Need another reason to exercise? New research from Tel Aviv University has found that "endurance exercises," such as a jogging or a spinning class, can make us look younger. The reason: exercise unlocks the stem cells of our muscles.

In a December 1 news release, Prof. Dafna Benayahu and her team at Tel Aviv University's Sackler School of Medicine say their findings explain for the first time why older people who have exercised throughout their lives age more gracefully. They have discovered how endurance exercise increases the number of muscle stem cells and enhances their ability to rejuvenate old muscles. The researchers hope their finding can lead to a new drug to help the elderly and immobilized heal their muscles faster.

"When we age, we experience sarcopenia, a decline in mass and function of muscles, and osteopenia referrers to bone loss," Benayahu said in the release. As a result, our musculoskeletal system is more susceptible to daily wear and tear, which also explains the increased risk of falling in the elderly.

In a rat study, the researchers discovered that exercise increased the number of satellite cells (muscle stem cells) - a number which normally declines with aging. Comparing the performance of rats of different ages and sexes, they found that the number of satellite cells increased after rats ran on a treadmill for 20 minutes a day for a 13-week period. The younger rats showed a 20 to 35 percent increase in the average number of stem cells per muscle fiber retained - and older rats benefited even more significantly, exhibiting a 33 to 47 percent increase in stem cells.

The results of the study were recently published here in the journal PLoS ONE.