This study randomized healthy sedentary people age 20-80 years to 16 weeks of supervised exercise versus no exercise. Several end points were evaluated after 16 weeks including insulin sensitivity and muscle physiology.

Healthy subjects performing < 30 min exercise twice per week were studied prior to randomization and after of sixteen weeks exercise. They were randomized to sixteen weeks of supervised exercise performed on a stationary bike vs. placebo exercise (a series of flexibility exercises performed at home). Intensity, duration and frequency of exercise were gradually increased to four sessions per week lasting forty minutes each and achieving 80% target heart rate. Participants were weighed perioidically and counseled appropriately when weight changed by > 2 %. Insulin sensitivity and muscle mitochondrial protein synthesis were studied.

Healthy subjects performing < 30 min exercise twice per week. Age 20-90 years. Willing to be randomized to exercise versus no exercise. Willing to be studied in General Clinical Research Center with studies including Muscle Biopsy.