2017 Mercedes Sprinter: Is it Going to Strand Me in a Remote Place?

Update: this blog post will not be updated further. The topic needs its own page, including an issue history and log. See:

Mercedes Sprinter Issues and Breakdowns: Sprinter Will Not Go, RPMs Drop Very Low (Normal idle, put into D or R, RPMs drop, Engine Lugs

... original post, not updated follows below...

Today’s problem‚ something new or just a symptom?

Today, my 2017 Mercedes Sprinter would start, but then lugs badly at 2 seconds at 500 rpm, then quit. Plenty of cranking amps no question. Repeated failures.

Temperature overnight hit maybe as low as 15°F at 1000' elevation, but Sprinter console showed 19°F at 8AM when failures occurred. Tried 3 or 4 times, then gave up and went for a hike. At 3PM it started up fine at 37°F. Ran fine once started in the afternoon, but I did let it idle 30 minutes to be safe before trying to move, because of ongoing issues detailed below.

OK, just for giggles, one might blame it on fuel but that seems unlikely—not really cold enough and no other issues noted on same tank of fuel for a week. Even though not winter blend fuel (AFAIK), it just did not get cold enough.

Today’s failure is actually not my main concern, as it may only be a symptom of the more insidious and ongoing issue, which is getting worse and worse, plaguing me before and after Service B (so not the fuel filter) for around a YEAR. So it's not a particular tank of fuel or a fuel filter or a particular temperature.

SYNOPSIS: normal idle, put into D or R, Sprinter goes nowhere, rpms drop and engine lugs

Having mentioned this problem to more than one service department on service visits, and getting little more than shrugs, my hopes are not high for seeing this resolved. I want a dealer to call Tech Service and track this down! I have one dealer in mind who might get the job done. My confidence in another is near zero.

Maybe all it is is software, but the truth is that mechanics hate doing them—my information is that Mercedes pays them very poorly for piecework that can take hours yet pays only for 30 minutes or so (not paid by hour). So one never knows if all software is up to date or not and it can be like pulling teeth to get the latest software.

Contact Lloyd with ideas or similar issues.

1. Start engine, give it half a minute or so to warm up. Observe rpms at 900 to 1300, depending on altitude and temperature.
2. Put into D or R (doesn’t matter).
3. PROBLEM: observe rpms drop to 500-600, engine lugs badly (audibly bad).
4. Floor accelerator pedal: absolutely nothing happens, even for minutes.
5. Put back into P: rpms return to normal. Rev engine—revs up to any rpm freely
6. Repeat ad nauseum. After some indeterminate period (2 to 10 minutes), the problem may resolve with the Sprinter reluctantly moving away. However, if there is any up-slope, it may have trouble for another minute or so.

Part 1, after idling 2 minutes to warm up:
https://www.youtube.com/watch?v=QHUHEwtjgOA

Part 2, after idling 9 minutes to warm-up:
https://www.youtube.com/watch?v=Gb9JglzSItg

Notes

• Might be altitude related, but this is not certain; I don’t start my Sprinter at home much, but it has not failed at home (500 feet altitude). Failures seen at 6000/9000/10000/112660 feet elevation.
• Goes into gear; does not appear to be transmission related—just makes no power
• Seen at least a dozen times over a year from 6000 to 11600 feet
• Happens over a wide temperature range, at least 14°F to 54°F, so if temperature related, does not have to be more than just cool temperatures.
• Intermittent problems so hard to diagnose.
• Full service B done in April 2019, problem occurs before and after a year, maybe more.

Possibilities

• Lack of turbo boost due to faulty altitude or other sensor(s)?
• Faulty ECU software? No problems seen prior to Feb 2018 ECU software update

Updates / log

2019-10-01: 9000’ elevation, 25°F @ 10PM dipping to 9°F overnight, started up fine @ 8:30AM @ 27°F idling @ 1300 rpm slightly rough idle, just let it warm up, and once warmed, it would roll in reverse without issue.

2019-09-30: 8100’ elevation, 27°F @ 10PM dipping to 20°F overnight, started up fine @ 8AM @ 28°F idling @ 1300 rpm slightly rough idle, died when tried to move with parking brake slightly applied on level ground after one minute of warmup. After two minutes warmup, was able to reverse on level ground (no brake), rolled away in D on level to downhill, engine steadily warmed up and behaved normally.

2019-09-29: stranded most of day as per full description.

2019-09-28: Sprinter would not go as per detailed description

2019/2018 year prior: perhaps a dozen such “no go” problems, ranging from a minute to 10 minutes in delay. All at altitude of 6000 feet or higher as far as I can remember.

Reader comments

Joe writes:

I have exactly the same experience.

First, I know my science is sub par to your excellent work but my ramblings may shed some light on it.

1) Because you like science I suggest the most knowledgeable MB dealer on “ cold” is Lone Star MB in Calgary,AB. Before calling them check their website blog - not sure if it has this item but it may be & they do have some useful info I have read.

2) My prior Diesel + Cold experience was with a Ford Excursion 6.0 Diesel. That puppy was dead at 20F & no amount of glow plug action could start it. Only spraying Ether in the Breather would work but I hate that stuff because strips the oil off the piston rings. The SOP was to wait until temps got above 25F & it would start reluctantly (assuming one had not totally depleted the 2 batteries during the failed Glow plug attempts)

3) In my experience the Sprinter will fairly well start above 20F but run rough. As the the temperature drops below 20F it requires successive Glow Plug cycles (without actually engaging the starter!) At 18F I found that it would require at lest 6-8 cycles. And it would start & stumble & cough etc etc, always die on the first full start attempt and then require 2 or 3 of the prior procedures to finally get it to run (very very rough & not quit).

Now for the next hurdle: assuming you got the engine running for awhile, at least to the point it “sounds “ normal (maybe 15 minutes) the Sprinter acts like its stuck to the ground. Without any authority I am fairly certain it’s due to the fact the transmission is still 15F & the fluid like glue. Since there are no shared fluids with the engine you are relying on plain old heat transfer from the adjacent engine block which might take 20 minutes of engine running to get the transmission to respond (& even at that, sluggishly).

4). The solution: install an Espar Hydronic Diesel water heater to solely to pre-heat the engine to 180F 🤪. Engine starts like its in Miami & the Tranny goes along for the ride. Then it never matters how cold it is ! (Bonus it saves all that ritual unassisted cold weather starting procedure which has to be hard on the engine.

DIGLLOYD: I never had these problems the first six months of operation. But after the Feb 2018 ECU update required by the California Air Resources Board (with sticker required to smog check), things seemed to not run so well. So I am dubious that it is a 'hardware' issue. And if it runs rough at start, it has always settled down pretty quickly in the past.

Moreover the Sprinter hardly ever pauses for glow plug operation... I didn’t even know it really had them! It had no pause whatsoever trying to start it today. Which raises the question as to whether they are working at all?

I’ve had the Sprinter start many times in sub-freezing conditions and run normally. But the sub-25°F experience is more limited. Last December I had it exhibit the symptoms going to bed at 25°F (engine still warm) but a warm front had moved in and it was 43°F when I started it, and had been for some hours from what I could tell. And I’ve had the no-go issue into the high 40°F range (and did not keep track all this time) I think also the low 50°F range. So I don’t think the no-go issue is heating issue. The does-not-start-and-stay-on issue today is all new, and definitely not the coldest temps I’ve been in it with—and I had gone to bed with a nice warm engine.

Still, the Espar Hydronic Diesel water heater might be worthwhile, but I admit to it being intimidating on who to have install it and inspire confidence that it won’t spring a leak or cause issues of its own.

Mark G writes:

Dang. Sorry to hear that. I have almost given up on the Mercedes Sprinter. Backed out of custom order at the last minute. Now waiting to test drive a 2020 Transit AWD with ecoboost (most powerful) gas engine. Planning on some custom suspension mods to improve ground clearance if I decide AWD is good enough for my needs.

I want a Sprinter for many specific strengths but diesel engine and all its related concerns are just too much to ignore. There's a good sprintersource post about block heaters and this issue you describe somewhere on the forum. They found a specific issue that was something related to the turbo, or some other part that a certain dealership had identified. They had an overnight test they could do in the dead of winter to diagnose. MB was made aware. That's all I remember. Let me know if you find a solution.

Hang in there sir!

DIGLLOYD: I guess one half-assed solution is to drive around and make the engine hot before going to bed, then wake up at 2 AM and (bad for a Sprinter) idle it for 20 minutes, then pray for morning.

The question of the turbo is a good one—my guess is a software bug and/or altitude sensor bug that causes the turbo to provide no boost. After all, how many people regularly camp out at 10K feet or (often) 11600 feet? Tonight I am at 8100' and I will see how it behaves in the morning. I parked where I have a cell signal and sunlight will hit early and it's flat, just in case!

My Strongest Ride Yet in 2019

Nice day/date for it!

Two antibiotics really got to me, requiring two months to feel normal again, which was very discouraging. I kept at it (riding) but performance was record slow (for me) in this year’s Eastern Sierra Double.

About 10 days ago I felt my strength increasing. Three days ago I had a strong ride with confirming signs of a body “happy” again.

Today I had the strongest ride of 2019. It’s so satisfying when my body works at its best—high power output with a sense of ease and fluidity, and only minor issues (a bit of patella pain starting at mile 52 or so, resolved by stretching bit between intervals).

The important thing is to keep at it, knowing that slumps and problems occur and will resolve!

Click for larger chart.

2019-07-04: Year’s Strongest Workout
4:38, 88.3 miles, 3712 kJ / 3549 calories
222W / NP=230W, HR=138 bpm, TSS=392, 4217 ft ascent

Gut Bacteria May Play a Role in Autism

The gut is a “second brain”. The brain controls the body, but the gut and its microbes also control the brain, as does blood and probably other things too.

In late 2014 Scientific American reported in Gut Bacteria May Play a Role in Autism that:

Autism is primarily a disorder of the brain, but research suggests that as many as nine out of 10 individuals with the condition also suffer from gastrointestinal problems such as inflammatory bowel disease and “leaky gut.” The latter condition occurs when the intestines become excessively permeable and leak their contents into the bloodstream. Scientists have long wondered whether the composition of bacteria in the intestines, known as the gut microbiome, might be abnormal in people with autism and drive some of these symptoms. Now a spate of new studies supports this notion and suggests that restoring proper microbial balance could alleviate some of the disorder's behavioral symptoms.

...

The Economist May 30 2019 in More evidence that autism is linked to gut bacteria reports that:

What causes ASD has baffled psychiatrists and neurologists since the syndrome was first described, in the mid-20th century, by Hans Asperger and Leo Kanner. But the evidence is pointing towards the bacteria of the gut. That suggestion has been reinforced by two recently published studies—one on human beings and one on laboratory rodents.

...

Two years ago they tested a process called microbiota transfer therapy (mtt) on 18 autistic children aged between seven and 16. Of their participants 15 were regarded, according to the Childhood Autism Rating Scale, as having “severe” autism.

...

Crucially, these changes in gut bacteria have translated into behavioural changes. Even 18 weeks after treatment started the children had begun showing reduced symptoms of autism. After two years, only three of them still rated as severe, while eight fell below the diagnostic cut-off point for asd altogether. These eight thus now count as neurotypical.

...

Meanwhile, the success of the study in Arizona has prompted America’s Food and Drug Administration (FDA) to look into the matter. A firm called Finch Therapeutics Group, based in Massachusetts, hopes to commercialise the use of mtt as a treatment for autism and the fda has now granted this effort “fast track” status, which should speed up the review process

WIND: how awesome that there is now hope of reducing or even curing autism—with gut bacteria of all things!

Siloed specialized knowledge has let autism wreak its havoc, and I daresay many maladies suffer the same fate until multiple specialists put their heads together. Perhaps AI will overcome that in the future and suggest posssibilities for curing many more human health issues.

Three Top Notch Professionals to Help Your Body Health and Cycling Performance

Here are three individuals that I am very impressed with, and highly recommend.

Imagine your body working at its best!

3D Bike Fit

Kevin Bailey, 3DBikeFit.com (San Francisco)

Kevin at 3DBikeFit.com (see https://3dbikefit.com/bike-fits) gets bike fitting right, with the most meticulous attention to detail I’ve seen—the very best. Kevin is the reason I can ride double centuries without pain. I also ride a saddle of his design, the best I have ever found (and I have half a dozen other ones in a box!).

Kevin also makes custom orthotics which are awesome—I rode a double century two days after he made my pair, with zero issues—that’s amazing, and a proper footbed means better power transfer and no pain.

Rikki Johansen

Dr. Rikki Johanseen CCSP, DACBSP, DACBR (Palo Alto, CA)

Also, certified triathlon coach and a USA Cycling, Level II certified cycling coach.

Rikke Chiropractic and about Rikke Johansen.

When I have any injury or problem with my body (muscular, tendon, left/right imbalance, and related pains or similar injuries), I go see Rikke first because she knows how to fix it, and fix it quickly—including casese that bothered me for weeks that improve immediately.

Rikki knows hers stuff and is not any ordinary “crack your back” chiropracter; she’s a cut way above that. She likes to fix things in one visit if possible (for me, that has been true with most injuries!).

I don’t bother going to doctors for sports injuries and similar anymore because they really don’t know how to fix things (expensive brief visits just result in a PT referral)! Unless it’s a broken bone or torn ligament or other true medical surgery-type issue, go so Rikke first.

Dee Sickles, MMT, LMT

Dee Sickles, MMT, LMT (Flagstaff, AZ)

See Intractable or Problematic Physical Issue? Medical Massage with Dee Sickles.

There is massage, there is medical massage, and then there are gifted hands with medical massage. If you have a seemingly intractable physical issue that doctors say is “impossible” to fix without surgery, think again, because what do you have to lose? All feedback from people I’ve recommended Dee to has been enthusiastic.

In 2018, after my 25 mph crash into an embankment with moderate-to-severe concussion, a twisted spine and torso and mashed-in ribs were not going to go away on their own, but Dee cleared it all up. I’ve had both injuries and massage before but never fixes like that. Problems solved.

Dee’s uncanny ability to zero in on the issue was startling to me. Pains I had for weeks after my crash were solved for good.

Reader comments below

anon writes:

I can attest to the importance of having a good massage therapist.

This past month, I was driven to near madness by mysterious tension headaches, neck discomfort and weird sensations. I attributed it all to job stress and started worrying if I'd be able to continue to work or even worse, that I had a serious health condition. Turns out it was just bad posture.

After a visit to a skilled massage therapist with myoskeletal experience, I learned I had Upper Cross Syndrome- pairs of weak and tense muscle groups caused by years of texting on a cellphone and hunched office work. After 3 hours of intense back and neck work my symptoms were 70%+ alleviated, permanently. Massage therapy saved my job, and sanity.

DIGLLOYD: nice outcome.

Mark N writes:

Thank you very much for your post about the products at 3DBikeFit. I am interested in their bike seat and would like to know which seat you use. Either the Throne GT or RS. It appears we have a similar body habitus.

DIGLLOYD: great to hear it’s useful—such stuff is why I bother—hoping someone can profit from sharing my experience. I ride the 3DBikeFit “Throne GT” saddle. As per Kevin Bailey of 3DBikeFit.com:

Lloyd has the Throne GT, and now we have another revised new version of it with a larger cut out. It’s same foam but front has longer channel. Looks better is more refined and has longer rails and new atoms base where cover raps under top base at front and back.

Science News: Gut microbes might help elite athletes boost their physical performance

I have a pretty solid personal feeling that gut microbes have a TON of influence on not just athletic peformance—from personal observation over 20 years of athletic and other performance.

Great preliminary work that deserves further study. The whole microbiome area is incredible and in my view will result in life-changing benefits once understood with “miracle” cures coming.

Science news: Gut microbes might help elite athletes boost their physical performance

Microbes that flourished in the guts of some runners after a marathon boosted the time that lab mice ran on a treadmill, researchers report June 24 in Nature Medicine. These particular microbes seem to take lactate, pumped out by muscles during exercise, and turn it into a compound that may help with endurance.

...

In the study, researchers collected stool samples from 15 elite runners for five days before and after they ran in the 2015 Boston Marathon, and compared the samples’ microbial makeup with that of poop collected from 10 nonrunners. The runners’ samples showed a bump in the abundance of bacteria from the genus Veillonella after the race. The team also saw an increase in Veillonella in a group of 87 ultramarathoners and Olympic trial rowers after a workout.

This finding raised the question of whether these microbes were mere bystanders or were actually helping their hosts. So the researchers cultured one strain, Veillonella atypica, from a runner and fed it to mice. Not all of the 32 mice responded to the treatment, but on average, mice that received the microbes ran for 13 percent longer in experiments than mice in a control group.

The work shows that “a single bout of exercise can have effects on your microbiome,” says Jeffrey Woods, an exercise physiologist at the University of Illinois at Urbana-Champaign. But he is skeptical of whether the improvement in the mice’s stamina is important, noting that the mice were tested in a series of short runs that “isn’t anything like the marathon run.” The researchers might have found other microbes at play if more stool samples had been studied, he says.

The authors, however, say that the microbes could boost athletic performance. In a race, “sometimes people worry about a fraction of a second … this could be much more than that,” says biotechnologist George Church at Harvard University.

...

Every Year is a Challenge, the Key is Having Faith in Recovery: Antibiotics Are Dangerous

I’m not a spring chicken any more, so I am coming to expect aging issues. Ah, to be young again, because no matter the attitude, the body just doesn’t perform as well.

This post is mostly about antibiotics: back in 2014 I sustained nerve damage from the antibiotic Metronidazole, taking nearly two years to fully recover (the worst symptoms were gone within 4 months), making me very leery of all antibiotics. But every few years, something pops up.

Beating a urinary tract infection

This is a postscript to what follows below: after the Eastern Sierra double century, I had burning while urinating two days later. I did NOT want to take antibiotics yet again.

While I obtained more Cipro as a precaution (being in a remote area), I did not take it, deciding instead to force a lot of extra fluid (with electrolytes) through my system, the idea being that steady flow of urine might help flush out kidneys an urinary tract.

I did so for a week, taking in about an up to an extra gallon of fluid each day (with electrolytes). The discomfort was mostly gone after 12 hours and gone with only mild sense of it for a few days, then it disappeared and did not return, and has not 3 weeks later. Hooray!

Antibiotics for UTI and Prostatitis

In March after the Solvang Double Century where my body worked supremely well, I came down with a urinary tract infection (UTI) a week later. I had not had such an infection since 2012. It only got worse, so I took the antibiotic nitrofurantoin (Macrobid). It was nasty stuff doing a job on my insides and even worse when done. It the UTI, but unfortunately it seems that prostatitis was probably the root cause/source of the infection, and nitrofurantoin does not get into the tissues and thus won’t cure prostatitis.

About two weeks after finishing the Nitrofurantoin, I was getting my strength back and resuming training, when prostatitis struck, which was uncomfortable and also made cycling impossible. It held steady at a tolerable level of discomfort but it was not improving, so I had to take a 10 day course of ciprofloxacin (Cipro), which surprisingly was much less troublesome than Nitrofuran tin.

By the time I was done with the Cipro, I was severely weakened, not just from losing fitness, but by damaging effects to body and brain. Even baseline rides were tiring. Worse, one or both of those antibiotics brought back certain post-concussion symptoms, which in terms of a self employment situation is a very serious side problem. I would say that more than half the days of the week, my productivity was cut in half or worse—unable to focus or concentrate, very easily distracted, etc.

I was weakened enough that I skipped three key double centuries, and had my doubts about doing one, but I did complete the Eastern Sierra Double by keeping cadence higher and power lower (I was also concerned about tendon rupture, a black box warning for Cipro, so I had kept training very aerobic). For the first 80 miles, my legs muscles and tendons were right as drums, a daily condition since the antibiotics (another cyclist told me of also experiencing the same tightness following antibiotic use).

Starting out dead last, I finished 5th and 90 minutes slower than 2018, though conditions this year were ideal compared to last year’s heat , so I deem that 2 hours slower. But I got it done, which restored some confidence. Setbacks happen, and if I cannot bounce back, I can at least roll over and stand up!

Summarizing antibiotics

• Maintain a strong aversion antibiotics; the cure can be worse than the disease.
• Antibiotics often have all sorts of side affects, including on body and brain.
• The gut is a second brain; since antibiotics kill the gut microbiome (and probably skin and other microbiomes in some cases), antibiotics in effect cause a sort of mild brain damage from which you can recover “fully” but the microbiome in the gut and body will NEVER be the same again.

IMO, antibiotics are far more dangerous than a similar course of narcotics or benzodiazepines! Because antibiotics for just 10-14 days can inflict changes from which there is no true recovery to prior condition.

Can Modern Technology Ever Make a Better Shoelace?

Shoelaces have long been a problem with just about every shoe I buy—premature failure.

See also Gear for the Mountains.

This is ridiculous—I’ve hardly worn these FiveTen Guide Tennie approach shoes. The laces ruptured into nearly useless junk. Now that Adidas bought FiveTen, the quality may go downhill further as costs are surely cut, and FiveTen was quite good at least in terms of the shoe itself.

One reader suggested parachute cord, which I tried, but it turned out to be useless—even worse—suffering the same sheath/core disintegration as the original laces, and there is no easy way to make stiff ends to feed through the holes.

A much better solution is to buy shoelaces for hiking shoes (63 inch length for these shoes)—which I did and will report on the quality when I try them.

Update: the DELELE 2 Pair Round Wave Shape Non Slip Heavy Duty and Durable Outdoor Climbing Shoelaces fit great and are a close match for the original laces, but look to be better made.

Shoelace failure with FiveTen (now Adidas) Guide Tennie approach shoes

f1.8 @ 1/30 sec, ISO 64; 2019-06-19 12:18:01
iPhone 7 Plus + iPhone 7 Plus 4.0 mm f/1.8 @ 28mm equiv (4mm) ENV: altitude 196 ft / 60 m

[low-res image for bot]

The Fungus that Can Kill You—Candida Auris Spreading and Very Hard to Decontaminate

Candida Auris is about as scary a threat as one might imagine: a fungus that is multidrug resistant, hard to identify, and very had to clean/kill from hospital settings.

Be afraid, be very afraid because assuming hospitals are going to make patients aware of an outbreak is something only those born yesterday will find credible. State governments are suppressing information about it, a Low State that will surely lead to unnecessary deaths going forward.

From NYT: How a Chicago Woman Fell Victim to Candida Auris, a Drug-Resistant Fungus:

Nearly 600 cases of C. auris have been reported in the United States, the majority of them in New York, New Jersey and Illinois. According to the Centers for Disease Control and Prevention, nearly half of people who contract the illness die within 90 days. But the true death rate is difficult to quantify because most patients have other medical conditions and their deaths may be attributed to other causes.

...on Tuesday, the C.D.C. confirmed that it has learned in the last month of the first known cases in the United States of so-called “pan-resistant” C. auris — a strain resistant to all major antifungals.

It often has been hard to gather details about the path of C. auris because hospitals and nursing homes have been unwilling to publicly disclose outbreaks or discuss cases, creating a culture of secrecy around the infection. States have kept confidential the locations of hospitals where outbreaks have occurred, citing patient confidentiality and a risk of unnecessarily scaring the public.

It’s not just fungus, there was a new deadly bacteria outbreak in Mexico that the CDC noted in January 2019 in Drug-Resistant Infections in Patients Who Had Weight-Loss Surgery in Mexico.

Comments on Bicycling.com: 'Pro Cyclists Open Up About Depression'

I commented on the death by suicide of 23-year-old is Stanford graduate student and Olympic cyclist Kelly Catlin earlier this month.

Reader Robert VB pointed me at an article in Bicycling.com: Pro Cyclists Open Up About Depression. There is of course nothing “pro” about anxiety and depression*, but pro cyclists presumably are going to get more attention than my concussion log —I applaud their sharing of their experiences and that Bicycling.com thought to publish the article.

* I suffered from depression for many years, but being the “strong silent type” (my high-school guidance counselor’s words), I suffered through it in college and beyond. At first I did not understand it, then I was ashamed to admit to it. Needless years of drained life. Only later in life have I mastered the skills to beat it off when (highs require lows but not too low!), but it requires energy.

Carmen Small’s experience

The account that resonated powerfully for me was that of zzzzzzzzz. It mirrors my experience (an OMG moment when I read it), differing only in that her trauma was more severe than mine and more than I care to contemplate, and the impacts on her have lasted longer, with less good resolution of symptoms.

And I’m different now. I have anxiety about everything, I cannot deal with stress, I am overly emotional, I am sad all the time, I am irritable, I have trouble with noise, driving makes all this worse (not the best in my profession), and the part that is the hardest is I have a fucking headache every day.

I'm screaming on the inside and looking fine on the outside. I get comments all the time, “Oh, you look great. How are you?” I just normally say, “Yeah, doing well thanks. You?” mostly because I am sick of explaining two years later that I still have problems with this damn concussion. I am frustrated, I get depressed, and I hate my life most days, but I put on a smile and head out to do my job and act "normal." I

My sense is that few people (not even trained psychiatrists) can begin to understand the complex set of feelings she has expressed in any 'gut' way—but having gone through it myself, I feel qualified to say her description is spot-on as far as words can go. I am glad to see it in print since just knowing one is not alone in the world is some comfort, and it might at least help non-victims to have some degree of understanding when no physical issue is visible. That last point cannot be emphasized strongly enough: brain injuries are invisible and yet most everyone sees only the physical body. No blame to them, but my own family could not understand, so how would any stranger?

No one can foresee the benefits of trying to help (for either party), but that can’t happen without communication, so in spite of being a very private person, I feel compelled to reach out: readers are welcome to contact me if they have had a concussion along these lines that they would like to discuss.

My experience, particularly after my concussion, is that out there for the finding exists a precious thing: minds that can operate on the same wavelength effortlessly, be it a shared experience like a concussion, or otherwise. If you’ve had a concussion, reach out and don’t give up because if you find the right person, it could be a breakthrough. Ditto for regular life. I meant that both intellectually and romantically and for the lucky few, both.

I consider my concussion very lucky in multiple ways. All of my symptoms have receded into the background, though I have some impairment in terms of workload, sleep needs and similar a year later, and maybe forever. The benefits have lingered: not a day goes by in which a positive perspective on life is not of some use, sometimes things of minor importance, sometimes more. Still, there are days (or series of days) where fighting the Anxiety Beast consumes nearly all my energy, problematic for a self-employed person. Yet that weakness has made me stronger and wiser and I am not sure I would trade it back for an “undo”. I have little idea how my own experience tracks, hence my interest in talking with others.

With full respect for medical professionals: I don’t think that doctors of any kind are really of much service post-concussion beyond some basics, and only in the most primitive sense (how to recover quickly and well is a empty book for the medical profession). Plus, not having any skin in the game (with rare exceptions not having experienced a concussion), what doctor of any kind can really relate, particularly those pressed to spend 5.87 minutes per patient on a rigorous schedule? Thus a dry clinical approach as with the physical body. Which is not to say that counseling* is without merit; it surely is in terms of tools and guidance in dealing with challenges. But it is cold comfort compared to a shared experience and very hard to access mental health services*, which are rendered in medical setting that is clinical and formalized and thus itself a source of stress—and stress is intolerable after a concussion, or it was for me—nature/outdoors was and is free and was my solution.

* A scandalous health care problem these days is claimed availability of mental health services that are not actually available due to excessive cost and/or distance and/or months-long waiting periods (in my experience with myelf and my family, all of those). Insurance company executives ought to be held criminally responsible for fraudulent claims about benefits.

Reader anon writes about a severe concussion involving a hematoma:

Amost six years for me. worse, things are *still* changing. it’s as if I have some sort of balance to maintain, something gets better, something else gets worse. my short term memory is better, but I have so far failed at picking up the guitar again. I used to be a finger-picker, but my right hand last three fingers don’t exactly work right so I thought I'd try it with a pick. for whatever reason my right arm, hand, etc have gotten worse recently so that’s on hold, sort of. it also ties in with the multitasking thing I mention below.

People ask me how I am, and if is someone I can level with the best I can say is “medium”. most breeze right by that.

It is difficult to decide what remaining thing is the worst pain in the ass. I’ve adapted to all sorts of things, for example my cellphone is now my memory for a lot of things, I still don’t ride a bike, etc. I think the worst thing is I can’t do things in parallel, i.e. when I start something I have to finish it before I can start the next thing; I can’t explain it any better than that. Another is I can perform pretty complex tasks, even if new to me, but only if there is a straight through path; all I need is a few seemingly equal choices for how to proceed and it is as if my brain freezes. That choices thing may be just a variation on doing things in parallel, it is getting hung up in a speculative execution loop (apologies to intel).

In all I think I am still making progress, but sometimes it is difficult to keep in mind that *this* is progress. of course I could barely walk when I got out of ICU rehab and I’m way past that now…sometimes I can even get on a ladder.

It is very difficult to talk about this shit, in this note I am practicing ;).

...

One more thing, not all of my symptoms are directly due to the original injury, for example I had a stroke to the thalamus while I was in ICU (after the surgery to slurp out the subdural hematoma), which probably is the source of a fair number of my problems. true I wouldn’t have had the stroke without the head injury, but still separate events. (note: this leaves out a lot of probably irrelevant detail, seizure(s), pneumonia, etc etc)

In all I’d say if TBI is on the menu have the cheeseburger instead. I *did* get a spectacular scar out of it, 46 staples and matching stitches I think, frankenhead if I shaved my head :). the surgeon did a good job with that, you can’t see any of the scar (skull canyon too mind you) without using the braille method.

...

Indeed so, I came very near to death. another oddity, my symptoms didn’t really go crazy until about a week had passed…I spent a few days in the hospital, no apparent issues, go home…oops. lucky me, I don’t have some of the worse leftovers, for example pain from the peripheral nerves on that side, and I do think I am still improving overall even though some parts are definitely not getting better.

I can’t believe high school kids play football and there is at least college level boxing. I may have mentioned this, when I was in high school a kid got a bad concussion playing football. his father, a doctor, signed a release to let him play again. He got hit, boom, lights out, dead. I am ok with adults taking stupid risks as long as they don’t damage other people and as long as I don’t pay for the consequences, but I don’t think kids are capable of making that judgement. Imagine being that kid’s father, living with that for the rest of your life.

I certainly don’t believe in living a risk-free life (as if that is actually possible), but some things are just stupid.

Another thing about TBI, I think you just about can’t generalize about them, there seems to be a huge variation in symptoms, recovery, etc. I think the doctors are really just groping other than the big stuff like relieving a subdural hematoma. the brain is an amazingly complex system. it would be nice if doctors had more training about them, but how?

BTW, you’ve probably noticed I’ve been giving this a drop at a time. two reasons for this: I knew about the diversity and didn’t want to scare the crap out of you unnecessarily; and of course because, as you know, it is difficult to talk about. I wish I had the magic wand, but there isn’t one.

DIGLLOYD: I am thankful that I did not snap my neck or have any truly serious injuries in either of my crashes. Setting expectations is key to recovery, without making cognitive commitments about limits that aren’t valid, but I have to admit I question my abilities more, and that never occurred to me prior to my concussion.

The two best days of my adult life were the day of my concussion (March 17 2018) and my 2nd crash (Dec 30, 2018). I say that because both times I could have easily broken my neck and/or had far worse issues. That's a darn good day! It never occurred to me to look at it in the reverse (except as pondering my reactions later). I don’t know if I could have that attitude had it been worse.

I’d point out for anyone with a concussion that symptoms can worsen after some days—I ended up in the ER (again) 5 days later, incoherent. There are physical changes that from what I can tell put the brain at heightened risk of damage, along with chemical destruction of cells in the brain.

Medical science is desert wasteland in terms of understanding and treating concussion. I think it will take 20 years and have to be its own specialty and we will need many new tools (scanners, anti-damage drugs for right after, neuro stimulator drugs and electric and electromagnetic tools that promote regrowth, etc).

As for high school football, someday it might be looked upon as child abuse; in my view it ought to be banned—guaranteed lifelong injuries for some players. Also, football is a game partly about hurting the other sideintentionally—tribalism at its worst—that was the explicit expressed sentiment at my locker room in high school (I did cross country and track, never football). Turned me off on the game forever—just loathsome. Then there is the implicit "you are a loser" undercurrent unless you are a starter on the football team—a few stars and who else benefits?

Commentary on Sodium Supplementation during Prolonged Exercise

Sodium (na) and salt (NaCl) are two different things in terms of weight (milligrams). Sodium is 39.3% by weight of NaCl. Hence 1000 mg (1 gram) of table salt contains 393 mg of sodium. Other electrolytes matter also and need to be in balance, such as potassium (K), Calcium (Ca), and Magnesium (Mg).

See prior posts such as Sodium and Electrolyte Losses During Prolonged Exertion — an Experiment.

This posts comments on selected excerpts from Sodium supplementation is not required to maintain serum sodium concentrations during an Ironman triathlon. I chose that paper because all the others I’ve found seem to have no relation to my reality over a decade of ultra endurance riding, whereas this paper seems to dovetail with my self-observation conclusions while avoiding any contradictions with my own self-observations.

Emphasis added in places.

Core summary

I would say with confidence that *no* supplementation is unwise, particularly under very hot conditions where fluid losses exceed 2L/hour and hyponatremia becomes a risk with too much fluid ingestion. Plus, pure water is absorbed more slowly than something approaching an isotonic solution. For years I used Hammer HEED as my sports drink, and it is very low in sodium (only 40mg per 100-calorie serving, which is 303mg per serving)*. I had no evidence of sodium deficiency when using HEED (e.g., cravings for salt).

* I stopped using Hammer HEED because I am pretty sure that its Xylitol and/or Stevia additives might be responsible for gastric distress, particularly at mile 140 and beyond.

Results

Subjects in the sodium supplementation group ingested an additional 3.6 (2.0) g (156 (88) mmol) sodium during the race (all values are mean (SD)). There were no significant differences between the sodium, placebo, and no supplementation groups with regard to age, finishing time, serum sodium concentration before and after the race, weight before the race, weight change during the race, and rectal temperature, systolic and diastolic blood pressure after the race. The sodium supplementation group consumed 14.7 (8.3) tablets, and the placebo group took 15.8 (10.1) tablets (p  =  0.55; NS).

Conclusions

Ad libitum sodium supplementation was not necessary to preserve serum sodium concentrations in athletes competing for about 12 hours in an Ironman triathlon. The Institute of Medicine's recommended daily adequate intake of sodium (1.5 g/65 mmol) seems sufficient for a healthy person without further need to supplement during athletic activity.

As I read it, the study is not saying that zero intake is advisable, only that additional supplementation over and above sports drinks is unnecessary.

Sodium stasis

What the study is saying here dovetails with my own finding using the simple “lick test”: there is just not that much salt on my skin after finishing a double century. There is notably more if it was very hot (very high sweat/fluid losses), but I don’t look like a floured dumpling that 9 grams of sodium X 12 hours would imply (the idea that over 100 grams of NaCl would be excreted is absurd).

Moreover, highly trained athletes surely well be mal-adapted if after years of training the body did not adapt its electrolyte balance to ultra endurance events.

Triathletes competing in the 2001 South African Ironman triathlon maintained their serum [Na+] within the normal range whether they drank the Na+‐poor drinks (water or a sports drink with [Na+]  =  18 mmol/l) or supplemented with ∼156 mmol Na+.

... Athletes in the placebo, sodium supplementation, and “no” supplementation groups did not differ in their finishing time nor in subjective measures of exercise intensity and mental wellbeing, nor in the prevalence of medical diagnoses after the race.

Clinical measures of fluid status, rectal temperature, blood pressure, absolute and percentage weight loss were also not different between groups

Therefore predictions of the expected consequences of “large” Na+ losses during prolonged exercise are inaccurate either because athletes sweat less or have lower sweat [Na+] than are currently believed. Alternatively, during acute states of Na+ loss, additional Na+ may be released either from intracellular body stores—for example, bone, skin—or by contraction of the extracellular fluid volume, in order to buffer acute Na+ losses until these are replenished by Na+ ingestion during the next meal.

Bottom line: extra sodium is of zero benefit.

Flawed studies

Other studies are clearly flawed and I don’t need this study to tell me that: glycogenolysis has long been part of my own planning for fluid-replacement. During the first five hours of a double century, considerable water is released as glycogen stores are largely burned off.

Not losing weight in my experience has always been associated with over-hydration and performance problems: I expect to be about 8 pounds lighter (e.g. 175 lb => 168 lb) after a double due to the loss of fuel and its associated water, and a moderation dehydration. I have seen such losses even on only 4 hour rides when ingesting 3L of water!

...two studies are often quoted to support the notion that Na+ ingestion during exercise is essential if a progressive fall in serum [Na+] is to be prevented. Both studies contain important logical flaws, not least because they encouraged trial subjects to drink to excess during exercise.

The goal of the study of Vrijens and Rehrer24 was for athletes to drink sufficiently to ensure that they did not lose weight during two hours of laboratory exercise. Normal fluid balance during exercise requires that some weight must be lost due to (a) the release of stored water consequent to glycogenolysis, and (b) irreversible loss of fuel through substrate oxidation.... athletes in any trial who do not lose weight during exercise must complete the trial in a mild state of over-hydration. That study therefore evaluated the effect of Na+ supplementation on serum [Na+] in subjects encouraged to overdrink during prolonged exercise. The data show that the response of the serum [Na+] to overdrinking was determined by the renal response to exercise, so that those athletes who passed the most urine during exercise were best able to maintain their serum [Na+].

This is compatible with the conclusion that serum [Na+] is far more sensitive to changes in total body water than to Na+ balance during prolonged exercise28 and with the explanation that acute hyponatraemia is always due to altered renal function in which the rate of free water clearance fails to match the rate of free water ingestion, whether at rest or during exercise.29 Finally only four of 10 subjects completed all trials in that study, further limiting the validity of these findings.

Similarly Twerenbold et al1 studied athletes who drank to excess while running ∼40 km in four hours. As sweat rates were only ∼500 ml/h whereas rates of fluid ingestion were ∼1000 ml/h, subjects gained an average of 2 kg weight during the run. In the presence of this large weight gain, the ingestion of additional [Na+] predictably lessened the fall in serum [Na+] by about 2–3 mmol/l. Yet, despite the ingestion of an additional 118 mmol Na+, the group that ingested the most Na+ still developed hyponatraemia during exercise (mean serum [Na+] after the run  =  134 mmol/l). The authors' suggestion that their data prove that all athletes should ingest additional Na+ during exercise is incorrect, as fully argued elsewhere.12 Rather the correct conclusion is that, as the single best predictor of post‐exercise serum Na+ is the change in body mass during exercise (fig 1​1),), avoidance of overhydration is the most important intervention necessary to prevent the development of symptomatic exercise associated hyponatraemia.14,30,31,32

Conclusion

My take away here is that the rate of ingestion of water should target finishing in a mild to moderate state of dehydration. A goal of mild to moderate dehydration seems best, because overhydrating is associated with stomach issues (bloating, very uncomfortable) and an increased risk of hyponatremia whether or not there is supplemental sodium/electrolytes, as per the comments above. I know that my very best performances have *always* left me depleted by at least 2 liters of body fluid, as determined by my fluid intake over the following 3-4 hours.

Put another way: the body has an easier time maintaining statis in a state of mild dehydration than it does trying to correct an electrolyte balance from excess fluid and/or excess sodium intake. Excess sodium intake is particularly problematic.

Tentative plan of attack

I conclude that I need to focus on the rate of fluid intake along with the caloric content. Typically I end up ingesting less than 1L/hour of fluid, as my stomach cannot handle it.

Possibilities:

• Ingest small amounts of fluid for the first two hours (assuming going out fully hydrated and with fluid in stomach). This implies a higher concentration of calories in the fluid in order to take in adequate calories (so as not to prematurely burn off body stores), e.g., 4 scoops of Tailwind per liter of fluid.
• Being ingesting 1L/hour of fluid by the end of hour 3, depending on intensity and beginning hydration status. Reduce caloric content of the fluid to 300 calories per liter.
• At hour 4 and beyond, shoot for 1L of fluid intake per hour, 200 to 300 calories per liter. Experiment with 200 vs 300.

Sodium and Electrolyte Losses During Prolonged Exertion — an Experiment

Sodium (na) and salt (NaCl) are two different things in terms of weight (milligrams). Sodium is 39.3% by weight of NaCl. Hence 1000 mg (1 gram) of table salt contains 393 mg of sodium. Other electrolytes matter also and need to be in balance, such as potassium (K), Calcium (Ca), and Magnesium (Mg).

Referring to Sodium and Electrolyte Losses During Prolonged Exertion, and with the intent of diagnosing the power “drop outs” I too often experience during double centuries, I decided to do an experiment to test out whether increased sodium intake helped or hurt.

The working scientific theory in some papers (which looks to have been debunked) is that when losing a liter or more of fluid an hour* that sodium losses are about 3500 mg, equivalent to about 9000mg of salt (sodium’s molecular weight is only fraction that of NaCl aka table salt). I maintain, based on a decade of riding experience, that the claim of losing 3500mg or even half that figure per hour is wildly inaccurate.

My tentative proposition is that most all scientific findings for sodium losses during exercise are BOGUS for athletes like me. The one exception in scientific papers that I found dovetails with my own experience and experiential results, that is, the findings for Ironman athletes found that sodium supplementation did not matter for 10-hour Ironman effort.

Ad libitum sodium supplementation was not necessary to preserve serum sodium concentrations in athletes competing for about 12 hours in an Ironman triathlon. The Institute of Medicine's recommended daily adequate intake of sodium (1.5 g/65 mmol) seems sufficient for a healthy person without further need to supplement during athletic activity.

My simple test below shows that sodium supplementation is not only not needed, but has a substantial negative effect (pronounced thirst) even replacing just half of theoretical sodium losses. Nothing matters except what actually works to improve performance.

* Losing 1L/hour of fluid is about the minimum for me riding at ~200 watt, even in cool weather, increasing to 2L or more in very hot weather on climbs. The stomach can absorb at most about 1L/hour fluid under optimal conditions.

Testing sodium supplementation

I wondered if increasing sodium (atomic symbol Na) intake in the form of Himalaya sea salt would improve or degrade performance. Of course, sea salt contains many things besides NaCl (table salt), presumably all good for blood electrolyte balance, e.g., Potassium (K), Magnesium (Mg), Calcium (Ca) and other trace elements.

Test conditions:

• Three-hour 2200-calorie ride of 57 miles, averaging 203 watts (216 watts normalized power). Ambient temperature of ~68°F, sunny (additional heat load vs being cloudy).
• 2 liters fluid intake: one bottle with 400 calories of Tailwind, the other 300 calories of Tailwind, 7 servings, caffeine-free.
• Supplementary sodium and other minerals: 1/2 teaspoon Himalayan sea salt in each bottle weighing 6 grams for an implied sodium content of 0.393 * 6000 = 2358 mg sodium. It has other elements/minerals as well of course.

Total theoretical sodium losses: 3500*3 = 10500 mg of sodium.

Total sodium intake: 7 * 303 = 2100 + 2358 = 4458 mg.

If scientific claims in some papers are valid, then I replaced less than half the sodium losses.

Results of replacing *half* theoretical sodium losses: awful thirst!

• At about the 2 hour mark, I was more thirsty when done that I have been for years, thirsty to the point of nagging discomfort/annoyance. Yet there is no chance that there was significant dehydration any more than similar workouts I have done for years—I was probably 'down' about 1.5L total fluid, which is an acceptable loss for a 3 hour workout.
• Licking my arm (heavy sweating area which dries quickly) I tasted only a trace of salt. Also, no white residue anywhere on my body (arms, legs, face).
• I had absolutely no craving for salt when done. I craved only pure water, promptly drinking about a liter. This cut the thirst within 5 minutes back to normal.

I repeated this experiment on a 4-hour 70-mile ride, but added an additional liter of pure water. I had better results with that but was still slightly thirsty. Even on that ride, not much salt accumulated on my skin, as per the taste test and visual inspection. While that extra liter seems to have added enough fluid to cut out most of the thirst problem, the core problem seems to be too much sodium relative to fluid intake.

Interpreting the results.

There are a few possible avenues of thought from the results.

• The thirst clearly seems to be the result of too much sodium, creating an imbalance in the body, or at the least too much sodium and not enough water. But it is not plausible that by replacing half the theoretical sodium losses that such a pressing thirst should result.
• Drinking 2 liters in 3 hours is ample and has never been an issue before in years of workouts. Moreover it can be difficult to stomach 3 liters of fluid in the first three hours.
• I lose far less sodium than scientific studies claim, perhaps because of years of training.
• Given that it is often difficult to fully hydrate, it seems very unwise to supplement with additional sodium.
• No evidence I can discern that sodium supplementation improved performance.
• No evidence that I was short on sodium when done, despite in theory having a 5000 mg deficit.
• Sodium supplementation in line with the (bogus) scientific findings in some studies might be a good way to damage the kidneys, judging by the very uncomfortable thirst; it’s the body’s way of signaling distress.

Bottom line: I will not be adding more sodium to my exercise drinks. I will focus instead on more consistent fluid intake.

Sodium and Electrolyte Losses During Prolonged Exertion

This page is a followup to my comments on the 2019 Joshua Tree Double Century. It is an attempt to understand what I term “drop outs” of power and focus during a double century.

Franklin K writes:

I have a few suggestion tracks regarding your double centuries. I’m not very familiar with sport medicine, - you know I’m a nephrologist and having worked very long in ICU - I feel involved in understanding precise and subtle mechanisms in physiology.

I point first you didn’t drink for the first two hours. OK, but what about sweat losses, I mean H2O and above all Na losses. You noticed temperature was as low as 34°F, but it won’t keep you to loose more than a liter per hour, which means more than 9g of NaCl per sweat loss, roughly 3.5g of sodium (Na). 66 miles, which means 2,5-3 hours without drinking, mean nearly 3 liters of H2O and 10.6 g sodium !!

And when you’re late about H2O and Na, as you quote, it is a long time to catch up. About this point , and for a better understanding go and read Na+/K+-ATPase OK I noticed you had four 1-liter bottles but as I told you, in this era when you’re late.

Our life system is organized to maintain constant body composition and the only organs to regulate this are the kidneys, yes… BUT… if you’re Na/H2O short, the kidneys are not able to manage this regulation. Do you know that the 2 kidneys are « using » 1,2l of blood per minute ? You understand what it means in terms of hypovolemia. By the end, I propose an explanation - I wrote « propose » ?, that your « slack » was H2O/Na dependant.

WIND: first a set-aside: given my relative lack of fatigue and very rapid recovery, it seems clear-cut that the issues I experienced were not a fitness issue. Indeed, my heart rate and breathing rate were relatively low. It surely has to be body statis of some kind, so I take the sodium (electrolyte) theory seriously as a key point to research.

This was about my 45th double on top of 90K miles of riding over the past decade and I’ve yet to crack this nut. Maybe it all comes down to some numbers game of increasing sodium+electrolytes until the problem goes away? Solving it would vault me into the top tier of riders consistently (maintaining 210 watts vs 180 for 10 to 12 hours is a HUGE difference), so I have a lot of incentive.

While I suspect it is a brain/neurological effect and not muscular/kidneys one, electrolytes could still be involved.

Quantifying sodium and electrolytes and energy

During the 2019 Joshua Tree Double Century, I took in about 2500 calories total (15 scoops Tailwind, 3 100-calorie Panda black licorice, 7 servings GU). That's plenty (36% of burn) for an event burning 6900 calories—much more than I typically consume by as much as double (usually it is 20% to 25% of total caloric expenditure). So I am going to rule out energy intake as a factor.

I use Tailwind for energy and electrolytes, 2.5 scoops per 1L bottle (see nutritional info for Tailwind). A one-liter bottle thus contains:

760mg Na + 220mg K + 65mg Ca + 35mg Mg + 250 calories

Since I consumed 6 such bottles during Joshua Tree, I took in from Tailwind alone:

4560mg Na + 1320g K + 390g Ca + 210mg Mg + 1500 calories

PLUS another bottle of some unknown drink (low in whatever it had) and 3 Panda 100-calorie black licorice sticks.. Plus about 7 servings of GU energy gel containing:

875mg Na + 280mg K + n/a Ca

= absolute minimum intake (not counting the licorice and that other unknown drink):

5430g Na + 1600g K + 390g Ca + 210mg Mg <=== accurate minimum taken in during JT

When done, my skin is salty, but not overly so unless it is very hot (in which case a lot drips off and fluid loss doubles). After Joshua Tree, I did not crave salt or anything like that, though I have done so after very hot double centuries.

If I were losing 3500g of sodium (Na) per liter of sweat, then my total intake for the day would replace only the first 1.5 hours worth, which seems dubious. Still, if the losses are 3500 mg/hour then the total loss is 35000mg or so, for a deficit of about 30000 mg. That does not seem believable: if it affected me at hour 5, then why did I feel no worse at hour 11?

Thus I remain a bit skeptical that I am losing 3500 mg/hour of sodium.

How to test it

Update: see my simple test of increasing sodium content.

I intend to change my dilution from 2.5 scoops of Tailwind per liter to 4 scoops in order to test that theory in the next double century. That matches up better for my cool weather (70°F or cooler) fluid intake needs balanced with caloric needs. In hot weather, I’d need more fluid and that concentration would need to be cut it back.

What science says

Science seems to have few good answers. Sodium and electrolyte losses can be high, yet one study of ironman participants concludes that no supplementation is needed!

Franklin K’s comments on 9000mg of sodium (Na) loss per liter of fluid are in line with the high end of what is suggested in studies. However, it is also true the acclimatized individuals might lose much less than that. I have no way of knowing my own sodium and electrolyte losses BUT I can say that in cool weather my skin is not particularly salty‚ nor does my clothing stain white under those conditions. During very hot weather my skin does get very salty and my clothing stiff with salts, but the sweating rate is at least double.

NIH: Sweat rate and sodium loss during work in the heat suggests 480 to 600mg sodium loss per hour for workers under hot conditions for workers, depending on acclimatization.

People working in moderately hot conditions for 10 hours on average will lose between 4.8 and 6 g of sodium (Na) equivalent to 12–15 g of salt (NaCl) depending on acclimatisation.

However due to the substantial interindividual variation in sweat rate and sodium concentration individual losses may be much higher. This essential electrolyte must be replaced in order to avoid fluid imbalances, thus eating during the shift is a must.

One work session in the heat, for an acclimatised person is sufficient to activate sodium-conserving mechanisms. However in the unacclimatised worker longer exposure is required. A worker starting work in harsh conditions should be given 10 days or more to acclimatise before performing heavy manual work in the heat.

Since I am highly trained and highly acclimatized, I take the 480mg/hour figure as most likely. However, riding at ~200 wattsfor 10+ hours continuallu is surely far more energy intensive than virtually all workers. Thus that should be considered a bare minimum.

NIH: Sweat Rates, Sweat Sodium Concentrations, and Sodium Losses in 3 Groups of Professional Football Players notes that overconsumption of fluid can be not only uncomfortable but dangerous—my rule of thumb has always been 1L/hour, as that is about all the stomach can handle, regardless of conditions.

Ironman study of sodium

An ironman effort is pretty darn close to a double century effort, both taking 10+ hour.

Sodium supplementation is not required to maintain serum sodium concentrations during an Ironman triathlon

Main outcome measures

Sodium supplementation was not necessary to maintain serum sodium concentrations in athletes completing an Ironman triathlon nor required to prevent hyponatraemia from occurring in athletes who did not ingest supplemental sodium during the race.

Results

Subjects in the sodium supplementation group ingested an additional 3.6 (2.0) g (156 (88) mmol) sodium during the race (all values are mean (SD)). There were no significant differences between the sodium, placebo, and no supplementation groups with regard to age, finishing time, serum sodium concentration before and after the race, weight before the race, weight change during the race, and rectal temperature, systolic and diastolic blood pressure after the race. The sodium supplementation group consumed 14.7 (8.3) tablets, and the placebo group took 15.8 (10.1) tablets (p  =  0.55; NS).

Conclusions

Ad libitum sodium supplementation was not necessary to preserve serum sodium concentrations in athletes competing for about 12 hours in an Ironman triathlon. The Institute of Medicine's recommended daily adequate intake of sodium (1.5 g/65 mmol) seems sufficient for a healthy person without further need to supplement during athletic activity.