34 | New Scientist | 17 July 2021Stretching
the point
How flexible do you actually need
to be, asks Caroline Williams
I
BEND so I don’t break.” No one knows who
first coined this phrase, but search for it
online and you will find it accompanying
numerous pictures of yogis in various states of
contortion. Flexibility, according to common
wisdom, is not only impressive to look at, but
something we should actively work towards.
Scientifically, however, the question
of whether we should stretch to become
more flexible has been difficult to answer.
Assumptions about the benefits of stretching
to prevent sports injuries and greater
flexibility being better for our overall physical
fitness hadn’t been confirmed by studies.
Does it matter if you can’t touch your toes,
let alone do the splits? Even in sports science,
where most of the research has been conducted,
there has been little agreement.
In recent years, though, answers have started
to emerge. The surprising outcome is that,
while stretching may well be good for us,
it is for reasons that have nothing to do with
being able to get your leg behind your head.
One thing is for sure: stretching feels good,
particularly after a long spell of being still. We
aren’t the only species to have worked this out.
As anyone with a dog or cat will know, many
animals take a deep stretch after lying around.
This kind of stretching, called pandiculation,
is so common in nature that some have
suggested it evolved as a reflex to wake up
the muscles after a spell of stillness.
Pandiculation aside, other species don’t seem
to spend any time maintaining and extending
their range of motion. Which raises the
question, is there any reason why we should?
Our flexibility is controlled by the tissues of
our musculoskeletal system, which determine
the maximum range that our joints can move HARR
IETNOBL
E/STUDIOPIFeatures Cover story
without causing injury. For a long time,
flexibility has been considered a key
component of physical fitness (along with
cardiovascular endurance, muscle endurance,
muscle strength and body composition – the
percentage of body weight which is muscle,
fat and bone) by groups such as the American
College of Sports Medicine. Its latest
guidelines, for example, recommend
stretching all the major muscles groups at least
two or three times a week, holding the stretch
for anywhere from 10 seconds to 1 minute.
But even for exercise-phobes, there are
good reasons to stretch: our species is
unique in having invented a way of resting
that works against the needs of our bodies.
Anthropological evidence suggests that from
at least 2 million years ago, and until the
invention of chairs, our ancestors rested by
squatting on their haunches, a position that is
still common among young children, modern
hunter-gatherers and in cultures across Asia.
For those who are used to it, squatting is a
comfortable resting position, and has the
added bonus that it keeps the hips, calves and
ankles mobile through the range of motion
needed to walk, run and otherwise move
around in the world.
Resting in chairs, however, does the
opposite, causing us to stiffen up. A study
last year by researchers at the University of
Salford, UK, suggested that this has a real
impact on range of motion. People who
regularly sat for less than 4 hours a day and
were generally active had 6 degrees more
range of motion in their hip joints than less
active people who sat for more than 7 hours.
There is also evidence that sedentary
lifestyles in general are having a knock-on“