Walking is good for your health, but moderate to vigorous exercise boosts fitness three times as much, new research finds

A recent study found that "bouts of moderate to vigorous exercise … drastically improves a person's fitness, compared to milder forms of exercise," says the study report from Boston University.

The results may seem obvious, but according to lead researcher Dr. Matthew Nayor, the study of about 2,000 participants from Framingham, Mass., answers some lingering questions, such as how rigorously should a person work out to improve fitness or whether going to the gym can cancel out hours spent sitting at a desk.

The actual links between physical activity and fitness level are not very well understood, Nayor says, and the "study was designed to address this gap, but we also were interested in answering several specific questions." For example, the study found that sedentary time didn't affect fitness levels if the person achieved a higher-than-average daily step count or performed some moderate-to-vigorous physical activity. On top of that, activities with higher exertion improved both the participants' peak exercise performance and their ability to start and sustain lower-exertion activities better than simply walking.

However, Nayor adds that higher step counts are still "associated with higher fitness levels," a fact that is reassuring for older people or those with medical conditions that may prohibit high exertion. Still, if your goal is to become more fit or slow the decline in your fitness as you age, "performing at least a moderate level of exertion [through intentional exercise] is over three times more efficient than just walking" at a casual speed.