June Furlan was alarmed when a mystery weakness started taking over her body, so her personal trainer suggested doing “dead bugs” to strengthen her core. She was already an avid gym goer, doing cardio and weight training several times a week. But Furlan suddenly found herself lacking energy and having trouble getting up.

— which target abs, obliques and spinal muscles — were meant to help. The bodyweight exercise involves lying on the back, then raising and lowering the opposite arm and leg. The funny name has earned it a , but Furlan felt the exercise working and regularly did three sets of 15.

But one day in the summer of 2022, she found she was too weak to lift her legs during her dead bugs. “I was proud that I could do them because they weren’t easy for me to do. And finally, I’ve mastered this exercise, and I could no longer do them.

I almost cried at that point,” Furlan, 71, who lives in Arlington Heights, Illinois, tells TODAY.com. “I became weaker and weaker and weaker.

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It was scary.” Soon, she could no longer go up the stairs in her split-level house or roll over in bed. Her husband had to help her to brush her hair and put clothes on.

Frightened, Furlan went to the doctor. A test revealed her level of creatine phosphokinase — an enzyme released into the blood when muscles are damaged — was 50 times normal. It indicated a serious problem.

Furlan was diagnosed with , inflammation of the muscles due to injury, infection or an autoimmune dise.