High-Intensity Interval Training Is
Time-Efficient and Effective, Study Suggests
The usual excuse of "lack of
time" for not doing enough exercise is blown away by new research
published in The Journal of Physiology.
The study, from scientists at
Canada's McMaster University, adds to the growing evidence for the
benefits of short-term high-intensity interval training as a
time-efficient but safe alternative to traditional types of moderate
long-term exercise. Astonishingly, it is possible to get more by doing
"We have shown that interval
training does not have to be 'all out' in order to be effective," said
Professor Martin Gibala. "Doing 10 one-minute sprints on a standard
stationary bike with about one minute of rest in between, three times a
week, works as well in improving muscle as many hours of conventional
long-term biking less strenuously."
training means doing a
number of short bursts of intense exercise with short recovery breaks
in between. The authors have already shown with young healthy college
students that this produces the same physical benefits as conventional
long duration endurance training despite taking much less time (and
amazingly, actually doing less exercise!) However, their previous work
used a relatively extreme set-up that involved "all out" pedaling on a
specialized laboratory bicycle. The new study used a standard
stationary bicycle and a workload which was still above most people's
comfort zone -- about 95% of maximal heart rate -- but only about half
of what can be achieved when people sprint at an all-out pace.
This less extreme high-intensity interval
training method may work well for
people (the older, less fit, and slightly overweight among us) whose
doctors might have worries about them exercising "all-out." We have
known for years that repeated moderate long-term exercise tunes up fuel
and oxygen delivery to muscles and aids the removal of waste products.
Exercise also improves the way muscles use the oxygen to burn the fuel
in mitochondria, the microscopic power station of cells.
Running or cycling for hours
a week widens the network of vessels supplying muscle cells and also
boosts the numbers of mitochondria in them so that a person can carry
out activities of daily living more effectively and without strain, and
crucially with less risk of a heart attack, stroke or diabetes.
But the traditional approach
to exercise is time consuming. Martin Gibala and his team have shown
that the same results can be obtained in far less time with brief
spurts of higher-intensity exercise.
To achieve the study's
equivalent results by endurance training you'd need to complete over 10
hours of continuous moderate bicycling exercise over a two-week period.
The "secret" to why high-intensity interval
training is so effective is unclear.
However, the study by Gibala and co-workers also provides insight into
the molecular signals that regulate muscle adaptation to interval
training. It appears that high-intensity interval
training stimulates many of the same
cellular pathways that are responsible for the beneficial effects we
associate with endurance training.
The upside of doing more
exercise is well-known, but a big question for most people thinking of
getting fit is: "How much time out of my busy life do I need to spend
to get the perks?"
Martin Gibala says "no time
to exercise" is not an excuse now that high-intensity interval
training can be tailored for the
average adult. "While still a demanding form of training," Gibala adds,
"the exercise protocol we used should be possible to do by the general
public and you don't need more than an average exercise bike."
The McMaster team's future
research will examine whether high-intensity interval
training can bring health benefits to
people who are overweight or who have metabolic diseases like diabetes.
As the evidence for high-intensity interval
training continues to grow, a new
frontier in the fitness field emerges.
For more information
on McMaster University,