In the 1960s, a man name Kenneth H. Cooper
came up with the concept of aerobics. Originally, aerobics, via the aerobics point system, measured
the effectiveness of different exercises and activities for improving cardiovascular health.
This lead to the coining of the term today known as cardio. Over time, however, the main
focus of these aerobic-based exercises began shifting from improving cardiovascular health
to helping people lose weight and burn fat. And it makes a lot sense since cardio exercises
do indeed help people lose weight by burning excess calories and also help people burn
fat by activating the fat-burning aerobic energy pathway in the body.
This aerobic energy pathway is the energy system in your body that uses stored fat-
after being converted into fatty acids- in conjunction with oxygen and other chemicals
to produce the body’s sole source of energy known as ATP. As long as this pathway is utilized,
more and more fat will be burned. Early science believed that the best way to activate this
pathway is by performing long-duration, low intensity exercises such as long-distance
jogging, cycling, or swimming. This ultimately lead to the creation of other forms of cardio
exercises today such as aerobic dance classes, step aerobics, and the extremely popular Zumba.
Although low intensity cardio is still the exercise king of weight loss and fat burning
today, newcomers have arrived to challenge for the crown. The biggest gripe with low
intensity cardio exercises is the duration, which often takes more than an hour. Cardio
might seem to be fun and exciting the first time it’s done, but over time, it begins to
feel way too repetitive and long. As more and more people become bored and lose interest,
more and more people will quit. And for some people, they simply do not have the time.
But are low intensity cardio exercises really the best option to burn fat and calories?
The science today says, “Ehh, probably not.” This is where the most prominent challenger
to low intensity cardio steps in. This challenger is known as High Intensity Interval Training.
High Intensity Interval Training, as the name suggests, is any “training” program that are
performed in “intervals” at a “high intensity.” High intensity interval training, also called
HIIT for short, are alternating periods of short high intensity activity with periods
of low intensity recovery. The most popular exercise for HIIT is alternating sprinting
with walking. Each sprint interval lasts between 5-30 seconds and each walk interval will also
last between 5-30 seconds. The more fit you are, the higher the work to rest ratio will
become. For example, if you’re really fit, you might be sprinting for 30 seconds and
walking for 10. Someone that is less fit might be sprinting for 10 seconds and walking for
30. The total session length varies between 5-20 minutes, and because of the intensity,
should only be done 3 days a week. When added together, that’s a maximum of only 60 minutes
of exercise per week! So what’s the science behind this? When the
body goes through intense activity, it needs to be able to keep up with the energy demand.
One way of doing so is by secreting high levels of fat-releasing hormones known as catecholamines
into the bloodstream. The more catecholamines, the more quickly fat is broken down into free
fatty acids. Free fatty acids are then used to replenish energy stores. Studies have also
shown that HIIT creates a strong EPOC effect. EPOC, short for excess post-exercise oxygen
consumption, is the extra oxygen your body needs in order to recover after an intense
activity. The more oxygen you take in also means more calories are being burned. This
effect can last up to an amazing 24 hours after the workout. However, other studies
have shown that the amount of calories being burned during EPOC isn’t all that much, where
at most an extra 60 calories being burned. There are also a few drawbacks. High intensity
interval training is extremely strenuous. People might drop out of low intensity cardio
becomes it’s long and boring, but people can just as easily drop out of HIIT because it’s
just too hard. High intensity interval training might also cause joint pain due to the high
impact, and over time, might lead to serious injuries. Also, low intensity cardio can actually
be done every day. HIIT, however, requires ample recovery time, which can interfere other
exercise routines. Although HIIT might challenge low intensity cardio for the crown, it’s not
exactly a knockout punch. Have you tried high intensity interval training
before? Please share your experience in
the comment section below!