What Causes Muscle Cramps? How Can I Prevent Them?

Muscle cramp
There are two main types of muscle cramps. If you can identify which one you are experiencing you may be able to stop cramping sooner and prevent future cramps.

Localized Muscle Cramping

Localized muscle cramps happen suddenly when a muscle is overworked and tired.

They feel like: constant pain.

Risk factors include: several factors may contribute to localized muscle cramping including: older age, history of cramping, metabolic disturbances, poor conditioning (or increasing the intensity of your training before you are ready) and not stretching. 

Treatment: for this type of cramping should include passive stretching, massage, active contraction of the antagonist or opposing muscle group (for instance, if your hamstrings are cramping, contract your quads), and icing.

Prevention:  Stretching (hold your stretch for at least 30 seconds), using proper movement patterns (biomechanics) and making sure you are conditioned before increasing the intensity of your training.

Exertional Heat Cramps

Exertional heat cramps are due to extensive sweating and low sodium levels from not consuming enough sodium and/or losing too much sodium through sweat.

They feel like: initially you may feel brief, spontaneous contractions that take time to develop followed by debilitating, widespread muscle spasms.

Risk factors include: high sweat rate, little sodium intake (especially if you lose a lot of sodium through sweat or over consume water or other no or low sodium drinks).

Treatment: replacing both fluid and sodium losses as soon as you start cramping. You can use an electrolyte replacement product or table salt! IVs are sometimes used to expedite this process. Massage and ice can also help relax the muscles and relieve discomfort.

Prevention: if you are a “salty sweater” – you see white salt crystals on your clothes, face or other parts of your body, be sure to salt your food prior to training and competing and consume enough sodium in your sports drink to prevent excessive sodium losses.

If you know what type of cramps you are prone to, you can better incorporate prevention methods and have treatment options readily available to stop cramping as soon as possible [ice, sports drinks, electrolyte products, table salt (restaurant salt packets in a ziplock bag always come in handy), a good athletic trainer nearby etc.].

As a review, here are your prevention strategies for cramping:

  • If you have a history of heat cramping, know that your cramps will likely reoccur at some point during training or competition.
  • Make sure you are conditioned before increasing the load or intensity of your training.
  • Incorporate stretching or hot yoga into your training regimen.
  • Give your body time to adjust to changes in elevation, heat and humidity.
  • Salt your food!
  • Do not over-consume water or any other low or no sodium beverage or you’ll dilute your blood sodium level and set yourself up for cramps.
  • Weigh yourself pre- and post- training. For each lb lost, consume 20 – 24 oz of an electrolyte-replacement drink.
  • Work with a sports dietitian or athletic trainer (ATC) to develop a hydration-electrolyte plan that specifically meets your needs. Sports drinks do not contain enough sodium for salty sweaters and those prone to exertional heat cramps.



Preventing Muscle Cramps

When a muscle contracts involuntarily and stays contracted, you end up with what’s commonly known as a muscle cramp.  If you’ve ever had to stop exercising because of a muscle cramp, you know how painful these can be.

The top sights for muscle cramps are the calf, hamstrings, thigh (quadriceps), feet, hands and arms. Four of the main causes of exercise related cramps include:

  1. The nerves that stimulate muscle become overstimulated
  2. Muscle fatigue
  3. Dehydration
  4. Electrolyte imbalance

So how can you prevent cramping?  First, warm up, stay warm (versus sitting in between bouts of physical activity, keep moving) and stretch after exercise. Try PNF stretching or yoga to achieve new levels of flexibility. Next, make sure you are trained for what you are doing – progressively increasing your workload by about 10% per week will decrease the likelihood of fatigue during exercise.

How much should you drink to stay hydrated? This varies tremendously between athletes based on sweat rate, heat acclimatization, body weight, clothing (more gear and more clothing = more fluid losses through sweat), age (older athletes and young kids are more likely to become dehydrated), conditioning level, heat, humidity and sport. General recommendations include:

  • 4 hours before exercise – consume 5-7 ml per kg body weight (13 – 17 fluid oz for a 160 lb person)
  • 2 hours prior to exercise – consume more fluid, especially if urine is dark in color and scant
  • Drink while exercising – about 3-8 oz of a sports drink every 10 – 20 minutes if exercising over 60-90 minutes (exercising intensely).

For those individuals walking or exercising lightly and aiming for weight loss versus performance, choose a zero calorie sports drink that contains electrolytes. That way, you’ll get the electrolytes you need to prevent hyponatremia and cramping without hampering your weight loss goals.

Also – weigh yourself before and after exercise. For every pound of sweat you lose, you should drink about 16 – 24 oz of fluid.

What about electrolytes? We lose the electrolytes sodium, chloride, potassium, calcium and magnesium in that order. So it makes sense to replace them in that order – i.e. choose a drink that contains mainly sodium  chloride as well as a little potassium and calcium (and possibly magnesium). Sports drinks generally have enough sodium for most athletes. However, some athletes are salty sweaters – you can see crystals of salt on their ears and face while they are exercising (or dogs happily run up and lick the salt off their legs when they are finished running). These athletes likely need more sodium and can get it by adding a product like SaltStick to their drinks (I recommend consulting with a sports nutritionist to add the right amount of sodium since the range is about 460-1150 mg per liter of fluid).