Here's a look at some of the top health news being talked about around the U.S. and the world today:

• It may help your body to work out regularly, but if you spend most of the rest of your time sitting down, you still have an increased risk of death compared to those who don't, according to new research. Reported on MSNBC, the findings suggest public health messages should focus more on increasing active hours throughout the day.

• A new gel that could block HIV infection could give women a tool in slowing the spread of the virus. It's likely the gel will be made available in South Africa first, where the rate of HIV is higher than other areas of the world and women often don't have the ability to ensure their partner uses a condom or remains faithful, the Philidelphia Inquirer reported.

• The top ways to prevent Alzheimer's disease might not be especially satisfying since researchers say they have no hard science to prove them - and they seem awfully similar to all those health recommendations given by doctors all the time anyway. But eating right, exercising and keeping your mind challenged at early and as much as possible are among the top recommendations, the Los Angeles Times reported.

Tina Reed covers health and the environment for AnnArbor.com. You can reach her at tinareed@annarbor.com, call her at 734-623-2535 or find her on Twitter @TreedinAA.