Amy, if you find any of those articles, can you post them or PM me with the links? I'd be interested in seeing where they are coming from & the reasoning behind the statements.
I think it's becoming one of those things where high-intensity training has become a trend, so the typical statement in certain publications is that "this new workout plan is the best, and everything else is a waste of time." Every form of exercise has it's place and it's specific set of benefits. In the same way that I would never tell someone to eat the same thing everyday, I try to encourage people not to do the same exercise everyday. Working out in the 'fat-burning' zone for, say, 30 to 60 mins should burn a higher proportion of calories from fat stores and has a low risk of injury; working out in the 'cardiovascular zone' for maybe 20 to 30 mins should burn a higher number of calories (per hour) overall as well as increasing aerobic capacity. HIIT is sort of seen as the best of both worlds, but is only appropriate if done correctly and if done after proper training has taken place (ie. HIIT is not really appropriate for beginners due to the risk of injury).
So, for beginners, I usually recommend just getting comfortable with between 30 to 60 mins of aerobic exercise (where they CAN still carry on a conversation relatively well) on any machine (this may have to be narrowed down if someone has an injury or other restrictions) 2-4 days per week. After a few weeks, try bumping up the intensity and doing a slightly shorter workout of 20-30 mins, possibly on a 'hill' program or something similar on whatever machine the person likes to do. So, if someone is doing 'cardio' 4 days per week, I would recommend 2 days of longer, lower intensity cardio and 2 days of shorter, but higher intensity cardio.
As for what machine is the 'best' for cardio... the best one is the one that someone likes the most, but again, I usually recommend using different machines on different days to reduce boredom.
sorry, long post as usual
