You’ve been lifting weights for some time now, but suddenly your deltoid muscle has begun twitching after workouts.

This has never happened before.

What’s even scarier is if you have not changed your shoulder routine.

The twitching in your deltoid muscle does not occur during your training.

It happens only afterwards at rest. And the degree of twitching ranges from occasionally to relentless.

You may or may not be able to see the muscle moving under the skin.

But you sure as heck can feel it.

Deltoid Muscle Twitch: What Happens Next

• A strength training enthusiast notices that their deltoid has been twitching a lot lately, seemingly shortly after shoulder workouts.

• Sometimes it’s hours later on the same day or next day.

• The twitching subsides within a few days, often within 24 hours or less.

• But at some point, you googled something that brought up frightening search results: links to pages about a fatal disease called amyotrophic lateral sclerosis.

• You then learn that “muscle twitching” comes up in the symptom descriptor for this lethal disease – no matter what medical site you’re on.

• You put your hand to your deltoid muscle. You notice the twitching is back.

• You now can’t get to sleep because you’re scared out of your mind you have a terminal motor neuron disease.

• Next day you can’t stop visibly inspecting your deltoid, even though the twitching has stopped.

• It looks smaller than the other one; could this be atrophy from a degenerative neurological disease?

I just described a sequence of events that afflicts many fitness enthusiasts.

Cause of Deltoid Muscle Twitching

“It would be important to note if symptoms are improved with activity or associated with physical activity,” says Mitzi J. Williams, MD, clinical neurologist with Morehouse School of Medicine and clinical advisor for the Multiple Sclerosis Foundation.

“The symptoms may temporarily improve and then return once activity ceases.

“This is often more typical of benign etiology.”

To put this succinctly, a section of your deltoid has been buzzed by the weightlifting (e.g., overhead press, bench press, dumbbell press, lateral raise).

The fact that only your deltoid has been affected is not indicative of disease. It’s simply a hot spot for twitching (also called fasciculations).

Tipoffs that It’s Benign

• You have not noticed a weakening of the shoulder; you’re lifting at least the same amount of weight as you’ve always been.

• A big sign that it’s benign is that you’re making strength gains.

• The twitching disappears when you resume moving the shoulder such as when doing housework, jogging, walking, etc.

Dr. Williams also explains, “Benign fasciculations can be associated with muscle cramping or muscle pain. The fasciculations can also occur in different muscles with benign disease.”

When cramping or aching are associated with the twitching, this is called benign fasciculation syndrome. However, if you truly had this, it would not be local to just your shoulder.

Fatal Neurological Condition

“If someone has a motor neuron disease, such as ALS, the fasciculations become more widespread, weakness worsens and the muscle atrophies or shrinks in size,” says Dr. Williams.

Now wait – before you panic because the twitching in your deltoid has recently “spread” to other parts of your body – this is a very common phenomenon that’s driven by anxiety and fear!

The body wide spreading may occur over a matter of hours, even minutes, as anxiety mounts.

It’s part of the body’s fight or flight response – just like your heart pounds while you keep reading the ALS sites.

• Think of the spreading twitching like a bull pawing the ground before charging.

• The body’s neuromuscular system is gearing up for a fight or flight.

• There is a perceived threat: ALS.

• The body cannot tell the difference between an Internet user’s fear of having ALS and an ancient man’s fear of a lion coming at him.

• The motor neurons are revving up for the fight or flee.

Nevertheless, ALS does eventually spread body wide – but not over days, let alone hours and minutes!

“These symptoms progress — and also, people with motor neuron disease may have difficulty swallowing or speaking,” says Dr. Williams.

“EMG can help distinguish benign fasciculations vs. disease. EMG is usually normal [in a person with benign twitching] aside from the fasciculations.

“An EMG test uses small needles to examine the function of the muscles at rest and with movement.”

Massage your deltoid muscle. Stretch it. Focus on the amount of weight you’re lifting. Stop panicking.

Mitzi Williams, MD

Dr. Williams is author of “MS Made Simple: The Essential Guide to Understanding Your Multiple Sclerosis Diagnosis.” She is a member of the American Academy of Neurology.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  



Top image: Shutterstock/pickingpok