the muscular damage is described as a condition which results in exhaustion , fatigue , loss 
 of power and pain after heavy exercises1 . 

this is 
 termed as micro trauma , micro injury or muscular damage in the literature2 .
different type of exercises cause pain in 
 different degree and they have different effects on the muscular damage3 .
strenuous and unaccustomed exercise can induce skeletal 
 muscle damage and this is particularly true of exercise including eccentric contraction4 .
although muscular damage is closely related 
 to the intensity of the exercise , unfamiliar exercises can cause muscular damage 
 frequently5,6,7 . increased activity of ck and ldh may occur in serum in healthy subjects after exercising 
 and serves as a marker of injury to skeletal muscle , where the degree of biochemical 
 abnormality reflects the extent of tissue injury . due to the nature of the orienteering 
 competitions which take place on both flat and rough surfaces ( downwards and uphill ) the 
 muscles
downwards the muscles are mainly subjected to eccentric contraction which cause more 
 muscular damage compared with the runs on flat surfaces where the muscles are subjected to 
 both eccentric and concentric contractions8 .
athletes loose water and electrolyte by sweat and consume a lot of energy during training 
 and competition periods .
the loss of even 2% of liquid as a result of training or a mild 
 dehydration may cause a significant decrease in their performance .
as the body is 
 dehydrated , the blood volume and the amount of sweat formation decrease and body temperature 
 increases . in order to compensate this excessive temperature , the body needs to work much 
 harder to support the blood circulation and produce more sweat .
the loss of essential 
 electrolytes of sodium and potassium salts causes complications such as muscle cramps , 
 fatigue and exhaustion and headaches . by the help of appropriate drink ,
the sports drinks were developed 
 to replace the liquid , electrolyte and energy lost during the training period .
the isotonic 
 drink quickly replaces the liquid lost by sweat and provides carbohydrate needed9 .
based on all this information , the aim of 
 the study is to determine the effects of the intake of the isotonic sports drink on the 
 level of the skeletal muscle damage of orienteering athletes .
the study was practiced on 21 male elite orienteering athletes who had at least two years 
 of sporting life .
the participants are divided into two groups as the experimental ( n=11 ) 
 and placebo group ( n=10 ) ( table 1table 1.the physical properties of placebo and experimental groupsgroupsage ( years)body height ( cm)body weight ( kg)bmi ( kg / m)body fat percentage ( % ) placebo15.7  2.2161.8  8.050.0  6.719.0  1.516.6  7.1experimental15.4  2.2160.1  9.648.4  7.118.8  1.615.5  7.7 ) .
four different 15 cc venous blood samples were taken from the athletes 
 pre - competition ( pre - c ) , post - competition ( post - c ) , 2 hours post - competition ( 2 hr post - c ) 
 and 24 hours post - competition ( 24 hr post - c ) .
the blood samples were first centrifuged at a 
 rate of 5,000 revolution / minute and the upper phases were transferred to eppendorf tubes and 
 kept at 80  c until the use .
the serum levels of troponin , myoglobin were determined by 
 immunoassay method using original beckman coulter kits in an au2700 auto analyzer , ck and 
 ldh enzyme levels were assayed by calorimetric method using beckman coulter kits in an 
 au2700 auto analyzer . after taking their first blood samples during the resting period
the first group was given the isotonic 
 drink ( in 500  ml water 137  kcal , 32 gr carbohydrate ( isomoltulose ) , 120  mg calcium , 248  mg 
 chloride , 230  mg sodium ) .
the second group chosen as the placebo group was given 500  ml pure 
 water in dark colored bottles .
since the participants were in the same camp they were 
 subjected to the same diet .
the competition was carried out an advanced 712  km long blue 
 tract with a target number of 20 and an estimated completion time of 6080 minutes10 , 11 .
the participants were given detailed information about the 
 objectives of the study in accordance to the helsinki medical declaration and they gave 
 their full content .
this study was carried out according to the approval of non enterprising 
 ethical committee ( decision number of 2015/3 ) . because the volume of the samples was less than n=30 the non - parametric test was employed . 

the measurement carried out unrelated to the non - parametric test for comparisons between the 
 groups were made by using mann whitney u - test ( mann whitney u - test for independent samples ) . 

the comparisons between the groups were made by using wilcoxon signed rank test for paired 
 samples .
all of variable levels were similar for both groups ( p>0.05 ) expect that it was founded 
 significantly different for 2 hr post - c myoglobin values ( p<0.05 ) ( table 2table 2.comparison of the serum troponin ( ng / ml ) , myoglobin ( ng / ml ) , ck ( u / l ) and ldh 
 ( u / l ) concentrations levels at time durationsvariablegroupsprepost2 hr24 hrcompetitioncompetitionpost - competitionpost - competitiontroponin ( ng / ml)placebo0.005  0.0010.008  0.003 * 0.040  0.055 * 0.007  0.006experimental0.005  0.0020.007  0.002 * 0.038  0.034 * 0.010  0.008*myoglobin ( ng / ml)placebo30.2  13.486.9  44.9 * 73.7  20.8 * 21.99  2.3experimental 24.9  5.561.0  34.6 * 50.2  29.7 * 51.58  19.3ck ( u / l)placebo259.1  83.6348.9  155.9 * 368.3  132.5 * 285.0  89.5experimental213.1  104.5267.9  127.4 * 273.1  136.5 * 233.3  101.1ldh ( u / l)placebo222.5  27.5233.5  19.1217.2  33.3215.5 
pre - c serum troponin level significantly different from post - c and 2 hr post - c values for 
 the placebo group ( p<0.05 ) .
2 hr troponin level significantly different from post - c and 
 24 hr post - c values ( p<0.05 ) .
post - c and 2 hr post - c myoglobin values were higher than 
 pre - c serum level for the placebo group ( p<0.05 ) .
24 hr myoglobin level was found 
 significantly lower than post - c and 2 hr post - c values ( p<0.05 ) . pre - c serum ck level 
 significantly different from post - c and 2 hr post - c values for the placebo group 
 ( p<0.05 ) .
24 hr ck level was found significantly lower than post - c and 2 hr post - c 
 values .
there were no differences between in other values ( p>0.05 ) ( table 2 ) .
pre - c serum troponin level was significantly lower than post - c , 2 hr post - c and 24 hr 
 post - c values for the experimental group ( p<0.05 ) .
2 hr troponin level was significantly 
 different from post - c and 24 hr post - c values ( p<0.05 ) .
pre - c serum myoglobin level was 
 significantly lower than post - c and 2 hr post - c myoglobin values for the experimental group 
 ( p<0.05 ) .
pre - c serum ck level was significantly lower than post - c and 2 hr post - c ck 
 values for the experimental group ( p<0.05 ) .
there were no differences between other 
 values ( p>0.05 ) ( table 2 ) .
schwane et al . investigated the relation between the muscle damage and plasma activities of 
 ck and ldh of seven athletes
the 
 athletes were asked to run first on a flat surface then on a surface with % 10 inclination . 
 following downhill running ( 57% of vo2max ) ,
significant delayed - onset soreness was 
 experienced in gluteal , quadriceps , anterior leg , and posterior leg muscles , and plasma cpk 
 ( but not ldh ) activity was significantly increased ( 351% at 24 h ) . in contrast , following a 
 78% of vo2max running , no statistically significant soreness occurred in any muscle group , 
 and plasma cpk and ldh activities were not elevated12 . another important factor regarding athletes
the increased need of liquid and decrease in sodium intake and the 
 marginal insufficiency of the calcium , potassium and magnesium may result in a decline in 
 the performance .
it is stated that the intake of drinks before , during and after the 
 competition within appropriate protocols would obviate the decrease in the performance of 
 athletes13 , 14 .
the main functions of water in relation to physical activity are 
 to carry oxygen to tissues , hormones and nutrients as well as carbon dioxide and other 
 metabolic wastes ; to help regulate the level of blood ph , and to help dissipate heat14 .
the water needs depend on the intensity 
 of the activity and thermal stress and 0.71 l / h of isotonic drink during activity should be 
 taken15
. the drink should contain 
 0.50.7  g na / l for sports of 23 hours , while na 0.71.2  g / l for ultra - endurance16 .
sports drinks should hydrate and prevent 
 dehydration during sports activity , provide mineral salts ( mainly na and cl and p ) ; provide 
 carbohydrates ( hc ) increase the absorption of water by the combination of mineral salts and 
 sugars ( fast and slow absorption in a ratio of 3/1)14 .
tested the hypothesis that calcium from the sarcoplasmic reticulum 
 contributes to exercise - induced muscle damage .
dantrolene sodium ( dantrium ) is a muscle 
 relaxant that affects the flux of calcium over the sarcoplasmic membrane .
rats were treated 
 with dantrolene sodium for a week before a 2  h run on a treadmill .
the total creatine kinase 
 activity and isoenzyme composition in plasma were measured before and after the exercise . 

the treated rats showed a marked decrease ( 34% ) in exercise - induced enzyme efflux , caused by 
 a decrease in the muscle specific isoenzyme . while a 13-fold increase found in control rats , 
 only a 6.5-fold increase in treated animals was observed .
it is concluded that dantrolene 
 sodium protects the muscle against exercise - induced damage17 .
brink et al . , studied the effect of the sports drink on the sustainability of the 
 performance in a tennis match on 8 tennis players .
their hypothesis was that drinking sports 
 beverages before , during and after each tennis match would limit the decrease in physical 
 performance compared to conditions where the only fluid intake was water .
the physical test 
 results for the lower limbs showed no significant differences between the groups . 

conversely , on the upper limbs the emg data showed greater fatigue of the triceps brachii in 
 the placebo condition compared to resting , while the ingestion of sports drinks attenuated 
 this fatigue18 . in another study , six 
 male volunteers exercised to exhaustion on a cycle ergometer at a workload which required 
 approximately 70% of vo2max .
after one preliminary trial , subjects performed this exercise 
 test on six occasions a week . immediately before the exercise , and at 10-min intervals 
 throughout , subjects ingested 100  ml of one of the following : control ( no drink ) , water , 
 glucose syrup , fructose syrup , glucose - fructose syrup or a dilute glucose - electrolyte 
 solution .
each of the syrup solutions contained approximately 36  g cho per 100  ml ; the 
 isotonic glucose - electrolyte solution contained 4  g glucose per 100  ml .
expired air samples 
 for determination of vo2 , respiratory exchange ratio and the rate of cho oxidation were 
 collected at 15-min intervals .
subjects drinking the isotonic glucose - electrolyte solution exercised longer ( 90.8 
 ( 12.4 )  min , mean ( sem ) than on the control test ( 70.2 ( 8.3 )  min ; p less than 0.05)19 .
also in another study , lukaski hc emphasizes the importance of magnesium for the work 
 performance .
acute , intense activity results in short - term increases in both urine and sweat 
 losses of minerals that apparently diminish during recovery in the days after exercise . 

states that in the athletes 
 given the carbon hydride and protein drink has 22% of their muscle glycogen refreshed after 
 40 minutes following a strenuous exercise and the replacement of the muscle glycogen after 
 two hours takes place 4 times faster than the athletes who take carbohydrate support 
 only21 .
saunders et al . , reported that 
 the athletes given a supplement cho - p ( carbohydrate and protein ) mixture throughout the an 
 exhaustive cycling exercise had 83% lower ck enzyme levels at the15th hour after the 
 exercise compared with those who took carbon hydride only22 .
some results obtained in literature also support the hypothesis of this research . for 
 example ; isomaltulose , for its slow rate of hydrolysis and low glycogenic index23 , and for the characteristics of fructose , 
 its component , with increased fluid and solute absorption in the small intestine and 
 increased exogenous oxidation24 , could 
 improve the duration of exercise .
sports drinks should : hydrate and prevent dehydration 
 during sports activity , provide mineral salts ( mainly na and cl and p ) ; provide 
 carbohydrates ( hc ) increase the absorption of water by the combination of mineral salts and 
 sugars ( fast and slow absorption in a ratio of 3/1 ) . for hydration to be adequate
, drinks 
 during the competition must be isotonic ( 200320 mosm / kg water ) . during physical activity , 
 in sports with a duration of less than 1 hour
it is clear that the isotonic drink acutely taken before the competition has protective 
 effect and decreases the muscle damage incurred during competitions .
although the muscle 
 damage of experimental group was lesser than the placebo group during the competition and 
 recovery period , it was not found to be significant .
it is possible that the isotonic drinks 
 could be useful for athletes since they prevent the muscle from being damaged and increase 
 the stability of muscle cells by establishing the liquid and electrolyte balance of the 
 body .
further research is needed to clarify the effect of the isotonic drinks on the cell 
 membrane .
sports drinks should moisturize by providing minerals and carbohydrates and 
 increase the absorption of water with an ideal combination of salts and sugars . therefore , 
 it is important to provide correct hydration - protocols before , during and after physical 
 activity , as well as know possible limitations of the sport .
 [ purpose ] the purpose of this study was to investigate the effects of the intake of an 
 isotonic sports drink ( 500  ml water , 32 gr carbonhydrate , 120  mg calcium , 248  mg chloride , 
 230  mg sodium ) the level of the skeletal muscle damage of orienteering athletes . 
 [ subjects 
 and methods ] the study was carried out on 21 male elite orienteering athletes . 
 the 
 athletes were divided into two groups by randomized double - blind selection . 
 the 
 experimental group ( n=11 ) was given the isotonic sports drink , while the placebo group 
 ( n=10 ) was given 500  ml pure water . 
 blood samples were taken pre - competition , 
 post - competition , 2 hours post - competition and 24 hours post - competition . 
 [ results ] the 
 pre - c troponin , myoglobin and creatinine kinase serum levels of the placebo group were 
 significantly lower than the post - competition and 2 hours post - competition values . 
 the 24 
 hours post - competition levels of the same analyses were also significantly lower than the 
 post - c and 2 hours post - competition . 
 the pre - competition troponin , myoglobin and 
 creatinine kinase levels of the experimental group were found to be significantly lower 
 than the post - competition , 2 hours post - competition 24 hours post - competition values . in 
 conclusion 
 , the present results suggest that the intake of supportive sports drinks before 
 exercising significantly prevents the observed muscle damage . 
 the study showed that serum 
 myoglobin levels between the experimental and the placebo group is significantly different 
 during the 2 hours post - competition period . 
 [ conclusion ] the level of serum creatinine 
 kinase and myoglobin accurately shows the extent of the muscle damage . however , further 
 studies on the effect of isotonic sports drink in different training programs on the cell 
 membrane and the muscle damage are needed . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION