After a grueling CrossFit workout on a hot Summer morning that involved kettlebell swings, goblet squats, and about 100 walking lunges, my lower body was toast. But what was weird was that my left glute started twitching that night and continued into the next day. It didn’t hurt at all, but it was annoying! Has your muscle twitched after working out? Here’s what you need to know.
What Causes a Muscle Twitch?
A muscle twitch, or sometimes referred to as a fasciculation, is a short, involuntary, unpainful contraction of skeletal muscle that may happen repeatedly, explained orthopedic surgeon Anthony Kouri, MD. Your muscle fibers are controlled by your nerves, and when a nerve fires, it causes movement in the muscle, making it twitch. Muscle twitches can be caused by several factors, and commonly occur after exercise, during periods of stress, when we are sleep deprived, when we consume too much caffeine or other stimulants, or when we’re dehydrated.
Why Does My Muscle Twitch After a Workout?
“A muscle twitch often occurs after a hard workout because the muscle has been overworked and there is hyper-excitability of the nerve on the muscle that has broken down from the exercise, and therefore it acts on its own accord,” explained Naresh Rao, DO, a sports medicine specialist and head physician for the USA Men’s Water Polo Team. If you can see the muscle twitch, it is called a fasciculation. If you can’t see the muscle twitch, it is called fibrillation. If it is painful, or more prolonged, then that is a muscle spasm.
Dr. Kouri explained that when we exercise, our muscle fibers become fatigued and we often develop a small imbalance of electrolytes from excessive sweating. Either one of those factors can cause muscle twitching. “A critical electrolyte related to muscle twitches is calcium,” said Dr. Kouri, and another is magnesium. Low levels of either mineral can disrupt normal muscle function, leading to twitching. A vitamin D deficiency can also cause muscle twitching, as it’s needed to help the body absorb calcium.
Although “electrolyte imbalance and muscle fatigue are the most common causes of muscle twitches,” said Dr. Kouri, “dehydration, from any cause, is a common culprit. The majority of muscle weight is water, and any dehydration can also lead to misfiring of muscle fibers.”