Are you a cardio junkie? Everyone seems to think that "cardio" is the best way to get in shape and 
lose body fat.  I'm going to show you in this article why I 
disagree!
It is quite common to hear fitness pros, doctors, and other health 
professionals prescribe low to moderate intensity aerobic training 
(cardio) to people who are trying to prevent heart disease or lose 
weight. Most often, the recommendations go something like this:
"Perform 30-60 minutes of steady pace cardio 3-5 times/week maintaining your heart rate at a moderate level"
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| Exercise work zones (Fox and Haskell formula between 20 and 70-year-old): red zone (VO2Max), anaerobic, aerobic, weight control and warming up. (Photo credit: Wikipedia) | 
Before you just give in to this popular belief and become the
 “hamster on the wheel”
 doing endless hours of boring cardio exercise, I’d like you to consider
 some recent scientific research that indicates that steady pace 
endurance cardio work may not be all it’s cracked up to be.
First, realize that our bodies are designed to perform physical 
activity in bursts of exertion followed by recovery, or stop-and-go 
movement instead of steady state movement. Recent research is suggesting
 that "physical variability" is one of THE most important aspects to 
consider in your training. 
This tendency can be seen throughout
 nature as most animals tend to demonstrate "stop-and-go" motion instead
 of steady state motion. In fact, humans are the only creatures in 
nature that attempt to do “endurance” type physical activities such as 
running long distances at the exact same speed the whole time.
Most competitive sports (with the exception of endurance running or 
cycling) are also based on stop-and-go movement or short bursts of 
exertion followed by recovery.
To examine an example of the different effects of endurance or steady
 state training versus stop-and-go training, consider the physiques of 
marathoners versus sprinters. Most sprinters carry a physique that is 
very lean, muscular, and powerful looking, while the typical dedicated 
marathoner is more often emaciated and sickly looking. Now which would 
you rather resemble?
Another factor to keep in mind regarding the benefits of physical 
variability is the internal effect of various forms of exercise on our 
body. Scientists have known that excessive steady state endurance 
exercise (different for everyone, but sometimes defined as greater than 
60 minutes per session most days of the week) increases free radical 
production in the body, can degenerate joints, reduces immune function, 
causes muscle wasting, and can cause a pro-inflammatory response in the 
body that can potentially lead to chronic diseases. 
Highly variable cyclic training
On the other hand, highly variable cyclic training has been linked to
 increased antioxidant production in the body and an anti-inflammatory 
response, a more efficient nitric oxide response (which can encourage a 
healthy cardiovascular system), and an increased metabolic rate response
 (which can assist with weight loss). Furthermore, steady state 
endurance training only trains the heart at one specific heart rate 
range and doesn’t train it to respond to various every day stressors.
On the other hand, highly variable cyclic training teaches the heart 
to respond to and recover from a variety of demands making it less 
likely to fail when you need it.  Think about it this way... Exercise 
that trains your heart to rapidly increase and rapidly decrease will 
make your heart more capable of handling everyday stress. Stress can 
cause your blood pressure and heart rate to increase rapidly. Steady 
state jogging and other endurance training does not train your heart to 
be able to handle rapid changes in heart rate or blood pressure. 
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| Cardio Boxing Group Fitness Class (Photo credit: Wikipedia) | 
The
 important aspect of variable cyclic training that makes it superior 
over steady state cardio exercise is the recovery period in between 
bursts of exertion. That recovery period is crucially important for the 
body to elicit a healthy response to an exercise stimulus. Another 
benefit of variable cyclic training is that it is much more interesting 
and has lower drop-out rates than long boring steady state cardio 
programs.
To summarize, some of the potential benefits of 
variable cyclic training compared to steady state endurance training are
 as follows: improved cardiovascular health, increased anti-oxidant 
protection, improved immune function, reduced risk for joint wear and 
tear, increased muscularity (versus decreased muscularity with endurance
 training), increased residual metabolic rate following exercise, and an
 increased capacity for the heart to handle life’s every day stressors. 
Sports Workouts and Sprinting
There are many ways you can reap the benefits of stop-and-go or 
variable intensity physical training. Most competitive sports such as 
football, basketball, volleyball, racquetball, tennis, hockey, baseball,
 etc. are naturally comprised of highly variable stop-and-go motion 
which trains the heart through a MUCH wider heart rate range compared 
to just steady walking or jogging.
Doing swimming workouts in a variable intensity fashion may also be 
more beneficial than just swimming for a long duration at the same 
speed.  Same goes for bicycling -- that is why mountain biking, which 
involves extreme ups and downs at various intensity levels may also be 
more beneficial than just a long flat steady pace bike ride.
One of the absolute most effective forms of variable intensity 
training to really reduce body fat and bring out serious muscular 
definition is performing wind sprints.  Wind sprints can be done by 
sprinting at near max speed for 10-30 seconds, and then taking 60 
seconds to walk for recovery before your next sprint. 6-12 total sprint 
intervals is usually a very challenging workout for most people.
In addition, weight training naturally incorporates short bursts of 
exertion followed by recovery periods. High intensity interval training 
(varying between high and low intensity intervals on any piece of cardio
 equipment) is yet another training method that utilizes exertion and 
recovery periods. For example, an interval training session on the 
treadmill could look something like this: 
Warm-up for 3-4 minutes at a fast walk or light jog
Interval 1 - run at 8.0 mi/hr for 1 minute 
Interval 2 - walk at 4.0 mi/hr for 1.5 minutes 
Interval 3 - run at 10.0 mi/hr for 1 minute 
Interval 4 - walk at 4.0 mi/hr for 1.5 minutes 
Repeat those 4 intervals 4 times for a very intense 20-minute workout.
Also, don't overlook other great ways to incorporate variable 
intensity cardio training by using a jump rope, a rowing machine, stairs
 running, or even outdoor hill sprints.
The take-away message from this article is to try to train your body at 
highly variable
 intensity rates for the majority of your workouts to get the most 
beneficial response in terms of heart health, fat loss, and muscle 
maintenance.
Article By Mike Geary – Certified Personal Trainer, Certified Nutrition Specialist
Author of best-seller:  The Truth about Six Pack Abs