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.
1 Anal sex is the highest-risk sexual activity for HIV transmission. 2  If you are HIV-positive, receptive anal sex (âbottomingâ) is less risky for transmitting HIV than insertive anal sex. 3  To learn more, see Lower Your Sexual Risk of HIV. 4  Get tested and treated for STDs and encourage your partners to do the same.