Do sprint interval training to lose fat fast and improve conditioning.
Research shows that sprint interval training is the best conditioning
method for fat loss, but you have to use a precise interval program in
order to get results—haphazardly making up intervals is not the best way
There are a wide variety of interval programs out there and research
shows that they yield different results based on how they stress the
body to adapt. For example, a recent study showed that an interval model
called 30-20-10 was highly effective at improving health markers and
performance in recreational runners, but it probably isn’t the best
method for fat loss because it’s not intense enough to generate high
levels of lactate or growth hormone.
The 30-20-10 model has trainees perform four 5-minute intervals in which
they jog for 30 seconds, run at a moderate intensity for 20 seconds,
and sprint for 10 seconds, and then repeat. After doing the program for 7
weeks, trainees improved performance on a 1,500 meter run by 21 seconds
and by 48 seconds on a 5 km run. They also decreased their systolic
blood pressure by 5 mm Hg and improved cholesterol levels.
Body composition wasn’t measured, but there was no change in muscle pump
activity, indicating that although the program improved performance and
health, it wasn’t metabolically taxing enough to produce significant
fat loss or muscle development.
In comparison, a 20-minute sprint interval program that used 60
intervals of all-out 8-second sprints followed by 12 seconds recovery on
a ergometer cycle resulted in 2 kg fat loss and 1 kg muscle development
in untrained men. The same program produced 2.5 kg fat loss in women.
Note that the difference between this program and the 30-20-10 method is
that for each minute trained, trainees sprint all out for a total of 24
seconds, compared to only 10 seconds with 30-20-10. The greater time
spent working at maximal intensity is the difference in metabolic stress
for fat loss.
For trained individuals or athletes, more demanding programs may be
necessary. Studies suggest longer all-out intervals will elevate growth
hormone to produce fat burning.
For instance a very demanding 1 to 1 interval-to-rest program has
produced significant fat loss and performance enhancement in trained
athletes. This program used four 4-minute intervals with a 30-second
sprint and 30-second jogging recovery.
Another model that allowed participants to lose 9 times more body fat
than a steady-state aerobic program used 10 sprints of 15 seconds each
increasing to 15 sprints of 30 seconds each as trainees began to adapt.
The recovery period was based on heart rate—once it returned to 120
beats per minute the next interval was performed.
A third model that produced a significant 2 kg loss of body fat in
trained runners included two interval protocols alternated for four
sprint sessions a week: Ten intervals of 30-second all-out sprints with
90-seconds active rest and 6 intervals of 2-mintue maximal intensity
sprints followed by 90 second active rest. The maximal intensity sprints
were performed at the maximal running speed achieved during a treadmill
stage test to exhaustion, so they weren’t at the maximal speed that the
trainees could run.
The take away is that you must program interval training to reach your
goal and if that goal is fat loss, near maximal intensity sprints in the
30 second range to produce lactate buildup are ideal. Rest periods
should be active rather than passive, and 1 to 2 or 1 to 3 work-to-rest
intervals have proven effective for eliciting a growth hormone response
for fat loss.