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 2010, African Americans represented 17% of teenagers and 16% of people aged 20â24 in the overall population, but accounted for 57% of new HIV infections among those aged 13â24. Young men who have sex with men (MSM), especially those of color, have the highest risk of HIV infection among young people. Among youth aged 13-24 diagnosed with HIV in 2014, 80% were gay and other MSM. Of those, 55% were black, 23% were Hispanic/Latino, and 16% were white. Adolescent females are also at risk.