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.
But sexual partners are usually infected by virus in sexual fluids, such as semen or vaginal or anal secretions. Unfortunately, the viral load in these fluids can be high even when the viral load in blood is low. And factors like STDs (sexually transmitted infections) can increase the risk of HIV transmission.