It's not uncommon for illness or periods of hospitalization to keep older adults from physical activity. But being bed-ridden can have an especially bad effect on seniors' health, raising the risk of type 2 diabetes and other metabolic issues.

Whether you are young or old, bed rest or limb immobilization decreases your ability to regulate blood sugar. Within days of muscle disuse both younger and older people also show decreased muscle mass and strength. The difference is that older people do not recover as quickly from these inactive periods as those who are younger do, so they are at greater risk for health problems.

Since their metabolisms don't rebound the way they used to, older adults should consider rehabilitation programs, dietary changes or medication to help recover their health and prevent further decline during periods of activity.

A study looked at what happens when seniors who have been sedentary for a period of time return to regular levels of physical activity. It found that even a short period of inactivity can have serious long-term consequences for older adults, and it concluded that older people need to be especially proactive about returning to activity and regaining their ability to regulate their blood sugar following a period of inactivity.

Twenty-two overweight, prediabetic men and women between the ages of 65 and 79 were enrolled in the study. Researchers measured participants’ usual level of physical activity for a baseline period of one week and then asked participants to reduce their step count to no more than 1,000 steps per day, the equivalent of being house-bound or hospitalized, for two weeks. Participants then had a two-week recovery period, during which their step count returned to usual levels.

When their step count decreased, participants’ insulin resistance increased and insulin sensitivity decreased and did not return to normal levels even when their activity increased. Their blood glucose levels also increased when step count decreased, and did not return to baseline levels during recovery. And muscle protein synthesis decreased during the period of inactivity, and did not return to baseline during recovery.

“We expected to find that study participants would become diabetic, but we were surprised to see they didn’t revert back to their healthier state when they returned to normal activity,” Chris McGlory, the lead author, said in a statement.

To counteract the fact that their metabolisms don't rebound the way they used to, older adults should consider rehabilitation programs, dietary changes or medication to help recover their health and prevent further decline during periods of activity. Future studies could focus on developing and fine tuning these strategies, according to the authors.

The study is published in The Journals of Gerontology Series A.