If you’re concerned about properly using a treadmill, look to your hands the next time you’re on the machine. Are you holding onto the handrails so hard that your knuckles are turning white? It may be a sign to slow down your pace, since you could be forcing your body into an uncomfortable position, potentially straining your muscles.
A death grip on cardio machines like treadmills and stair-climbers also burns fewer calories because, “your legs don’t have to work as hard when you lean on the machine,” says a trainer for the Life Fitness Academy, in Myrtle Beach, South Carolina.
To ensure proper form, you should be able to stand tall on a treadmill and pump your arms. If you feel you need to hold on to other cardio machines, as long as you’re maintaining good posture—centered body, head up, relaxed shoulders—you should be okay.
Prefer to walk outside? Check out our list for the best walks in the United States’ most walkable cities.