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.
Regardless of whether a young person takes drugs, unsafe sex increases a person's risk of getting HIV. But drugs and alcohol can increase the chances of unsafe behavior by affecting how a person makes decisions. For the latest HIV/AIDS statistics by age, visit the Centers for Disease Control and Prevention website.