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The purpose of this study is to find what effects the sport drink Pocari sweat has on some selected physiological variables. The main aim of the sports research world is to improve athlete’s performance. The ways in which this is accomplished is by either developing products to aid in performance or determining how to make an athlete’s body more efficient in sport activities. Two main research areas are water and sports drinks.
The human body is composed of nearly 60% water (Guyton & Hall, 2006). The importance of water in the body cannot be overstated. If an individual goes without water for only a few days he will die. One of the most important functions of water in the body is temperature regulation and maintaining normal blood pressure. On the other hand sports drinks are improving and develop the level of athletic achievement, especially in sports. Sports drinks play a major role in fluid homeostasis, because exercise may lead to substantial sweat losses, considerable attention has been given to the electrolyte composition of sweat and the possible need to replace these electrolytes during exercise. The only valid method to determine total sweat electrolyte losses during exercise is the analysis of whole-body sweat. Also sports drinks are necessary to compensate lost of fluids and to maintain the level of physiological variables during high intensity exercise.
Furthermore , during exercise , the body will lose water and energy as a consequence of sweating. Fluid replacement is critical to ameliorate the deterioration in physiological function and performance that accompanies dehydration (Convertino et al, 1996).
Iman identifies in his study some physiological variables to the players’ long distances under the influence of high intensity accompanied by drinking of different types of liquids or no drink during the different times, as well as to identify differences on heart rate as an indicator of the efficiency of the heart when dealing with fluids between different times. (Saying too many things – making this sentence very long, complex and confusing. Break this into shorter sentences to describe one idea at time).
In addition to the experimental method used in this study, research was done on a sample of 9 athletes who were national long distance runners from Iraq. The most important devices and tools that were used in this study were: body weight medical apparatus, treadmill, ECG, and clock radio with a belt (to measure and monitor the heart rate). Some of the more important points inferred from this study were : first, that a lack of fluid in the first group has a negative effect on heart rate during high intensity physical workouts and during the period of rest. Second, drinking of liquids (water, glucose) by the second group and the third group has a positive impact in maintaining a low heart rate during high intensity physical workouts and the stage of recovery. These positive cases are the effect of liquids on the athletes. Third, sodium intake had a negative impact on the fourth group where their heart rates were high during high intensity physical workouts and the stage of recovery. (Iman, 2001)
In another study by Isabela et al, the participants who volunteered were twenty soccer players). Players were allocated to two assigned trials according to their positional roles in the team: CHO group (ingesting a 6% carbohydrate electrolyte solution at regular 15 minutes intervals) and NCHO (ingesting no fluid) during 75 min on field soccer game. During the trials, body mass loss, heart rate, time spent running, number of sprints and core temperature were measured. There were statistically significant changes (p < 0.05) in body mass loss (CHO: 1.14 ± 0.37 kg vs. NCHO: 1.75 ± 0.47 kg) and number of sprints performed (CHO: 14.70 ± 4.38 vs. NCHO: 10.70 ± 5.80) between groups.
The main finding of this study provides encouraging evidence that soccer players should drink a carbohydrate electrolyte drink throughout a match to avoid the negative consequences of dehydration, especially regarding performance. (Isabela et al, 2004)
According to Neil (2007) the water or fluid important to the maintenance of sweat rates, especially in the heat, is extremely important for temperature regulation. In hypohydrated individuals, the compromise between cardiovascular function and temperature regulation is broken and sweat rates and skin blood flow are reduced to maintain adequate cardiac output.
Fluid replacement during exercise appears to offset thermal strain caused by dehydration. Dehydration prior to exercise leads to excess heat storage due to a reduction in sweat sensitivity when individuals were not allowed to drink fluids during exercise. When individuals were allowed to drink cool water ad libitum, heat storage was reduced and sweat sensitivity and cardiovascular function (HR) were restored. Similarly, complete restoration of body fluids during exercise by forced water intake equal to fluid lost during exercise results in uncompromised cardiovascular function, indicated by cardiac output, stroke volume, and heart rate, and temperature regulation. However, it should be noted that, although typically occurring less often than significant hypohydration, research has correlated incidences of hyponatremia during exercise with large quantities of dilute beverages, such as water especially in individuals that are predisposed to excess water intake and inappropriate suppression of arginine-vasopressin.
a study by Edward (2004) showed that creating a practical recommendations for fluid and fuel intake during exercise based upon interpretation of the scientific literature, with heavy reliance upon controlled laboratory studies as well as careful study of athletes in the field during training and competition. the amounts of water, carbohydrate and salt that athletes are advised to ingest during exercise are based upon their effectiveness in attenuating both fatigue as well as illness due to hyperthermia, dehydration or hyperhydration. (Meaning, punctuation, are unclear for this paragraph) When possible, fluid should be ingested at rates that most closely match sweating rate. When that ingestion rate is not possible, practical or sufficiently ergogenic, some athletes might tolerate body water losses amounting to 2% without significant risk to physical well-being or performance in cold environment (e.g. 5-108C) or temperate environment (e.g. 21-228C). However, when exercising in a hot environment (4308C), dehydration by 2% of body weight impairs absolute power production and predisposes individuals to heat injury. Fluid should not be ingested at rates in excess of sweating rate and thus body water and weight should not increase during exercise. Fatigue can be reduced by adding carbohydrate to the fluids consumed so that 30-60g of rapidly absorbed carbohydrate are ingested throughout each hour of an athletic event. Furthermore, sodium should be included in fluids consumed during exercise lasting longer than 2 h or by individuals during any event that stimulates heavy sodium loss (more than 3-4 g of sodium). Athletes do not benefit by ingesting glycerol, amino acids or alleged precursors of neurotransmitter. Ingestion of other substances during exercise, with the possible exception of caffeine, is discouraged.
Serge et al (2004) found that fluid levels are vital to help achieve maximum performance, with fluctuating electrolyte levels and dehydration in excess of 2% of body weight shown to consistently impair aerobic exercise performance. Several studies have confirmed that performance will be impaired when athletes are dehydrated. Endurance athletes have to drink beverages containing electrolyte and carbohydrate during and after training. Drinking during competition or training is desirable compared with liquid ingestion before or after training or competition only. Athletes seldom replace fluids fully due to sweat loss. Suitable hydration during training or competition will lead to enhanced performance, avoid resulting thermal stress, delay fatigue, and prevent injuries associated with dehydration and sweat loss. In contrast, hyperhydration or over-drinking before, during, and after endurance events may cause Na+ depletion and may lead to hyponatremia. It is imperative that endurance athletes replace sweat loss by fluid intake containing about 4% to 8% of carbohydrate solution and electrolytes during training or competition. It is recommended that athletes drink approximately 500 mL of fluid solution 1 to 2 h before an event and continue to consume cool or cold drinks in regular intervals to replace liquid loss due to sweat. For intense prolonged exercise lasting longer than 1 h, athletes must consume between 30 and 60 g/h and drink between 600 and 1200 mL/h of a solution containing carbohydrate and Na+ (0.5 to 0.7 g/L of fluid). Maintaining suitable hydration before, during, and after training and competition will help decrease fluid loss, maintain performance, lower submaximal exercise heart rate, maintain plasma volume, and reduce heat stress, heat exhaustion, and possibly heat stroke.
Suitable hydration during training or competition will lead to improve performance, avoid ensuing thermal stress, maintain plasma volume, delay fatigue, and prevent injuries associated with dehydration and sweat loss.
Maughan et al, (1996) showed that it is generally accepted that the performance of prolonged exercise can be improved by the ingestion of carbohydrate-electrolyte drinks during exercise. It is well established that the ingestion of carbohydrate-containing drinks can improve the performance of prolonged exercise. The present study examined the effects of ingestion of water and two dilute glucose-electrolyte drinks on exercise performance and on cardiovascular and metabolic responses to exercise. Twelve subjects exercised to exhaustion on a cycle ergometer at a workload corresponding to 70% VO2 max on five occasions each separated by 1 week. The first trial served to accustom subjects to experimental conditions. On one trial, no drinks were given and on the others subjects drank 100 ml every 10 min. Drinks consisted of water, an isotonic glucose-electrolyte solution (I: 200 mmol/l glucose; 35 mmol/l NA2; 310 mosmol/kg) and a hypotonic glucose-electrolyte solution (H: 90 mmol/l glucose; 60 mmol/l Na+; 240 mosmol/kg). Treatment order was randomized. Blood and expired air samples were taken and heart rate and rectal temperature measured at intervals during exercise. Median exercise time was greatest for treatment H (110.3 min) followed by treatment I (107.3 min), water (93.1) and no drink (80.7). Endurance times differed significantly overall, and for pairwise comparisons (P < 0.01) between the no-drink trial and both treatments H and I: a difference between water and no drink was seen at the 5% level. At exhaustion, a significant treatment difference was found for the change in plasma volume, with the greatest decrease (6.7%) on the no-drink trial and the smallest decrease (0.5%) on treatment H. Significant treatment effects were also observed for heart rate, rectal temperature and serum osmolality. The results suggest that the ingestion of glucose-electrolyte drinks can improve exercise performance even when the amount of added glucose is small, and that performance may also be enhanced, albeit to a lesser degree, by ingestion of water. This suggests that muscle glycogen depletion may not cause fatigue if an alternative source of carbohydrate fuel in the form of blood glucose is available to the muscles.
According to George et al (1998) the onset of fatigue during prolonged submaximal high-intensity exercise is associated with (a) reduction, if not depletion, of muscle glycogen, (b) reduction in blood glucose concentration, and (c) dehydration. The sample for this study was nine subjects (eight men and one woman) ran to exhaustion on a motorised treadmill on two occasions separated by at least 10 days. After an overnight fast, they performed repeated 15 second bouts of fast running (at 80% VO2MAX for the first 60 minutes, at 85% VO2MAX from 60 to 100 minutes of exercise, and finally at 90% VO2MAX from 100 minutes of exercise until exhaustion), separated by 10 seconds of slow running (at 45% VO2MAX). On each occasion they drank either a water placebo (P) or a 6.9% carbohydrate-electrolyte (CHO) solution immediately before the run and every 20 minutes thereafter.
The result of this study was (showed that) performance times were not different between the two trials (112.5 (23.3) and 110.2 (21.4) min for the P and CHO trials respectively; mean (SD)). Blood glucose concentration was higher in the CHO trial only at 40 minutes of exercise (4.5 (0.6) v 3.9 (0.3) mmol/l for the CHO and P trials respectively; p<0.05), but there was no difference in the total carbohydrate oxidation rates between trials.
These results suggest that drinking a 6.9% carbohydrate-electrolyte solution during repeated bouts of submaximal intermittent high intensity running does not delay the onset of fatigue.
Another study done by Sergej & Sanja (2002) showed that fatigue during prolonged submaximal high intensity exercise is associated with a reduction, of muscle glycogen, a reduction in blood glucose concentration, and dehydration. The participants in the study were twenty two professional male soccer players. The players were allocated to two assigned trials ingesting carbohydrate-electrolyte drink or placebo during a 90 min on-field soccer match. The trials were matched for subjects’ age, weight, height and maximal oxygen uptake. Immediately after the match, players completed four soccer-specific skill tests. Blood glucose concentration (mean ±SD) was higher at the end of the match-play in the carbohydrate-electrolyte trial than in the placebo trial (4.4±0.3 vs. 4.0±0.3 mmol.l-1, P < 0.05). Subjects in the carbohydrate-electrolyte trial finished the specific dribble test faster in comparison with subjects in the placebo trial (12.9±0.4 vs. 13.6±0.5 s, P < 0.05). Ratings of the precision test were higher in the carbohydrate-electrolyte trial as compared to the placebo trial (17.2±4.8 vs. 15.1±5.2, P < 0.05) but there were no differences in coordination test and power test results between trials.
The main finding of this study provides further supportive evidence that soccer players should drink carbohydrate-electrolyte fluid throughout a game to help prevent deterioration in specific skill performance and improve recovery. These findings have relevance in the design of optimal rehydration plan to improve performance and reduce fatigue and cardiovascular stress during match play.
Study by Khanna & Manna (2005) showed that loss of fluid electrolyte and reduction of the body’s carbohydrate stores are the major causes of fatigue in prolonged exercise. The objective of this study is to show if Carbohydrate-electrolyte drink has a significant role on energy balance during exercise. For this study, a total of 10 male athletes (age range: 20-25yr) were selected.) The experiment was performed in the laboratory in two phases; phase 1 – no supplementation, and phase 2 – a 5 g per cent carbohydrate-electrolyte drink was given orally during exercise and a 12.5 g per cent carbohydrate-electrolyte drink during recovery. Subjects performed an exercise test at 70% VO2max. Performance time, heart rate during exercise and recovery were noted, blood samples were collected during exercise and recovery for the analysis of glucose and lactate levels in both the phases. The result for this study found significant improvements were noted in total endurance time, heart rate responses and blood lactate during exercise at 70% VO2max after the supplementation of 5 g per cent carbohydrate-electrolyte drink. However, no significant changes were noted in blood glucose and peak lactate level irrespective of supplementation of carbohydrate-electrolyte drink. Significant improvement in cardiovascular responses, blood glucose and lactate removal were noted during recovery following a 12.5 g per cent carbohydrate-electrolyte drink.
Therefore it may be concluded that carbohydrate replacement during exercise may enhance performance of sports and activities, which typically deplete body carbohydrate stores, by providing an additional fuel source for the muscle. Carbohydrate and electrolyte balance keeps low heart rate as well as low blood lactate level during exercise.
Nicholas et al (1995), examined the effects of a 6.9% carbohydrate-electrolyte drink on performance during intermittent, high-intensity shuttle running designed to replicate the activity pattern of stop-and-go sports. Nine trained male games players performed two exercise trials, 7 days apart. On each occasion, they completed 75 min exercise, comprising of five 15-min periods of intermittent running, consisting of sprinting, interspersed with periods of jogging and walking (Part A), followed by intermittent running to fatigue (Part B). The subjects were randomly allocated either a 6.9% carbohydrate-electrolyte solution (CHO) or a non-carbohydrate placebo (CON) immediately prior to exercise (5 ml kg-1 body mass) and every 15 min thereafter (2 ml kg-1 body mass). Venous blood samples were obtained at rest, during and after each PIHSRT for the determination of glucose, lactate, plasma free fatty acid, glycerol, ammonia, and serum insulin and electrolyte concentrations. During Part B, the subjects were able to continue running longer when fed CHO (CHO = 8.9 ± 1.5 min vs CON = 6.7 ± 1.0 min; P < 0.05) (mean ± s.e.m.). These results show that drinking a carbohydrate-electrolyte solution improves endurance running capacity during prolonged intermittent exercise. Also there is a growing body of evidence which indicates that consuming sports drinks during intermittent, intense activities (stop-start sports) of less than one hour can improve performance.
Carey, et al determined the effect of fat adaptation on metabolism and performance during 5 h of cycling in seven competitive athletes who consumed a standard carbohydrate (CHO) diet for 1 day and then either a high-CHO diet (11 gzkg21 zday21 CHO, 1 gzkg21 zday21 fat; HCHO) or an isoenergetic high-fat diet (2.6 gzkg21 zday21 CHO, 4.6 gzkg21 zday21 fat; fat-adapt) for 6 days. On day 8, subjects consumed a high-CHO diet and rested. On day 9, subjects consumed a preexercise meal and then cycled for 4 h at 65% peak O2 uptake, followed by a 1-h time trial (TT). Compared with baseline, 6 days of fat-adapt reduced respiratory exchange ratio (RER) with cycling at 65% peak O2 uptake [0.78 6 0.01 (SE) vs. 0.85 6 0.02; P, 0.05]. However, RER was restored by 1 day of high-CHO diet, preexercise meal, and CHO ingestion (0.88 6 0.01; P, 0.05). RER was higher after HCHO than fat-adapt (0.85 6 0.01, 0.89 6 0.01, and 0.93 6 0.01 for days 2, 8, and 9, respectively; P, 0.05). Fat oxidation during the 4-h ride was greater (171 6 32 vs. 119 6 38 g; P, 0.05) and CHO oxidation lower (597 6 41 vs. 719 6 46 g; P, 0.05) after fat-adapt. Power output was 11% higher during the TT after fat-adapt than after HCHO (312 6 15 vs. 279 6 20 W; P 5 0.11).
In conclusion(?), this is the first investigation to determine the effects of a high-fat diet and CHO restoration on metabolism and performance during ultraendurance exercise. The researchers found that 6 days of exposure to a high-fat, low-CHO diet, followed by 1 day of CHO restoration, increased fat oxidation during prolonged, submaximal exercise, yet, despite this sparing of CHO, this study failed to detect a statistically significant benefit to performance of a 1-h TT undertaken after 4 h of continuous cycling. (Carey et al, 2001)
Alford et al (2000) found for red bull drink(,) many effects and benefit for athlete therefore this study conform the drink consume extra amounts of fluid before they become thirsty. The researchers studied the effect of Red Bull drink which included some hydration, electrolyte and energy enhancements on 36 volunteers. This was done in 3 studies. Assessments included psychomotor performance (reaction time, concentration, and memory), subjective alertness and physical endurance. When compared with control drinks, Red Bull Energy Drink significantly (P _ 0.05) improved aerobic endurance (maintaining 65-75% max. heart rate) and anaerobic performance (maintaining max. speed) on cycle ergometers. Significant improvements in mental performance included choice reaction time, concentration (number cancellation) and memory (immediate recall), which reflected increased subjective alertness. These consistent and wide ranging improvements in performance are interpreted as reflecting the effects of the combination of ingredients.
Neil et al, (1999) in a study showed that exercise is known to cause physiological changes that could affect the impact of nutrients on appetite control. This study was designed to assess the effect of drinks containing either sucrose or high-intensity sweeteners on food intake following exercise. Using a repeated-measures design, three drink conditions were employed: plain water (W), a low-energy drink sweetened with artificial sweeteners aspartame and acesulfame- K (L), and a high-energy, sucrose-sweetened drink (H). Following a period of challenging exercise (70% VO2 max for 50 min), subjects consumed freely from a particular drink before being offered a test meal at which energy and nutrient intakes were measured. The degree of pleasantness (palatability) of the drinks was also measured before and after exercise. At the test meal, energy intake following the artificially sweetened (L) drink was significantly greater than after water and the sucrose (H) drinks ( p , 0.05). Compared with the artificially sweetened (L) drink, the high-energy (H) drink suppressed intake by approximately the energy contained in the drink itself However, there was no difference between the water (W) and the sucrose (H) drink on test meal energy intake. When the net effects were compared (i.e., drink1 test meal energy intake), total energy intake was significantly lower after the water (W) drink compared with the two sweet (L and H) drinks. The exercise period brought about changes in the perceived pleasantness of the water, but had no effect on either of the sweet drinks. The remarkably precise energy compensation demonstrated after the higher energy sucrose drink suggests that exercise may prime the system to respond sensitively to nutritional manipulations. The results may also have implications for the effect on short-term appetite control of different types of drinks used to quench thirst during and after exercise.
According to Maurin& Fisher (2005), body composition will vary according to energy intake and expenditure. Energy is basically expended three ways. Energy is required for the following processes: resting metabolic rate (RMR), thermic effect of food (TEF), and physical activity. RMR is essentially determined by the amount of lean or fat-free tissue, which accounts for 60-75% of total daily energy expenditure. TEF is approximately 10% of total energy expenditure, while the effect of physical activity is highly variable and individualized. Individuals who have a greater amount of lean tissue will have a 5% higher resting metabolic rate compared to individuals with a greater amount of body fat. Consumption of carbohydrate or fat will increase metabolic rate by 5% of total energy consumed, while a meal consisting of only protein may increase metabolic rate as much as 25%. Excess intake of any macronutrient above what the body uses will be stored as fat. If carbohydrate intake is inadequate, protein needs will increase, since protein normally used to synthesis tissue and perform various other functions would need to be used for energy. Dietary intake of at least 100 grams of carbohydrate per day will prevent ketosis and the breakdown of muscle tissue Daily energy intake is an important factor for muscle tissue formation and growth, which takes place during ositive nitrogen balance.
Dehydration has been proposed to decrease lactic acid buffering ability of the body. However, current research suggests dehydration leads to Lactate Threshold occurring at lower absolute exercise intensity .It has been shown that subjects performing 5 and 10 km time trials in a dehydrated state compared with subjects in a hydrated state have decreased blood lactate concentrations (Kenefick, 2002).
Therefore, if the blood lactate concentrations are lower, the subject’s Lactate Threshold is at higher absolute exercise intensity. In other investigations there have been no detected changes in blood lactate levels when comparing a dehydrated to a hydrated state.
(Kenefick, 2002). The varying information regarding the correlation between hydration and its effects on lactate accumulation in the blood may be due to the protocol used in hydrating or dehydrating subjects. Armstrong et al used a diuretic method to dehydrate their subjects (-2% body mass). Other research methods include saunas, extended exercise without hydration, and exercise with or without a sweat suit. Due to the conflicting results, it has not been determined whether a certain level of hydration will adversely affect blood lactate accumulation.
Aaron et al (2007) found in his study that rating of perceived exertion (RPE) could be a practical measure of global exercise intensity in team sports. The purpose of this study was to examine the relationship between heart rate (%HRpeak) and blood lactate ([BLaâˆ’]) measures of exercise intensity with each player’s RPE during soccer-specific aerobic exercises. Mean individual %HRpeak, [BLaâˆ’] and RPE (Borg’s CR 10-scale) were recorded from 20 amateur soccer players from 67 soccer-specific small-sided games training sessions over an entire competitive season. The small-sided games were performed in three 4 min bouts separated with 3 min recovery on various sized pitches and involved 3-, 4-, 5-, or 6-players on each side. A stepwise linear multiple regression was used to determine a predictive equation to estimate global RPE for small-sided games from [BLaâˆ’] and %HRpeak. Partial correlation coefficients were also calculated to assess the relationship between RPE, [BLaâˆ’] and %HRpeak. Stepwise multiple regression analysis revealed that 43.1% of the adjusted variance in RPE could be explained by HR alone. The addition of [BLaâˆ’] data to the prediction equation allowed for 57.8% of the adjusted variance in RPE to be predicted (Y =âˆ’9.49âˆ’0.152 %HRpeak + 1.82 [BLaâˆ’], p < 0.001). These results show that the combination of [BLaâˆ’] and %HRpeak measures during small-sided games is better related to RPE than either %HRpeak or [BLaâˆ’] measures alone. These results provide further support for the use of RPE as a measure of global exercise intensity in soccer.
Kovacs, et al (1998) observed that caffeine (Caf) ingestion improves endurance performance. The effect of the addition of different dosages of caffeine (Caf) to a carbohydrate-electrolyte solution (CES) on metabolism, Caf excretion, and performance was examined. The subjects of this study was Fifteen healthy male ingested 8 ml/kg of water placebo (Pla-W), 7% CES (Pla-CES), or 7% CES with 150, 225, and 320 mg/l Caf (CES-150, CES-225, and CES-320, respectively) during a warm-up protocol (20 min) and 3 ml/kg at one-third and two-thirds of a 1-h time trial. Performance was improved with Caf supplementation: 62.5 61.3, 61.5 61.1, 60.4 6 1.0, 58.9 61.0 and 58.9 6 1.2 min for Pla-W, Pla-CES, CES-150, CES-225, and CES-320, respectively. The post exercise urinary Caf concentration (range 1.3-2.5 Î¼g/ml) was dose dependent and always far below the doping level of the International Olympic Committee (12 Î¼g/ml) in all subjects. Sweat Caf excretion during exercise exceeded post exercise early-void urinary Caf excretion. Caffeinated CES did not enhance free fatty acid availability, ruling out the fact that performance improvement resulted from enhanced fat oxidation. It is concluded that addition of relatively low amounts of Caf to CES improves performance and that post exercise urinary Caf concentration remained low. Additionally, Caf intake during exercise appears to have no effect on sweat loss, body temperature, and plasma volume.
Study by Grandjean et al, (2000) was in examining the effect of various combinations of beverages on hydration status in healthy free-living adult males. In a counterbalanced, crossover manner, 18 healthy adult males ages 24 to 39, on four separate occasions, consumed water or water plus varying combinations of beverages. Clinical guidelines were used to determine the fluid allowance for each subject. The beverages were carbonated, caffeinated caloric and non-caloric colas and coffee. Ten of the 18 subjects consumed water and carbonated, non-caffeinated, citrus soft drink during a fifth trial. Body weight, urine and blood assays were measured before and after each treatment. Slight body weight loss was observed on all treatments, with an average of 0.30% for all treatments. No differences (p.0.05) among treatments were found for body weight changes or any of the biochemical assays. Biochemical assays conducted on first voids and 24-hour urines included electrolytes, creatine, osmolality and specific gravity. Blood samples were analyzed for hemoglobin, hematocrit, electrolytes, osmolality, urea nitrogen, creatinine and protein. This preliminary study found no significant differences in the effect of various combinations of beverages on hydration status of healthy adult males. Advising people to disregard caffeinated beverages as part of the daily fluid intake is not substantiated by the results of this study. The across-treatment weight loss observed, when combined with data on fluid-disease relationships, suggests that optimal fluid intake may be higher than common recommendations. Further research is needed to confirm these results and to explore optimal fluid intake for healthy individuals.
According to Gianluca et al (1996) Insulin resistance in the offspring of parents with non- insulin-dependent diabetes mellitus (NIDDM) is the best predictor of development of the disease and probably plays an important part in its pathogenesis. The researchers studied the mechanism and degree to which exercise training improves insulin sensitivity in these subjects. Ten adult children of parents with NIDDM and eight normal subjects were studied before starting an aerobic exercise-training program, after one session of exercise, and after six weeks of exercise. Insulin sensitivity was measured by the hyperglycemic-hyperinsulinemic clamp technique combined with indirect calorimetry, and the rate of glycogen synthesis in muscle and the intramuscular glucose- 6-phosphate concentration were measured by carbon- 13 and phosphorus-31 nuclear magnetic resonance spectroscopy, respectively.
During the base-line study, the mean (_SE) rate of muscle glycogen synthesis was 63_9 percent lower in the offspring of diabetic parents than in the normal subjects (P_0.001). The mean value increased 69_ 10 percent (P_0.04) and 62 _ 11 percent (P_ 0.04) after the first exercise session and 102 _ 11 percent (P_ 0.02) and 97_ 9 percent (P_ 0.008) after six weeks of exercise training in the offspring and the normal subjects, respectively. The increment in glucose-6-phosphate during hyperglycemic- hyperinsulinemic clamping was lower in the offspring than in the normal subjects (0.039_ 0.013 vs. 0.089_ 0.009 mmol per liter, P_0.005), reflecting reduced glucose transport-phosphorylation, but this increment was normal in the offspring after the first exercise session and after exercise training. Basal and stimulated insulin secretion was higher in the offspring than the normal subjects and was not altered by the exercise training program. Exercise increases insulin sensitivity in both normal subjects and the insulin-resistant offspring of diabetic parents because of a twofold increase in insulin-stimulated glycogen synthesis in muscle, due to an increase in insulin-stimulated glucose transport-phosphorylation.
In a study by Hassan et al (1999) it was argued that
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