Resistance training: The maximal weight that can be lifted with correct form in a single repetition (1RM) will be used to prescribe intensity. Strength testing will be repeated every 4 wks and the training loads adjusted so that they are consistent with the 70% 1RM goal. Participants will exercise 3 d/wk on Nautilus resistance machines, under the supervision of two exercise leaders who are trained in basic life support and in emergency management procedures. All exercise will take place at Wake Forest University's Department of Health and Exercise Science Clinical Research Center (CRC). Participants will exercise in small groups which will allow a rotation/rest between machines and enhance the social environment. Heart rate and blood pressure will be measured before and after each session. Subjects will warm-up by walking or cycling for 5 minutes at a slow pace followed by large muscle flexibility exercises. The interventionists will ensure that participants adjust the equipment appropriate to their body size and complete the exercises with correct form. Training sessions will end with a cool-down by walking or cycling for 5 minutes at a slow pace followed by light stretching.