Contorting your body
and cranking your muscles through extreme ranges of motion, also known as
‘stretching’, can be used to improve performance if done correctly, but
unfortunately the majority of those who attempt to use various stretches to
improve performance do so incorrectly and actually end up decreasing
performance.
Before explaining
how stretching can be used advantageously, it’s worth explaining the different
kinds of stretches, and the downstream effects they have. The different types
of stretching and types of flexibility are:
1. Ballistic – Using
momentum to propel your body or limbs into extreme ranges of motion that would
be considered beyond normal. This type of stretching is perceived by the brain
as dangerous to which it responds by increasing the firing rate to the
stretched muscle group, making it beneficial for those looking to improve
performance (assuming performance consists of generating more power/force).
2. Dynamic – The
difference between dynamic stretches and ballistic is that with a dynamic
stretch you don’t try to explosively force your body or limbs beyond its normal
range, you rather gradually increase speed, intensity, and range of motion. These
are best suited at the beginning of a training session to prepare the body for
the movements to come (AKA, movement preparation).
3. Active – An
active stretch is an unassisted stretch, meaning there is no external factor
affecting the stretch like leaning on a wall or bench, or using bands to
increase the range of motion to create leverage. When a muscle contracts, the
opposite muscle, or antagonist, is forced to relax, in almost all cases (one
exception being a sit up in which both the abs and spinal erectors contract
simultaneously). Anyone can take advantage of this to enhance almost any
stretch. For example, to enhance the stretch of the biceps, you could
‘actively’ flex your triceps as hard as you can while extending the elbow. The
same can be said for the quads in that, by flexing as hard as you can, you can
really maximize the stretch in the hamstrings, and vice versa. This phenomenon
is called reciprocal inhibition and can be used to instantly improve
performance, as by rapidly contracting the antagonist, you in turn rapidly
stretch the agonist, to which the nervous system responds by increasing the
amount of motor units sent to the working muscles to prevent what it perceives
could be potentially dangerous. This ‘trick’ is best suited for those looking
to build more strength or muscle mass and is especially effective for the
muscles responsible for flexing and extending the knee and elbow joint.
4. Passive – A
passive stretch is an assisted stretch, meaning there is some sort of external
factor used to create leverage and increase the range of motion. Having a partner
pull your arms back with your hands resting on your head is an example of a
passive stretch for the pecs, and this type of stretching is best suited at the
end of a training session to help clear away any metabolic waste that may have
accumulated during the workout and not been cleared, and assist with recovery. Also,
stretching a pumped muscle can facilitate growth as the cells could perceive
the stretch as a threat to their integrity, to which they respond by increasing
the sensitivity of their IGF-1 receptors which increases protein synthesis, and
also by stretching the surrounding connective tissue (fascia) which essentially
makes room for the cells to grow larger.
5. Static/isometric
– The difference between a static stretch and a passive stretch is that a
passive stretch is ‘relaxed’, and no attempt is made to resist the stretch,
whereas a static stretch is one in which you attempt to resist the muscles from
being lengthened by contracting them eccentrically. The benefit to this type of
stretching is that some of the muscle fibers that would normally remain
inactive, or at rest, are actually stretched as the fibers close to them
contract and pull on them.
6. PNF – Which stands
for PROPRIOCEPTIVE NEUROMUSCULAR FASCILITATION, is a combination of passive and
static/isometric stretches. There are a few different types of PNF techniques,
but to explain all in great detail goes beyond the scope of this article as the
purpose is to shine light on why certain types of stretching during your
workout can either increase, or decrease performance.
Now that the
different types of stretches are out of the way, here’s a brief rundown of the
physiology of stretching to help one better understand what happens to muscles
when they are stretched, so you can use them to your advantage, and avoid using
them disadvantageously.
The body is made up
of bones, and muscles that attach to them which provide movement.
A joint refers to an
intersecting area where bones connect via ligaments.
Muscles are
connected to bones via tendons, and located around all of this is connective
tissue which envelopes not only muscles, bones, tendons, and ligaments, but
also each and every muscle fiber.
Proprioceptors are the
nerve endings which relay all information about the musculoskeletal system to
the nervous system, and are responsible for detecting any change of movement or
tension within the body.
When a muscle is
stretched, a proprioceptor called a muscle spindle, records the change in
length, and how fast it occurred, and sends signals to the brain that convey
this information. This activates the stretch reflex (AKA myotatic reflex),
which attempts to resist the change in length by forcing the muscle to shorten
by forcefully contracting.
The harder and
faster your muscles are stretched, the harder they will be instructed to resist
being lengthened by being forced to contract by the stretch reflex, which is
basically a built in self defence system.
The proprioceptors
habituate to new lengths and ranges of motion the longer a stretch is held, and
reduce their firing rate (basically they shut off), enabling you to achieve a
greater stretch.
When a muscle
contracts, it produces tension at a point where the muscle is connected to the
tendon called the Golgi Tendon Organ (GTO). The GTO also records the change in
tension, and the rate at which it occurs.
When the tension
exceeds a certain threshold it activates the lengthening reaction which
disables a muscle from contracting. The purpose of the GTO is to prevent the
muscles, tendons and ligaments from getting injured (although it may not seem
that way based on the fact that it temporarily disables the muscles ability to
produce force). The lengthening reaction takes place when the GTO overpowers
the proprioceptors that are telling the muscle to contract.
Where a lot of
people go wrong is they use the wrong stretches at the wrong times. Stretches
are time dependent, meaning the longer they are held, the greater habituation
that occurs, yet so many people hold stretches for prolonged periods of time
for the muscle they are training between sets, not realizing that they are
basically shutting off the muscles they are training (which is as
counterproductive as it gets).
While it is possible
to recruit dormant muscle fibers by cranking and contorting your body and
holding stretches for a sustained period of time, the pay off of possibly
recruiting a few more muscle fibers at the expense of possibly shutting most of
them off simply isn’t worth it. A more logical approach may be to hold
stretches for the antagonistic muscle groups so there is a greater level of net
motor unit recruitment to the agonist, but even still you risk losing stability
which negatively affects force production.
The stretches, or
rather types of stretches, are presented in order from those which are held for
the shortest periods of time, and also have the greatest potentiating effect,
to those which are held for the greatest periods of time, but have the greatest
habituating effect, and should be used in that order in relation to the
beginning and end of a workout.
If you have any
questions about stretching as far as when, and what types of stretching you
should be doing, feel free to contact me at ben@paramounttraining.ca. I'm available for online consulting and personalized program design,
as well as one on one training if you are located in the Greater Toronto Area
(GTA).
Great read, thank you very much.
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