My last blog was about some anti-runners who recommended a grueling, once per week, 12 minute routine in which you do extreme resistance (weights or machine) exercise to the point your muscles fail. Half their book was a dire warning that running will debilitate or kill you.
Then I got an email from Al Sears, MD, who promotes a copyrighted program called PACEBOOK (I bought a copy and found some good stuff) that recommends short, intense, progressive interval training, which can be sprinting, biking, swimming, lifting, jump roping, etc. Like his book, his email had more dire warnings about jogging/running. Check out: http://www.alsearsmd.com/jogging-injuries.html
So I cringed when I picked up the the August issue of Trail Runner magazine (in which you'll find a snatch of poetry about running in mud they printed from my April 2009 blog) to see an article entitled "The Fabulous 4 (Minutes) - The Short - Intense - Workout That Delivers." It is about a system developed Izumi Tabata, at a Japanese sports institute in the early 90s, that involves sprinting as hard as you can for 20 seconds, then resting 10 seconds, then sprinting again. You do this eight times. Tabata discovered that this painful regimen can confer tremendous improvements in aerobic and anaerobic capacity. (I'd be wary of any regimen developed in Japan because, even today, it will be influenced by medieval samurai culture, which places a high value on suffering.)
I think there are great benefits to be gained from interval training. I do sprints once or twice a week. But it should be noted that the only injury I've had this year was a pull in the lower left Achilles tendon that occurred when -- sprinting! The anti-runners always offer scientific studies to support their attacks on jogging/running, however, often these studies are flawed or incomplete. If you want to read a good blog, with solid scientific thinking, that questions these broad claims for interval training over running, go to http://frayedlaces.blogspot.com/2009_06_01_archive.html.
If you haven't done intervals in a long time, start very slowly and build up. There is no hurry to get to "fitness." The journey itself is the goal. Start with the slow gentle approach to interval training recommended by Covert Bailey.
A TOJ knows that all physical activities come with some risk of injury. So what? To a TOJ, the real problem with the 4 minute this and 12 minute that is he or she enjoys exercising too much to be subject to time limits. Life's too short as it is.