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.
What Increases Your Risk. Most people get HIV by having unprotected sex with someone who has HIV. Another common way of getting the virus is by sharing needles with someone who is infected with HIV when injecting drugs. You have an increased risk of becoming infected with HIV through sexual contact if you: 1  Have unprotected sex (do not use condoms). 2  Have multiple sex partners. 3  Are a man who has sex with other men.  Have high-risk partner(s) (partner has multiple sex partners, is a man who has sex with other men, or injects drugs).
1 The presence of STDs in an HIV infected person can increase the risk of HIV transmission. This can be through a genital ulcer which could bleed or through genital discharge.  An HIV negative person who has an STD can be at increased risk of becoming infected with HIV through sex. This can happen if the STD causes breaks in the skin (e.g. syphilis or herpes), or if it stimulates an immune response in the genital area (e.g. chlamydia or gonorrhoea).