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.
Risk Factors for HIV and Other Sexually Transmitted Diseases Among Adolescents in St. Petersburg, Russia. Context: Over the past several years, there have been sharp increases in the prevalence of HIV and other sexually transmitted diseases (STDs) among young people in Russia. Very little is known about Russian adolescents' behaviors and attitudes that might influence their risk of acquiring these infections.