WASHINGTON, May 29 (Xinhua) -- Many wearable devices or mobile apps set the daily step goal at 10,000 but its origin is unclear. A study on older women showed that 7,500 steps could be enough.

The study published on Wednesday in the journal JAMA Internal Medicine showed that older women who took 4,400 steps per day had lower mortality than those taking 2,700 while risk of death continued to decrease with more steps up to 7,500 steps per day before leveling off.

Researchers from Brigham and Women's Hospital analyzed more than 16,000 women with an average age of 72. Participants were followed for an average of more than four years when they wore an accelerometer device on hips.

They found that participants in the bottom 25 percent of steps walked (average of 2,700 steps per day) were at greatest risk of death, with 275 women dying, and those who walked modestly more (average of 4,400 steps per day) were at 41 percent lower risk of death.

The death risk continued to drop with more steps walked, up to 7,500 steps per day, after which risk leveled off, according to the study.

Also, how fast or slow those women walked was not linked with risk of death.

The researchers cannot definitively separate between "do more steps lower mortality?" or "do women in better health step more?". But they tried to translate the correlation into cause-and-effect.

They excluded women with heart disease, cancer and diabetes and excluded the first year of follow-up data.

"We hope these findings provide encouragement for individuals for whom 10,000 steps a day may seem unattainable," said I-Min Lee, an epidemiologist at the Brigham and Women's Hospital.