Dynamic Stretching
Dynamic stretching, as the name implies, involves movement and muscular effort for the stretch to occur. While static stretching takes a muscle to its full length and holds it there for 15 to 60 seconds, a dynamic stretch takes soft tissues to their full length and rather than holding it, after a brief pause of 3 to five seconds, the muscle being stretched contracts and the muscles and tendons exert a force in that lengthened position. In this way we can lengthen the muscle, strengthen it in its new range, and also work on balance and coordination. It also provides a good warmup before a sport or activity. Dynamic stretching exercises have been shown to improve performance when done before an activity that requires a lot of power, strength or speed.
All movements during a dynamic stretch are done deliberately and slowly
so as to avoid activating the stretch reflex at the end of the movement
and movements used are those that mimic those movements used in a
specific sport but in a controlled yet exaggerated manner.
What is involved?
What are the benefits?
Using this stretching exercise as part of a warm up.
How do I start a this kind of stretching program?
Dynamic and Static stretching exercises prior to running?
What is an example?
The effect of a stretch on previously injured athletes
Dynamic vs Static stretching on Hamstring Flexibility
Does this method of stretching prevent injury?
What is involved in performing a dynamic stretch?
This type of stretch starts from the joint's neutral position. A slow movement occurs in the limb to its end range, and then slowly returning to the neutral position with an eccentric contraction. This contraction by the antagonist muscle allows the lengthening muscle to relax by reciprocal inhibition.
What are the benefits?
- Increased power
- Increased endurance
- Improved coordination
- Muscle stretching
- Improved balance
- More efficient neuromuscular activation
- Increased speed of contraction
- Improvements in mental preparedness
As Part of a Warm Up
It is important to warm up
appropriately and efficiently prior to activity in order to prevent
injuries. Stretching that includes movement patterns that are involved
in the sport will help to prevent injury as the body is prepared for
the movements and ranges necessary for the sport. This cannot be
achieved with static stretching.
The warm up period prior to
a practice is an important part of training. Many athletes don't
understand the purpose of the warm up and therefore find it boring.
Half hearted unsupervised attempts at warm up lead to more injuries on
the field.
This type of stretching exercises are functional
exercises using sport specific movements that cater to the needs of a
particular athlete. Warm up programs incorporating this type of
stretching exercise are designed by analyzing movements occurring
during a given sport and using those movements to improve flexibility
and the necessary balance for that sport. Stretching is useful for
learning sport specific movements that the athletes need during a
competition.
Studies have shown significant improvement in
vertical jump height after this type of stretching exercises. Static
stretching on the other hand affected vertical jump height
negatively.(1) Any number of reasons could be responsible for this
difference: increased muscle temperature increases neural drive,
improved efficiency of contraction, and increased responsiveness of
motor units of the muscle. Movements are rehearsed during a dynamic
stretch also improving efficiency of movement. Static stretching
increases muscle compliance which affects its ability to store elastic
energy which would in turn diminish force generated.
How do I Start a Dynamic Stretching Program?
When beginning a program it is
important to start at your appropriate level of intensity. The
intensity is determined by the following factors:
- the range of motion
- the speed of the movement
- the force generated during the movement
- the number of stretches
- total time stretched
When you first begin, you should start with short, slower movements,
that don't require a lot of force. A light aerobic activity for five
to ten minutes will get blood circulating and increase your body
temperature. Increases in particular muscle temperature will depend on
the aerobic activity chosen. For example running is more likely to
increase calf muscle temperature than it is hamstring muscle
temperature.
If the intensity of stretching is increased too
rapidly it increases your risk of injury, so be sure to increase
intensity by no more than five to ten percent per week.
Should I Perform Dynamic or Static Stretching?
What type of stretching exercises your do really depends on your goals.
There is a good study that compared a dynamic method of stretching to
static stretching in runners (2). This study showed that the dynamic
method performed immediately prior to running, improved running speed
in a way that was superior to static stretching. However, if the goal
is to increase range of motion, the dynamic method increased range less
than static stretching. In this study by Bandy and Briggler(3) the
dynamic method used was shown to increase range by 4.3 percent whereas
static stretching increased range by 11.4%.
There is room for
both dynamic and static stretching in a training regimen. Static
stretching to improve and maintain mobility, dynamic to prepare for a
sport and improve power.
Examples
These are similar to static
stretches in that they often incorporate the same body position but are
followed or preceded by some sort of movement. Instead of holding a
calf stretch for 15 to 60 seconds, the dynamic method of stretching the
calf would be to walk on ones toes for 20 m forward and backward, and
then walk on one's heels 20 m. This can be progressed to include a heel
to toe walk and at quicker paces.
The Effects on Previously Injured Athletes
A study published in BMC
Musculoskeletal Disorders in 2009 (4) examined the effects of a 3 30
second static stretch after a warmup period and 3 30second bouts of
dynamic stretching after a warmup period, and warmup alone over the
short term in 18 individuals who had previously injured their
hamstrings and 18 uninjured controls. Range of motion was measured
immediately after the stretches and then again at 15 minutes
post-stretch.
Results were as follows:
- range of motion increased significantly with warmup.
- Range of motion significantly increased after static stretching.
- range of motion decreased significantly in the dynamic stretching group over time.
- The increase in range in the static stretching group decreased significantly after the 15 minutes of rest but remained significantly better than original baseline measurement.
- The group tested that had a previous hamstring injury responded slightly better to the warmup and static stretching than the uninjured group but this difference was not statistically significant.
Dynamic Stretching vs Static Stretching on Hamstring Flexibility
A study published in the Journal of
Orthopaedic and Sports Physical Therapy (5) compared the effects of
dynamic stretching, static stretching and no stretching on knee
extension range of motion to measure hamstring flexibility. This study
used 58 individuals between the age of 21 and 41 with tight hamstrings.
The following protocol was performed over six weeks.
- One group performed dynamic stretching five days a week by lying on their back with hip at 90 degrees. The individual then straightened their knee over five seconds, held the knee straight for five seconds and then took five seconds to lower the leg. This was repeated six times for a total stretch time of 30 seconds.
- The other group performed a 30 second static stretch once a day for five days.
- The control group did not stretch.
Results were as follows:
- Both static stretching and dynamic stretching increases hamstring flexibility.
- A 30 second static stretch is more effective than 30 seconds of dynamic stretching in increasing hamstring flexibility.
- A 30 second static stretch over 6 weeks resulted in more than 2 times the gain in range of motion compared to dynamic stretching.
Injury Prevention?
According
to a study done in 1999 (6) a dynamic warmup prior to an explosive
activity will reduce the likelihood of sustaining an injury.
- This is probably because the dynamic stretching will permit muscles to tolerate the stresses of the particular sport with less strain.
- The specific dynamic stretches used will prepare the central nervous system for necessary activation of motor units and the necessary coordination.
- Rates of injury may be less because practicing the movement patterns will help eliminate the awkward and inefficient movements.
1. L Parsons, N Maxwell, C Elniff , M Jacka, N Heerschee. Static vs.
dynamic stretching on vertical jump and standing long jump. Department
of Physical Therapy, Wichita State University, Wichita, Kansas 67260,
U.S.A.
2. T Little, AJ Williams. Effects of differential stretching protocols
during warm-ups on high speed motor capacities in professional
footballers (submitted).
3. WD Bandy, JM Irion, M Briggler. The effect of static stretch and
dynamic range of motion training on the flexibility of the hamstring
muscles. J
Orthop Sports Phys Ther. 1998;27:295–300.
4. K O'Sullivan, E Murray, D Sainsbury. The effect of warm-up, static
stretching and dynamic stretching on hamstring flexibility in
previously injured subjects. BMC Musculoskelet Disord. 2009; 10: 37.
5. WD Bandy, PhD, PT, SCS, ATC lM Irion, MEd, PT, SCS, ATCZ M Briggler,
MS, PT3. The Effect of Static Stretch and Dynamic Range of Motion
Training on the Flexibility of the Hamstring Muscles. J Orthop Sports
Phys Ther. 1998;27(4):295-300
6. B Gesztesi. Stretching during exercise. Strength and Conditioning Journal, 1999;21(6),44.