How to do long cardio and not lose muscles size?

I am mostly into Fitness, Running. I had hamstring strain for the last couple weeks and I didn't run. Meanwhile I've started doing some full body workouts/core workout to strengthen upper body and build at least some muscles. Now I'm back to running, question is how do you keep and even gain muscles capacity while running? I mean before the strain I was running like 3,4 times a week. Some were 10k runs, that makes you burn Calories and lose muscles.

Just keep lifting and you'll retain - most if not all - of your muscle mass.

I run four times a week - I did 75 minutes, approx 12 miles this evening for instance - and nearly always longer than 10K. I go the gym the other three days. You won't lose the muscle so long as you continue to go the gym. Just make sure you train hard at the gym.

You should get good defination and cut by cross-training.

It's not as if you should weight train seven days a week anyhow.

10k runs, ...makes you burn Calories and lose muscles.

Tell that to the Fruitarian that just won the Vermont ultra-marathon (100 miles).

Michael Arnstien runs 150 miles a week. He eats 70-100 grams of protein a day.

The key is, he eats enough carbs that fuel the muscle. Fruit after a workout gets stored as glucose easier, in the muscles. Muscle only gets used up if that glucose runs out.

Protein doesn't save muscle. Too much protein gives the body extra work to metabolize and remove.

10k runs, ...makes you burn Calories and lose muscles.

Tell that to the Fruitarian that just won the Vermont ultra-marathon (100 miles).

That's a fact though unless you eat couple times during the run. I am sure he's spending his time at the gym doing some weight training to keep muscle capacity. Look at most of the marathon runners not too much muscles capacity there. I don't see how eating before and after the run, can give you enough calories not to burn anything during long runs. I wasn't even running marathon distance and my upper body got pretty much slim.

I wasn't even running marathon distance and my upper body got pretty much slim.

But it sounds like you weren't doing weights then, until you got injured - 'Meanwhile I've started doing some full body workouts/core workout to strengthen upper body and build at least some muscles.'

Runners are by default mostly slim by the nature of their exercise so no surprises there, it's what happens when you run. If you stop running, as you did when you got injured, and then started training with weights it's no great shock that you put on muscle either.

I may be wrong, but what it sounds like you haven't been doing so far, is running and weight training at the same time? Until you are incorporating both into your fitness regime, then you cannot know that running will consume all your muscle. It won't either, so long as you train hard with the weights.

It won't either, so long as you train hard with the weights.

And eat plenty. Losing muscle = losing weight. Weight-loss will only occur if you have an energy defecit. When you are endurance training you are burning a lot of calories. Make sure you eat enough to maintain your current body weight, lift heavy and you should maintain most of your mass.

I wasn't even running marathon distance and my upper body got pretty much slim.

 

But it sounds like you weren't doing weights then, until you got injured - 'Meanwhile I've started doing some full body workouts/core workout to strengthen upper body and build at least some muscles.'

 

Runners are by default mostly slim by the nature of their exercise so no surprises there, it's what happens when you run. If you stop running, as you did when you got injured, and then started training with weights it's no great shock that you put on muscle either.

 

I may be wrong, but what it sounds like you haven't been doing so far, is running and weight training at the same time? Until you are incorporating both into your fitness regime, then you cannot know that running will consume all your muscle. It won't either, so long as you train hard with the weights.

You are right I was running only. I started weight training only recently.

Well in my own experience I lose a fair bit of muscle when I am running ~ my marathon weight is around 127-130 compared to the 140-145lb that I weigh when I am powerlifting.

Runners often simply don't eat enough to cover their running. for example I can head out at the weekend on a 4-6hr run and burn 5-6,000cals; it's pretty hard to get that back into you even though you are eating and drinking fairly constantly on the run. Someone like myself that runs a few hours most days and averages 60-100km/week, I feel that I am constantly in a calorie deficit. Having said that I don't tend to fall below my running weight of 127, regardless of how much I train or eat. But that weight is largely determined from the distances I cover in training and the length of the races I like to do.

Pretty sure if I transitioned to becoming a 5km or 10km runner I would naturally be able to carry a little more muscle

I use to loose muscle during my consistent speed runs. If you don't use em, you loose em.

I have also noticed that consuming legumes causes major muscle loss in my leg muscles. I love lentils but not at the cost of my muscles.

I've been training for my 1st marathon for the last several months & have lost a lot of muscle! I usually run 8-10 miles 4 times a week and then one day a week will go 15-20 miles plus I'm lifting 3-4 times a week.

I think it's all about eating enough. I know that I have not been eating enough calories. After losing a lot of weight I have a fear of getting fat again, so I constantly under-eat!

I'm new to this and leaning toward going vegan. I used to run but took up indoor rowing. Indoor rowing is fantastic cardio and can compliment running. I was a slow runner. I actually burn more on the rower and the rower packs muscle on where I had a really hard time keeping muscle in my legs running.