Bobbie Walters was 31 years old when she started running. She was living in Miami at the time and her sister, who lived in in a different state, was about to have a baby. "Our mum called me with the news that my sister was in labour and I was so excited, nervous and overwhelmed, I didn't know what to do," she says. “So I went for a run.” This was something she literally had never done before.

The next day, Walters had a new nephew—and a new hobby. "I felt so wonderful after that first run, I woke up and ran a few kilometres the next day," she said. Walters, now 70, has run 6 kms every morning ever since. And while she says in many ways her runs feel the same as always, there have also been some changes as she ran her way through her 40s, 50s, and 60s.

Orthopedic surgeon Dr Khaled J. Saleh says this is common, and something people shouldn't ignore. "Knowing how your running might change as you get older can help you prevent injury and even maintain peak performance," Saleh says.

Here, Saleh and Walters share some of the ways running changes—as well as how it stays the same—after 40: