I'm pretty sure it's a bad-ish thing, as it certainly doesn't feel good. Not painful though. The tingling is mostly at the back of my head, and it's also sometimes accompanied with a cold feeling through my body. I feel a little faint, but nowhere close to actually fainting.

I brought it up to my personal trainer a few weeks ago, and he didn't know what it was and jokingly said it was endorphins pumping.

Yesterday I started the day with a 3 mi. interval (1:1) jog and walk. I had a pre-workout snack an hour before PT (5pm), but I still went into it with under 400 calories for the day. I had a head tingling spell during my session (very intense circuit with cross-jacks, power squats, stance-jacks, suicides, kettle ball swings, etc.). I didn't have to take a break to sit down at any point, and my heart-rate recovery was pretty good. I stay hydrated with ease.. I had a 20 minute break before my bootcamp class..

I brought up the tingling with my bootcamp instructor and he said it was a sign of over-exertion and that it's potentially dangerous. Fainting and coma dangerous. He had a football teammate who had frequent episodes of it and would sometimes faint.

The internet is scary and there are all sorts of neurological causes, but mostly I find it on forums for people with MS and such, not just during a workout.. So I don't think those causes apply to me.

My breathing and heart seem fine during the workout, so is it just fatigue? Do I just need to up the calories a bit? Or cut back on how hard I'm pushing myself? Has anyone experienced this before?

I haven't experienced that before. Maybe you should see your doctor. Just for reassurance. The Internet is never good when trying to diagnose yourself. I have a question for you though? Where the heck do you get all this energy to workout? I just started back in the gym yesterday. And it killed me to do 10 min on the elliptical. But before surgery I was on phentermine. Energy and food depressant. And I could run/walk miles, stairmaster, and elliptical. Now trying to workout naturally. I struggle

I'm wondering if it's maybe a pre-cursor to hyperventilating? I know when you hyperventilate you get tingling and numbness in extremities. Is it happening when you're very breathless? I agree about checking with the doctor.

If it doesn't get worse and you don't actually pass out, it might not be dangerous but it's worth checking.

when im under extreme stress, i get what it is called stress induced scalp itching (and tingling). this sounds similar. you are probably putting your body under a bit too much duress during workouts.

and YES, if your instructor is saying it is a bad sign...i would take heed and calm down on the workouts a bit. just because your heart is fine doesn't mean your entire body is!

as an ex medic, I can say this, what you are describing is the one of the beginning stages of oxygen deprivation. As you body realizes it needs more oxygen that it is currently getting it pulls blood away from the extremities and the blood flow closest to the skin is greatly decreased. As a result the nerves under the skin activate randomly, which causes that tingling sensation some describe it is itching or crawling depends on the person. If you continue to have this you will cause you body to shut down and you will pass out there is no doubt in my mind on this I was a medic for 11 years. If I were to come upon scene and you had this complaint I would put you on high flow O2 , start an IV for fluids and elevate your feet to get blood flow back to your brain fast.

I wont say the s word that rhymes with broke, because that's too alarming. But it can be a very distinct possibility.

It sounds a lot like your lungs have not sufficiently grown to accommodate your workout..fervor. Some of my colleagues talk about this with crossfit people. they do "exercises" that are not normally done as exercises except by specific highly trained athletes and as a result they get calls to the crossfit centers all the time. One case I remember discussing was a gentleman who was made to do clean and jerk heavy weights, well when he went to put the weights up over his head he wasn't used to doing so, toppled backwards and the bar with weights landed on his leg crushing it. They have had people passed out in their cars in the parking lot from overexertion, for some reason mostly women seem to suffer from the dehydration more so than the men, not sure why, I think that's more social than physical. Anyway sorry to digress. I would however check with your doctor, and please go a bit easier, it sounds like you are going a bit hard on the workouts. Its great to lose the weight, but you have gone through massive body changes. Be careful.

I had tingling in my head and my physician said it was low b12. Started taking monthly injections and no more head tingling. However, it was not at a certain time such as exercising.

With endorphins, it almost feels high. I do get a headache after also, cause my body/brain just isn't as used to getting endorphins that way.