Only a few times have I exerted an effort that resulted in a very short period of 180+bpm showing on my Garmin that was then immediately followed with an almost overwhelming feeling like I was going to puke. Those times were when my resting HR was routinely below 40bpm and I would be doing 3 rides/week of intense effort. There were then other efforts resulting in elevated HR (not 180+bpm) and most likely lactic acid release causing pain, weakness, shortness of breathe BUT NO HURLING feeling. Just anaerobic exercise effort I guess.