Side effects of workout grow common

Studies show that high-intensity exercise offers myriad health benefits

Three years ago, Christina D’Ambrosio went to her first spin class, pedalling fast on a stationary bike to the rhythms of popular music as an instructor shouted motivation.

But D’Ambrosio, who exercises regularly, found the hour-long class was harder than she anticipated. By the end her legs were sore and wobbly. “I thought my body just wasn’t used to that kind of muscle ache because it was my first class,” said D’Ambrosio, a kindergarten teacher from Pleasantville, New York.

Over the next two days, her legs throbbed with excruciating pain, her urine turned a dark shade of brown, and she