Many people in America need to spend more time exercising. But can anyone be exercising too much? The Department of Health and Human Services recommends that you lift weights twice a week and have either 150 minutes of moderate aerobic activity or 75 minutes of intense aerobic activity per week. As a general goal they recommend aiming for 30 minutes of exercise per day with a higher goal of 300 minutes per week.
According the the Department of Agriculture they recommend 30 minutes of exercise per day. However, their viewpoint conflicts because they say that certain people may need up to 90 minutes of exercise per day to keep from gaining weight.
On another hand, the Institute of Medicine recommended that we should all engage in 60 minutes of daily vigorous activity. Comparing this to the observation made by the Department of Health and Human services, they recommend almost six times as much vigorous exercise per week. I tried to evaluate the accuracy of these articles by looking at the sources in which they claim to be from. I think that because the first two articles agree on the 30 minutes of exercise per day mark you can rule out the Institute of Medicine's finding that claims we need 60 minutes of vigorous exercise per week.
Overall, I found no evidence claiming that you can exercise too much per week. The minimum amount you should exercise in one week if you want to be fit should be 30 minutes per day.