Leg cramps

[Rick Murchison]

I often have new students who experience cramps with very little exercise in fins - some of the worst are runners, which would seem to disassociate "good shape" as a preventative - but it doesn't (stick with me here)...
Let's think a little about the acts of walking or running - our "normal" use of the leg muscles, and finning. In a walk or a run, the power stroke of the leg begins with the foot in a "toe up" position. The muscles in the bottom of the foot are stretched, the calf is at least partially stretched. As the leg straightens, the calf muscle goes through a fully stretched phase, then provides the final push as the toe is brought forcefully down (or the heel pulled forcefully up).
When finning (flutter kick), the power stroke, the downward stroke, begins with the toe pointed (not so much with Force Fins - that's why they help) - the muscles of the calf and the bottom of the foot are bunched up more than they ever are in normal walking or running - and because the leg straightening power stroke retains the pointed toe position, the calf and bottom of the foot remain more bunched up than they're accostumed to being during their normal everyday work. So the muscles of the calf and bottom of the foot never reach full stretch...
Doc (BillP) sez "Passively stretching the cramped muscle stimulates stretch receptors in the muscle that creates an inhibiting feedback reflex in the nerves from the spine to the muscle, relaxing the spasm." But in normal finning the muscles of the calf and bottom of the foot never make it to the "stretched" position, and the "inhibiting feedback reflex" doesn't happen. And without this "stretched muscle feedback" the muscle tends to cramp. The calf and bottom of the foot are not worked very hard in normal finning (flutter kick), yet they are the muscles where we see most cramping. I believe it is this lack of stretch that sets off cramping at much lower than normal cramping fatigue levels, especially in new divers.
Therefore, I believe that "conditioning" the muscles to operate in these somewhat abnormal movements is probably at least as important as being in "good shape."
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The other way to help prevent cramps is to get some stretch to those calf and foot-bottom muscles while we're swimming, and switching from the flutter to the frog kick from time to time is an excellent way to do that.
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Bottom line - the best way to condition yourself to avoid cramps is to put your fins on, get in the water and swim, swim, swim. Regularly.
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Hydration is also extremely important.
Rick

 

[BillP]

Rick Murchison said...

Doc (BillP) sez "Passively stretching the cramped muscle stimulates stretch receptors in the muscle that creates an inhibiting feedback reflex in the nerves from the spine to the muscle, relaxing the spasm." But in normal finning the muscles of the calf and bottom of the foot never make it to the "stretched" position, and the "inhibiting feedback reflex" doesn't happen. And without this "stretched muscle feedback" the muscle tends to cramp.
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Bottom line - the best way to condition yourself to avoid cramps is to put your fins on, get in the water and swim, swim, swim. Regularly.
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Howdy Rick:

In quoting me, I hope you weren't trying to imply that I was saying that normal finning does cause the stretching I was talking about. Such was not my intent. I was talking about the kind of stetching that you probably teach your students to employ when they get a cramp. I was merely using the passive stretching example as some possible confirmatory evidence for one cause of muscle cramps. I was not talking about cramp prevention with that example.

Your points about "conditioning" the muscles specifically for finning is well taken, and is really what I was talking about when I was talking about "fitness" and recommended swimming laps in dive gear. Thanks for bringing it up. Your explanation of that point was clearer than mine.

Bill

 

[The Iceni]

Hi Nick,

Cramp is very unpleasant and sometimes quite dangerous so I agree you must do all you can to prevent it. It is quite impossible to swim or fin if the calf muscles are in spasm.

What none of the previous contributors have pointed out is that the cramps may indeed be physiological and due to localised electrolyte imbalance but another more sinsister possibility is that you coulkd be describing a pathological condition. For example intermittant claudication is due ito "hardening of the arteries"(in layman's terms). This is associated with middle age and smoking and is closely related to ischaemic heart disease.

I admit this is unlikely particularly if you are in the wrong age and it is not a frequent occurrence.

I was interested to hear that this sometimes happens at night. Nocturnal cramps are often helped by quinine bisulphate tablets, which are thought to have an effect on the calcium channels in muscle.

The other doctors are right to dismiss a generalised lack of potassium as the cause. Potassium levels are very tightly controlled by the body and only vary in severe illness such as renal failure or Addison's disease. Indeed an abnormal potasium level can kill becuse it causes cardiac arrythmias. (Do you remember the anaesthetist convicted of manslaughter for using an IV injection of potassium chloride to euthanise a patient?)

So forget about bananas. It honestly is a load of bananas! (and expensive urine)

So my thoughts on some tips that might help.

Cramp is much more likely when the muscle is cold or the circulation to it is impared by tight fitting clothing. (This us why athletes always warm up before a race)

Ill-fitting fins will cause your finning action to be awkward and unbalanced making certain muscle groups work excessively, they tire and stop working properly due to the localised build up of lactic acid and go into spasm - cramps.

British waters are cold. Is you new suit efficient? The need to wear a bulky dry suit means you may not be completely comfortable and relaxed. Make sure all you equipment fits snugly.

I hope you do not mind me adding my tuppence worth. (I know its not worth much more than that!)

 

[Rick Murchison]

BillP once bubbled...


Howdy Rick:

In quoting me, I hope you weren't trying to imply that I was saying that normal finning does cause the stretching I was talking about. Such was not my intent.

Not at all, Doc. I was using you to support the "why" of getting cramps at much lower muscle fatigue levels with finning compared to walking or running. No, you were quite clear in your post. No one had brought up the differences in muscle action between walking and finning yet, so I felt it needed, as fatigue alone doesn't explain lots of folks' cramping experiences.
Your input is valuable and greatly appreciated.
Rick

 

[Red Rover]

BillP once bubbled...


Howdy Red Rover:

I'm glad that you found relief for your cramps. But do you have any evidence other than anecdotal reports to support your claim?

How many mEq of potassium are in the average sized banana? How many bananas over what period of time do you need to eat to change your muscles' potassium level (assuming you don't have a medical condition causing a potassium deficiency)? Could there be other causes for muscle cramps in divers, or is lack of potassium present in the muscle tissue the only possible explanation?

Fascinating subject, isn't it?

Bill

I have no evidence other than what worked for me when I swam for UW Wisconsin Madison. However, our team NUTRITIONIST and our team DOCTOR were the ones who gave us this advice, which incidently, worked like a charm.

Oddly enough, I asked another athlete (he runs triathalons) what he took to prevent cramps. "Banannas" he said. "You should know that, you were a swimmer for God's sake!" he said.

I just smiled.

Thanks,
Red Rover