***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Abstract Strenuous exercise may be associated with immune suppression . However , the underlying mechanism is not known . A decrease in the plasma level of glutamine , which is utilised at a high rate by cells of the immune system , and an increase in the plasma level of some cytokines may impair immune functions such as lymphocyte proliferation after prolonged , exhaustive exercise . In two separate studies of the Brussels marathon , using similar protocol s , the time course of the changes in the plasma concentrations of some amino acids ( glutamine , glutamate , alanine , tryptophan and branched chain amino acids ) , acute phase proteins and cytokines ( interleukins IL-1α , IL-2 , IL-6 , tumour necrosis factor type a ) was measured in male athletes . The numbers of circulating leucocytes and lymphocytes were also measured . Amino acid and cytokine concentrations have not previously been measured concomitantly in marathon runners ; the measurement of some of these parameters the morning after the marathon ( 16 h ) is novel . Another novel feature is the provision of glutamine versus placebo to marathon runners participating in the second study . In both studies the plasma concentrations of glutamine , alanine and branched chain amino acids were decreased immediately after and 1 h after the marathon . Plasma concentrations of all amino acids returned to pre-exercise levels by 16 h after exercise . The plasma concentration of the complement anaphylotoxin C5a increased to abnormal levels after the marathon , presumably due to tissue damage activating the complement system . There was also an increase in plasma C-reactive protein 16 h after the marathon . The plasma levels of IL-1α were unaffected by the exercise , while that of IL-2 was increased 16 h after exercise . Plasma IL-6 was increased markedly ( ≈ 45-fold ) immediately after and at 1 h after exercise . Neopterine , a macrophage activation marker , was significantly increased post-exercise . There was a marked leucocytosis immediately after the marathon , which returned to normal 16 h later . At the same time there was a decrease in the number of T-lymphocytes , which was further reduced within 1 h to below pre-exercise levels . Glutamine supplementation , as administered in the second study , did not appear to have an effect upon lymphocyte distribution This r and omized , double-blind , placebo-controlled study was design ed to determine the influence of 6 % carbohydrate ( C ) vs. placebo ( P ) beverage ingestion on cytokine responses ( 5 total sample s over 9 h ) to 2.5 h of high-intensity running ( 76.7 + /- 0.4 % maximal O2 uptake ) by 30 experienced marathon runners . For interleukin-6 ( IL-6 ) , a difference in the pattern of change between groups was found , highlighted by a greater increase in P vs. C immediately postrun ( 753 vs. 421 % ) and 1.5 h postrun ( 193 vs. 86 % ) [ F(4,112 ) = 3.77 , P = 0.006 ] . For interleukin-1-receptor antagonist ( IL-1ra ) , a difference in the pattern of change between groups was found , highlighted by a greater increase in P vs. C 1.5 h postrun ( 231 vs. 72 % ) [ F(2,50 ) = 6.38 , P = 0.003 ] . No significant interaction effects were seen for bioactive IL-6 or IL-1 beta . The immediate postrun plasma glucose concentrations correlated negatively with those of plasma cortisol ( r = -0.67 , P < 0.001 ) ; postrun plasma cortisol ( r = 0.70 , P < 0.001 ) and IL-6 levels ( r = 0.54 , P = 0.003 ) correlated positively with levels of IL-1ra . Taken together , the data indicate that carbohydrate ingestion attenuates cytokine levels in the inflammatory cascade in response to heavy exertion OBJECTIVE Intense long- duration exercise has been associated with immunosuppression , which affects natural killer cells , lymphokine-activated killer cells , and lymphocytes . The mechanisms involved , however , are not fully determined and seem to be multifactorial , including endocrine changes and alteration of plasma glutamine concentration . Therefore , we evaluated the effect of branched-chain amino acid supplementation on the immune response of triathletes and long-distance runners . METHODS Peripheral blood was collected prior to and immediately after an Olympic Triathlon or a 30k run .  Lymphocyte proliferation , cytokine production by cultured cells , and plasma glutamine were measured . RESULTS After the exercise bout , athletes from the placebo group presented a decreased plasma glutamine concentration that was abolished by branched-chain amino acid supplementation and an increased proliferative response in their peripheral blood mononuclear cells . Those cells also produced , after exercise , less tumor necrosis factor , interleukins-1 and -4 , and interferon and 48 % more interleukin-2 . Supplementation stimulated the production of interleukin-2 and interferon after exercise and a more pronounced decrease in the production of interleukin-4 , indicating a diversion toward a Th1 type immune response . CONCLUSIONS Our results indicate that branched-chain amino acid ( BCAA ) supplementation recovers the ability of peripheral blood mononuclear cells proliferate in response to mitogens after a long distance intense exercise , as well as plasma glutamine concentration . The amino acids also modify the pattern of cytokine production leading to a diversion of the immune response toward a Th1 type of immune response The influence of exercise mode and 6 % carbohydrate ( C ) vs. placebo ( P ) beverage ingestion on granulocyte and monocyte phagocytosis and oxidative burst activity ( GMPOB ) after prolonged and intensive exertion was measured in 10 triathletes . The triathletes acted as their own controls and ran or cycled for 2.5 h at approximately 75 % maximal O2 uptake , ingesting C or P ( 4 total sessions , r and om order , with beverages administered in double-blind fashion ) . During the 2 . 5-h exercise bouts , C or P ( 4 ml/kg ) was ingested every 15 min . Five blood sample s were collected ( 15 min before exercise , immediately after exercise , and 1.5 , 3 , and 6 h after exercise ) . The pattern of change over time for GMPOB was significantly different between C and P conditions ( P < /= 0.05 ) , with postexercise values lower during the C trials . Little difference was measured between running and cycling modes . C relative to P ingestion ( but not exercise mode ) was associated with higher plasma levels of glucose and insulin , lower plasma levels of cortisol and growth hormone , and lower blood neutrophil and monocyte cell counts . These data indicate that C vs. P ingestion is associated with higher plasma glucose levels , an attenuated cortisol response , and lower GMPOB The purpose of this study was to examine the effects of bovine colostrum supplementation ( Bioenervi ) on serum insulin-like growth factor I ( IGF-I ) , immunoglobulin G , hormone , and amino acid and saliva immunoglobulin A concentrations during a strength and speed training period . Nine male sprinters and jumpers underwent three r and omized experimental training treatments of 8 days separated by 13 days . The only difference in the treatments was the drink of 125 ml consumed per day . Posttraining increases were noticed for serum IGF-I in the 25-ml Bioenervi treatment ( 125 ml contained 25 ml Bioenervi ) and especially in the 125-ml Bioenervi treatment ( 125 ml contained 125 ml Bioenervi ) compared with the placebo ( normal milk whey ) treatment ( P < 0.05 ) . The change in IGF-I concentration during the 8-day periods correlated positively with the change in insulin concentration during the same periods with 25-ml Bioenervi treatment ( r = 0.68 ; P = 0.045 ) and with 125-ml Bioenervi treatment ( r = 0.69 ; P = 0.038 ) . Serum immunoglobulin G , hormone , and amino acid and saliva immunoglobulin A responses were similar during the three treatments . It appears that a bovine colostrum supplement ( Bioenervi ) may increase serum IGF-I concentration in athletes during strength and speed training Abstract . Exercise increases oxygen consumption and causes a disturbance of intracellular pro-oxidant-antioxidant homeostasis . Few data are available as to the cumulative effects of exercise on the antioxidant defenses of the neutrophil . We studied the effects of 90 days ' supplementation with placebo or an antioxidant cocktail of vitamin E ( 500 mg/day ) and β-carotene ( 30 mg/day ) and the last 15 days also with vitamin C ( 1 g/day ) on sportsmen 's basal neutrophil antioxidant defenses . We analyzed the activities of catalase , glutathione peroxidase , glutathione reductase and the activities and levels of superoxide dismutase , glutathione and glutathione disulfide in neutrophils purified from antecubital vein blood of sportsmen before and after  diet supplementation .  Plasma vitamin E , β-carotene and vitamin C concentrations in the antioxidant-supplemented group were approximately 1.6 , 10 , and 1.2 times higher respectively than those of the placebo group . The antioxidant-supplemented group presented a significantly higher glutathione versus glutathione disulfide ratio in neutrophils ( about 20 % ) than the placebo one . Antioxidant supplementation  enhances the antioxidant enzyme activity of superoxide dismutase and catalase in neutrophils This r and omized , double-blind , placebo-controlled study was design ed to determine the influence of carbohydrate supplementation on the granulocyte and monocyte response to 2.5 h of high-intensity running [ 76.7 + /- 0.4 % of maximal oxygen consumption ( VO2max ) ] . Thirty experienced marathon runners ( VO2max 53.4 + /- 1.0 mL.kg-1.min-1 , age 41.5 + /- 1.4 y ) were r and omly assigned to carbohydrate-supplement ( n = 17 ) and placebo  ( n = 13 ) groups . Subjects rested for 10 - 15 min before a blood sample was taken at 0715 , and then ingested 0.75 L carbohydrate beverage or placebo . At 0730 subjects began running at 75 - 80 % of VO2max for 2.5 h , and drank 0.25 L carbohydrate or placebo fluid every 15 min . Immediately after the 2.5-h run ( 1000 ) , another blood sample was taken , followed by 1.5-h , 3-h , and 6-h recovery sample s. Carbohydrate supplementation had a significant effect compared with placebo on the pattern of change in plasma glucose and cortisol , and the blood concentration of neutrophils ( F[14 , 112 ] = 5.13 , P = 0.001 ) and monocytes ( F[14 , 112 ] = 4.78 , P = 0.001 ) , but not on blood granulocyte and monocyte phagocytosis or oxidative burst activity after 2.5 h of intensive running This study determined whether daily supplementation with 600 mg vitamin C would reduce the incidence of symptoms of  upper-respiratory-tract ( URT ) infections after participation in a competitive ultramarathon race ( > 42 km ) . Ultramarathon runners with age-matched controls were r and omly divided into placebo and experimental ( vitamin C-supplemented ) groups . Symptoms of URT infections were monitored for 14 d after the race . Sixty-eight percent of the runners in the placebo group reported the development of symptoms of URT infection after the race ; this was significantly more ( P < 0.01 ) than that reported by the vitamin C-supplemented group ( 33 % ) . The duration and severity of symptoms of URT infections reported in the vitamin C-supplemented nonrunning control group was also significantly less than in the nonrunning control group receiving the placebo ( P < 0.05 ) . This study provides evidence that vitamin C supplementation may enhance resistance to the postrace URT infections that occur commonly in competitive ultramarathon runners and may reduce the severity of such infections in those who are sedentary OBJECTIVE To evaluate the effect of carbohydrate supplementation upon some aspects of the immune function  in athletes during intense indoor cycling . METHODS Twelve male athletes cycled for 20 min at a velocity corresponding to 90 % of that obtained at the anaerobic threshold and rested for 20 min . This protocol was repeated six times . The athletes received , during the trial , water ad libitum , or a solution of carbohydrate ( 95 % glucose polymers and 5 % fructose ) at 10 % ( w/v ) , 1 g kg h every 20 min , starting at the 10th minute of the first exercise period , plus extra water ad libitum 
    Output:
    
Carbohydrate supplementation attenuated the increase in cortisol and neutrophils after exercise ; vitamin C attenuated the decrease in lymphocytes after exercise .
The available evidence failed to support a role for other nutritional supplements in preventing exercise-induced immune suppression .