When I work out and go faster/harder, I almost past out.. It really sucks cause I have the motivation to do it but I can't do it now how I want to... Already tried instead of water to drink some energy drink...
I think its because you suffer from dehydration you should drink water before, during and after your workout
Have you had your blood sugar checked? Do you have a history of low blood sugar? That exact thing was happening to me and my blood sugar was very low at 47.
On days you workout hard you should be drinking more than a gallon of water through out your day