The effect of zinc supplementation on the urinary excretion of elements in female athletes.

This study was carried out to find out how oral zinc supplementation to elite athletes affects the element changes in the urine. The study registered 10 female athletes who were on the women's volleyball team of Gazi University Sports Club and whose mean age, weight, and height were 14.2±0.42 years, 59.8±7.79kg and 173.6±6.15 cm. The study protocol was approved by the local ethics committee. The athletes who continued their daily routine training sessions (6 days/week) were supplemented with 220mg/day oral zinc sulfate for 4 weeks. In order to induce exhaustion, the subjects were put to a 20-meter shuttle run test before and after supplementation. A total, 7 times urine samples were collected follows as pre and post exercise before the start of the experiment and at the end (4 times), at the end of first, second and third week (3 times). Urinary levels of magnesium, phosphorus, and calcium (mg/dl), as well as zinc, copper, and selenium (µg/dl) were analyzed in the atomic emission device (ICP-MS). Arithmetic means and standard errors of the data were calculated. Kruskal Wallis test was used to determine differences between weeks. Values for which p<0,05 were considered significant. When compared to resting values, urinary excretion of copper and selenium decreased in exercise (p<0,05), but increased with zinc supplementation (p<0,05). Pre- and post-supplementation exercise resulted in reduced urinary zinc excretion (p<0,05). Zinc supplementation increased urinary zinc excretion in one-week intervals over the course of 4 weeks (p<0,05), and reduced selenium levels (p<0,05). When zinc is supplemented to athletes, the relation between the duration and dose of supplementation is important. The results of the study indicated that zinc does not have any negative effect on the urinary excretion of the concerned elements. It can thus be concluded that athletes may benefit from zinc support.

Protective role of L-carnitine supplementation against exhaustive exercise induced oxidative stress in rats.

The objective of this study was to investigate temperature dependent effects of oral l-carnitine supplementation on exhaustive exercise induced oxidative damage in rats. 42 male Spraque Dawley rats were randomly divided into seven experimental groups. These groups were formed as three non-carnitine exercise groups, three carnitine-exercise groups and a sedentary group. l-carnitine was given intraperitoneally to the carnitine-exercise groups 1h before the exercise in 100mg/kg. Blood was collected to measure paraoxonase-1 (PON1) activity, plasma malondialdehyde (MDA), low-density lipoprotein (LDL) and cholesterol concentrations. These biomarkers were measured in venous blood samples collected before and after the rats swam in pools at different water temperatures (18°C, 28°C and 38°C). In the non-carnitine group, exercise caused a significant decrease in PON1 activity and a significant elevation in MDA concentration at 28°C compared to the sedentary group. No significant alterations were evidenced in LDL and cholesterol concentrations upon exercise. The decrease in PON1 activity became higher with increasing temperature whereas the elevation in MDA levels increased at 18°C. In the l-carnitine supplementation group, recovery in PON1 activity was observed significant at 28°C and very significant at 38°C. MDA concentration was almost the same with that of the non-carnitine group at 18 and 38°C, but it significantly decreased at 28°C. Considering the recovery in PON1 and MDA levels at 28°C, which is the temperature of the sedentary group; our results suggest that l-carnitine supplementation has a protective role on exhaustive exercise-induced oxidative stress. Findings of this study also demonstrate influences of thermal stress on these parameters during exhaustive exercise.

Effects of exercise and zinc supplementation on cytokine release in young wrestlers.

The present study aims to examine the effect of zinc supplementation on the release of some cytokines in young wrestlers actively involved in wrestling. A total of 40 male subjects of the same age group were included in the study: half were wrestlers and the other half were not involved in sports. The subjects were equally divided into four groups and treated during an 8-week period as follows: group 1, zinc-supplemented athletes; group 2, non-supplemented athletes; group 3, zinc-supplemented sedentary subjects, and group 4, non-supplemented sedentary group. Blood samples were taken from each subject at the beginning and at the end of the study period. The serum tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), and interpheron-γ levels (IFN-γ) were determined using the enzyme-linked immunosorbent assay method. At the beginning of the study, there were no significant differences of the measured parameters between the four study groups. At the end of the study, the levels of TNF-α, IL-2, and IFN-γ were significantly higher in the two zinc-supplemented groups compared to those that did not receive supplementation, regardless of the activity status (p < 0.01).

Elements in sera of elite taekwondo athletes: effects of vitamin E supplementation.

Many researchers have emphasized the relation between nutrition and development and sustaining performance. Two methods are commonly employed to identify the interaction between physical activity and nutrition. The first consists of administering food with a variety of contents to people engaged in physical activity and observing their performance responses, and the other is concerned with determining the effects of physical activity on nutrition. Therefore, it can be said that there has been a growing interest in the explorations into the relation between exercise and vitamins, minerals, and elements. The present study reports the effects of 6 weeks administration of 300 mg/day vitamin E on the distribution of serum elements in elite taekwondo athletes. Seven male athletes, mean ages 22.1 ± 0.5 years weighing on average 66.4 ± 2.4 kg were included in the study. The athletes had been practicing taekwondo for 10-12 years. Resting blood samples were collected in duplicate before and after supplementation for determination of serum levels of cobalt, boron, cadmium, chromium, nickel, manganese, sulfur, copper, iron, zinc, phosphorus, sodium, potassium, and calcium. Supplementation resulted in significant increases of all elements relative to values before supplementation (p < 0.001), with the exception of boron and sulfur, which remained without change. The results of the present study demonstrate that vitamin E supplementation crucially influences the element and mineral metabolism in elite athletes.

Effect of zinc supplementation on antioxidant activity in young wrestlers.

This study aims to examine the effect of zinc supplementation on free-radical formation and antioxidant system in individuals who are actively engaged in wrestling as a sport. The study registered a total of 40 male subjects, of whom 20 were wrestlers and 20 were sedentary individuals. The subjects were equally allocated to four groups: group 1, zinc-supplemented sportsmen group; group 2, sportsmen group without supplementation; group 3, zinc-supplemented sedentary group; group 4, sedentary group without supplementation. Blood samples were collected from all subjects twice, once at the beginning of the study and once again at the end of 8-week procedures. The blood samples collected were analyzed to determine the levels of malondialdehyde (MDA), serum glutathione (GSH), serum glutathione peroxidase (GPx) activity, serum superoxide dismutase (SOD) activity (ELISA colorimetric method) and zinc (colorimetric method). No difference was found between MDA levels of the study groups in the beginning of the study. The highest MDA value at the end of the study was obtained in group 4 (p < 0.01). MDA levels in group 2 were established to be significantly higher than those in groups 1 and 3 (p < 0.01). GSH level, GPx, and SOD activities and zinc level measured in the beginning of the study were not different between groups. Measurements performed at the end of the study showed that groups 1 and 3 (zinc-supplemented groups) had the highest GSH level, GPx, and SOD activities and zinc level (p < 0.01). These parameters were not different in the groups without supplementation (groups 2 and 4). Results obtained at the end of the study indicate that zinc supplementation prevents production of free radicals by activating the antioxidant system. In conclusion, physiologic doses of zinc supplementation to athletes may beneficially contribute to their health and performance.

The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc.

OBJECTIVES: The present study aims to investigate how exhaustion exercise affects thyroid hormones and testosterone levels in elite athletes who are supplemented with oral zinc sulfate for 4 weeks. METHODS: The study included 10 male wrestlers, who had been licensed wrestlers for at least 6 years. Mean age of the wrestlers who volunteered in the study was 18.70 +/- 2.4 years. All subjects were supplemented with oral zinc sulfate (3 mg/kg/day) for 4 weeks in addition to their normal diet. Thyroid hormone and testosterone levels of all subjects were determined as resting and exhaustion before and after zinc supplementation. RESULTS: Resting TT3, TT4, FT3, FT4 and TSH levels of subjects were higher than the parameters measured after exhaustion exercise before zinc supplementation (p<0.05). Both resting and exhaustion TT3, TT4 and FT3 values after 4-week zinc supplementation were found significantly higher than both of the parameters (resting and exhaustion) measured before zinc supplementation (p<0.05). Resting total testosterone and free testosterone levels before zinc supplementation were significantly higher than exhaustion levels before zinc supplementation (p<0.05). Both resting and exhaustion total and free testosterone levels following 4-week zinc supplementation were found significantly higher than the levels (both resting and exhaustion) measured before zinc supplementation (p<0.05). CONCLUSION: Findings of our study demonstrate that exhaustion exercise led to a significant inhibition of both thyroid hormones and testosterone concentrations, but that 4-week zinc supplementation prevented this inhibition in wrestlers. In conclusion, physiological doses of zinc administration may benefit performance.

Effect of zinc supplementation on hematological parameters in athletes.

The hematological effects of oral supplementation of zinc to training athletes are reported in the present study. A total of 30 subjects between 16 and 22 yr of age volunteered to participate in a 4-wk study. They were equally divided into three groups. Group 1 acted as resting controls receiving daily doses of 3 mg Zn/kg body wt. Group 2 was actively engaged in wrestling and exercised for 90-120 min, 5 d a week. Group 3 was also actively engaged in wrestling and exercised for 90-120 min, 5 d a week, but they were supplemented with 3 mg Zn/kg body wt per day. The erythrocyte, leukocyte, and thrombocyte counts and the hemoglobin values of all subjects participating in the study were measured before and after exercise at the beginning and at the end of the 4-wk study period. In all groups, there were no significant differences in the measured parameters before and after exercise. At the end of the supplementation period, the parameters of the subjects in groups 1 and 3 were significantly higher than those of group 2, both before (p<0.005) and after (p<0.05) exercise. These results suggest that zinc supplementation has a positive effect on hematological parameters in athletes.