See a video of an exercise bike program.
Recent research also suggests that short intense intervals on a bike of one minute with a one minute recovery can significantly improve cardiovascular fitness and also lower blood sugar in patients with Type 2 Diabetes. Below is an excerpt from a recently published NY Times article about the subject:
"Several years ago, the McMasters scientists did test a punishing workout, known as high-intensity interval training, or HIIT, that involved 30 seconds of all-out effort at 100 percent of a person’s maximum heart rate. After six weeks, these lacerating HIIT sessions produced similar physiological changesin the leg muscles of young men as multiple, hour-long sessions per week of steady cycling, even though the HIIT workouts involved about 90 percent less exercise time.
Recognizing, however, that few of us willingly can or will practice such straining all-out effort, the researchers also developed a gentler but still chronologically abbreviated form of HIIT. This modified routine involved one minute of strenuous effort, at about 90 percent of a person’s maximum heart rate (which most of us can estimate, very roughly, by subtracting our age from 220), followed by one minute of easy recovery. The effort and recovery are repeated 10 times, for a total of 20 minutes." Read the full article here.
I think the point is clear. Almost anyone can begin with one minute intervals. The data suggests that if you can build on that, your heart and blood sugar will improve in addition to strengthening your knees. Not a bad suggestion for all of us.