Ballistic Stretching
What is Ballistic Stretching?
How Does this Form of Stretching Exercise affect Tendons?
How can a Stretching Exercise Prevent Tendon Injuries?
Elasticity of Tendons.
Tight Hamstrings.
Will Stretching Ballistically Improve Performance?
A Definition
This
type of stretching exercise involves bouncing into a range when the
muscle is not prepared or relaxed such that it can enter that range.
This exercise can be dangerous if done without supervision or training
by a professional.
Stretching to improve flexibility is a
common practice amongst athletes both recreational and competitive.
There are many studies that show joint range of motion improves with
stretching exercises and many have looked at the different types of
stretching. But, stretching doesn't just affect the muscle, it can
affect the tendons as well.
How Does This Affect Tendons?
Muscles and tendons behave differently depending on what type of sport
is taking place. The musculotendinous unit can create forces in two
different ways:
- Jumping requires the tendon to perform as an elastic, shortening, An eccentric contraction is immediately followed by a concentric contraction. The muscle is forced to lengthen while working and then suddenly shorten.
- Swimming or cycling requires the direct conversion of biochemical energy into mechanical energy through primarily concentric contraction.
We know
that if a muscle is stretched immediately before it is shortened
concentrically, that the force generated is greater than a concentric
contraction alone. This is the result of energy being stored in the
elastic noncontractile elements of a musculotendinous unit. The
noncontractile, elastic component consists of the tendon, aponeurosis,
epi, endo, and perimysium, and other proteins at the level of the
sarcomere. The elastic structures store energy from mechanical work
during the eccentric contractions.
On the other hand, a more
rigid tendon will more efficiently transfer force from the muscle to
the bone and energy from metabolism will more efficiently be converted
into mechanical work. So, activities such as swimming and cycling would
benefit from more rigid tendons.
Tendons of those involved in
jumping sports need a high capacity to store potential energy in the
musculotendinous unit and therefore benefit from a more elastic tendon.
How can Ballistic Stretching prevent Tendon Injuries?
Tendon injuries occur in every sport, but more frequently in those
sports that require the eccentric contractions quickly followed by the
concentric contractions. (ie jumping) The more frequent these
movements, the higher the incidence of tendon injuries.(1,2)
Clearly individuals with a more compliant and elastic tendon would have less injuries.
Ballistic Stretching and the Elasticity of Tendons
Animal studies have shown that the elasticity of tendons can be changed
through stretching and human studies have shown that repetitive
stretches increase hamstring compliance. Stretching changes the
viscoelastic properties of the the musculotendinous unit.(3,4)
Research using
Achilles tendons shows us that this type of stretching exercise will
result in a significant reduction in Achilles stiffness; however,
static stretching of the Achilles had no effect on Achilles tendon
stiffness suggesting that both types of stretching could be beneficial
in terms of training and physical therapy. (5)
It is likely
that there is adaptation of the collagen fibers within the connective
tissues of the musculotendinous unit due to the stretches. During this
type of stretching exercise, because the muscle is contracted, a
greater force is transmitted through the tendon since the muscle is
stiffer.
Ballistic Stretching and Tight Hamstrings
A comparative study involving the stretching of hamstrings in 40 individuals between the age of 20 and 40 with tight hamstrings was done in 2010 and published in the British Journal of Sports Medicine. (4) Static stretching of hamstrings was compared to ballistic stretching over the course of six weeks. Results showed that after six weeks in this population ballistic stretching was better than static stretching in improving flexibility of the hamstrings.
Will Ballistic Stretching Improve Performance?
While this type of stretching exercise can improve tendon elasticity,
there doesn't appear to be much evidence that if used prior to a
competition it will improve performance. Results of much research has
shown negative effects of static and proprioceptive neuromuscular
facilitative stretching prior to competition.
A study was
published in the Journal of Strength and Conditioning Research that
compared ballistic stretching to dynamic stretching in terms of jump
height, force produced, and jump power. (6) 20 healthy male and female
individuals between the age of 22 and 34 took part in a daily program
of ballistic stretching and a program of dynamic stretching and were
compared to a group that didn't stretch. Results showed that neither
dynamic nor ballistic stretching resulted in increased vertical jump
height, or force. Dynamic stretching did however improve jump power
post stretch. (The force was generated more quickly)
1. Jozsa L, Kvist M, Balint JB, et al. The role of recreational sport
activity in Achilles tendon rupture: a clinical , pathoanatomical and
sociological study of 292 cases. Am J Sports Med 1989;17:338–43.
2.
Lian O, Engebretsen L, Bahr R. Prevalence of jumper’s knee among elite
athletes from different sports: a cross-sectional study. Am J Sports
Med 2005;33:561–7.
3. Viidik A. Tensile strength properties of
Achilles tendon systems in trained and untrained rabbits. Acta
Orthopaedica Scandinavica 1969;40:261–72
4. C K Kishore
Kumar1, Surajeet Chakrabarty A comparative study of static stretching
versus ball istic stretching on the flexibility of the hamstring
muscles of athletes Br J Sports Med 2010;44
5.
Mahieu N, McNair P, De Muynck M, et al. Effect of static and ballistic
stretchingon the muscle-tendon tissue properties. Med Sci Sports Ex,
2007.
6. Jaggers JR, Swank AM, Frost KL, Lee CD. The acute
effects of dynamic and ball. stretching on vertical jump height, force,
and power. J Strength Cond Res. 2008 Nov;22(6):1844-9.