How stretching actually changes your muscles - Malachy McHugh
Here we have an athlete
preparing for a game.
They’ve put on their gear
and done their warmup,
and now it’s time for one
more routine— stretching.
Typically, athletes stretch before
physical activity to avoid injuries
like muscle strains and tears.
But does stretching actually prevent
these issues?
And if so, how long do the benefits
of stretching last?
To answer these questions,
we need to know what's actually happening
in the body when we stretch.
There are two kinds of stretching
our athlete might be doing.
Dynamic stretches,
which are controlled movements
that engage a range of muscles
throughout the motion.
And static stretches,
where the stretcher holds a position
to keep specific muscles
at a fixed length and tension.
Our athlete is currently doing
a static hamstring stretch—
a 30 second interval
where he pulls his hamstring
beyond its usual range of motion.
However, while we often think
of stretching a muscle
like stretching a rubber band,
muscles are actually comprised
of various tissue types,
which interact to make a complex material.
Rubber is elastic, meaning
it resists being stretched
and then returns to its original shape.
But muscle is viscoelastic.
This means that, in addition
to those elastic qualities,
muscle changes under the stress
of being stretched.
Let’s see this in action.
At the large scale, this hamstring stretch
is pulling on layers of protective tissue
surrounding the muscle fibers,
as well as the tendons that connect
this muscle to nearby bones.
These tissues contain elastic proteins
like collagen and elastin,
which allow them to slightly elongate
over the duration of the stretch.
At the smaller scale, these skeletal
muscle fibers are comprised
of millions of sarcomeres—
the smallest contracting unit
of muscle tissue.
Sarcomere’s long, fibrous proteins can
relax to elongate muscle fibers
or they can contract to shorten them—
pulling on tendons and protective tissue
to create the force
propelling our athlete’s body.
And when those tissues have
been stretched out,
they retain their strength
at longer lengths,
allowing our athlete to take full
advantage of his improved range of motion.
Unlike a rubber band, this muscle’s
resistance to stretching decreases
with each 30 second stretch,
allowing our athlete
to continually elongate his hamstring.
And this improved flexibility
likely decreases the chance
of incurring certain muscle injuries.
But due to muscle’s elastic properties,
this effect will be gone in just
10 minutes without further activity.
The exercise from his match should
elevate his muscle’s temperature
and continue elongating the muscle,
maintaining his increased flexibility
throughout the game.
But once he gives his hamstrings a break,
they’ll retract back
to their previous state.
So if all this is just temporary,
how can you permanently improve
your flexibility?
For skeletal muscles, improved flexibility
comes from additional sarcomeres,
which allow you to maintain strength
at even greater lengths.
Sarcomeres are added and subtracted
to muscles
depending on how frequently they’re used,
so improving overall flexibility requires
a comprehensive stretching regimen.
Plus, you need to stretch often—
very often.
Current research suggests at least
10 minutes a day for roughly two months.
And since it's unsafe to hold
any stretch for too long,
it's recommended that you break up your
stretching within any given session.
Frequent stretching also makes lasting
changes to your brain.
The more you stretch a muscle,
the higher your pain threshold becomes,
allowing you to stretch
further and further.
Long-term improvements
to your flexibility can provide
a better range of motion for your joints,
potentially reducing your risk of muscle
injury in the short and long-term.
But it’s also possible
to stretch too much,
as flexible people can move their joints
in potentially dangerous ways.
Stretching also isn't helpful
for every kind of movement,
especially those where muscle
injuries aren't very common.
For example, long distance running only
involves a small range of motion
for the joints involved,
so stretching is unlikely to prevent
that sport’s most common injuries.
When it comes down to it,
different lifestyles require
different kinds of mobility.
And no single stretching regimen is
flexible enough to fit every situation.
