Pretty slim guy here, just a bit better than the fag in the image.

Ill pass along a small secret. When you start lifting. Lift 60-70% of your 1rm and do not lift to failure.

Don't think it's your heart really. It's more probably tightness / poor mobility resulting in nervous tension. OR you forget to breath properly.

>>39098420
>I get dizzy and I end up feeling exhausted
I suggest you eat and sleep more.

Pay lots of attention to your breathing, I used to get this all the time just because I would "forget" to breathe while doing overhead press. Concentrating in my breathing fixed it for me.

>>39098464
I sleep 11 hours per day and I eat 4 meals per day, about 3000 cals I think

yes do cardio

>>39098420
Could be a condition but you may be able to pass through it. How long have you been lifting?

>>39098476
>I sleep 11 hours per day
This is too much, everythjng above 8 hours is too much.

>>39098487
About a month now, but I've been mostly doing chest, back and leg exercises since OHP and lat pulldowns make me feel like fainting.
>>39098491
Anything below 8 hours make me feel dead during the next day
>>39098471
What's the good breathing technique? I usually inhale through the nose when I lower the barbell and exhale through the mouth when I raise it.

>>39098420

This is 100% a blood oxygen issue (specifically the partial pressure of oxygen in venous vs arterial blood). It's the same phenomenon that causes some people to pass out from deadlifts. What's basically going on is when you create a lot of intraabdominal pressure your blood pressure spikes as well, but when the pressure is released (between reps, end of set etc) it doesn't normalize equally quickly in the blood vessels with and without oxygen. For brief periods you are inadvertantly creating a situation where the normal oxygen pressure difference between arterial and venous blood that causes oxygen to travel from one to the other (via tissues that need oxygen, like your brain) doesn't exist. No pressure difference, no oxygen transfer, no oxygen transfer in brain = lose balance, vision, and consciousness in roughly that order and potentially very very quickly.

tl;dr you are having problems getting oxygen to your brain while you lift, make sure you aren't anemic, are breathing and that your blood pressure in general isn't fucked.

>>39098541
Any way to do that? Blood samples?

>>39098541
I had these issues when i started lifting 2 months ago, and doctors have told me my blood pressure is too low. Now I basically up my blood sugar, and drink large amounts of caffeine before working out, and I haven't had those problems since.