There is also great info on that very same site, about gene expression (a very different view/theory then what you hear about genes, that we get dealt bad genes and need to accept it) as well as GREAT information about cholesterol.
The site can be a little “heady” at times, but I urge everyone to take a good look at the wealth of information it offers.

A study (abstract here) published online in the American Journal of Physiology, Regulatory, Integrative & Comparative Physiology suggests that short but intense bouts of exercise can confer the same health benefits for the heart as longer, less-intense activities.

For the study, researchers from McMaster University in Ontario, Canada recruited 20 healthy but untrained individuals and assigned them to perform a six week series of either low-volume sprint interval training (SIT) or traditional high-volume endurance training (ET). Specifically, the SIT group performed between 4 and 6, 30-second “all-out” Wingate Sprint Tests separated by 4.5 min of recovery, 3 days per week. The ET group, meanwhile, completed 40-60 min of cycling at moderate intensity, 5 days per week.

After six weeks, both groups experienced equal improvement in the structure and function of heart vessels, specifically those that deliver blood to and from the heart and muscles.

Based on these findings, the researchers conclude that SIT is a “time-efficient strategy to elicit improvements in peripheral vascular structure and function that are comparable to ET.” They note that the findings underscore the value of brief, high-intensity forms of exercise and say that the data could be used to prove that even those with a limited amount of time can still benefit from exercise.

As we’ve discussed previously here at Mark’s Daily Apple, short, intense bursts of exercise aren’t just as good as long duration aerobic activities, they are better in many ways! In fact, our hunter-gatherer ancestors would have thought we were wasting resources (not to mention looking ridiculous!) if we took off on a moderately-paced jog around the plains for an hour a day! Today we strive to increase efficiency in every aspect of our lives – from eating on the go to multi-tasking on the job – so it seems almost comical that the one area where we have trouble condensing our time is in our exercise program (that is, of course, if you are someone who exercises to begin with).

Perhaps it started with Jack LaLanne who, at 93, still boasts 2 hour daily workouts or perhaps we as a society have come to equate endurance with fitness (because, seriously, who could argue that a marathon runner is not a fit human!). However, you have to remember, overtraining – or simply following an endurance-focused fitness regimen – can up your risk of overuse injuries, reduce energy, inhibit fitness gains, weaken the immune system and just really sap time! Again, this is not to say that short, interval training is the only way to exercise, but rather it’s an excellent foundation for your fitness routine and a wonderful way to get back to your primal roots!