But is 20 minutes of intense exercise as beneficial as longer, more moderate, exercises? There has been some recent research on interval training (highlighted on the NY Times' Well blog) that I think sheds some light:
"(In 2006) Martin Gibala, a physiologist at McMaster University in Ontario, and his colleagues published a study showing that a three-minute sequence on an electronic stationary bicycle — 30 seconds of punishing, all-out pedaling followed by a brief rest, repeated five or six times — led to the same muscle-cell adaptations as 90 to 120 minutes of prolonged bike riding."
A similar study in 2010 found that:
10 one-minute intervals — essentially, 10 minutes of strenuous exercise braided with one-minute rest periods between — led to the same changes within muscle cells as about 90 minutes of moderate bike riding.The answer to the above question appears to be "yes." Workouts like Insanity that incorporate this thinking are also selling well and getting big results. To me, Jillian's workouts are the same concept; a precursor to the interval training movement.
In a favorite post of mine entitled "The Scientific 7-Minute Workout,"featuring an awesome routine, the importance of rest intervals between the circuits is emphasized (example given is 10 seconds). Naturally, it takes a few seconds to move from doing sit-ups to doing something with handweights. Jillian may not give you a full 10 seconds, but there's nothing keeping you from taking it-- just hit pause to get those 2-3 extra seconds. The article states that the exercises should emphasize
"the large muscles in the upper body with those in the lower body. During the intermezzo, the unexercised muscles have a moment to, metaphorically, catch their breath, which makes the order of the exercises important."
30 Day Shred sort of accomplishes this by moving on in this order. You may do an exercises focusing on arms and upper-body followed by jumping lunges focusing on your core.
Another doctor tells us:
“150 minutes of moderate exercise each week is clearly associated with improved health outcomes,” including longevity and reduced risk of many diseases.To me, Jillian's workouts combine the concept of interval training, but you end up with 140 minutes a week of at least "moderate" exercise, so you get a great workout and a great week together.
I've done this DVD many times in multiple countries. The reason is because it's simple, and it works-- that's why it still sells. My last round of 30 Day Shred was to get in shape to do P90X, a more demanding fitness routine. But I still use 30 Day Shred on my rest days, and sometimes as an additional supplemental exercise (instead of Cardio X). It gets my heart rate up higher than any single P90X workout, including Plyo X.
1. Get some wrist and ankle weights, they will make the exercises more intense. I picked these up for $1 at a garage sale last week, they're 1 pound each.
I also have some 5-pound ankle weights ($3.50 at Goodwill) that really make the Level 3 workout intense (think of the plank with leg raise).
2. If you've done other exercises, like P90X, modify Jillian's exercises to match. For example, do 10-second "supermans" instead of ten 1-second ones. Do a "spider man" push up instead of a walking one.
3. Go back and do Level 1-2 with hand/ankle weights when you're punching, jumping jacks, etc. If you don't have hand weights, use some canned goods for resistance instead. Whatever you have around the house.
4. Stretch longer than they do at the end. Take care of your body and do more meaningful stretches, or you may regret it.
You can do anything for 20 minutes and you can do anything for 30 days. Every day all of us ultimately do whatever it is we really want to do.