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My final set of squats has me going until I can do no more. I usually stop when I feel one more rep may or may not might be possible, but it's going to totally wipe me out trying. I usually sense that point when I'm squatted down, so have to bail out with the safety bars.

During the whole set, I'm fine.

When I climb out from under the bar, that's when it hits me, a second or two of light-headedness.

My training partner says he gets the same. Is this normal?

Additional info requested

Warmup sets: Starting Strength style
Working sets: 100kg (220 pounds) currently, 2 x 5, then AMRAP which has been working out anywhere from 10 - 20 reps lately.
Bodyweight: 100kg.

Update

Also noticed today it happens with deadlifts, which I stopped at 20 in the final set today, possibly had another 5-10 in the bag. With ez-curls though, an exercise which my final rep might take 10 seconds to get up and total failure during the next one, I don't get the lightheadedness.

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It might help if you posted how much you are squatting (weight, reps, sets) and since when you are experiencing this. Do you only feel this after bailing out or always? –  Baarn Dec 16 '12 at 8:39
    
It's been happening pretty much since day 1 as the final set I seem to go to the same level of exertion. –  jontyc Dec 16 '12 at 9:11
    
I seem to bail out every week, so can't really say if I'd feel it if I racked standing up. I definitely don't get it in the initial 2 x 5 worksets, but I haven't reached the stage where they are taxing yet. –  jontyc Dec 16 '12 at 9:35
    
AMRAP, As Many Reps As Possible is saving 1 or 2 full reps. If you are bailing you are going too long. Stop when form breaks down--going beyond that isn't going to help anyone. –  Berin Loritsch Dec 17 '12 at 12:43

3 Answers 3

up vote 12 down vote accepted

When you lift heavy deadlifts and squats, your whole body is under high compressive force. The muscles squeeze your blood vessels, which increases the hydrostatic pressure of your circulatory system. In other words, your blood pressures spikes up during the lift. The body attempts to restore homeostasis during the lift by engaging physiological responses which lower the blood pressure - mostly by releasing vasodilators, which are chemical signals telling the smooth muscles lining your blood vessels to get relax. When you finish the rep, your muscles relax, and the pressure drops suddenly - but the vasodilation response has been activated, and your blood pressures spikes down for a few seconds before the body can act again to restore equilibrium.

It's normal - nothing to be alarmed about. All serious lifters have experienced this, including to myself. However, this physiological effect can lead to passing out, and passing out can be dangerous because you can take a nasty fall. It's also a reason to squat over a rack. Even if you think you could dump the weight if things got out of hand, you might pass out at the top of the rep one day, and then the only thing that's going to save you from a squashing is the rack.

To mitigate this effect, work on your breathing. Having good breathing will give your whole body, including your brain, more oxygen. It won't stop the blood pressure spikes, but it will allow you to stay conscious at a lower blood pressure. Exhale strong and long after you pass the sticking point on the way up from the rep. (Say at the top 25% of the ROM). At the top, after you finish a full exhale, and while keeping your core tight and engaged, breathe deep into your chest and upper belly (diaphragm). If your vision is clear and your head is solid, take the rep. Otherwise, go through one more deep breathe cycle - without ever losing tension in your stomach. This is hard and takes practice, but you can do it. (It's the same kind of breathing for singing, by the way.)

Note that lightheadedness during a rep, or prolonged lightheadedness after a set, cannot be explained by this mechanism. Only brief lightheadedness at the top of a rep or after the set is explained by this physiological response.

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While I don't think the derivative of this solution is correct, the answer is 100% correct. My hesitation comes in the fact your body doesn't vasoconstrict during heavy lifting. Your heart does slow when holding your breath because of the vaso-vagal response. Internal body pressures spike while not breathing during the repetition. Upon completion of the repetition there is a rapid drop in pressure, and coupled with the vasodilatory response from lifting (the pump) can cause you to feel light headed, see stars, and have a narrowing field of vision. Still... this is the correct solution. –  Grohlier Dec 16 '12 at 22:22
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I updated the answer to remove the work "vasoconstriction". I think that's what you're taking a stand against, and since it doesn't matter whether we use the word or not, I got rid of it. –  masonk Dec 16 '12 at 22:34

If you are dumping the bar every time, you are going to failure--not AMRAP. There is a big difference. Every place I've seen AMRAP defined, it's as many good reps as possible, with 1-2 reps left in the tank. If form breaks down, or you aren't getting to full depth, your set needs to be over.

That said, I have experienced the light-headedness you are talking about after widowmakers. In my case, it was a combination of factors: excessive heat in the gym and insufficient food. I was shaking pretty badly after the exertion, and every calorie I consumed after that helped the feeling subside.

When you have the feeling, do sit down and rest until the worst feeling passes. Don't keep going on the session. If you keep going, you risk hurting yourself. High rep sets are very taxing on your body, both from the perspective of getting enough oxygen to your body and from the glycogen depletion that goes on. The good news is that the lower weight is usually easier to recover from--as long as you don't go to failure.

  • Learn to recognize when that feeling of lightheadedness is going to come, and stop before then. Usually you can tell about two reps beforehand.
  • Do have some kind of recovery aid like BCAAs if this happens regularly. 10g of Branched Chain Amino Acids (BCAA) mixed with water can help recover enough to overcome that feeling.
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The light headedness only lasts for a second or two, so it's over before I'd have a chance to sit down. –  jontyc Dec 17 '12 at 22:53
    
With my final set, my final rep suffers no loss of form (I'd stop if I feel loss of form simply knowing the injuries awaiting if I don't, plus I go down until I hit the safety bars so I can't cheat). I do feel I could make another rep, possibly two, but it would be vein-popping. By bailing out, I'm meaning I just stopping in the down position rather than collapsing from fatigue. Does that sound ok? –  jontyc Dec 17 '12 at 22:59
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My recommendation would be to stop before it becomes vein popping reps. Yes, pushing yourself is good, but you want to finish in the top position. When you are repping only 20kg more than that it does become more of a question of making a whole rep vs. not. –  Berin Loritsch Dec 18 '12 at 1:13
    
Dizziness for a second or two occasionally isn't something serious. However, if your limbs are shaking and it takes a little longer for the dizziness to stop, you probably expended all the energy you have. –  Berin Loritsch Dec 18 '12 at 1:14
    
I want to second the sentiment that getting used to failing on reps is a bad thing. –  Dave Liepmann Dec 18 '12 at 21:38

The first thing that comes to mind is that your sugar level is very low at the end of your workout. I'm guessing that you don't only do squats when you are working out and if your workout partner feels the same, maybe there's not enough oxygen in that area of the gym?

Either way, it's a heavy exercise and you're lifting heavy too. Try doing squats earlier in your routine, maybe that can help.

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This is incorrect information. Consistent light-headedness coupled with clamminess, sweating, blurred vision, mood changes that are remedied by consuming glucose is indicative of low blood-sugar. –  Grohlier Dec 16 '12 at 22:14

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