36 | New Scientist | 14 March 2020
Mechanics of
locomotionWhen people walk, at least
one foot is always touching the
ground. It is an efficient technique
in which, mechanically, the body
acts like an inverted pendulum
during each foot’s contact. Each
of us has an optimum stride
frequency related to the length
of our legs – the longer they are,
the lower the frequency.
Running is less efficient and
the motion is more like the
compression of a spring than a
pendulum’s swing. The movement
is characterised by a flight phase
when both feet are airborne,
followed by one foot making
contact with the ground for a
mere quarter of a second or so.
During this impact, the body
experiences forces that are
more than double those
encountered when standing.Running also gets a glowing bill of health in
several large-scale studies that follow people
for many years: they show that this exercise
has a dose-related effect. More running is
better, though with diminishing returns, but
the good news for couch potatoes is that the
largest gains come by going from nothing to
something. “The biggest health benefits are
observed with just a little running per week,
less than 60 minutes, an amount that would fit
in most people’s schedules,” says Angelique
Brellenthin, an exercise researcher at Iowa
State University.
Further benefits are clear from long-term
US studies. In the National Walkers’ and
National Runners’ health studies, Paul
Williams and Paul Thompson of the
Lawrence Berkeley National Laboratory
measured the health of about 16,000 walkers
and 33,000 runners over six years. Compared
with walkers, runners had a 38 per cent lower
risk of high blood pressure and a 71 per cent
lower risk of type 2 diabetes.
When the researchers controlled for energy
expenditure and weight difference between
the groups, however, the benefits from walking
and running were comparable. Williams later
analysed data for breast and brain cancer, and
the reductions in risk of death from running
or walking were, again, similar if energy
expenditure was the same.
Even a small amount of exercise brings
significant health gains. This was the case
in a massive study from 2011 that followed
more than 400,000 people in Taiwan over
an average of eight years, noting their exercise
habits and the number of deaths from
different causes. This showed that just
15 minutes a day of moderate exercise such
as fast walking was enough to reduce risk ofdeath by 10 per cent compared with sedentary
participants. This effect could also be gained
by around 5 minutes of vigorous exercise such
as running, giving a time-versus-benefit ratio
between running and walking of three to one
(see “Survival of the fittest”, right).
So far, so clear. If you have time on your
hands, the gains of walking are comparable to
those of a jog so long as you are moving at a
moderate pace. But for the time poor, running
is the best way to get a dose of exercise. “The
fact that running confers similar benefits as
walking but in half the time is one major
reason that running is attractive for health,”“ The largest
gains come
by going from
nothing to
something”
ZIVICA KERKEZ/ALAMYEven walking
the dog confers
a boost to healthIs exercise worth it?
Runners and other active people
tend to live longer. But if these
bonus years are equivalent to all
the time spent working up a sweat
throughout life, then is it all a
waste of time? It is a pertinent
question for those who find
exercise a penance.
Duck-chul Lee of Iowa State
University and his colleagues dug
into the data to find out. They
calculate that between the ages
of 44 and 80, someone who runs
2 hours per week will spend a total
of 0.43 years running. This would
still provide an average “bonus”
of 2.8 additional years of life on
top of the time spent running.
In other words, 1 hour of running
typically adds an extra 7 hours
to lifespan. “It is controversial
whether progressively more
running provides further mortality
benefits, but running certainly
provides cost-effective longevity
benefits,” they concluded.