Tunnel vision
#1
Junior Member
Thread Starter
Tunnel vision
So if I forget to bring an energy bar or whatever, somewhere between 2 and 3 hours into a ride with a lot of climbing I start to get tunnel vision. Like, I literally start to lose my peripheral vision and I have to really concentrate in order to make sure that I'm processing what I can see correctly. My legs feel fine, my energy feels fine, I'm not out of breath, I don't feel exhausted, I feel like I could keep going for a while--except I almost can't see. I assume this is like a blood sugar issue? Or liver bad at releasing glycogen? Is this common? I got into cycling late but I would guess that this wouldn't have happened when I was younger (I'm 37).
Edit: and then after the ride, when this happens, I feel like I need to go to sleep--but for "head" reasons not for "body" reasons, if that makes sense.
Edit: and then after the ride, when this happens, I feel like I need to go to sleep--but for "head" reasons not for "body" reasons, if that makes sense.
Last edited by coffeecherrypie; 10-17-20 at 03:14 PM.
#2
Senior Member
Join Date: May 2014
Location: Treasure Coast, FL
Posts: 987
Bikes: 2014 Cannondale Supersix EVO 3, 2015 Trek 520, 2017 Bike Friday Pocket Rocket, 2022 Moots Vamoots Disc RSL
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 285 Post(s)
Liked 267 Times
in
140 Posts
It sounds like you were hypoglycemic (low blood sugar) and you were about to pass out. I almost passed out (not cycling) but that’s how it felt. It was as if a black curtain was closing from both sides.
If you sometimes forget to take an energy bar, I would consider always having some kind of electrolyte powder in at least one of your water bottles. Also, go get a physical with your doctor if you’ve not had one recently. Make sure your heart is ok and no diabetes is developing.
If you sometimes forget to take an energy bar, I would consider always having some kind of electrolyte powder in at least one of your water bottles. Also, go get a physical with your doctor if you’ve not had one recently. Make sure your heart is ok and no diabetes is developing.
#3
Senior Member
Join Date: Jun 2018
Location: SW Ohio
Posts: 2,397
Mentioned: 93 Post(s)
Tagged: 0 Thread(s)
Quoted: 1104 Post(s)
Liked 1,825 Times
in
878 Posts
Given your lack of perceived exertion during the hypoxic vision change (due to the brain not getting enough oxygenated blood); I'd go get a full physical and tell the doctor. Tunnel vision during massive efforts should be accompanied with a great deal of perceived exertion. I'm not a doctor but there are serious vascular conditions (in the neck) than can starve the brain for oxygen when the rest of the body is in an aerobic state (operating with enough oxygen for the task).
Seriously, get that checked asap.
Seriously, get that checked asap.
__________________
#4
Senior Member
Join Date: Jan 2010
Location: TC, MN
Posts: 39,520
Bikes: R3 Disc, Haanjo
Mentioned: 354 Post(s)
Tagged: 1 Thread(s)
Quoted: 20810 Post(s)
Liked 9,456 Times
in
4,672 Posts
Likes For WhyFi:
#5
Senior Member
Join Date: Aug 2019
Location: Québec, Canada
Posts: 2,112
Bikes: SL8 Pro, TCR beater
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 988 Post(s)
Liked 584 Times
in
439 Posts
Frankly, I will go see my MD if this ever happens to me. This seems serious enough to seek professional advice. Unless there is a physician on this forum, you'll get tons of non-relevant answers.
I ride fasted almost all the time, but my usual rides are 2h max. Anything longer than that, I take a dried fruit bar and I carry a protein bar in case.
I ride fasted almost all the time, but my usual rides are 2h max. Anything longer than that, I take a dried fruit bar and I carry a protein bar in case.
#6
Galveston County Texas
Join Date: Nov 2007
Location: In The Wind
Posts: 33,221
Bikes: 02 GTO, 2011 Magnum
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 1350 Post(s)
Liked 1,243 Times
in
621 Posts
So if I forget to bring an energy bar or whatever, somewhere between 2 and 3 hours into a ride with a lot of climbing I start to get tunnel vision. Like, I literally start to lose my peripheral vision and I have to really concentrate in order to make sure that I'm processing what I can see correctly. My legs feel fine, my energy feels fine, I'm not out of breath, I don't feel exhausted, I feel like I could keep going for a while--except I almost can't see. I assume this is like a blood sugar issue? Or liver bad at releasing glycogen? Is this common? I got into cycling late but I would guess that this wouldn't have happened when I was younger (I'm 37).
Edit: and then after the ride, when this happens, I feel like I need to go to sleep--but for "head" reasons not for "body" reasons, if that makes sense.
Edit: and then after the ride, when this happens, I feel like I need to go to sleep--but for "head" reasons not for "body" reasons, if that makes sense.
Have You had a Brain Injury?
I had a Mini Blood Clot caused from medication.
It only showed up on an MRI
__________________
Fred "The Real Fred"
Fred "The Real Fred"
Last edited by 10 Wheels; 10-18-20 at 07:39 AM. Reason: add
#7
Senior Member
Join Date: Jan 2010
Location: TC, MN
Posts: 39,520
Bikes: R3 Disc, Haanjo
Mentioned: 354 Post(s)
Tagged: 1 Thread(s)
Quoted: 20810 Post(s)
Liked 9,456 Times
in
4,672 Posts
Likes For WhyFi:
#9
Junior Member
Thread Starter
Given your lack of perceived exertion during the hypoxic vision change (due to the brain not getting enough oxygenated blood); I'd go get a full physical and tell the doctor. Tunnel vision during massive efforts should be accompanied with a great deal of perceived exertion. I'm not a doctor but there are serious vascular conditions (in the neck) than can starve the brain for oxygen when the rest of the body is in an aerobic state (operating with enough oxygen for the task).
Seriously, get that checked asap.
Seriously, get that checked asap.
Today I did a harder ride than yesterday, brought an energy bar, and was fine -- compared to yesterday when I didn't bring an energy bar and it happened.
I suppose I will heed everyone's advice and see a doc sometime reasonably soon. I'm not *super* concerned since an energy bar seems to avert this from happening, but may as well cover all bases. Thx all.
Likes For coffeecherrypie:
#10
Junior Member
Thread Starter
It sounds like you were hypoglycemic (low blood sugar) and you were about to pass out. I almost passed out (not cycling) but that’s how it felt. It was as if a black curtain was closing from both sides.
If you sometimes forget to take an energy bar, I would consider always having some kind of electrolyte powder in at least one of your water bottles. Also, go get a physical with your doctor if you’ve not had one recently. Make sure your heart is ok and no diabetes is developing.
If you sometimes forget to take an energy bar, I would consider always having some kind of electrolyte powder in at least one of your water bottles. Also, go get a physical with your doctor if you’ve not had one recently. Make sure your heart is ok and no diabetes is developing.
#11
Advocatus Diaboli
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,635
Bikes: Merlin Cyrene, Nashbar steel CX
Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4733 Post(s)
Liked 1,532 Times
in
1,003 Posts
1/2 tab Nuun
1/2 strength gatorade powder (about 1/4 scoop per bottle)
1.5 scoops maltodextrin powder
Likes For Sy Reene:
#12
Senior Member
Join Date: Sep 2017
Posts: 7,877
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 6963 Post(s)
Liked 10,961 Times
in
4,687 Posts
OP: Are you stating that, on a 2-3 hour ride with lots of climbing, you just eat a single energy bar? I wouldn't think that is enough. And if you forget the energy bar, yeah, you're gonna suffer.
#13
Senior Member
Join Date: Jan 2010
Location: TC, MN
Posts: 39,520
Bikes: R3 Disc, Haanjo
Mentioned: 354 Post(s)
Tagged: 1 Thread(s)
Quoted: 20810 Post(s)
Liked 9,456 Times
in
4,672 Posts
Hard 2-3 hour rides, without additional calories, aren't an issue if you're conditioned for it. More to the point, if a mid-ride snack prevents tunnel vision, I have a hard time believing that there isn't some other underlying condition.
Last edited by WhyFi; 10-19-20 at 09:39 AM.
#14
Senior Member
Join Date: Jan 2010
Location: TC, MN
Posts: 39,520
Bikes: R3 Disc, Haanjo
Mentioned: 354 Post(s)
Tagged: 1 Thread(s)
Quoted: 20810 Post(s)
Liked 9,456 Times
in
4,672 Posts
#15
Senior Member
Join Date: Sep 2017
Posts: 7,877
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 6963 Post(s)
Liked 10,961 Times
in
4,687 Posts
I agree that a fit rider can indeed do a hard 2-3 hour ride without additional calories...But some additional carbs will enhance performance. (If I'm wrong, I sure would like to see the sources.)
#16
Senior Member
Join Date: Jan 2010
Location: TC, MN
Posts: 39,520
Bikes: R3 Disc, Haanjo
Mentioned: 354 Post(s)
Tagged: 1 Thread(s)
Quoted: 20810 Post(s)
Liked 9,456 Times
in
4,672 Posts
#17
Senior Member
Join Date: Sep 2017
Posts: 7,877
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 6963 Post(s)
Liked 10,961 Times
in
4,687 Posts
https://trainright.com/what-to-eat-a...e%20necessary.
Coach Hughes: Nutrition for Cycling Endurance
https://www.theglobeandmail.com/life...030%20minutes.
#18
Senior Member
I personally do 3 hour rides multiple times a week with a good amount of climbing and exertion and I never take extra fuel, besides a water bottle, and even then sometimes I go the whole ride without taking a sip. I do fuel up before the ride though, but never during. I've went 5 hours without a single calorie and felt fine and could keep going. But to the OP, were you at any high elevation by any chance? And did you consume caffeine or an abnormally large amount of caffeine prior to the ride?
#19
Senior Member
Join Date: Jan 2010
Location: TC, MN
Posts: 39,520
Bikes: R3 Disc, Haanjo
Mentioned: 354 Post(s)
Tagged: 1 Thread(s)
Quoted: 20810 Post(s)
Liked 9,456 Times
in
4,672 Posts
So look up information on glycogen stores and take a look at your burn rate (if you have a power meter) and get a feel for it on your own rides. Eating on a two hour ride is undoubtedly no benefit for me, given adequate stores at the outset, and at three hours I'm still very much in the "is it more trouble than it's worth?" tipping point.
#20
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,049
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22596 Post(s)
Liked 8,925 Times
in
4,158 Posts
The OP should see a doctor in person just to be safe.
#21
Junior Member
Thread Starter
I personally do 3 hour rides multiple times a week with a good amount of climbing and exertion and I never take extra fuel, besides a water bottle, and even then sometimes I go the whole ride without taking a sip. I do fuel up before the ride though, but never during. I've went 5 hours without a single calorie and felt fine and could keep going. But to the OP, were you at any high elevation by any chance? And did you consume caffeine or an abnormally large amount of caffeine prior to the ride?
#22
Junior Member
Thread Starter
Just reading about glycogen. Seems like one should be able to store roughly 2000 calories worth. I guess *if* I'm on the low end of that and *if* I'm burning ~750 calories per hour (tho that seems high?) then I could just be running out at say 2.5 hours in. So maybe I'm just "bonking" after all and it's manifesting as tunnel vision. I definitely don't do a good job eating carbs before a ride, I usually eat yogurt in the morning before heading out. Nonetheless, I will talk to a doctor about it at some point this winter.
With respect to hypotension, I don't have any other symptoms like problems when standing up quickly .
With respect to hypotension, I don't have any other symptoms like problems when standing up quickly .
#23
Klaatu..Verata..Necktie?
Join Date: May 2007
Location: SF Bay Area
Posts: 17,960
Bikes: Litespeed Ultimate, Ultegra; Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace; Cannondale R500 RX100; Schwinn Circuit, Sante; Lotus Supreme, Dura Ace
Mentioned: 41 Post(s)
Tagged: 0 Thread(s)
Quoted: 10424 Post(s)
Liked 11,895 Times
in
6,093 Posts
Up until last month, my Sunday rides were routinely 2 1/2- 3 1/2 hours with 2-3000 feet of climbing (per Strava), and it wasn't till I started stretching them to 4+ hours that I felt any need for food on the ride. In fact, I had the same Clif Bar in my jersey pocket for a couple months.
__________________
"Don't take life so serious-it ain't nohow permanent."
"Everybody's gotta be somewhere." - Eccles
"Don't take life so serious-it ain't nohow permanent."
"Everybody's gotta be somewhere." - Eccles
#24
Senior Member
Join Date: Sep 2017
Posts: 7,877
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 6963 Post(s)
Liked 10,961 Times
in
4,687 Posts
So look up information on glycogen stores and take a look at your burn rate (if you have a power meter) and get a feel for it on your own rides. Eating on a two hour ride is undoubtedly no benefit for me, given adequate stores at the outset, and at three hours I'm still very much in the "is it more trouble than it's worth?" tipping point.
Here is an article from the Cleveland Clinic which references the American College of Sports Medicine. The takeaway line is "Cyclists riding for longer than 60 minutes need to start to fuel after one hour."
Here is a peer-reviewed journal article on the subject, which includes the observation that "In practical terms, 2 hours or more of even moderate physical activity (eg, 65% VO2max) is sufficient to markedly lower muscle glycogen stores."
Here is an article by Selene Yeager which seems well-researched. Again, the recommendation is to start eating carbs even on moderate-length rides.
etc.
Bear in mind that your body needs glycogen for more than just working your legs while riding. So, even though your body can store a bunch, that doesn't make it all available for exercise.
When I was starting out, and knew very little, I would routinely go on 50-60 mile rides, and longer, with just a couple water bottles and a Powerbar in my pocket. I could do it. But that didn't mean it was optimal.
Last edited by Koyote; 10-19-20 at 11:50 AM.
Likes For Koyote:
#25
Senior Member
Not normal. The only time I've ever experienced true tunnel vision was while under a 6+g load for 10-15 seconds. As soon as the g's dropped my vision returned to normal. This happened over 30 years ago and it was rather disturbing to me.
Go see a doctor before you pass out on the road and get injured or killed.
Go see a doctor before you pass out on the road and get injured or killed.