Leg cramps are powerful contractions of the muscles in the lower leg which causes great pain. It often occurs in the middle of the night and therefore wakes up the patient. The pain persist for hours thereafter although of lower intensity. Anyhow, it can disturb the sleep to a great extent.
Increasing the extracellular Ca2+ enhances transmitter release; lowering it reduces and ultimately blocks synaptic transmission. The facilitating effect of Ca2+ on synaptic transmission is inhibited by Mg2+, a blocker of Ca2+ channels.
Any local irritating factor or metabolic abnormality of a muscle - such as a severe cold, lack of blood flow to the muscle, or overexercise of the muscle - can elicit pain or other types of sensory impulses that are transmitted from the muscle to the spinal cord, thus causing reflex muscle contraction. The contraction in turn stimulates the same sensory receptors still more, which causes the spinal cord to increase the intensity of contraction still further. Thus, a positive feedback develops so that a small amount of initial irritation causes more and more contraction until a fullblown muscle cramp ensues.
Reciprocal inhibition of the muscle can sometimes relieve the cramp. That is, if a person purposefully contracts the muscle on the side of the joint opposite the cramped muscle while at the same time using the other hand or foot to prevent movement of the joint, the reciprocal inhibition that occurs in the cramped muscle can at times relieve the cramp.
There is little knowledge of the exact nature of leg cramps and as an effect of this there is no primary cure. I will mention a few of which magnesium have been of help for me.
Water intoxication and hyponatremia (low concentration of sodium (salt) in the blood) can cause cramps.
Leg cramps can in a few cases be a result of a reduction of thyroid glandular activity (hypothyroidism). Hypoglycemia, hypocalcemia, hypo- and hypernatremia can produce cramps. Cramps is common with hypoparathyroidism.
Hypomagnesemia (low concentration of magnesium in the blood) causes neuromuscular hyperexcitability. NMDA (N-methyl-D-Aspartate) receptors are involved in generating the locomotor pattern. NMDA receptor-channel's voltage-dependent blockade by Mg2+ is responsible for the inhibition by magnesium. Too low Mg2+ will make the inhibition too small.
Magnesium is necessary for the release of PTH (Para Thyroid Hormone) and for the action of the hormone on its target tissues. The most common clinical presentations of hypomagnesemia are caused by associated hypocalcemia (due to interference with the secretion and action of PTH) and hypokalemia (low potassium, due to an inability of the kidney to preserve potassium).
Magnesium inhibit calcium entry into nerve terminal. Severe magnesium depletion leads to tonic-clonic convulsions. Restless legs are often caused by a deficiency of magnesium, try 250 - 500 mg before bedtime.
In obstetrics magnesium sulfate has an anticonvulsive, sedative and blood pressure lowering effect due to its blockade of the neuromuscular transmission.
Therapeutic serum concentration 2-3 mmol/L.
Patellar reflex extinct at over 3.5-5.0 mmol/L.
Respiration depressed at over 5.5-7.0 mmol/L.
Normal concentration of magnesium in serum is 0.7-1.1 mmol/L.
Magnesium sulfate is given intravenously as peroral administration has an osmotic effect in the gastrointestinal canal and causes diarrhaea. Magnesium sulfate has no place in the therapy of leg cramps. I only mention this practice in obstetrics to illustrate the cramp lessening effect of magnesium.
The RDA for magnesium is 350 mg/day. Average intake in the USA is between 143 and 266 mg/day. 500-1000 mg/day would be good for most bodybuilders as they have an increased need for this mineral. Hard training seems to deplete the body of this mineral as well as other minerals.
Beans, nuts, seeds and dark chocolate are rich sources of magnesium. Some low sodium salts are enriched with magnesium. Try these magnesium sources.
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A special form of niacin (vitamin B3) called inositol hexanicotinate is supposed to help treat chronic calf cramping and Raynaud's disease. Start with 500 mg 3 times a day and work up to 1 g 3 times a day after 2 weeks.
Pyridoxine, vitamin B6, is also supposed to reduce leg cramps.
Taurine, an amino acid in meat, can have an effect in the treatment of leg cramps. It is often used in combination with glutamic acid and aspartic acid.
DL-Phenylalanine is supposed to dampen the pain when cramping.
Vitamin E (tocopherol) has a weak action and has to be taken in doses of circa 400 mg/day.
Many persons recommend calcium (sometimes in the form of dolomite), potassium (bananas), anti-oxidants (like pycnogenols, grape-fruit seed extract) and to avoid dehydration (drink plenty of water).
Peppermint has a weak action but can anyhow lessen cramps.
Doctors often prescribe quinine. Quinine raises the treshold for acetylcholine at the motor end plate. Quinine sulfate 300 mg orally.
Some doctors have prescribed diazepam, carbamazepine or diphenhydramine. Some even prescribe phenytoin 0.3-0.6 g daily during the day if the patient have leg cramps at daytime. To my knowledge leg cramps isn't an indication for phenytoin.
I have had good use of 250 mg magnesium daily (tablets or capsules). Initially you can double the dose for a week or two. It can take some weeks before relief. It's prudent not to take too high a dose as diarrhaea will be the result with a diminished uptake as a result of this. The treatment can have a duration for years. Try a period of no supplementation now and then to see if a remission has occured. I recommend you to adjust your diet to a more nutritious one with a higher content of the mineral(s) you're deficient of. You can first experiment with different treatments, be it exercise, minerals, vitamins or medicine, and then when you know what causes your leg cramps, treat it adequately.
Great thanks to all who have shared their knowledge with me.
It's prudent to consult a doctor although most leg cramps are due to stress, malnutrition or diabetes.