my heart gets a very high heartbeat so that last time l stopped going upper. it was 2650 m altitude. l had been climing with a very slow speed. was it because of high altitude or because of my body weakness??

The best thing to do is to acclimate in the altitude for a couple of days prior to doing a high altitude climb. For example if climbing in CO (some of the 14teeners) u can stay in Denver for a couple of days before.

In addition, breathing. Learning deep breathing techniques & practicing them consistently before hike or a high altitude climb.

Do not for get to stay hydrated too.

There r also some medications one can take to help combat altitude effects. Talk to ur doctor. This always helps.

Best of luck.

At 2500m, l doubt that you were experiencing altitude effects (although it is possible). It is much more likely that you were experiencing effects of exersion and dehydration - make sure you train by climbing stairs often and hydrate while climbing.

Good Luck

You can come stay a few nights in my home state. l live in Fort Collins Colorado. So l am more used to the altitude. If u really want to get used to it, spend a summer in Aspen, Colorado or Breckenridge. It is double the advantage, cause when l go to low altitude places like florida, then l can do pretty much everything and feel like l have pleanty of air. Colorado is beautiful. Viva Colorado!

Yeah does not really sound like the effects of altitude, especially at only 2650m, unless u come sealevel & went to that height very fast..
The altitude effects l usually find in myself r shortness of breath & feeling a bit more tired than usual, & eventually headache if l keep pushing hard. Other people start to feel nauseous.
To combat altitude, the best thing u can do is practice a few lower level walks before attempting the thing u want to do, so start low & build up towards ur intended altitude. l think it is important that u actually do exercise on these warm-ups - one couple l spoke to one a lift up on the Mont Blanc Massif this week said they were acclimatising for summiting Mont Blanc by taking cable cars up to peaks & then sitting around. This may work, l am no doctor, but it seems to me that u should have to get ur body working for it to get used to it.
Also, another thing that seems to me that it should help but again may not, is ur general level of fitness beforehand. I've found whilst doing hard uphill plods to reach my climb that because of my shortness of breath, if only I'd done more running in the weeks preceding the climbs that l could've coped better with the altitude.