Understanding the Causes of Muscle Cramps and Spasms

You’re in the middle of a workout or just lying in bed and suddenly your calf seizes up in a sharp, painful spasm. Muscle cramps and spasms can happen to anyone, regardless of fitness level, and while usually harmless, they’re often incredibly uncomfortable.

Understanding why they happen can help you avoid them in the future. Here's what science knows so far.

What Is a Muscle Cramp?

A muscle cramp or spasm is an involuntary contraction of a muscle that doesn't relax on its own. These contractions can range from a subtle twitch to a severe, rock-hard spasm that lasts several minutes.

Commonly affected muscle groups include:

• Calves (gastrocnemius)

• Thighs (hamstrings and quadriceps)

• Feet and hands

• Abdomen and arms

Cramps often occur during or after physical activity, but they can also strike during rest or even sleep. Some cramps are so intense they can leave bruising or tenderness afterward.

What Causes Muscle Cramps?

While the exact cause remains unclear, researchers have narrowed it down to several likely factors:

• Muscle fatigue

• Dehydration

• Electrolyte imbalance (low sodium, potassium, magnesium, or calcium)

• Overexertion during new or intense activities

• Poor conditioning or lack of stretching

• Exercise in extreme heat

Interestingly, more recent studies point to something called “altered neuromuscular control” as a primary cause especially for exercise-related cramps.

What Is Altered Neuromuscular Control?

This theory suggests that muscle fatigue leads to disrupted communication between nerves and muscles. Essentially, the nerves misfire, causing a muscle to contract when it shouldn't. It may explain why cramps are more common:

• At the end of workouts

• After long periods of exertion

• During the preseason, when athletes may not be fully conditioned

A 2018 review found stronger support for this theory than for the more traditional views involving hydration and electrolytes, although those can still play a role.

How to Treat and Prevent Muscle Cramps

In most cases, cramps go away on their own, but the pain can linger or come back. While there's no one-size-fits-all fix, these tips are often recommended:

• Stop the activity that triggered the cramp

• Gently stretch and massage the muscle

• Hold the joint in a stretched position until the muscle relaxes

• Hydrate before and after activity, especially in hot weather

• Improve conditioning to reduce muscle fatigue

Targeted Stretching Tips:

• Calf: Stand in a lunge position with your back leg straight and heel pressed down.

• Hamstring: Sit on the floor with one leg straight and one bent inward. Lean forward toward the straight leg.

• Quadriceps: While standing, grab the top of your foot behind you and gently pull your heel toward your glutes.

Stretching before and after physical activity can help prevent cramps, especially in the legs, which are among the most commonly affected areas.

When to See a Healthcare Provider

Most muscle cramps are not serious and don’t require medical intervention. However, consult your provider if your cramps are:

• Frequent or severe

• Accompanied by swelling or weakness

• Occur with no clear trigger

• Interfere with sleep, daily activity, or mobility

In rare cases, persistent muscle cramps may be linked to underlying conditions like nerve compression, metabolic disorders, or medication side effects.

The Takeaway

Muscle spasms and cramps are common, but still not fully understood. Most evidence suggests that muscle fatigue and neuromuscular miscommunication play a bigger role than dehydration alone.

To reduce your risk, stretch regularly, stay hydrated, and build a fitness routine that improves strength and flexibility. And if cramps become more than just an occasional annoyance, check in with a medical professional.

Israel is advancing research into neuromuscular health and athletic performance, offering innovative insights into how we move, train, and recover.

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