Monthly Archives: August 2007

The importance of staying salty…

Salt (or at least the sodium component of it) is perhaps the most underappreciated and under-discussed nutrient for endurance cyclists.

Given my recent history, I’ve been doing a fair bit of research into the topic, and frankly I’ve been surprised how little information there is. That, coupled with a lot of bad press around sodium because of its well-established link to hypertension, means that most cyclists don’t think about salt. They do perhaps think a bit about hyponatremia.

Which is really a bit strange, when you think about it, as many of us have white stains on our helmet straps and that sandy feeling on our faces after a hard ride.

So, here’s what’s going on WRT salt, and a few things that you might want to think about.

When you sweat, you lose salt, along with a number of other electolytes.

Here’s a table I pulled from Burke’s Serious Cycling

Blood Plasma 140 100 4 1.5
Muscle Tissue 9 5 160 30
Sweat 40-60 30-50 4-5 1.5-5

This chart uses mEq/L, which is basically a measure of the concentration of the various elements. What we’d like instead is a chart that shows the actual amount of the substance (which we get by multiplying by the molecular weight). My wife tells me that medicine is the only place that uses mEq/L as a measure…

Here’s the converted chart:

Blood Plasma 3220 3550 156 18
Muscle Tissue 207 172 6240 365
Sweat 920-1380 1065-1775 156-195 18-122

This chart shows the difference between salt (sodium and chloride), and the other major constituents of sweat. For potassium and magnesium, the concentration in the blood is fairly low compared to the concentration in muscle tissue. This means that loses of those two elements through sweat are relatively unimportant to the body’s total supply.

For sodium and chloride, however, the amount stored in muscle tissue is fairly minor. The majority of the storage is in the blood. And there’s really not that much there.

So, say that you’re out riding and only taking in water. Your sodium level drops. Your body wants to get rid of the water, but it doesn’t want to lose more sodium, so it stashes the water between cells, and you’re on your way to hyponeatremia.

This happens more quickly if you’re on a low-salt diet, which is what got me into this topic in the first place.

What that means is that you need to replace the salt. Serious Cycling suggests that you need from 400-1100mg of sodium and 500-1500mg of chloride. ACSM recommends 500-700mg of salt/liter.

Many hydration drinks have some salt in them – here’s a good comparison chart. Searching through that chart, I find that the accelerade that I drink only has about 500 mg of sodium per liter. That’s at most around 50% of the amount I need to replace the salt I sweat out (I’m a fairly salty sweater). Which explains a lot.

Almost all of the the drinks have some electrolytes – as they’re needed to help you absorb the drink – but some of them are pretty low. So, take a look at what your drink has in it, and that will help you figure out if you need supplementation. If you are riding for long periods, my guess is probably *yes*.


  • Fatigue (yeah, I know, it’s a bit hard to judge after 60 miles)
  • Upset stomach
  • Headache
  • Aversion to sugary foods (I get this rather than a salt craving, though salt tastes good. This may also just be food fatigue)
  • Weight gain during the ride
  • Lack of urination, especially if you are drinking a lot.

A note on hypertension…

If you have hypertension (high blood pressure), this is an area that you will want to be careful with, and you may want to consult your physician before supplementation.

What supplements to use

A classic supplement is beef jerky, which tends to be around 1000mg per service. If you want a capsule you can swallow, both Lava Salts and Succeed E!Caps have a good reputation on the ultra (bike/run) sites.

A lot of people talk about Hammer’s Endurolytes capsules. The hammer hydration products are quite low in electrolytes (see the chart I linked to earlier), and frankly, I’m mystified by what’s in the endurolytes – they only have 40mg sodium and 60mg chloride, which is a really small amount. They suggest that you can take up to 6 of them per hour, but even that may not be enough. They do have other electrolytes, but you are probably okay without supplementation of potassium and magnesium during exercise.

One final note

As with all things related to nutrition/hydration, people have different responses, so you’ll probably have to play around to find out what works for you. If you are used to sweating a lot, your body has likely adapted so that you don’t lose as much electrolyte when you exercise. Conversely, if you don’t work out in the heat and/or don’t sweat as much, you may be near the upper end of electrolyte loss.


Ultracycling has two great references on this:

Low Blood Sodium

Water and Salt Intake during exercise

Your weight loss goal is reasonable…

I was playing around, and came a cross a diet evalution page. I entered my weight (165 pounds), my height (6’2″), and my desired weight (120 pounds), and hit “go”

It replied with “please go back and change your target weight to at least 140.4 pounds. For the sake of your health, we refuse to accept a lower target than this.”

So, I go back, and set my desired weight to 141 pounds, and it says:

Though your current weight is already within normal limits, your weight loss goal is reasonable, because when you reach 141 pounds, your new BMI will be 18, still within the ‘normal’ range.

Umm… Yeah…

I have some muscle on my legs, not much on my upper body, I’m somewhere below 10% body fat, but yeah, I’m sure I can find 20 pounds to lose somewhere.



It’s happening again.

I’m on acuweather, weatherunderground, and my local news sources throughout the day – trying to find a forecast I like. It’s been a bit wet, but it seems like it’s clearing up.  

I get home from work, mix up my hydration drink, get my newtons ready, put on my riding clothes, and head downstairs to play Halo until it’s time to go. I munch on a Clif bar and drink a tall glass of water. And then it’s 5 after 6, time to go.

I head upstairs, grab my cycling bag, go into the garage, open the door, pull the bike off the wall, pump up the tires, and roll it out to put it in the truck.

And then it happens.

A tickling on my bare arms. I stretch my arms out and stand still.

It’s definite. It’s drizzling.

I wheel the bike back into the garage, and hang it up. Head back inside, go downstairs, and get on the trainer, trading two hours of fun with my friends for 45 minutes of boredom on the trainer.


Figuring calories per mile…

It’s not uncommon for people to ask how many calories they burn per mile, and if you do a few web searches, you’ll find numbers in the 35-50 cal/mile range.

Or rather, you’ll find *estimates* in that sort of range.

The problem being that the amount of calories you burn depends drastically on how hard you are riding. And if you are riding for 30 miles, you could get anywhere from 1000 calories to 1500 calories, which is a pretty big difference, if you care about how many calories you are burning.

You can also use an online calculator to figure out your calorie burn. If plug my numbers on this, I get the following values in cal/hour:

15 mph 27 cal/hr
16 mph 30 cal/hr
17 mph 33 cal/hr
18 mph 36 cal/hr
19 mph 39 cal/hr
20 mph 42 cal/hr

Now, that’s a purely flat ride. And there are obviously some aero calculations in there that may not be particularly accurate.

Another option is to use a heart rate monitor. My polar 720i claims to be able to compute the calorie burn for a ride. It knows my weight, my age, and my base HR. It also knows my altitude and speed, which could be very useful to compute calories, but AFAICT, it doesn’t use that in the calorie calculations.

On a recent ride, it claimed that I burnt 1110 calories in a 26.2 mile ride with 1445 feet of climbing, which comes out to around 42 cal/mile. How does that compare with the calculator above? Well, 1445 over 26.2 miles averages 1% over the whole climb – plug that in, and it gives an estimate of 1104 calories.

Which is really quite a bit closer than I expected.

When I was suffering up the climb to Sunrise on Ramrod, I was wondering how many calories I was burning. Given that it’s a climb and the speeds are slow, the amount of energy expended on climbing vs the energy expended overcoming air resistance is pretty high.

Here’s what the Polar says about that climb:

Duration: 95:30
Distance: 13.4 miles
Elevation Gain: 2820 ft (really 3000 feet, but the polar was low on the altitude of the top).
Calories: 1146 (85 cal/mile)
Speed: 8.4 MPH

The speed calculator suggests only 905 calories, for a paltry 68 cal/mile.

My bicycle climbs wattage calculator figures the following:

Wattage(Climb): 134 watts
Wattage(Rolling): 10 watts
Wattage(Aero Drag): 14 watts
Wattage(Total): 160 watts

Now, 160 watts is 138 Kcal/hour. But humans are only about 25% efficient at converting food calories into work, so that means the food calorie expenditure is 552 Kcal/hour, and the overall expenditure = 95.5/60 * 552 = 878 calories total (66 cal/mile).

Interestingly, that’s very close to the online calculator.

So, at least for that climb, if I’m of normal efficiency, the polar calorie estimation is perhaps 50% high. If I was dehydrated (and I was, a bit), that would tend to push the HR higher than normal.

Now, of course, the real way to figure out calories burned is with a power meter, but I haven’t taken that step. yet.

Another climb showed up with Polar=603 calories (97 cal/mile), calculator=465 cal (75 cal/mile), website = 446 cal (71 cal/mile).

What does that all mean? Well, it means that cal/mile calculations aren’t really worth much – which really isn’t a surprise to me. It also means that the online calculator does a pretty good decent job on pure climbs.

It also means that the polar seemed to drastically overestimate calories on pure climbs, but it seemed to be okay on normal rides.