Effects of Energy Drink on Hematological Parameters and Renal Function in Soccer Players

Soccer is one of the most popular sports that is played by men and women, children and adults at different competitive levels. Metabolism and high energy demand in soccer training and matches, accumulation of lactic acid due to long-term play and short time between two halves of the match, do not allow the player to fully recover and rebuild his energy sources. This, in turn, can lead to the weakness of the body's immune system and, as a result, cause muscle fatigue. Some studies revealed that the pressure caused by playing soccer increases creatinine, urea and derivatives of white blood cells (leukocytes, monocytes and granulocytes), red blood cells and nitrates, and as a result, it causes disturbances in performance. The increase in urea production during sports activity indicates an increase in protein catabolism. An increase in serum values and a decrease in urinary values after sports activity indicate a decrease in kidney function in the elimination of waste products caused by heavy sports activity. According to the results of some studies, energy drinks consumption increases the metabolic rate, increases sports performance, or both. Hype energy drink (HED) is one of energy drinks that contains large amounts of taurine and caffeine. Taurine, which is the most abundant amino acid in type 2 muscle fibers, increases the strength of athletes and muscle hypertrophy and helps protein synthesis and muscle contraction ability. Also, caffeine has a lot of energy and many physiological effects, such as increase in plasma epinephrine concentration, release and reabsorption of calcium by the sarcoplasmic reticulum, as well as increase in muscle contraction. However, there is little information about the effects of energy drinks on markers of kidney damage caused by exercise. The results of limited studies showed that the consumption of energy drinks during exercise caused a significant change in the serum levels of urea and creatinine. White and red blood cells, hemoglobin and hematocrit did not increase compared to resting state, but the results of other research showed a significant increase in urea and creatinine levels. Considering the contradiction of previous research results and the lack of research on the effectiveness of energy drinks on kidney damage markers and hematological indicators in football, the main goal of the current research is to "investigate the effect of HED consumption on hematological and kidney damage indicators of soccer players after match.

Twenty-two male soccer players competing in Division 2 league with mean age of 91.36+1.20, weight of 70.50+8.01, and body mass index of 22.58+0.93 voluntarily participated in the study. All participants had at least 5 years of soccer experience and during the past year, they practiced 2 hours a day, at least 3 days a week. They were informed about the nature of experimental procedures, including potential risks and benefits and then, received written consent. The experimental protocols were approved by the Ethical Committee of Islamic Azad University of Rasht Branch, Iran, according to Helsinki Declaration Guidelines. All participants were subjected to two different conditions (HED and placebo consumption), under similar conditions (ambient temperature 20±1 °C and relative humidity 70±5). The two different conditions of the research were separated by 14 days to allow enough time for recovery between the tests and ensure the absence of caffeine's effect. In order to avoid diurnal effects, both experimental sessions were held in the early evening hours. Once, the participants consumed HED (2 servings of 250 ml per day) for 5 days before the soccer match, the day of the match and one day after the match. HED contains 99.1 kcal, carbohydrates, protein and fat, taurine, caffeine, glucuronolactone, vitamins, inositol, B6, B12, flavor and color. Participants were instructed to drink one serving with breakfast and one serving with dinner. Blood samples were collected before the race, immediately after the race, and 1 day after the race. All tests were performed at the same time of day to minimize the effect of circadian variation. In the second condition, a placebo drink was administered by an expert. Food industries without caffeine and taurine were prepared, which contained 50 mg/liter of sodium saccharin and 2.5 mg/liter of vitamin C powder supplement. It should be noted that both energy drinks and placebo were iso-calories. On test days, players were asked to eat lunch at 1:00 p.m., consume the cooled drinks in opaque and pressed plastic water bottles during (0.5 + 1 minute) under the supervision of the researchers at 4 p.m. At 5:00 p.m., the participants first warmed up for 15 minutes to increase the body temperature and improve the efficiency of the nervous and muscular system, then they were divided into two teams and played a soccer match in two halves. They played one minute with a 15-minute break between the two halves. During each trial, they were allowed to drink water to prevent dehydration. The measurements were done in 4 stages. Collected data using analysis of variance with repeated measurement of intersection at the level of significance of α=0.05 was analyzed.

The results showed that immediately after the football game, there was a significant difference in the levels of serum creatinine, hematocrit and white blood cells between the two conditions of HED and placebo (P = 0.001). Also, compared to placebo, consumption of HED 24 hours after the game caused a significant decrease in red and white blood cells, hemoglobin, hematocrit, urea and creatinine (p=0.001).

According to the results of the present study, it seems that the consumption of Hype energy drink causes a decrease in the levels of some enzymes of kidney function such as urea and creatinine and a decrease in the levels of some hematological parameters such as white and red blood cells, hematocrit and hemoglobin, and improves the performance of soccer players 24 hours after the match through accelerating the return to the initial state. Of course, due to the lack of scientific evidence in this field, it is not possible to make a definitive statement and the need to conduct more research in this field seems necessary.