Sports Medicine

SportsMedicine
ttGreatinett
PennyHeyns usesit and she is a good,
clean-livingyoung ladywho has recently
set a spate of world records.
Manyofthe top rugbyand soccer playersrole models to our sporting school
children- use it and extol its virtues. lt
has been dubbed as "Nature's own
anabolicsteroid"; is freely availableand
"without any known side effects".
ls it the ultimate panaceaand sports
supplement?Shouldnt we all be usingit?
How canyou as a sportsperson compete
if you dont use it when your competitors
are doing so?
I havetried to make some senseof the
articles below and the following is a
distillationof this bibliography.
What is creatineand what does it do?
C r e a t i n e i s a p h y s i o l o g i c a l l ya c t i v e
s u b s t a n c ei n d i s p e n s i b l et o m u s c l e
contraction. In the form of creatine
phosphate it is an important store of
energy in musclecells.
.
Our knowledgeconcerningcreatine
dates back to | 835.
. lt is synthesizedfrom amino acids
glycine,arginineand methioninein
the kidneys,liver and pancreas.
. lt is predominantlyfound in the
skeletal muscle- approx 40% in the
free form and 60% as creatine
phosphate.
. Daily turnover is approximately 29
both
from
ingestion and
endogenous
synthesis.
.
.
ingestand this providesthe energy that
keeps our engineticking over. Muscle
tissue converts chemicallybound
energyto kinetic energywhich is used
in musclecontraction.
l. The immediateenergy system or
the ATP- Creatine phosphate
enerSy sysrem
2 The Short term or lactic acid /
anaerobicsystemand
3. The aerobic systemor the
longterm system
Which system is used depends upon
the intensity and duration of the
exercise.
products-fish and meat.
Oral creatinesupplements
are
T M M E D | A TEEN E R G Y( A T P- C P
ingestedas creatinemonohydrate. system)
We require energyto makeour heart
beat,ourbrainsfunctionandour muscles
workAll our chemical
proceeses
require
energy.Our body hasto transformthe
foodwe eatintoa useable
form of energy.
Physical
activitydemandsa greatamount
of energy.
Thisdemandcanbe upto 120
timeshigherthanat restinglevels.
Our sourceof energyis food that we
Creatine phosphate comes into play
for immediate energy needs and
provides the energy for the first few
seconds.
The Primary source of energy exists
in the form of AdenosineTriphosphate Thus it is important in sprintingand
(ATP).Thisenergy is releasedwhenATP power events.
is hydrolysed to
Adenosine
D i p h o s p h a t e ( A D P ) a n d i n o r g a n i c SHORTTERM ENERGY (LacticAcid
phosphateat the cross bridgesof the
System)
myofibrillar proteins in the actomyocin
complex.
For exerciseto continue beyonda brief
ATP is constantly being used up and period of time, high-energyphosphates
replenishedby the energy systemsin must be continuallyresynthesised.
This
our body.
energy comes from the glucoseand
stored glycogen during the anaerobic
E n e r g y u t i l i s a t i o ni n t h e b o d y i s v i a processof glycolysiswith the resultant
aerobic or anaerobicmetabolism.
formation of lactic acid. During
glycolysisthe energy releasedis rapid
There are broodly speoking three
and does not requireoxygen,but little
energy systerns in the body:
ATP is resynthesised.
The major sourcesof chemicalenergy
f o r A T P r e s y n t h e s i sa r e l i p i d s a n d
Dietaryintakeismainlyfrom animal carbohydrates.
PHYSIOLOGY
energyfor a short duration.
LONG TERM ENERGY (Aerobic
System)
Aerobic reactions provide the final
important stagefor energy transfer.
THE ENERGY SPECTRUMOF
EXERCISE
During strengthand power sprint
activities,
the primaryenergytransfer
involves
the immediate
andshoft term
energysystems.
The long-termaerobic
energysystembecomesprogressively
more important in activitieslasting
longerthan2 minutes.
Duringintenseexercise
of +l-2 minutes
Short duration exerciseand exercise (e.g.sprinting)
we usethe:
requiring brief maximal effort, requires
l. lmmediate
and
an immediatesupply of energy which 2. Shortterm energysystems.
is obtained almost exclusivelyfrom the
high energy phosphates(ATP and CP)
stored in the muscles.
At the initiationof movement- stored
phosphates
(ATPand CP) provide
immediate energy for muscle
contraction.
We have stores for approximately one
minute of brisk walkingor sprintingfor
s i x s e c o n d s . T h e q u a n t i t y o f i n t r a - Halfof the energyisobtainedfromthe
muscularphosphatesmay significantly ATP-CPsystemand half from the
influencethe ability to generateintense anaerobicsystem.
I n t e r m e d i a t e e x e r c i s e so f 5 t o l 0
minutes (eg. soccer,basket-ball)- the
e n e r g y i s s u p p l i e dm a i n l y f r o m t h e
anaerobic reactions.
How does creatinework?
Side effects:
.
.
.
Long duration exercises(eg.marathon
running)- mainlyaerobicenergy,with
.
minimallacticacid production.
.
For example,the percentageof energy
contributed to ATP generationin the
following eventshasbeen estimatedas
the following:
l t w o r k s b y i n c r e a s i n gm u s c l e
creatineand phosphocreatine.
This leads to a higher rate of ATP
resynthesis.
This results in a delay in onset of
muscularfatigue.
lt facilitates recovery during
repeated bouts of high intensity
exercise.
Creatine improves strength by
i n c r e a s i n gm y o f i b r i l l a r p r o t e i n
synthesis.
Resistancetraining and longterm
creatine supplementation =
increased muscle creatine =
.
Increasein massin short-term,
possiblydue to water retention
( | -2kg).
Minor gastrointestinalupset.
Safety:
It does not appear to have any effect
o n t h e k i d n e y ,o r h a e m a t o l o g i c a l
.
parameters in healthy subjects.
Peoplewith preexistingrenalconditions
may be at risk for deterioration of renal
.
function.
Event lmmediate Short
Long
No long-term studies are as yet
a v a i l a b l ea n d m o s t a u t h o r s a d v i s e
| 00m
s0%
50%
increasedtraining intensity,greater caution. However creatine has been
*
t r a i n i n g s t i m u l u s = i m p r o v e d used as a nutritinal supplementfor l0
5000m
12J% 87J%
p h y s i o l o g i c a lr e s p o n s e - t r a i n i n g years or more, and as yet there are no
effect.
documented long-term significant sideSoccer
t0%
70%
20%
effects
There are anecdotal reDorts of other
+ Creatinephosphateis usedin the first Ergogenic effects of Creatine
side-effects,such as cramping and a
few seconds and if it has been
greater incidenceof musclestrains,but
resynthesisedduring the race,in the . l t i m p r o v e s p e r f o r m a n c e i n
these have not been adequately
sprint to the finish.
repeatedsprints.
documented.
. Single competition events do not
It is not recommendedfor adolescents,
seem to benefit.
but the basisfor this recommendation
HENCEWECAN SEETHATTHE
USE
l m p r o v e s p e r f o r m a n c e i n h i g h appearsto be more that there havenot
O F C R E A T I NSEH O U L DI N F L U intensityshort term exercisetasks been any long-termstudiesperformed
E N C ET H E I M M E D I A TEEN E R G Y that are dependentprimarily upon i n t h i s g r o u p , r a t h e r t h a n a n y
TRANSFER
SYSTEM
andthisseemsto
creatine i.e. less than 30 seconds, detrimental effectsreported in this age
grouP.
correlate with findingsin research.
e s p e c i a l l yw h e r e r e c o v e r y t i m e
between bouts of exerciseis limited.
The rationale behind the use of
e . g . c y c l i n g , s p r i n t i n g s, w i m m i n g , Dosages;
creatinesupplementationis:
kayaking,
lumpingand weightlifting.
An improved capacity for energy
lmproves work performance.
59 of creatine monohydrate increases
transfer usually translates into
lmproves power and strength.
b l o o d c r e a t i n e l e v e l sn e a r l y l 0 - f o l d .
improved exercise performance. As
No
ergogenic effects on
Ingesting59 4-5 times daily over 5-7
p h o s p h o c r e a t i n es t o r e s b e c o m e
s u b m a x i m a lo r e n d u r a n c es p o r t s days increasesuptake of creatine into
depleted,outputpower is reduced as
have been recorded.
muscleby as much as 30%.
ATP cannot be regenerated fast
I n c r e a s e st i m e t o f a t i g u e , a n d
Lower dosesof 3g per dayalso increase
enough.Thisresultsin musclefatigue.
maximal strength in large muscle m u s c l e c r e a t i n e ,b u t g r a d u a l l yo v e r
lf ingestingcreatinecan improveenergy
weeks.Hence,loadingdosesare usually
8rouP.
Enhancesmaximal strength,body
transfer, exercise performance will
used for 5 -7 days at 59 4 times a day,
improve.
mass,fat free mass.
or at 0.25-O.3 g per kg in divideddoses.
enhances This is followed by maintenancedoses
Creatinesupplementation
What is known?
musclemorphology when usedwith
of 3 - 6 g daily. Ingestion of a
heavyresistancetraining.
carbohydratesolutionwith the creatine
Training does not appear to affect
Increasesareas of muscle fibre in
improves the variability of uptake.
c r e a t i n e l e v e l s i n t h e m u s c l e s ,b u t
men.
Normal concentrationsof creatine in
supplemenation does increase
Not all studiesshow benefits.
skeletalmuscleare l20mmol/kg(range
There can be marked individual
concentrations of free creatine and
I l0- l50mmol/lg).
creatinephosphate.
variation.
The upper limit of creatineaccumulation
is approx 155-l60mmol/lg.
Dosages vary and many different
dosage regimens have been tried and
a r e b e i n g s t u d i e d .A f a i r l y c o m m o n
dosagescheduleappearsto be 20-259
per day daily loadingdose for 5-7 days,
followed by a continuousmaintenance
dose of 59 a day
In summary;
.
Creatine does help power and
immediate energy supply.
.- lt appearssafe.
. lt appears most useful where
repeated short sprints or powertype energy reqirements are
required.
. Individualresponsevaries gready.
There seem to be responders and
non-responders.
. S i d e - e f f e c t sa p p e a r t o b e o n l y
short-term weight gain due to fluid
retention.
. Elite athletes could benefit from
creatine becauseof the increased
ability to perform repeated highintensity exercise bouts, either
during trainingor competition.
. In adults, if you can afford it, it
appearsto do good with no harm.
. lt is also currently a legal
supplement.
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recharîs'ns
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