OnFitness Magazine - March/April 2022 - 21

21 WWW.ONFITNESSMAG.COM | VOL 22 NO 5 | 2022
Excess post-exercise oxygen
consumption is the actual amount of
energy (calories) that your body continues
to burn after a workout is over in the form
of fuel replenishment; shuttling of
metabolites and hormones to cells that
need repair; returning much of the blood
and oxygen back to internal organs (rather
than muscles), and facilitating recovery of
heart and respiratory rates. Your body is
using oxygen and subsequent energy to do
cleanup after intense exercise.
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Aerobic or " steady-state " exercise such as
jogging, floor aerobics, and bike riding,
uses oxygen and expels carbon dioxide
equally at a constant rate with no lactic
acid accumulation; enough oxygen is
always available so that energy production
is achieved.
In contrast, exercising anaerobically
means that inadequate oxygen is being
delivered to working muscles to
accommodate energy needs. Thus, an
alternate energy pathway called glycolysis
is used, a byproduct of which is lactic acid.
Lactic acid buildup has a characteristic
burning feel that eventually makes an
exerciser stop. Examples of anaerobic
activities include sprints, bounding up
stairs or hills, and intense weight training.
Both aerobic and anaerobic activity
burn calories and use energy. However,
anaerobic activity is particularly powerful
in expediting excess post-exercise oxygen
consumption.
A study in the Journal of the
International Society of Sports Nutrition
outlined the differences in caloric
expenditure involved in aerobic versus
anaerobic activity.
First, the study examined caloric
expenditure via aerobic means during a
steady-state walk, and also caloric
expenditure via aerobic means for
intermittent sprints. Each activity was
performed so that equivalent amounts of
work were completed.
For a given amount of work, the
steady-state walk burned twenty-eight
calories aerobically, while the equivalent
amount of work done via intermittent
sprints burned only four calories
aerobically. However, once calories burned
during excess post-exercise oxygen
consumption were taken into account
(aerobic calories burned plus excess postexercise
oxygen consumption), the steadystate
walk burned thirty-five calories total,
and the sprints burned thirty-nine calories.
Furthermore, once anaerobic energy
expenditure was added into the equation
(aerobic calories burned plus excess postexercise
oxygen consumption plus
anaerobic calories burned), the steady-state
walk consumed thirty-nine calories total,
while the intermittent sprints burned
sixty-five total calories with the same
amount of work and much less time
invested. The only difference between
workouts was intensity.
The amount of excess post-exercise
oxygen consumption that a particular
activity can induce is based on several
hormonal responses to exercise.
The first batch of related hormones
consists of testosterone, human growth
hormone, and cortisol. The
extent to which these hormones
are released greatly depends on
exercise intensity and modality.
Modality can greatly increase
ability to burn calories for
hours and even days after a
tough workout.
For an activity to be
anaerobic, there must be a lactic
acid accumulation and a perceived
exertion that forces the exerciser to stop.
Weight training fits the bill. However, a
certain intensity is required for an
anaerobic threshold to be breached; the
weight must be heavy enough to induce a
muscular burn or induce mechanical
failure (the weight can no longer be lifted).
When these conditions are met,
testosterone, human growth hormone, and
cortisol are released in amounts that create
a caloric ripple effect.
A study in the International Journal of
Sports Medicine examined two exercise
protocols' ability to raise levels of
testosterone, human growth hormone, and
cortisol post-exercise.
In the first protocol, exercisers
completed twelve repetitions of leg presses,
squats, and leg extensions using a twelverepetition
maximum weight. In the second
protocol, exercisers used weight that was
heavier than a twelve-repetition maximum,
and performed leg presses, squats, and leg
extensions to failure, and then were
assisted for the remaining repetitions to
complete the twelve.
In the group who performed
repetitions to failure, measurements of
acute hormonal responses were greater
than the traditional protocol of straight
sets unassisted. It's the elevation of these
important hormones via intense weight
training that dictates the extent to which
excess post-exercise oxygen consumption
creates a caloric difference in energy
consumption.
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Vary sets and repetitions for maximum
results, but remember to keep the pace on
the quicker side to increase workout
density. To maximize excess post-exercise
oxygen consumption, it's advisable to limit
rest time so that lactic acid dissipation is
minimal.
Short, frequent within-set rests are
more beneficial from a metabolic
standpoint than long, drawn-out rests
between sets. A dense workout allows for
exercisers to cram a lot of exercise in a
short amount of time.
Excess post-exercise oxygen
consumption is likewise elevated
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