work that way. So I think it's safe to say, I'm an evening cardio gal.


Well-Known Member
20 Jul 2011
Hmm. Cardio on an empty stomach. I'd really like to see more research into this, for all I know is that it's been well-implemented in many recomposition programmes designed by various trainers. Well... now that I think about it, just HOW catabolic is walking up and down a hill for 30 minutes on an empty stomach? I suggest that the best time to do cardio is... any time of the day. As long as you do it, I don't see what's wrong with doing it at that particular point of the day. All that science-y stuff may make things tougher for someone trying to get motivated to burn dat phat.


19 Jul 2011
In my opinion, do cardio when you best feel like doing it. when you can feel the energy going through you and able to give it your best. No point in going for a run at certain time of the day when you feel tired, low energy. You wont be able to give it your best. For me, morning runs are never there for me, I'm always on a "Cold Engine" in the upper half of the day haah. I think this applies to other workouts too, like weights workout etc. Do it when you best feel it!!!


New Member
1 Jun 2012
Excellent information! I have to keep all that in mind now, I think I've been doing it all wrong for a while, lol.