New York, Jan 10 (IANS) Older people suffering from arthritis can remain fit by engaging in 45 minutes of moderate physical activity such as brisk walking a week, says a study. According to US federal guidelines, achieving 150 minutes of moderate activity per week helps in preventing premature death and serious illness. However, only one in 10 older adults with arthritis meet these guidelines. The team from Northwestern University conducted a study on both men and women to determine that 45 minutes per week is the magic number for seniors. The researchers measured the physical activity of 1,600 adults who had pain, aching or stiffness in their hips, knees or feet. "We found the most effective type of activity to maintain or improve your function two years later was moderate activity, and it did not need to be done in sessions lasting 10 minutes or more, as recommended by federal guidelines," Dunlop concluded. Approximately, one third of participants improved or had high function after two years. But those participants who achieved the minimum of 45 minutes of moderate activity per week were 80 percent more likely to improve over two years compared with those doing less. "For older people suffering from arthritis who are minimally active, a 45-minute minimum might feel more realistic. Even a little activity is better than none," said Dorothy Dunlop, professor at Northwestern University's Feinberg School of Medicine. Achieving this less rigorous goal will promote the ability to function and may be a feasible starting point for older adults dealing with discomfort in their joints," Dunlop added in a paper which appeared in the journal Arthritis Care and Research.