Your glutes and quads are more engaged when you’re on an uphill than they are on a flat road, says Michael Olzinski, a Precision Run coach at Equinox locations in San Francisco.
But if you use your hands to grip the treadmill and lean back, those muscles don’t have to do as much legwork. Plus, he says, it shifts your weight onto your lumbar spine, which compresses the disks and increases the impact on your low back and pelvis—a recipe for injury down the line.
The bottom line:
If you can’t manage the speed and incline hands-free, you need to go slower or flatter. You should feel like you’re power-walking with strong, natural arm drive and follow-through in the back leg, Olzinski says. Up the incline gradually and if you max out at 12 percent, wear a weight vest to increase the demand on the heart, hips, and glutes, he suggests.