Tight hamstrings on a run can cause a muscle cramp or muscle spasm. When your muscle cramps, it doesn't contract smoothly while running, which can lead to sore and tender muscles. In many cases, the cause of hamstring cramps is something simple and is easily correctable by taking preventive measures. If your cramps persist, however, you should consult your doctor to rule out an underlying medical problem.
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Anatomy of a Cramp
A hamstring cramp, also referred to as a spasm, is the result of your hamstring muscles forcibly contracting and not relaxing. A mild cramp can be felt as an annoying, dull ache while a more severe cramp is experienced as a sharp, stabbing pain. If the contraction is strong enough, your muscle can knot up, forming a bump or lump beneath your skin. The calf, thigh and hamstring muscles are the most commonly afflicted by muscle cramps.
Causes of Cramps
The exact cause of cramps is not clear, but certain conditions increase the chances they will occur. Conditions leading to cramps include dehydration, electrolyte imbalance or deficiencies, muscle fatigue and lack of a proper warm-up before running. Working out in a hot environment can be a contributing factor, primarily because it leads to rapid dehydration. In some instances, the cause of the cramps is a prescription medication, such as a diuretic, that causes the depletion of electrolytes. Rarely, an underlying medical problem, such as a nerve disorder, is to blame.
Hot and Cold
When your hamstring starts to tighten, stop running and stretch your muscles. Place firm pressure on the affected muscles or massage them, keeping your muscles stretched, until the cramp goes away. Drink water or a sports drink enhanced with electrolytes to help you hydrate. Eating a banana, which is high in the electrolyte potassium, may help. If the cramp is severe or does not go away, cease all activity and apply heat as soon as possible to relax the muscle. To treat sore and tender muscles post-run, apply an ice pack or other cold source. Seek medical attention if self-care measures don't get rid of your hamstring cramps.
Water and Salty Snacks
To prevent hamstring cramps, drink plenty of water before, during and after running. Warm up before you run by performing calisthenics, such as jumping jacks, for five to 10 minutes. Gently stretch your leg muscles, particularly your hamstrings and calf muscles, after your warm-up. Cool down after running by walking for several minutes and gently stretching your muscles. Eat a nutrient-dense diet with plenty of electrolytes, particularly potassium, sodium and magnesium. Carry a salty snack with you on long runs to replace lost sodium -- an electrolyte involved in muscle contraction. Take a multivitamin daily. Avoid running if your hamstrings are fatigued or sore, and pace yourself while running to avoid overexertion. Talk to your doctor about any medications you are taking to verify that muscle cramps are not a side effect. If you take preventive measures and still feel tight muscles while running, consult a doctor.