NEW YORK (CBSNewYork) – With summer fast approaching, many people are hitting the gym to get beach ready.

Expecting to be a little sore after a workout can mask dangerous cases of overdoing it, damaging muscles and leading to a potentially deadly illness.

Jared Shamburger, 17, is one such muscle damage patient who has just started a new gym membership with his family, reports CBS2’s Dr. Max Gomez.

“It was super-duper sore,” he said. “Everything hurt. It hurt to the touch. It was swollen.”

As his dad and older brother has been lifting weights for years, Jared was eager to ramp up his fitness performance.

“I gotta catch up to them, I have to get as big as them,” he said. “I have to go hard fast.”

After an intense arm workout last week, the soreness wasn’t going away and there was a lot of swelling.

“The farthest I could move was like to here,” said Jared, trying to lift his arm. “I was like, this is not right.”

Jared’s mom searched the symptoms online and came to her own diagnosis.

“The mama bear in me kind of took over and I called the pediatrician and said, I really think my son has rhabdo,” said Judy Shamburger, Jared’s mother.

She was right:”rhabdo” is short for rhabdomyolysis, a serious condition caused by direct or indirect muscle injury. It can be caused by anything that damages muscle tissue: trauma, infection or even hitting the gym too hard.

Jared was hospitalized for five days because the rhabdo caused a breakdown of his muscle fibers, releasing a damaging protein into the blood, damaging his kidneys.

“In extreme cases it can also cause death,” said Jared.

Jared is expected to make a full recovery, and he plans to get back in the gym soon, but his family hopes others will be aware that muscle pain, weakness and severe swelling after intense exercise may warrant a trip to the doctor.

“If he hadn’t told me… I don’t want to think about what could have happened,” said Judy Shamburger.

It’s not just weightlifting that can lead to rhabdo as it’s also been seen in runners, cyclists and spinning.

Muscle soreness isn’t always present with rhabdo. The telltale sign to watch for is very dark, red or tea-colored urine that signals potential kidney damage.

At that point, the patient needs medical attention immediately.