The way you exercise affects your metabolism for several days

While short duration exercise actually increases levels
of growth hormone. Researchers from Loughborough
University in Leicestershire, England tested growth
hormone levels in sprinters and endurance athletes. On
average, the sprinters had 3 times as much growth hormone
as the endurance runners.
But the biggest point is this: The most important changes
from exercise occur after, not during, the exercise period.
The way you exercise affects your metabolism for several
days. The important changes begin after you stop exercising.
This is good news. It means that all you have to do during
your exercise is to stimulate the adaptive response you
need. Then, your body will continue making the important
changes afterwards – while you rest.

Signal Your Body to
Build What It Lacks
Short bursts of exercise tell your body that storing energy
as fat is inefficient, since you never exercise long enough to
utilize the fat during each session. Carbohydrates, which
are stored in muscle rather than fat, burn energy at high
rates. Exercising for short periods will use these carbs and
burn much more fat after exercising while you replenish the
carbs. Short interval exercise maximizes fat “after burn.”
Researchers at Laval University in Quebec divided
participants into two groups: long-duration and repeated
short-duration exercisers.8 They had the long-duration
group cycle 45 minutes without interruption. The shortterm
interval group cycled in numerous short bursts of 15
– 90 seconds, while resting in between.

Rediscover Your Native Fitness
The long duration group burned twice as many calories,
so you would assume they would burn more fat. However,
when the researchers recorded their body composition
measurements, the interval group showed that they lost the
most fat.
In fact, the interval group lost 9 times more fat than the
endurance group for every calorie burned. Doesn’t this
defy the laws of physics? No, it just illustrates that exercise
continues to affect your metabolism after you stop. The
short bursts stimulated a greater after burn.