Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Tunnel vision

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Tunnel vision

Old 10-17-20, 03:10 PM
  #1  
coffeecherrypie
Senior Member
Thread Starter
 
Join Date: Oct 2017
Posts: 99
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Liked 10 Times in 7 Posts
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.

Last edited by coffeecherrypie; 10-17-20 at 03:14 PM.
coffeecherrypie is offline  
Old 10-18-20, 03:19 AM
  #2  
Bassmanbob
Senior Member
 
Join Date: May 2014
Location: Treasure Coast, FL
Posts: 867

Bikes: 2014 Cannondale Supersix EVO 3, 2015 Trek 520, 2017 Bike Friday Pocket Rocket

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 231 Post(s)
Liked 187 Times in 103 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.
Bassmanbob is offline  
Old 10-18-20, 04:47 AM
  #3  
nomadmax 
Senior Member
 
Join Date: Jun 2018
Location: SW Ohio
Posts: 1,908
Mentioned: 93 Post(s)
Tagged: 0 Thread(s)
Quoted: 852 Post(s)
Liked 1,163 Times in 585 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.
__________________
nomadmax is offline  
Old 10-18-20, 07:25 AM
  #4  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 36,457

Bikes: R3 Disc, Haanjo

Mentioned: 347 Post(s)
Tagged: 1 Thread(s)
Quoted: 18244 Post(s)
Liked 6,823 Times in 3,478 Posts
Originally Posted by coffeecherrypie View Post
Is this common?
No, and it's not condition where you look to random internets people for consultation - go see a doctor.
WhyFi is online now  
Likes For WhyFi:
Old 10-18-20, 07:28 AM
  #5  
eduskator
Senior Member
 
eduskator's Avatar
 
Join Date: Aug 2019
Location: Québec, Canada
Posts: 1,045

Bikes: TCR Pro 0 / Revolt 2

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 458 Post(s)
Liked 268 Times in 202 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.
eduskator is offline  
Old 10-18-20, 07:29 AM
  #6  
10 Wheels
Galveston County Texas
 
10 Wheels's Avatar
 
Join Date: Nov 2007
Location: In The Wind
Posts: 32,265

Bikes: 02 GTO, 2011 Magnum

Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1105 Post(s)
Liked 695 Times in 351 Posts
Originally Posted by coffeecherrypie View Post
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.

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"


Last edited by 10 Wheels; 10-18-20 at 07:39 AM. Reason: add
10 Wheels is online now  
Old 10-18-20, 07:33 AM
  #7  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 36,457

Bikes: R3 Disc, Haanjo

Mentioned: 347 Post(s)
Tagged: 1 Thread(s)
Quoted: 18244 Post(s)
Liked 6,823 Times in 3,478 Posts
Originally Posted by eduskator View Post
Unless there is a physician on this forum...
There are a handful and I would expect that all would advise to him to see a doctor.
WhyFi is online now  
Likes For WhyFi:
Old 10-18-20, 09:17 AM
  #8  
Steamer
Zircon Encrusted Tweezers
 
Steamer's Avatar
 
Join Date: Nov 2008
Location: high ground
Posts: 1,227
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 201 Post(s)
Liked 71 Times in 47 Posts
Not normal. See a doctor.
Steamer is offline  
Old 10-18-20, 05:35 PM
  #9  
coffeecherrypie
Senior Member
Thread Starter
 
Join Date: Oct 2017
Posts: 99
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Liked 10 Times in 7 Posts
Originally Posted by nomadmax View Post
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.
Sorry, I don't think I was clear. There's plenty of exertion happening, I was just trying to get across that other than the vision issue it doesn't feel like my body has totally run out of energy.

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.
coffeecherrypie is offline  
Likes For coffeecherrypie:
Old 10-18-20, 05:37 PM
  #10  
coffeecherrypie
Senior Member
Thread Starter
 
Join Date: Oct 2017
Posts: 99
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Liked 10 Times in 7 Posts
Originally Posted by Bassmanbob View Post
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.
Yeah thanks. I usually stick a Nuun in for the caffeine but that has no calories. I will probably just make sure I never ride w/o some form of extra calories in the future.
coffeecherrypie is offline  
Old 10-18-20, 08:14 PM
  #11  
cubewheels
Senior Member
 
Join Date: Jun 2020
Location: Manila, Philippines
Posts: 2,128

Bikes: A really old BMX bike, Jackal Mio Gravel Bike

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 957 Post(s)
Liked 436 Times in 353 Posts
Originally Posted by coffeecherrypie View Post
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.
I started cycling at 38 and into training for competition just a couple months ago. This is not an age problem. You just need to "fuel up" (food and water) before and during the ride in regular intervals in small, discrete amounts.

It's also possible you might be pushing yourself too hard. Back off a little if that's the case. Your body will adapt eventually.
cubewheels is online now  
Old 10-19-20, 05:57 AM
  #12  
Sy Reene
Advocatus Diaboli
 
Sy Reene's Avatar
 
Join Date: Feb 2015
Location: Wherever I am
Posts: 7,538

Bikes: Merlin Cyrene, Nashbar steel CX

Mentioned: 12 Post(s)
Tagged: 1 Thread(s)
Quoted: 4048 Post(s)
Liked 1,078 Times in 703 Posts
Originally Posted by coffeecherrypie View Post
Yeah thanks. I usually stick a Nuun in for the caffeine but that has no calories. I will probably just make sure I never ride w/o some form of extra calories in the future.
Also maybe not a bad idea to make 1 of your 2 bottles with an energy drink.. my recipe:
1/2 tab Nuun
1/2 strength gatorade powder (about 1/4 scoop per bottle)
1.5 scoops maltodextrin powder
Sy Reene is offline  
Likes For Sy Reene:
Old 10-19-20, 08:34 AM
  #13  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 4,135
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 4342 Post(s)
Liked 5,712 Times in 2,562 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.
Koyote is online now  
Old 10-19-20, 09:33 AM
  #14  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 36,457

Bikes: R3 Disc, Haanjo

Mentioned: 347 Post(s)
Tagged: 1 Thread(s)
Quoted: 18244 Post(s)
Liked 6,823 Times in 3,478 Posts
Originally Posted by Koyote View Post
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.
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.
WhyFi is online now  
Old 10-19-20, 09:35 AM
  #15  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 36,457

Bikes: R3 Disc, Haanjo

Mentioned: 347 Post(s)
Tagged: 1 Thread(s)
Quoted: 18244 Post(s)
Liked 6,823 Times in 3,478 Posts
I'm sure that datlas and MoAlpha will appreciate being tagged in this thread.
WhyFi is online now  
Old 10-19-20, 09:58 AM
  #16  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 4,135
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 4342 Post(s)
Liked 5,712 Times in 2,562 Posts
Originally Posted by WhyFi View Post
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.
I don't know whether the OP has a medical condition, so we agree on that. At 37, he should have an annual physical with a doctor.

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.)
Koyote is online now  
Old 10-19-20, 10:03 AM
  #17  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 36,457

Bikes: R3 Disc, Haanjo

Mentioned: 347 Post(s)
Tagged: 1 Thread(s)
Quoted: 18244 Post(s)
Liked 6,823 Times in 3,478 Posts
Originally Posted by Koyote View Post
But some additional carbs will enhance performance. (If I'm wrong, I sure would like to see the sources.)
What are your sources?

You should have 2000+ calories in glycogen reserve.
WhyFi is online now  
Old 10-19-20, 10:15 AM
  #18  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 4,135
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 4342 Post(s)
Liked 5,712 Times in 2,562 Posts
Originally Posted by WhyFi View Post
What are your sources?

You should have 2000+ calories in glycogen reserve.
My sources are pretty much every training book and site I've ever read. A few (from a quick google search) are listed below - I haven't read them carefully, just scanned them, and they all seem to confirm the advice of around 60 calories per hour (with caveats) beginning 60-90 mins into a ride. But: I do wonder just how much of the "conventional wisdom" is driven by companies that make energy bars and drinks, so am interested in reading your source(s). I don't know enough about on-bike nutrition, so am sincerely interested.

https://trainright.com/what-to-eat-a...e%20necessary.

Coach Hughes: Nutrition for Cycling Endurance

https://www.theglobeandmail.com/life...030%20minutes.
Koyote is online now  
Old 10-19-20, 10:34 AM
  #19  
oleg232000
Senior Member
 
Join Date: Mar 2017
Location: Cali
Posts: 118

Bikes: Litepseed Catalyst Neutral Support Bike, La Pierre Spicy Team, Mercier Kilo TT, Cannondale Multisport2000, Goffa BMX, Haro Dave Mirra Freestyle

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 82 Post(s)
Liked 21 Times in 12 Posts
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?
oleg232000 is offline  
Old 10-19-20, 11:05 AM
  #20  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 36,457

Bikes: R3 Disc, Haanjo

Mentioned: 347 Post(s)
Tagged: 1 Thread(s)
Quoted: 18244 Post(s)
Liked 6,823 Times in 3,478 Posts
Originally Posted by Koyote View Post
But: I do wonder just how much of the "conventional wisdom" is driven by companies that make energy bars and drinks, so am interested in reading your source(s). I don't know enough about on-bike nutrition, so am sincerely interested.
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.
WhyFi is online now  
Old 10-19-20, 11:20 AM
  #21  
datlas 
Beyond Bogus
 
datlas's Avatar
 
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 36,405

Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix

Mentioned: 508 Post(s)
Tagged: 2 Thread(s)
Quoted: 16239 Post(s)
Liked 3,934 Times in 1,945 Posts
Originally Posted by WhyFi View Post
I'm sure that datlas and MoAlpha will appreciate being tagged in this thread.
No thanks. The tunnel vision symptom suggests possibly hypotension (drop in BP to the brain) but the history is more consistent with hypoglycemia.

The OP should see a doctor in person just to be safe.
__________________
Originally Posted by rjones28 View Post
Addiction is all about class.
datlas is offline  
Likes For datlas:
Old 10-19-20, 11:27 AM
  #22  
coffeecherrypie
Senior Member
Thread Starter
 
Join Date: Oct 2017
Posts: 99
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Liked 10 Times in 7 Posts
Originally Posted by oleg232000 View Post
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?
Negative to high elevation. I have one espresso in the morning and head out on the ride. During the ride I have a Nuun in the water bottle which I guess would be the equivalent of another coffee.
coffeecherrypie is offline  
Old 10-19-20, 11:37 AM
  #23  
coffeecherrypie
Senior Member
Thread Starter
 
Join Date: Oct 2017
Posts: 99
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Liked 10 Times in 7 Posts
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 .
coffeecherrypie is offline  
Old 10-19-20, 11:46 AM
  #24  
genejockey 
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 7,902

Bikes: 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: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 4133 Post(s)
Liked 4,402 Times in 2,239 Posts
Originally Posted by Koyote View Post
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.
Define "lots of climbing"

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
genejockey is online now  
Old 10-19-20, 11:47 AM
  #25  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 4,135
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 4342 Post(s)
Liked 5,712 Times in 2,562 Posts
Originally Posted by WhyFi View Post
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.
I'm glad you know what works for you, but don't confuse your personal impressions with evidence.

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.
Koyote is online now  
Likes For Koyote:

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.