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.
Physical factors contributing to sexual problems include: Drugs, such as alcohol, nicotine, narcotic analgesics, stimulants, antihypertensives (medicines that lower blood pressure), antihistamines, and some psychotherapeutic drugs (drugs that treat psychological problems such as depression )