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.
Most people diagnosed with HIV in the UK acquire HIV through unprotected vaginal and anal sex. It's also possible to catch HIV through unprotected oral sex, but the risk is much lower. The risk is higher if: the person giving oral sex has mouth ulcers, sores or bleeding gums.