Participants will be 60-80 y men and women who vary their physical activity (steps/day) while their lipid metabolism is studied (n=24). Thereafter, another group (n=60) will perform 6 months of exercise training focused on developing maximal cycling power, during which their changes in muscle mass and practical function will be carefully measured.

In a society that is growing in the number of older adults who are also becoming more sedentary, it is critical to identify the types of exercise that harness significant health benefits. First, we hypothesize that older adults (60-80 y) need a certain background level of physical activity, judged by number of steps per day. This is important, especially to fat metabolism. Secondly, because older adults claim they don't have time to exercise, we have developed a time efficient program (10 min/day) that has shown promise for offsetting sarcopenia and significantly improving cardiovascular function.

Our Aim 1 is to determine the range of daily step counts in older adults (60-80 y; n=24) that is needed to prevent acute impairment of post-prandial fat metabolism, measured the morning after exercise. We have recently shown in young adults that when their level of background physical activity drops below the range of 5,000 - 8,500±500 steps/d, that they don't adapt positively to an acute 1 h bout of exercise (i.e.; 'exercise resistance') that normally improves fat metabolism.

Our Aim 2 is to determine the ability of a time-efficient 24-week program of exercise training for both maximal neuromuscular power and aerobic power to counteract sarcopenia and declines in aerobic power and functional tests in men and women 60-80 y. We have recently found in a preliminary study of older men and women (50-70 y) that performing multiple maximal 4 s sprints of rapid acceleration cycling bouts for only 8 weeks, eliciting maximal power, displayed significant (p<0.05) increases in muscle thigh volume (MRI), whole body muscle mass, maximal neuromuscular power and peak oxygen consumption. We now propose to train older men and women (i.e.; 60-80 y; n=60) for longer durations (i.e.; 24 weeks) and describe the time course of adaptations. We will additionally monitor their background levels of daily physical activity and determine if it correlates with improvements in neuromuscular and cardiovascular function.

Inclusion Criteria:

• relatively healthy

Exclusion Criteria:

• relatively unhealthy