Muscle Cramping?: The Mechanics

[Lifelover]

I just got home from a 75 mile attempt of a Century. About 67 mile in my legs started cramping pretty badly. It was hotter than expected, we were can harder than expect, I didn't drink early enough, blah, blah, blah.

As my Road Angel was pulling me home at 15 MPH, I was contemplating the mechanics of cramping.

Can anyone explain the mechanics? I don't mean the cause(s) and I'm not looking for advise on avoiding them, I'm just interested in what is going on with the muscles.

[sebseb]

hello, I have the same problem, but in my feet - get cramps in my right foot toes...always(!) after maybe 70km if I push really hard...but if I go on riding the cramps go away after one hour or so (experience during the trondheim-oslo race this year...otherwise I would have stopped...)...too magnesium tablets for quite some time but bothing changed...

[Dekonick]

Not sure if this is the answer or not - but
for muscle fiber to work, you need several components - of which two seem the most important -

energy (ATP) and Calcium (to bond fibers)

without either component the system won't work -

Look at a dead person - Rigor mortis is the result of no energy. The bond is there and the muscles stay put. May I suggest you don't die? :p

It is a wee bit more complicated than this, if you want more Ill go into detail (or someone esle can)

:)

Oh - one more major component is electrolyte balance (Potassium and sodium) as they are key in nerve and muscle impulses. Again - a bit complicated but if interested I'll gladly explain in detail.

[false_Aest]

Cramping = tums. . . . . super quick shot of calcium. My friend cramps at night and swears that they go away really fast if he chews two of them.

Tums are the antiacid with calcium right? Somethign your body needs anyways?

[WadePatton]

hmph, cramping is early stages of rigor mortis...noted.

It does seem odd that muscles lock up when you'd think they should go flaccid.

I had a few pre-cramp twinges today, but nothing like the full-on cramps I encountered after showering and kicking back--and then moving outside the range of motion used in cycling...some real whammos.

Biggest contributor today is dehydration--working hard on getting that back in order. The beer certainly doesn't help, but it makes the water more palatable. Sip beer, chug water, repeat until urine flow gets back up there.

On cramping--90% of mine is due to undertraining and overdemanding--I'll never forget the first quad lockup I had. These days I can feel the early warning signs and if necessary work around them.

More on the mechanics of the full on, lock-out cramp please. Just for reference, you won't be quoted... ;)

[Peter P.]

Heat cramps could be a cause. If it's hot enough to sweat, then you can consider it heat cramps.

"Heat cramps can be very painful. In cyclists they usually occur in leg muscles. The cause is hard exertion in hot weather when fluid and salt intake is inadequate."

"Sweat is very dilute when compared to other body fluids. Thus, during sweating you lose a far greater amount of water than electrolytes (sodium chloride, potassium, magnesium)."

"Many commercial drinks contain some form of sugar, buth the addition of even small amounts can drastically impair the rate at which fluids leave the stomach. Anything above a 2.5% sugar solution (one Tbsp. per waterbottle) begins to slow the process."

All of the above excerpts are from "Inside The Cyclist", Physiology For The Two Wheeled Athlete.

I experienced just what you did on a ride this year. I'm notoriously cheap, so I only use water in my bottles-and Gatorade gives my instant diarrhea. My friends were similarly equipped but had electrolyte drinks in their bottles. I was sufficiently fit but succumbed to severe leg cramps. We did the same ride later in the season under similar conditions but this time I found a suitable electrolyte drink. Cramping was not an issue.

[michael white]

I have a major cramping problem. I take pills for it. They work for me without question. Not just Tums; I believe you need the full spectrum of electrolytes. I take one before and one during a longer (like a century) ride. With lots of water.

[WadePatton]

Good info, but methinks we (me and the OP) are interested in the actual physiology at the tissue/cellular level. You know med-school stuff.

[Lifelover]

.... Again - a bit complicated but if interested I'll gladly explain in detail.


I'm not claiming that I will understand,but I would love to hear more.

[regularguy412]

Lots of good information here:

http://www.cptips.com/muspain.htm

But not sure it really addresses the OP's basic question.

Hope it helps.

Mike in AR :beer:

[93LegendTG]

http://www.hammernutrition.com/za/HNT?PAGE=ARTICLE&ARTICLE.ID=777&OMI=&AMI=&RETURN_URL=/za/HNT?PAGE=ENDURANCE_LIBRARY&OMI=&AMI=&RETURN_TEXT=Endurance%20Library

[WadePatton]

I suppose since we/they don't have a solid theory for exactly what IS going on, we can discuss the situation from the other angle.

I read a little here and there and--wow, it didn't take much to blow the electrolyte theory away.

Here's one of the places where I found that: http://www.sportsscientists.com/2008/01/featured-series-on-science-of-sport.html

[michael white]

wade:

the electrolyte theory is not blown away at all. Most people I've talked to believe it, and I am one of many who find very positive results from taking electrolytes. I know there are a few who discredit it. There are many more serious scientists who don't, and a lot of gray area.

[Lifelover]

I suppose since we/they don't have a solid theory for exactly what IS going on, we can discuss the situation from the other angle.

I read a little here and there and--wow, it didn't take much to blow the electrolyte theory away.

Here's one of the places where I found that: http://www.sportsscientists.com/2008/01/featured-series-on-science-of-sport.html

I would have never guessed the whole issue was this complicated and misunderstood. I was really expecting a quick easy answer.

Your link is really interesting and I would agree that based on my experiences, electrolytes don't seem to be the issue.

I have quite a few friends that think they help and have experiences where taking them reduced the cramping. Of course, usually, they stop, rest and stretch while taking them!?

I have always been prone to cramping. More than once, everybody in a meeting has stop and turned to find me wincing due to sudden cramping.

It does make for an interesting discussion.

[michael white]

http://www.prevention.com/cda/article/muscle-cramps/b8c488dc78803110VgnVCM10000013281eac____/fitness/getting.started/staying.motivated

Last year I rode a century in warm weather, sweated a lot and cramped so severely I was basically disabled. Eventually I was able to get on the bike with severe spasms, and a ride leader pushed me the last two miles. That was humiliating.

I am a lifelong cramper, but that was a pretty bad case. Traditionally it afflicts me a little while after finishing a longer ride, not during it. That was a day when I'd sweated so much my shorts had white salt on them. That is something to look at--if you really sweat like that. A PT told me it's often the heavy sweaters like me who have the problem. Do you sweat a lot? With supplements this year, I've not had a bad day of cramping since then, despite many hot rides. When I cramp, it's when I forget to take them.
I believe another factor to look at is caffeine. It's complicated, of course, but I seem to cramp less when I cut way back on coffee.

[regularguy412]

Here's one of the places where I found that: http://www.sportsscientists.com/2008/01/featured-series-on-science-of-sport.html


What I took away from the cramping part of the article was that one of the major causes of cramps has to do with the position of the muscle WRT whether it's mostly contracted when one attempts to contract it even more. This sounds to me that a person's position ON the bike and how the muscles and joints are positioned relative to full contraction (or not) is very important.

I can see how this could well be a viable argument.

Mike in AR:beer:

[WadePatton]

I don't notice much difference with electrolyte supplementation, but I also eat 2-4 bananas every morning and usually have a couple more on longer rides. My cramping is always when I'm pushing my limits (endurance or power) and often exacerbated by dehydration.

Thing about sodium etc. supplementation is that the more you take in--the more freely you body releases them. There is a very fine balance and the body must maintain it. I can dig up some research on that, but not this evening.

Like I said--for me it's overtaxing undertrained muscles and dehydration. Every body is a bit different.

[WadePatton]

Otay, here's some stuff:

All muscles have two elegant sensing systems physically built into them. The first of these is based on the muscle spindle. Many spindles are found in every muscle belly, running parallel to the muscle fibers. The spindle senses, and things are wired so that the muscle responds to, length, changes in length and the rate of change of length in the muscle. When a muscle is quickly stretched, the spindle tells the muscle to contract, and to do so right now! (Different nerve cells conduct signals at different rates, and these are the fastest conductors in the body.) The spindle itself can, like muscle fibers, contract. If the muscle stays shortened, the spindle will eventually detect this state and will itself shorten. In other words, it re-sets itself so that it will be ready to tell the now shorter muscle to contract when once again it is quickly stretched.

Snipped from: http://www.ultracycling.com/training/cramping.html

There's more there.

[Dekonick]

OK -

back from a few days cramming in overtime to pay for this hobby...

anyhoo

as far as cramping - I am not perfectly up to date on the physiology - probably 10 years 'en arrier si tu veux...'

well

the function of muscle is really quite fascinating. If you have ever taken an anatomy course, then you can relate...

Look under a microscope (we are talking about skeletal muscle tissue, there are three types...smooth - like that which surrounds your intestines, cardiac..duh - your heart...and skeletal) and you can see the individual fibers that 'slide' when you contract. These individual fibers are joined into larger groups, and so on until you have a 'muscle' - say your bicep for example. The muscle, if never exercised, stretched, etc... will eventually seize up and stay in that position - if you have ever worked with the elderly you know what I mean... someone who is 'shriveled up' essentially has muscles that are contracted. (Yes - you do have opposing muscles, but lets not get into that) Why does this happen? Well - there are proteins in your muscle fibers - and with help they form a bond. Actin and Myosin, with calcium form a bond (not ionic, but an actual covalent bond - pretty strong compared to alot of the chemical bonds in physiology - alot of hydrogen bonds, (weak) and Ionic bonds (stronger) as well as just plain old concentration gradients... resulting in weak electrical differences.)
When actin and myosin form a bond, they essentially lock two parts of the fiber together. With energy (primarily adenoside tri-phosphate, which cleaves off a phosphate group to become adenosine di-phosphate) the shape to the proteins change. The actin-myosin perform what is called a power stroke. The action of cleaving off the phosphate changes the shape of ATP to ADP - and this is a physical change of shape and results in 'energy' - that essentially causes the actin-myosin to 'bend' and thus move the filliments of a muscle fiber. The more actin-myosin that 'bend' the further the fiber will slide, and the stronger the contraction will be. Once a contraction has occured, it is kinda a set deal - after all a covalent bond will not break on it's own accord. Your body then sets to break that bond and re-set the shape of the actin - myosin (no longer bonded) to repeat as needed.

That is the action of contraction. If you are missing calcium, then actin can not bind to myosin - and thus the above can't work.

But - what makes a muscle contract in the first place?

Well....

that is even more interesting. (please forgive me as I am drinking some really good Pinot and am not refering to any texts. As previously stated, my sciences are probably 15 years old so I am a bit out of date... and this is off of the top of my head so to speak.)

Muscles need a trigger to act. This comes from a nerve impulse - and the nerve iteself has to send a message from one cell to the next... electrically, and chemically. Think about that. You decide to pedal...your brain sends a message to start contracting... all of this happens cell by cell in milliseconds. Pretty amazing. Without getting really deep (it is REALLY cool - it is amazing how ion gates segregate what they are designed to pass from what they aren't, how sodium/potassium pumps (among other pumps) work... I digress...
well - to make it somewhat simple, the ability of a nerve to work is dependant on proper balances of salts - electrolytes. Too much of one type, and it ceases to work as it should. Too little, same thing. What we worry most about is sodium and potassium. The cells set at a ratio that results in more potassium inside the cell membrane, compared to outside, and more sodium outside compared to inside. This causes a net negative charge inside the cell, even though both are cations. More stuff outside (posive) compared to stuff inside (also positive) results in a created negative charge. When that charge is at the right ratio, the cell is in a pre-excited state and is ready to act - if it gets a message from another nerve cell (chemicals sent passively from little storage buttons called dendrites passively diffuse over a gap called a synapse until they reach the next cell. If the chemicals are the right type, and in the righe concentration, the pre-excited cell will then depolarize and send the message on via the same method until it reaches a muscle motor end plate - in our case - and cause the muscle to contract)

So not having calcium to make the actin myosin bond, not having enough potassium, or sodium, all can result in a muscle that doesnt work as it should. As far as stretch and receptors, that is another complicated - but also cool - interaction.

Lets face it - the human body is an absolutely amazing machine. The more we learn, the more we really don't know...

damn - this is good wine. Yumm

hopefully I did not make too many mistakes in my ramble... Ill go over it again tomorrow and actually crack a book or two to make sure its correct - I believe it is but that is from memory...and buzzed memory at that....

:beer:

[William]

Hey Deko,

Thanks for the ride back to my Biology/Anatomy/Physiology/Kinesiology courses back at OSU. Fun stuff. :banana:


In all the sports I've been involved with over the years, I've never had an issue with cramping muscles. I can't recall even one incident.




William

[Lifelover]

the function of muscle is really quite fascinating.............

Lets face it - the human body is an absolutely amazing machine. The more we learn, the more we really don't know........


Is my brain a muscle, I think it's cramping :crap:

Interesting stuff! I may have to read it a few more times to grasp it, but this is along the lines of what I was looking for.

The body really is amazing. Like alomost everything else involving the body. I don't think there is a single, easy answer.

As I type this, two days after trying to ensure I rehydrate and get some electrolytes in me, the same muscle are twitching away.

[Dekonick]

-mmmm-
how about the mechanics for a hangover... (J/K -yummy wine tho...)

My short paragraph above is really not enough detail to explain what really is going on- If you are truly interested, may I suggest picking up a used anatomy and physiology textbook from a local university. You don't want anything like Gray's anatomy - good for the names of all of the little parts we never knew we needed to know (right...when will I ever need to know the insertion, action, blood and nerve supply for the orbicularis oculi...Hmmm NEVER! wink...wink...)

Also a simplified combined organic/biochemistry book - usually a nursing school or similar will offer some such - a full blown organic textbook is useless unless you want to be able to read the back of a bottle of shampoo...

Oh - don't forget the free Wikipedia...

snipped:

There are six basic causes of cramping:[1] hyperflexion; inadequate oxygenation; exposure to large changes in temperature; dehydration; low blood salt; or low blood calcium. Muscle cramps may also be a symptom/complication of pregnancy, kidney disease, thyroid disease, hypokalemia or hypocalcemia (as conditions), restless legs syndrome, varicose veins[2], and multiple sclerosis.[3]

Electrolyte disturbance may cause cramping and tetany of muscles, particularly hypokalaemia (a low level of potassium) and hypocalcaemia (a low level of calcium). This disturbance arises as the body loses large amounts of interstitial fluid through sweat. This interstitial fluid is composed mostly of water and table salt (NaCl). The loss of osmotically active particles outside muscle cells leads to a disturbance of the osmotic balance and swelling of muscle cells as these contain more osmotically active particles. This causes the calcium pump between the muscle lumen and sarcoplasmic reticulum to short circuit and the calcium ions remain bound to the troponin and the muscle contraction is continued. This may occur when the lactic acid is high in the cells.


[edit] Iatrogenic causes
Statins are known to cause myalgia and cramps among other side effects. Additional factors increasing probability for these adverse side effects are physical exercise, age, female gender, history of cramps and hypothyroidism. Up to 80% of athletes using statins suffer significant muscular adverse effects including cramps [4], the rate appears to be approximately 10-25% in typical population using statins [5][6]. In some cases these adverse effects will disappear after switching to a different statin, however they should not be ignored if they persist as they can rarely develop into a more serious problem. Coenzyme Q10 supplementation can be helpful to avoid some statin related adverse effects but currently there is not enough evidence to prove effectiveness in avoiding myopathy or myalgia [7].

:p