Nightime Muscle Cramps and Restless Leg Syndrome in Athletes

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Not all cramping is training-related. The causes of muscle cramping and the diagnosis of restless leg syndrome including some medical and non-medical treatments.

By Glenn Kotz, MD

Member AMSSM
 

One 55 year old competitive male master’s athlete in our practice presented for years complaining of nighttime muscle cramps, with a standard work-up being unrevealing. We tried stretching, hydrating, adding electrolytes, and changing training schedules, but nothing helped. Last year he was asked to describe his symptoms in more detail. He said his legs felt very uncomfortable, at times painful, at times like an electric current ran through his legs whenever he was resting. This would occur at work or in bed. He would have to get up and move around or stretch to relieve the pain. Frequently, in the middle of the night, he would experience these leg sensations and need to get out of bed and stretch or do some simple exercises to relieve the pain.

Muscle cramps – part of every athlete’s life – are involuntary, painful muscle contractions that are only relieved with stretching. The likelihood of developing muscle cramps varies from individual to individual. Some risk factors for muscle cramps include exercise beyond what is accustomed (either higher intensity or longer duration), old age, high body weight, family history of muscle cramps, and inadequate stretching (Schwellnus, 2003). Dehydration and electrolyte deficiencies such as calcium, potassium, sodium, magnesium and zinc have not been consistently shown to increase risk for cramping.

The causes of muscle cramps

The ultimate cause of muscle cramps is unknown, but a current accepted theory is muscle fatigue. Muscles have nerves that can either stimulate or inhibit muscle contractions. The signals that inhibit muscle contractions are just as important to performance and injury prevention as the signals that activate them. When muscles fatigue, the inhibitory signals protect the muscles from muscle strain injuries by blocking ongoing contractions.

It is believed that in some individuals, this inhibitory signal either weakens or is overcome by contraction-promoting signals, leading to muscle cramps from excessive continuous contractions (Schwellnus, 2003). The mechanism to revive the inhibitory signal is stretching of the muscle receptors, either during or after the activity. It has been shown that some individuals can prevent nighttime muscle cramps with a thorough stretching routine before sleep.

Restless leg syndrome

This theory of nocturnal or evening muscle cramps does not fit the majority of individuals with rest or sleep-related muscle discomfort. Restless leg syndrome is different than nocturnal muscle cramps, and is much more common. It is estimated that 3-15% of the population (or about 15 million people) suffer with restless leg syndrome (Allen, 2005). Restless leg syndrome was first described in Europe in 1945, but it was not until 1999 when the first clinical guidelines were published by the American Academy of Sleep Medicine (Hening, 1999).

People with restless leg syndrome will describe symptoms such as “creepy, crawly legs,” or complain of sensations that feel as if there is an electrical current running down the leg. They may complain of these sensations starting before bed, or during periods of prolonged sitting, such as in a chair watching television, or when flying in a plane. Once the individual gets up and moves around, the sensation will resolve for a period of time. This will frequently result in fatigue during the day because of recurrent awakenings during sleep. Restless leg syndrome frequently starts early in life and progresses with age. It is common for mild intermittent symptoms to begin in the third decade, and to progress in frequency as a patient approaches his/her fifties.

Table 1: The diagnostic criteria for restless leg syndrome (Allen, 2003)

Generally, restless leg syndrome is diagnosed based on history alone, and is idiopathic (no known cause). There are a few secondary causes for restless legs – pregnancy, end stage renal failure, neuropathy, rheumatoid arthritis, varicose veins, and iron deficiency (Allen, 2003 and Paulson, 2000). Iron deficiency is a very common problem with endurance athletes, and low ferritin levels have been associated with decreased performance. For restless leg syndrome, ferritin levels in the low normal range of < 50 mcg per L have been associated with more severe symptoms (Allen, 2003).

To combat both restless leg syndrome and the risk of developing a relative anemia, I generally recommend endurance athletes to maintain a minimum ferritin of 35 mcg per L with a target ferritin of > 50 mcg per Liter. Iron supplementation, especially in males, should be monitored by a physician to avoid the risk of hemochromatosis, or iron overload. There are a number of medications that may aggravate restless leg syndrome, including antihistamines, some nausea medications, some anti-hypertensives (calcium channel blockers), and many antidepressants (Paulson, 2000, Thorpy, 2005, and Silber, 2004). Lifestyle may contribute to severity of the syndrome with a greater risk of symptoms being associated with high alcohol or caffeine intake and tobacco use.

Non-medical intervention

For patients with mild or intermittent symptoms, we recommend an initial trial of non-medicinal interventions:

1. Abstinence from alcohol, caffeine or medications that may worsen or precipitate restless leg syndrome (Silber, 2004).

2. Engrossing mental activities during rest times to preoccupy the mind (Paulson, 2000 and Silber, 2004).

3. Good sleep hygiene, including:
   • Going to sleep and waking at the same time every day.
   • Maintaining the bedroom temperature five degrees cooler then the rest of the house.
   • Exercising during the daytime, with reduced activity for at least two hours before bed. Light activities such as walking are acceptable.
   • Using the bedroom for sleep and sex only.
   • Consuming no food or alcohol within 2 hours of going to sleep.

Medications

If lifestyle modification does not work, or if symptoms are more severe, there are a number of medications that may be beneficial. The different classes of medicines available for this problem include dopaminergic agents, sedative-hypnotic agents, anticonvulsants, and opioids. If symptoms are intermittent (< 2 times / week) one may find benefit from any class. The opioids and benzodiazepines work as sedatives, improving sleep quality. Major side effects of benzodiazepines include over-sedation, constipation, and tolerance to the medication.

The first FDA approved treatment specifically for restless leg syndrome was released in 2005. Ropinirole stimulates dopamine receptors in the brain, and is very effective with less frequent side effects. Those side effects that do occur include fluid retention, nasal congestion, sedation, and, on rare occasions, aggravation of the problem. This worsening of symptoms can occur with many of these medications, and will usually stop with discontinuation.

Not all cramping is training-related. If you have a long-standing history of nocturnal muscle cramping, discuss your concerns with your physician.

Glenn Kotz, MD

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date: May 21, 2007