Hi Guys,
There has just been a research study done in Australia by an
army physiotherapist who looked at stretching v's non stretching
prior to exercise, and its effect on calf muscle injuries in army
recruits.  I'm unsure as to the efficacy of the design of the study
as the results are yet to be published, although I believe they will
soon be in the AJSM.  He found that there was no difference in
injury between the groups.  (the guys name is Rod Pope if you want
to do a literature search).
An interesting comment was made about this in one of our newsletters
by a trainer of Queensland's Rugby Union team.  He said he doesn't
do stretching with the players prior to the game becasue he believes
that it induces a degree of relaxation.  He does an active warm up and
incorporates stretching into the teams day to day program.

Scott Epsley
Physiotherapist, Brisbane, Australia.
--

On Fri, 17 Dec 1999 14:06:43   saspinall wrote:
>
>----- Original Message -----
>From: Tobias Sundberg <[log in to unmask]>
>To: List - Physio; Inldgg <[log in to unmask]>
>Sent: Thursday, December 16, 1999 9:56 PM
>Subject: warm-up effects
>
>
>> Dear listers,
>>
>> Is there anyone out there aware of any scientific studies on the effects
>of various warm up procedures on physical performance (spec. related to
>short term bouts of exercises like jumping, weight lifting, sprint running
>etc.). I have used on-line internet search engines and PubMed/Medline with
>little result. Funny thing is that allmost every sports medicine textbook
>claim the enhancing effects of a warm-up, but I have yet to see specific
>references to back that up! Any thoughts on resources/references/other?
>Thanks you for your time.
>>
>> Sincerely,
>>
>> Tobias
>>
>>
>> --------------------------------------------
>> Tobias Sundberg, PT
>> [log in to unmask]
>> --------------------------------------------
>
>Hi Tobias,
>
>Just a few thoughts on warming up. As you say there's not much research to
>exactly quantify the effects of warming up on performance but here's a few
>points you may already know:
>
>A rise in muscle temperature increases the conduction velocity across the
>sarcolemma which increases the frequency of stimulation and hence the
>production of muscle force (Phillips, C .A, and Petrofsky, J. S.:Mechanics
>of Skeletal and Cardiac Muscle. Springfield, IL, Charles C Thomas, 1983).
>Increased temperature also causes greater enzymatic activity which further
>increases muscular efficiency (Frankel .V .H and Mordin. 1989. Basic
>Biomechanics of the Musculoskeletal System. USA. Lippincott Williams and
>Wilkins.) Collagens elasticity also improves as temperature rises, leading
>to greater extensibility and  greater possible prestretch and hence possible
>force production of a muscle. This positive effect on the collagen and
>elastin units to deform will also reduce the chance of injury due to violent
>overstretching. Another couple of references that may be worth looking at
>are:1) Shellock, F. and Prentice, W. E. 1985. Warm up and stretching for
>improved physical performance and prevention of sport related injury. Sports
>Med 2:267-78.    2) Safran, M. R., et al: The role of warm up in muscular
>injury prevention. Am. J. Sports Med., 16:123,1988.
>
>A quick summary of basic physiological considerations, increased muscle core
>temp and blood flow can lead to:
>
>Increased speed of contraction and relaxation of muscles.
>Lower friction resistance within muscles and joints hence greater economy of
>movement.
>Increased/more efficient oxygen utilization as hemoglobin releases oxygen
>more readily at higher temps.
>Improved muscle metabolism and nerve transmission.
>Increased blood flow through active tissues which increases delivery of
>oxygen and nutrients and the removal of wastes.
>
>
>A number of studies have evaluated the cardivascular response to strenuous
>exercise both with and without a warm up. One study clearly demonstrated an
>improved ECG and blood pressure response in the warm up group compared to
>the immediate strenuous exercise group (Bernard, R.J., et al.: Ischemic
>response to sudden strenuous exercise in healthy men. Circulation, 48:936,
>1973).
>
>There are also psychological considerations where pre practice of skills can
>enhance co-ordination and accuracy (although I don't have any research to
>hand I'm sure Schmidt or Singer have done plenty of research on this). It
>may also be worth considering that an athlete who has warmed up gradually
>may feel more ready to commit to maximal exertion than an athlete who
>launches straight into maximal exertion without a warm up (From a personal
>perspective, when I'm training I'm fairly sure that I couldn't perform at my
>maximum level instantaneously without a warm up, although this may come from
>my pre-programming that tells me that I need to warm up gradually, there
>again I think most athletes will also have this pre-programming).
>
>When I was rooting around in the library the other day I came across a
>recent article on the scientific research behind warming up, unfortunately I
>can't remember which journal, but if you have access to them it may be worth
>having a glance at the contents of The Canadian Journal of Applied
>Physiology, The Journal of Strength and Conditioning and the NSCA Journal of
>applied Biomechanics (I'm not sure if this is the correct title but it is
>definately the journal of the NSCA).
>
>In view of the above, is it worth not doing an appropriate and specific warm
>up??? Regardless of the fact that performance increases have not been
>quantified and isolated due to the warm up alone.
>
>
>Hope this is some use,
>
>Steve Aspinall.
>
>


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