LOS ANGELES — Middle-aged men and women are having a tougher time moving around, according to a new study that saw a boost in mobility-related problems among people 50 to 64 years old.

The study, published in the April issue of the journal Health Affairs, looked at mobility-related disability trends among those taking part in the 1997-2007 National Health Interview Survey, a nationally representative study. The participants were asked if they had difficulty with nine particular physical functions, if they had a health problem requiring the use of equipment such as a cane or wheelchair, and what health conditions might be responsible for their limitations. Overall, the number of people ages 50 to 64 who need help with personal care activities is less than 2 percent.

The number of people reporting difficulty with physical functions didn't change much, but difficulty with certain functions saw an uptick over the 11 years: stooping, bending and kneeling; standing for two hours; walking a quarter mile; and climbing 10 steps without resting. More than 40 percent of people surveyed said that due to a health problem they had trouble with at least one of nine physical functions, without using any equipment.

The researchers, from the University of Michigan and the RAND Corp., also saw an increase in people needing help with personal care endeavors such as getting in and out of bed or moving around in their homes.

From 2005 to 2007, the most common reasons for needing help were arthritis; rheumatism; back or neck problems; diabetes; and depression, anxiety or emotional problems.