Some people look at electric bicycles as being simply a "lazy" alternative to conventional bikes, providing the rider with less of a workout. Proponents of e-bikes, however, point out that they may open bicycle-commuting up to people who would otherwise never bother with it, thus providing them with more exercise overall. A new study confirms that in such cases, use of an e-bike does indeed still boost the user's fitness level.
Conducted by scientists at the University of Colorado Boulder, the study focused on 20 volunteers who got little regular exercise, and who ordinarily commuted by car.
For a period of one month, they were instructed to instead commute using an electric-assist bike at least three days a week, for a minimum of 40 minutes per day. They wore a heart rate monitor and GPS unit while cycling, and were free to set their own speed and level of intensity. According to the GPS data, the participants' average speed was 12.5 mph (20 km/h).
Once the four-week period was over, all of the volunteers had their health tested in a lab. When compared to readings taken before they started riding, it was found that their cardiovascular health had improved significantly – more specifically, they saw increased aerobic capacity and improved blood sugar control.
A paper on the research was recently published in the European Journal of Applied Physiology.
Source: University of Colorado Boulder
Additionally, I would bet that commuting by motorcycle is better for you than by car. In the car, you are sitting just as you would on a couch, where as on a motorcycle, you have to hold your self up (more muscle activity), and you are forced to be more mentally alert to stay out of trouble. I can attest to this myself when I used to drive my CBR600 or even the 150cc scooter in to work (before my e-bike).