Stretching and strengthening exercises help new military recruits avoid knee pain from hard training, UK researchers have found.

Nearly a quarter of physically active people suffer from so-called anterior knee pain, researchers say, making it the most common knee problem. It’s also the main reason new British soldiers drop out of the Army.

To find out if the problem could be prevented, researchers from the Defense Medical Rehabilitation Center in Surrey followed more than 1,500 recruits during a grueling 14-week training program.

Half were told to do eight different types of exercise during every training session, focusing on strengthening their leg muscles and making them more flexible by stretching.

The other half did standard military warm-up and cool-down exercises.

According to the researchers, their work is the first rigorous study to examine whether preventive exercises can slash knee injuries.

With traditional warm-up, nearly 5 percent of the soldiers developed knee pain. That number dropped to just more than 1 percent among those who did the special exercises - a 75-percent decrease.

“Our study shows that a simple set of targeted exercises was effective in producing large reductions in the risk” of anterior knee injury, the researchers write in the American Journal of Sports Medicine.

Only three recruits who did the new exercises ended up getting discharged as “unfit for army service,” compared to 25 of those who didn’t.

It’s still not clear if the findings will hold up in the general population, the researchers note, not least because people outside of the Army are less likely to follow a strict exercise routine.

But in the Army, introducing targeted work outs could lower drop-out and injury rates, potentially saving money as well, the authors conclude.

SOURCE:  American Journal of Sports Medicine, online January 6, 2011.