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S Nikpour, Z Atarodi Kashani, Sh Mokhtarshahi, S Parsay, M Nooritajer, H Haghani,
Volume 14, Issue 54 (4-2007)
Volume 14, Issue 54 (4-2007)
Abstract
Background & Aim: Preeclampsia and eclampsia are threatening complications of pregnancy that influence the health of mothers and their fetuses therefore,the prevention of these complications is very important. The need for vitamin C increases during pregnancy and breast-feeding, so providing mothers with vitamin C through natural diet is very prominent. The aim of the present study is to evaluate the correlation between the consumption of diet rich in vitamin C and preeclampsia and eclampsia. Patients & Method: In this case-control study, data collection was done through interviews and filling out questionnaires consisting of two parts. The first section included questions related to background variables and the second part contained some questions relevant to the frequency of the consumption of vitamin C-rich foods. Then, the reported amounts of ascorbic acid in urine and plasma were recorded. 154 women who participated in this study had been selected through a continuous sampling method. The subjects were divided into two groups of case and control. The case group included 75 women with preeclampsia and eclampsia, and 79 women not attacked by preeclampsia or eclampsia formed the control group. The age range of the subjects was between 18 and 35 years. Both groups were matched according to their gravida and multivitamin supplement consumption. Results: The findings indicated that there was a meaningful relationship between preeclampsia, eclampsia and the consumption of vitamin C-rich foods. This relation was significantly meaningful according to the number of servings and also the amount of vitamin C received: for the number of servings for both fruit and vegetables (P=0.00), and for the amount of vitamin C received from diet(≥85mg/day)(P=0.00). Also, the concentrations of ascorbic acid in plasma and urine were(P=0.03) and(P=0.05) respectively, which was significantly related to the presence of preeclampsia and eclampsia. Conclusion: As the results showed, there were direct relations between preeclampsia, eclampsia and insufficient consumption of vitamin C. Proper educational programs about nutrition during pregnancy, especially during the first trimester of the first pregnancy, are recommended and prospective studies are also suggested in order to confirm the existing findings.
Student Hadi Atarod, Dr Farshad Ghazalian, Dr Javad Mehrabani, Dr Hossein Abed Natanzi, Dr Mandana Gholami,
Volume 28, Issue 7 (10-2021)
Volume 28, Issue 7 (10-2021)
Abstract
Background & Aims: Athletes are always looking for a way to improve their performance(1). Caffeine is one of the most common supplements which may increase mental and physical performance and acts as an ergogenic aid especially in repeated running (2-3). It has been shown that acute caffeine supplementation may affect endothelium and vascular smooth muscles which may be due to: caffeine acts as adenosine receptors antagonist, phosphodiesterase inhibition, increase in intracellular calcium concentration, nitric oxide synthase enzyme gene expression (4). At resting individuals, caffeine consumption can increasing intracellular calcium concentration, leading to nitric oxide synthase (NOS) enzyme gene expression which stimulates nitric oxide (NO) production. Increase in NO level will ultimately cause vascular smooth muscles relaxation and vasodilation.(5-6)caffeine supplementation an hour before aerobic exercise, could reduce extracellular fluid and blood flow, despite it has showed beneficial effects for increased demand during exercise (7-10). Caffeine may increase systolic and diastolic blood pressure (11). Beetroot-juice is an antioxidant and nitric oxide source which may have anti-inflammatory effect against free radicals and beneficial effects for cardiovascular system and lead to better physical performance (12-18) nitrate consumption can produce nitric oxide from L-arginine amino acid and improve performance (19-20). Nitrate supplementation can increase nitric oxide level In in plasma and decrease blood pressure (21). Nitric oxide may regulate vasodilatory factors and vascular tone (22). Studies have suggested that nitrate supplementation may increase vasodilation in active tissues and increase vasoconstriction in inactive tissues via increasing endothelin-1 level (23), moreover, it has been suggested that Beetroot-juice supplement may decrease blood pressure and improve performance related factors (24). The purpose of this study was to evaluate the effect of acute caffeine supplementation along with beetroot-juice on vasodilatory factors and physical performance in athletes.
Methods: In this study, ten high performance runners were divided into three experimental trials as high dosage,low dosage supplementation and placebo. Participants drink the supplementations with 250 ml water two times per day during seven days before 5000 meter endurance performance. Rest heart rate, blood pressure, endothelin-1, collagen-18 and nitric oxide level were measured. Participants for this study were 18-30 years old male runners with at least 2 years of running experience which were randomly divided into the following 3 groups after introduction session. At the first day of experiment, participants were present fasted for (8-10 hours) and inactivity status for at least 48 hours. Heart rate and blood pressure were measured with digital pulse meter and rosmax sphygmomanometer. Blood samples were collected from antecubital vein. After 5 minutes warm up, participant started 5 km running.
Participants were randomly divided in to three supplementation groups as following:
1. 9.6 mmol Beetroot-juice and 400 mg caffeine
2. 4.8 mmol Beetroot-juice and 200 mg caffeine
3. Placebo (PLB) group
physical activity was considered as 5 km running tests. At the first day, heart rate and blood pressure were assessed before the running test. Venous blood samples were collected to assess vasodilatory factors including: coll-18, ET-1, NO and nitrite. Participants start the running test after 5 minutes warmup and at the end of the test, all the measurements were repeated. At the second day, participants completed 1500 running test after 5 minutes warm up and consumed supplement. From the third day until day 6, supplementation was continued and participant were fellow up via calls. At the seventh day, heart rate and blood pressure were measured, participants consume supplements according to their group tags 60 minutes prior to their running test, and completed 5 km test after 5 minutes warm up. At day eight, participants consumed supplements and completed 1500 running test. Wash out phase was started from day 9 to 14 and participants did not consume any supplements for a week.
In this study, regression analysis with repeated measurements with generalized estimation equation approach.
Results: The results from the study showed no significant difference for endothelin-1 between the 3 groups before and after the intervention which means that Beetroot-juice combined with caffeine supplementation had no effect on serum endothelin-1 level (p=0.52).
The results from statistical analysis showed no significant difference between the groups for collagen-18 which means supplementation was not effective on collagen-18 level (p=0.87).
The results suggest that supplementation could not affect NO level significantly (p=0.97) but physical activity increased NO level by 90.58 units (p=0.001). Systolic bp was not affected by the supplementation dosage (p=0.17). supplementation did not affect systolic BP significantly (p=0.09). systolic BP was affected by physical activity and systolic BP was increased by 2.58 mmHg. Supplementation dosage did not make any significant difference in experimental groups (p=0.28). Supplementation did not have any significant change in heart rate (p=0.25), despite physical activity effect (p=0.001) there was an increase in heart rate within 1500 meter running in comparison with start moment (p=0.001).
Conclusion: This study suggests that the combination of caffeine and Beetroot-juice supplementation may not have beneficial effects of vasodilatory factors and physical performance in elite male runners which may be due to NO effect reduction when consumed in combination with caffeine while exercise may influence vasodilatory and performance parameters.
Hadi Atarod, Farshad Ghazalian, Javad Mehrabani, Hossein Abed Natanzi, Mandana Gholami,
Volume 30, Issue 1 (3-2023)
Volume 30, Issue 1 (3-2023)
Abstract
Background & Aims: Athletes use variety of compounds to improve athletic performance and are constantly striving to improve capacity and performance. Various supplements are used by the masses and regularly by athletes in exercise to take advantage of the energizing properties as well as to prevent or delay fatigue (1). Dietary supplements, in addition to proper exercise and nutrition to improve athletic performance, are recognized, including caffeine and nitrate supplements. Since both beet juice and caffeine supplements are safe, effective, and legal, it seems that combining these two supplements and using them by athletes can have an increasing effect on improving athletic performance. Caffeine is used by many athletes as an ergogenic supplement, and low and moderate doses of caffeine (3 to 6 mg/kg) are very useful for a variety of exercise (2).
Also, the use of beet juice supplementation in speed runners increased the concentration of lactate in the blood, while there was no difference in the amount of oxygen consumed (7). According to the results of other studies, it seems that the use of nitrate supplementation can reduce the time required to run 10 km and maintain lactate levels in the constant range. However, it seems that 30 days of nitrate supplementation combined with continuous aerobic exercise can improve the performance of running 10 km compared to running alone, one of the mechanisms for which is stability at the surface Blood lactate (8). The results of a study showed that the use of nitric oxide as supplement can accelerate the clearance of lactate from the body after exercise and thus accelerate recovery (9). In study of Bescós et al. (2011) two randomized blinds stated that the use of nitrate supplementation as a single dose of 10 mg per kg of body weight 3 hours before exercise had an effect on athletic performance and arrival time. Also, it did not cause fatigue and the use of this supplement and with this dose did not affect the heart rate (10). Belbis et al. (2018) examined the effect of 200 mg of caffeine on repetitive running activity on heart rate and lactate levels. The results of this study showed that caffeine supplementation at dose of 200 mg can increase performance in repetitive doses compared to counterparts in the control group (11).
Due to the very limited studies of supplementation of caffeine and beet juice and the lack of comparison of doses used in professional runners with field protocol and considering the conditions of intense aerobic and anaerobic training subsequently and in a short time in most sports to Improves anaerobic power and lactate threshold, as well as strengthens cardiovascular endurance during training and tournaments that probably have more than one training session per day, and considering that running is used as one of the pillars of training to increase the performance of athletes by coaches., Therefore, the aim of this study was to investigate the effect of short-term caffeine-beet juice supplementation on catecholamine changes, lactate and Rating of Perceived Exertion following intense anaerobic activity in elite male runners.
Methods: In this quasi-experimental study, 30 elite male runners (age 27.5±3.8 y, height: 176.7±7 cm, body fat: 9.9±1.7 %) were randomly divided into three exercise groups with 1) high dose supplement (9.6 mmol Beet extract and 400 mg caffeine), 2) low-dose supplement (4.8 mmol beet extract and 200 mg caffeine) and 3) placebo group (natural beet juice). total of 36 sessions were performed in three stages and two stages of six-day wash out between the first and second stages and the second and third stages. Levels of epinephrine and norepinephrine, lactate and pressure perception were measured. Data were analyzed using analysis of variance with repeated measures at the P<0.05.
Results: The results showed that supplementation and exercise no significant changes in epinephrine levels (p = 0.93), norepinephrine (p = 0.89) and lactate (p = 0.37), but has had a significant effect on the perception of runner pressure (p<0.001). Also, supplementation and exercise caused significant changes in catecholamine levels (p<0.001). As the time elapsed after running, lactate levels decreased more than at baseline (p<0.001). Also, with increasing running distance, the rate of pressure perception increased (p<0.001).
Conclusion: The results of the present study showed that short-term supplementation with beet juice and caffeine was not able to significantly change the levels of catecholamines, lactate in elite runners, but was significantly reduce the pressure perception. The findings of this study were consistent with the results of Previous research (14-19). It has been shown that nitrate supplements for 15 days can reduce the perception of pressure, increase oxygen saturation and also increase the time to reach fatigue (23). Nitrate is an organic ion found in many foods, especially vegetables such as celery, beets, lettuce and spinach (24, 25). Following consumption, nitrate enters the bloodstream and has a shelf life of about 5 hours. Once absorbed into the bloodstream, nitrate is converted to nitrite and then nitric oxide, which can dilate blood vessels, increase blood flow, reduce muscle energy expenditure, improve nutrient delivery to muscle, and increase calcium ion release, and ultimately Improve runners' performance (26,27). Short-term nitrate supplementation appears to increase nitric oxide bioavailability and inhibit sympathetic vasoconstriction in resting or contracting muscle, however, some studies have shown conflicting results. Nitrate supplementation has been shown to be unable to alter vascular contraction due to sympathetic effects in young male athletes (27). also, the physiological effects of caffeine supplementation are not well understood, but it appears that the effects of caffeine on heart rate are influenced by the intensity of exercise and caffeine supplementation can reduce heart rate and blood pressure perception (32). It seems that the lack of significance in high and low doses of caffeine and beet juice supplementation on catecholamine variables indicates the lack of sympathetic effect of this combined supplement or that the presence of caffeine and nitrate together can neutralize each other. In relation to the exercise pressure perception index, the difference in the dose received by this combined supplement had a significant effect, which indicates that by increasing the amount, the pain perception threshold can be increased. Possible mechanisms include vasodilation, increased blood flow, improved delivery of nutrients and oxygen to the muscle, and increased calcium ion release and reduced fatigue. One of the limitations of this study is the lack of precise control of subjects in terms of food intake between the second to seventh day and also in the rest period between each stage. It also seems that individual differences in athletes' eating habits and body reactions may affect the response to variables due to the short duration of the intervention, especially in the case of caffeine, which despite the relative control during the study but the body Athletes show different responses to it, or the duration of the research is limited due to the professionalism of the athletes and the time that coaches allow them to participate in applied research. One of the strengths of this research is the use of supplements that are extracted from natural and daily foods. It is suggested that in future research on the recommended amounts of supplements with several different doses or in combination with other ergogenic supplements, preferably with a nutritional nature and not chemical and with a synergistic effect similar to this study and with longer use or in non-professionals. As well as other sports with the nature of endurance, strength or speed and skill to be considered. The results of this study showed that short-term supplementation with caffeine and beetroot juice as a source of nitrate did not cause significant changes in catecholamine, lactate and heart rate, but caused significant changes in runners' perception of pressure. Further studies are also needed to investigate possible mechanisms involved in athletes' anaerobic performance and more effective doses. It does not seem to combine these two supplements with each other or in higher doses compared to smaller amounts.
Also, the use of beet juice supplementation in speed runners increased the concentration of lactate in the blood, while there was no difference in the amount of oxygen consumed (7). According to the results of other studies, it seems that the use of nitrate supplementation can reduce the time required to run 10 km and maintain lactate levels in the constant range. However, it seems that 30 days of nitrate supplementation combined with continuous aerobic exercise can improve the performance of running 10 km compared to running alone, one of the mechanisms for which is stability at the surface Blood lactate (8). The results of a study showed that the use of nitric oxide as supplement can accelerate the clearance of lactate from the body after exercise and thus accelerate recovery (9). In study of Bescós et al. (2011) two randomized blinds stated that the use of nitrate supplementation as a single dose of 10 mg per kg of body weight 3 hours before exercise had an effect on athletic performance and arrival time. Also, it did not cause fatigue and the use of this supplement and with this dose did not affect the heart rate (10). Belbis et al. (2018) examined the effect of 200 mg of caffeine on repetitive running activity on heart rate and lactate levels. The results of this study showed that caffeine supplementation at dose of 200 mg can increase performance in repetitive doses compared to counterparts in the control group (11).
Due to the very limited studies of supplementation of caffeine and beet juice and the lack of comparison of doses used in professional runners with field protocol and considering the conditions of intense aerobic and anaerobic training subsequently and in a short time in most sports to Improves anaerobic power and lactate threshold, as well as strengthens cardiovascular endurance during training and tournaments that probably have more than one training session per day, and considering that running is used as one of the pillars of training to increase the performance of athletes by coaches., Therefore, the aim of this study was to investigate the effect of short-term caffeine-beet juice supplementation on catecholamine changes, lactate and Rating of Perceived Exertion following intense anaerobic activity in elite male runners.
Methods: In this quasi-experimental study, 30 elite male runners (age 27.5±3.8 y, height: 176.7±7 cm, body fat: 9.9±1.7 %) were randomly divided into three exercise groups with 1) high dose supplement (9.6 mmol Beet extract and 400 mg caffeine), 2) low-dose supplement (4.8 mmol beet extract and 200 mg caffeine) and 3) placebo group (natural beet juice). total of 36 sessions were performed in three stages and two stages of six-day wash out between the first and second stages and the second and third stages. Levels of epinephrine and norepinephrine, lactate and pressure perception were measured. Data were analyzed using analysis of variance with repeated measures at the P<0.05.
Results: The results showed that supplementation and exercise no significant changes in epinephrine levels (p = 0.93), norepinephrine (p = 0.89) and lactate (p = 0.37), but has had a significant effect on the perception of runner pressure (p<0.001). Also, supplementation and exercise caused significant changes in catecholamine levels (p<0.001). As the time elapsed after running, lactate levels decreased more than at baseline (p<0.001). Also, with increasing running distance, the rate of pressure perception increased (p<0.001).
Conclusion: The results of the present study showed that short-term supplementation with beet juice and caffeine was not able to significantly change the levels of catecholamines, lactate in elite runners, but was significantly reduce the pressure perception. The findings of this study were consistent with the results of Previous research (14-19). It has been shown that nitrate supplements for 15 days can reduce the perception of pressure, increase oxygen saturation and also increase the time to reach fatigue (23). Nitrate is an organic ion found in many foods, especially vegetables such as celery, beets, lettuce and spinach (24, 25). Following consumption, nitrate enters the bloodstream and has a shelf life of about 5 hours. Once absorbed into the bloodstream, nitrate is converted to nitrite and then nitric oxide, which can dilate blood vessels, increase blood flow, reduce muscle energy expenditure, improve nutrient delivery to muscle, and increase calcium ion release, and ultimately Improve runners' performance (26,27). Short-term nitrate supplementation appears to increase nitric oxide bioavailability and inhibit sympathetic vasoconstriction in resting or contracting muscle, however, some studies have shown conflicting results. Nitrate supplementation has been shown to be unable to alter vascular contraction due to sympathetic effects in young male athletes (27). also, the physiological effects of caffeine supplementation are not well understood, but it appears that the effects of caffeine on heart rate are influenced by the intensity of exercise and caffeine supplementation can reduce heart rate and blood pressure perception (32). It seems that the lack of significance in high and low doses of caffeine and beet juice supplementation on catecholamine variables indicates the lack of sympathetic effect of this combined supplement or that the presence of caffeine and nitrate together can neutralize each other. In relation to the exercise pressure perception index, the difference in the dose received by this combined supplement had a significant effect, which indicates that by increasing the amount, the pain perception threshold can be increased. Possible mechanisms include vasodilation, increased blood flow, improved delivery of nutrients and oxygen to the muscle, and increased calcium ion release and reduced fatigue. One of the limitations of this study is the lack of precise control of subjects in terms of food intake between the second to seventh day and also in the rest period between each stage. It also seems that individual differences in athletes' eating habits and body reactions may affect the response to variables due to the short duration of the intervention, especially in the case of caffeine, which despite the relative control during the study but the body Athletes show different responses to it, or the duration of the research is limited due to the professionalism of the athletes and the time that coaches allow them to participate in applied research. One of the strengths of this research is the use of supplements that are extracted from natural and daily foods. It is suggested that in future research on the recommended amounts of supplements with several different doses or in combination with other ergogenic supplements, preferably with a nutritional nature and not chemical and with a synergistic effect similar to this study and with longer use or in non-professionals. As well as other sports with the nature of endurance, strength or speed and skill to be considered. The results of this study showed that short-term supplementation with caffeine and beetroot juice as a source of nitrate did not cause significant changes in catecholamine, lactate and heart rate, but caused significant changes in runners' perception of pressure. Further studies are also needed to investigate possible mechanisms involved in athletes' anaerobic performance and more effective doses. It does not seem to combine these two supplements with each other or in higher doses compared to smaller amounts.
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