1 Isotonic -a muscle fiber contraction in which force production is unchanged when the muscle contracts causing movement of an external load.  Isokinetic -a muscle fiber contraction in which force production of the contraction is sufficient to overcome the external load.
HIV/AIDS. HIV Risk Behaviors. The risk of getting HIV varies widely depending on the type of exposure or behavior (such as sharing needles or having sex without a condom). Some exposures to HIV carry a much higher risk of transmission than other exposures.
In the United States, HIV is mainly spread by having sex with someone who has HIV. There are several steps you can take to reduce your risk of getting HIV through sexual contact, and the more of these actions you take, the safer you can be. These actions include: 1  Choose less risky sexual behaviors. Your risk of HIV infection increases if you or your partner also has an STD. 2  You can lower your risk of getting HIV and other STDs by always using a new condom. 3  Oral or hormonal contraceptives (e.g., birth control pills) do not protect women against HIV or other STDs.