Stretch Shorten Reflex

Stretch Shorten Reflex

stretch shorten reflex

Performance Stretch-Shorten Reflex

The Stretch Shorten Reflex (SSR) is an active stretch of a muscle
followed by an immediate shortening of that same muscle. The
SSR is utilized frequently during sports because most movements
involve two phases of muscular contraction in rapid succession.
First, the eccentric phase the muscle lengthens while under tension,
and second, the concentric phase the muscle shortens while
generating force. During the eccentric phase, the muscle acts to
decelerate the joint during the movement, getting the body
prepared for the concentric phase, where the muscle works to pull
a joint in the direction of the muscle contraction.


When you have a concentric muscle contraction that is followed
directly after an eccentric movement there is a significant
performance benefit associated with muscle contractions because
the SSR is activated. It works because during the eccentric phase
the muscle gains elastic energy and increased muscle activation
due to the load being applied. The key to utilizing this stored
elastic energy involved in the SSR is to minimize the amortization
phase, the time between the eccentric and concentric phase of the
movement. You also get a bonus supply of power generated to the
muscle because the SSR activates the muscle spindles. The muscle
spindles are stretch receptors inside your muscle that detect
changes in muscle length and force muscle contraction to protect a
muscle from overstretching. You can take advantage of the muscle
spindle activation to generate even more power during the SSR.
However, if the amortization phase takes to long, you begin to lose
the added power giving by the muscle spindles, and the elastic
energy and increased muscle activation starts to dissipate. Look at
the difference between standing still and jumping versus getting a
running start, even one step before the jump will better results.


Running, jumping, throwing, kicking, swinging, and changing
direction are all major movements in sports that require the SSR
for best performance. Each of the movements above requires
multiple joints to extend and flex and muscles to stretch and flex as
quickly as possible. Golf for example, the SSR plays an important
role in the generation of power in an efficient golf swing,
especially during the transition phase, where the body segments are
changing direction sequentially. In the transition phase, each body
segment — the hips, then the chest, then the lead arm, and finally
the hands and club — change direction from backswing to
downswing in a precisely timed sequence. Each segment changes
direction while the next segment in the kinetic chain is still moving
back, stretching the muscles in an eccentric contraction, thus
activating the SSR in the subsequent muscle concentric contraction
forces in the downswing.


Electrolytes are essential for good reason. These major nutrients
(calcium, sodium, magnesium, chloride, potassium, and phosphate)
aid numerous vital bodily functions—such muscle function; blood
pressure stability, blood clotting; maintenance of fluids, bones and
teeth; nerve signaling; and heart beat regulation. However, an
electrolyte imbalance can trigger a domino effect of negative and
even deadly responses and just being dehydrated slows down your
body’s natural metabolism. Make sure to stay hydrated but that you are
drinking more than just water.

How do you replenish electrolytes?
Electrolytes lost from sweat are replaced through food, and plain water is what your body prefers for adequate rehydration. Eat foods high in electrolytes. This is not difficult to do when eating a plant-based diet. For instance high potassium fruits include banana, dates, raisins, coconut and avocado.
Which fruit has the most electrolytes?
Apples, corn, beets, carrots and green beans, are all rich in electrolytes. Other electrolyte-laden fruits and veggies include limes, lemons, oranges, sweet potatoes, artichokes, all types of squash and tomatoes.
Can you have too many electrolytes?
However, too much magnesium can cause muscular and neurological damage. Symptoms include muscle weakness, nausea, dizziness, confusion and heart arrhythmia. When drinking sports drinks or taking electrolyte supplements, always consume in moderation and take with plenty of plain water.