have before you is a summary of some of the current findings and proposed
hypotheses regarding the state of knowledge on stretching. Use this article as a cure for insomnia
or as a spark for further reading…I’ll see you in the pool!
Stretching is the movement of the muscles and tendons
about a joint to a point of resistance within the available range of movement
(ROM) at which point a force is applied, generally past its end range. The tissue is subjected to a pulling
force resulting in elongation of the musculotendinous unit. What happens to the tissue is dependent
on its viscoelastic properties.
Viscoelasticity is a combination of viscosity and elasticity. Viscosity refers to a material’s ability
to dampen and lubricate. Elasticity
refers to a material’s ability to return to its original state following
deformation after the removal of the deforming load. In addition to affecting the tissue’s
structural elements, stretching affects different sensory receptors in the
muscle and tendon resulting in important neurophysiologic phenomena.
Flexibility is the ability to move muscles and joints
through a full ROM. Flexibility is
necessary for efficient movement.
Flexibility varies from person to person and from joint to joint within
an individual. Most consider good
flexibility essential for successful athletic performance and injury
prevention. This premise has not
been proven, however, in clinical studies.
What has been shown is that flexibility is maintained through regular
and proper stretching regimens and will diminish over time if tissues are not
stretched or exercised. Aging
affects tissues to the extent that flexibility is decreased. This gradual shift toward increased
stiffness can be countered by remaining active and working on flexibility. The goal of any flexibility program is
to improve the joint ROM by improving muscle extensibility. In addition, flexibility can be affected
by joint laxity (looseness). Each of these elements is separate. Individuals with joint laxity may have
poor musculotendinous extensibility (muscle stiffness).
Strength and stretching: Most studies have found acute decreases
in strength following stretching.
This finding is more prominent the longer the stretching protocol or the
higher the number of exercises and sets. Overall performance seems to be
minimally reduced in studies compared to strength loss. For instance, jumping ability is a
measure of performance while weight moved with a single leg press is a measure
of strength. Studies have
demonstrated minor reduction in jumping compared to larger loss in weight moved
with a single leg press with stretching. Thus, in strength-dependent activity,
stretching may actually have a negative acute effect such as in maximum effort
endeavors like single repetition maximal lifts. Preservation of performance may be due to
the practice of mixing in warm up with stretching. In addition, strength and performance
may actually be separate entities with unique features and distinctions.
Reviews of stretching routines have suggested that they
do not protect against injury, especially due to overuse, but may help prevent
Chronic stretching on strength performance has been
looked at as well. Over time,
flexibility improves with chronic stretching routines as has improvements in
strength. The key difference
between these seemingly contradictory findings is acute vs. chronic stretching
What could be happening?
Electrical activity in the muscle and tendon receptors
is affected by stretching. This
change in neuromuscular activity may lead to changes in muscular activity and
Improved tolerance to stretching has been identified as
a benefit of stretching.
Rather than promoting increased elasticity in the muscle itself, the
benefit seems to come from changes in how the neural receptors in the muscle,
joint, and tendon operate in the stretched muscle. The stretched muscles have a reduction
in sensitivity which allows for smoother functioning.
Stretching may alter the properties of the muscular and
tendinous structures making them more elastic and less viscous. Stretching may, therefore, lead to a
decrease in viscosity acutely, which can allow the muscle fibers to slide with
less resistance to movement. This
can lead to increased compliance (stretchiness) that may lead to decreased
ability of the muscle to produce force.
Cellular adaptations from stretching may include
increased muscle cell formation, a finding seen in animal studies. Whether increased muscle cell formation
has a positive effect on strength in this instance is not known.
Finally, certain hormonal changes take place with
stretching such as an increase in the production of insulin-like growth factor
that can lead to muscle development.
Flexibility and strength are fundamental fitness
components in many sports. Strength
performance may be diminished by a preceding stretching routine. Studies of acute exercise programs
include routines that are often much longer in duration and include a greater
number of sets than are traditionally practiced and recommended. Further studies with more realistic
designs are needed. In addition,
many of the studies include very few subjects calling into question the
validity of the results.
Chronic stretching routines seem to offer a benefit to
participants with maintenance of flexibility and strength. This may be due in part to actual
changes in anatomy allowing for improved ROM or an increased tolerance to pain
allowing for a greater ROM closer to the maximal limit of the stretched structures.
Pre-exercise stretching leads to a decrease in the
ability to generate a maximal force.
These effects are less apparent when combined with other pre-swimming
activities typically used in a warm-up such as drills or low intensity movements.
Stretching may reduce the incidence of muscle strains
but will not have an impact on injury risk due to overuse injuries.
Based on the existing literature it seems reasonable to
Target pre-participation stretching to
muscle groups known to be at risk for a particular sport.
Apply 4-5 x 60 sec stretches to pain
tolerance to the target muscle groups and perform bilaterally
Perform some dynamic pre-participation
drills before actual performance