inmy last ND I have realized that it was soo hard to run and this happened in many of my dreams. ist like i try to run but i cant ! why >?
Why that’s hard to say if you only say this. Dreams are very personal. Maybe if you give some more background information we can help you 
Maybe the next things can help you too.
Are you trying to do something in waking life what isn’t working? You try really hard, but it still doesn’t have nearly any affect. In the dream you’re trying to run but it doesn’t work, just like the thing IWL.
Where do you want to run away for in the dream; why are you running? Maybe the answer on this question will help you with the interpretation.
Maybe your SC is trying to tell you that you shouldn’t run away for something but try to face it. Instead of running away for it, trying to solve the problem.
I get those dreams too, where it is physically difficult to run, because my feet feel very weak. I wonder if it can come from the fact that our body is actually paralysed in REM sleep? In sleep paralysis, we wake up while the body is still unable to move. Maybe we are just sleeping lightly in these dreams, so it is possible to feel some of the paralysis inside the dream?
yes it feels like my feet are very weak and like i also get the tingly feeling kinda like when the blood rushed back to the feet after crossing them. I remember just showing off and acting like a professional while playing basketball and there was a girl in front of me which i adore
That’s funny. For me, running is one of the easiest things to do in LDs, although I don’t particularly like running in real life. You know the way cartoon characters’ legs spin around in circles when they run really quickly? That’s been me in numerous LDs, although I’d much rather fly. Funny how different people have different problems.
My advice: first decide if this is a long-term problem. Keep track of it, but don’t give it too much thought. If it continues, see if there are any common factors–such as the girl you adore, for instance. Heck, sometimes a girl can make things difficult in real life, too. 
Perhaps your subconscious is trying to tell you to be “real” with her IRL, rather than pretend to be something you’re not? I dunno.
Those “being chased” nightmares go really well with not being able to run, in my dreams… I also can’t run sometimes, but then again, sometimes I can. 
If you exercise, it gets easier in dreams—at least I think so, because the time I had more slow running dreams was when I had tendinitis and was forbidden of running for months.
Strange. When I run in dreams, usually I run too fast and accidentally fly… I’ve only been able to run properly when I was lucid and on a sinking ship, but besides that, I haven’t been able to run, and that includes LD’s…
Anymore I find running in my dreams next to impossible, I have to either fly or use a vehicle if I want to travel faster than walking speed. I would wager that the SP is to blame, but hey, wouldn’t you rather fly anyway? 
I could usually run in my dreams but there are times where everthing feels really thick and I could barely move. I hate those dreams.
For me I can run in NDs easily although not seldom in low gravity. In LDs This low gravity makes running slow because there is little contact with the ground. Also sometimes I get the same as Wyvern where everything feels thick. The Air feels thicker than water and it increases until i can’t move at all. Then I wait for a while for it to pass. I don’t enjoy being stuck but it is a really good dreamsign.
I have a lot of dreams were I’m really really sleepy and I just want to get to sleep, but once I do, I wake up 
Sometimes during the dreams I can’t do anything, and when I try to run, it does feel really slow and thick, kind of like I’m going through molasses.