Understanding Muscle Cramps

Understanding Muscle Cramps

MUSCLE CRAMPS Most commonly these occur at night and affect the legs, especially the calf muscles, and the feet. These kinds of cramps occur more frequently in elderly people. PHYSIOLOGY OF MUSCLE CRAMPS In a normal resting muscle, calcium is stored in the sarcoplasmic reticulum(reservoir within the muscle). Magnesium acts as a calcium blocker, inhibiting calcium release from the sarcoplasmic reticulum. Normally for a muscle to contract, a nerve impulse must travel to the muscle and cause calcium to be released from the sarcoplasmic reticulum. This causes a series of reactions whereby ATP is used to cause the actin and myosin filaments in the muscle fibers to engage and cause muscle contraction. Any local irritating factor such or metabolic abnormality of a muscle-such as severe cold, lack of blood flow to the muscle, over-exercise of the muscle-can elicit pain and 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 the contraction still further. Thus a positive feedback develops so that a small amount of local irritation causes more and more contraction until a full blown muscle cramp ensues. Reciprocal inhibition can help. This means to purposely contract the muscle on the side of the joint opposite to the cramped muscle while at the same time using the other hand or foot to prevent movement of the joint, (isometric contraction) the reciprocal inhibition that occurs in the cramped muscle can at times relieve the cramp. This is used in physical therapy quite often as a treatment to relieve muscle tightness and spasms. What Causes Muscle Cramps • Muscle cramping is most commonly caused by an imbalance in the levels of calcium and magnesium in the body or a deficiency of Vitamin E. Magnesium is necessary for the release of PTH(ParaThyroid Hormone) and for the action of the hormone on it’s target tissues(PTH causes increase in blood levels of calcium and magnesium and increases osteoblasts, bone building cells). 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 inability of the kidney to preserve potassium). Magnesium inhibit calcium entry into the nerve terminal. Severe magnesium depletion can result in tonic-clonic convulsions. Restless legs are often caused by a deficiency of magnesium(try 250-500 mg of magnesium before bedtime) • Hypothyroidism • Hypoglycemia(low blood sugar) • Hypoparathyroidism • Hypocalcemia • Hypo- and Hypernatremia(low and high sodium) • Hypomagnesemia(low concentration of magnesium in the blood) can cause neuromuscular hyperexcitability. • Dehydration • Anemia • the use of tobacco • Inactivity • fibromyalgia, arthritis • atherosclerosis can result in cramping • heat stroke • varicose veins • or more rarely, the early stages of amyotrophic lateral sclerosis ALS, or Lou Gehrig’s Disease • The use of diuretic drugs for high blood pressure or heart disorders may lead to electrolyte imbalances, causing muscle cramps. • Poor circulation also contributes to cramps. A NOTE ON STATIN MEDICATIONS Certain statin medications(cholesterol lowering drugs) such as Lipitor, Lescol, Mevacor, Pravachol, Crestor, and Zocor can result in muscle cramping. Statin medications inhibit the enzyme HMG-CoA reductase. This enzyme is the rate-limiting enzyme important in the synthesis of am important precursor molecule called farnysl pyrophosphate, from which our body makes cholesterol and CoQ10. Without CoQ10, our body’s ability to produce ATP(our main energy source) is significantly compromised. The human body utilizes the same biomechanical pathway to produce cholesterol as it does to produce ATP. Research has shown that we can get about a 25 % reduction in CoQ10 when taking statins. In addition to driving ATP synthesis, CoQ10 also functions as an important antioxidant and regulates skeletal muscle gene expression, so it should not be a wonder that muscles suffer with statin use.1 RECOMMENDED TREATMENT These recommendations are listed here as a reference only. They are not intended to be used as direct medical advice. Consult your physician before taking any of the following, and be sure to discuss any other medications or suppliments you are currently taking which may have interactions with these suplliments> • 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 athletes and active individuals who exercise frequently, as they have an increased need for this mineral. Hard training seems to deplete the body of this mineral as well as other minerals. • Be cautious about taking too much magnesium, as it may result in diarrhea. • Beans, nuts, seeds, and dark chocolate are rich sources of magnesium. • A special form of niacin(vitamin B3) is called inositol hexanictinate is supposed to help treat chronic calf cramping and Raynaud’s disease(vascular problem). Start with 500 mg 3 times per day and work up to 1 g 3 times a day after 2 weeks. • Pyroxidine(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. • Vitamin E (tocopherol) has a weak action and has to be taken in doses of about 400 mg/day. • Bananas, antioxidants(like pycnogenols, grape-fruit seed extract) and avoid dehydration are also good ways to prevent cramping. The Restless Leg Syndrome Foundation promotes research and offer support. www.rls.org or The National Institute of Neurological Disorders and Stroke NINDS Restless Leg Syndrome Information Page http://www.ninds.nih.gov/disorders/restless_legs/restless_legs.htm References 1. Seaman, D. Statin Drugs and the Problems They Impose on the Patients We See. FCA Journal, Sept-Oct. 2004 2. Vorgerd M. Therapeutic Options in Other MetabolicMyopathies.Neurotherapeutics. 2008 Oct;5(4):579-82. 3. Reid, IR., Ames, R. et.al. Randomized Contol Trial of Calcium Supplementation in Healthy, Nonosteoporitic, Older Men. Arch Intern Med. 2008 November 10 ;168(20):2276-82. 4. Schwellnus MP, Drew N, Collins M. Muscle Cramping in Athletes-Risk Factors, Clinical Assessment and Management. Clin Sports Med. 2008 Jan;27(1):183-94 5. Maquirriain, J. Merrello, M. The athlete with muscular cramps: clinical approach. J Acad Orthop Surg. 2007 Jul;15(7):425-31