***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Regulation of maximal Na(+)-K(+)-ATPase activity in vastus lateralis muscle was investigated in response to prolonged exercise with ( G ) and without ( NG ) oral glucose supplements .  Fifteen untrained volunteers ( 14 males and 1 female ) with a peak aerobic power ( Vo(2)(peak ) ) of 44.8 + /- 1.9 ml.kg(-1).min(-1 ) ; mean + /- SE cycled at approximately 57 % Vo(2)(peak ) to fatigue during both NG ( artificial sweeteners ) and G ( 6.13 + /- 0.09 % glucose ) in r and omized order . Consumption of beverage began at 30 min and continued every 15 min until fatigue . Time to fatigue was increased ( P < 0.05 ) in G compared with NG ( 137 + /- 7 vs. 115 + /- 6 min ) . Maximal Na(+)-K(+)-ATPase activity ( V(max ) ) as measured by the 3-O-methylfluorescein phosphatase assay ( nmol.mg(-1).h(-1 ) ) was not different between conditions prior to exercise ( 85.2 + /- 3.3 or 86.0 + /- 3.9 ) , at 30 min ( 91.4 + /- 4.7 vs. 91.9 + /- 4.1 ) and at fatigue ( 92.8 + /- 4.3 vs. 100 + /- 5.0 ) but was higher ( P < 0.05 ) in G at 90 min ( 86.7 + /- 4.2 vs. 109 + /- 4.1 ) . Na(+)-K(+)-ATPase content ( beta(max ) ) measured by the vana date facilitated [(3)H]ouabain-binding technique ( pmol/g wet wt ) although elevated ( P < 0.05 ) by exercise ( 0<30 , 90 , and fatigue ) was not different between NG and G. At 60 and 90 min of exercise , blood glucose was higher ( P < 0.05 ) in G compared with NG . The G condition also result ed in higher ( P < 0.05 ) serum insulin at similar time points to glucose and lower ( P < 0.05 ) plasma epinephrine and norepinephrine at 90 min of exercise and at fatigue . These results suggest that G results in an increase in V(max ) by mechanisms that are unclear This study examined the effectiveness of ingesting a carbohydrate or carbohydrate + medium-chain triglycerides ( MCT ) on metabolism and cycling performance .  Eight endurance-trained men [ peak O(2 ) uptake = 4.71 + /- 0.09 ( SE ) l/min ] completed 35 kJ/kg as quickly as possible [ time trial ( TT ) ] while consuming 250 ml/15 min of either a 6 % ( wt/vol ) carbohydrate solution ( C ) , a 6 % carbohydrate + 4.2 % MCT solution ( C+M ) , or a sweet placebo ( P ) . Time to complete the set amount of work was reduced in both C and C+M compared with P by 7 and 5 % , respectively ( C : 166 + /- 7 min ; C+M : 169 + /- 7 min ; P : 178 + /- 11 min ; P < 0.01 ) . Plasma glucose concentration was maintained at or above resting values throughout both C and C+M trials but decreased ( P < 0.05 ) below resting values in P at the completion of the TT . The estimated rate of carbohydrate oxidation was not different during the first 90 min of exercise but thereafter was reduced ( P < 0.05 ) in P and was maintained in both C and C+M. These data demonstrate that carbohydrate ingestion during exercise improves 100-km TT performance compared with a sweet placebo , but the addition of MCT does not provide any further performance enhancement On three occasions cyclists completed , as fast as possible , two exercise tasks ( T1 and T2 ) separated by 30 min rest . T1 and T2 were equivalent to the work performed during 2 h cycling at 75 % VO2max and 30 min at 75 % VO2max , respectively . Every 20 min subjects drank 275 mL of a 6 % ( MC ) or 2.5 % ( LC ) carbohydrate-electrolyte beverage or a water placebo ( P ) . The initial drink during both T1 and the rest period contained 20 g D2O as a marker for entry of ingested fluid into blood . No differences in drink effects were found for heart rate , sweat rate , change in plasma volume , rectal temperature , or D2O accumulation in blood . Blood glucose and respiratory exchange ratios were higher and T2 was performed faster with MC than with P. Ingestion of MC can help maintain blood glucose and enhance performance of prolonged cycling exercise without compromising fluid replenishment The study examined the effect of carbohydrate ingestion on exercise performance capacity .  Nine male cyclists performed two separate trials at 70 % VO2max for 60 min followed by a maximal ride for 10 min . During trials subjects were fed either an 8 % glucose solution ( CHO ) or a placebo solution ( PL ) , which were administered at rest and during and immediately after submaximal exercise . Statistical analyses indicated that glucose levels at rest increased significantly 15 min after the ingestion of CHO compared to PL . At 30 and 60 min during submaximal exercise , plasma glucose levels decreased significantly in the CHO but not in the PL trial . Following the performance ride , glucose levels increased significantly only during the CHO test trial . Free fatty acids did not change significantly during testing trials . The maximal performance ride results showed that in the CHO trial , a significantly greater external work load was accomplished compared to the PL trial . It is concluded that CHO ingestion improves maximal exercise performance after prolonged exercise Hypoglycemia ( blood glucose less than 45 mg per deciliter [ less than 2.5 mmol per liter ] ) occurred in seven of 19 healthy men who exercised to exhaustion on a cycle ergometer at 60 to 65 per cent of maximal aerobic power . The hypoglycemic subjects exercised for 15 to 70 minutes despite blood glucose levels of 25 to 48 mg per deciliter ( 1.4 to 2.7 mmol per liter ) , and their exhaustion time ( mean + /- S.E.M. , 142 + /- 15 minutes ) was not significantly different from that of the euglycemic group ( 165 + /- 11 ) . Plasma epinephrine was inversely related to blood glucose ( P less than 0.01 ) and was three times higher in the hypoglycemic subjects ( P less than 0.05 ) . Glucose ingestion ( 40 or 80 g per hour ) prevented the hypoglycemia and result ed in a smaller rise in plasma epinephrine but did not alter perceived exertion or consistently delay exhaustion . We conclude that hypoglycemia occurs in normal subjects during prolonged exercise and results in an exaggerated rise in plasma epinephrine . However , hypoglycemia fails to effect endurance , and its prevention does not consistently delay exhaustion The effects of a commercial sports drink on performance in  high-intensity cycling  was investigated . Nine well-trained subjects were asked to complete a set amount of work as fast as possible ( time trial ) following 24 h of dietary ( subjects were provided with food , energy 57.4+/-2.4 kcal/kg and carbohydrate 9.1+/-0.4 g/kg ) and exercise control . During exercise , subjects were provided with 14 mL/kg of either 6 % carbohydrate-electrolyte ( CHO-E ) solution or carbohydrate-free placebo ( P ) . Results showed that subjects ' performances did not greatly improve ( time , 62:34+/-6:44 min : sec ( CHO-E ) vs. 62:40+/-5:35 min : sec ( P ) ; average power output , 283.0+/-25.0 W ( CHO-E ) vs. 282.9+/-29.3 W ( P ) , P > 0.05 ) while consuming the sports drink . It was concluded that CHO-E consumption throughout a 1-h time trial , following a pre-exercise dietary regimen design ed to optimize glucose availability , did not improve time or power output to a greater degree than P in well-trained cyclists Solutions containing multiple carbohydrates utilizing different intestinal transporters ( glucose and fructose ) show enhanced absorption , oxidation , and performance compared with single-carbohydrate solutions , but the impact of the ratio of these carbohydrates on outcomes is unknown . In a r and omized double-blind crossover , 10 cyclists rode 150 min at 50 % peak power , then performed an incremental test to exhaustion , while ingesting artificially sweetened water or one of three carbohydrate-salt solutions comprising fructose and maltodextrin in the respective following concentrations : 4.5 and 9 % ( 0.5-Ratio ) , 6 and 7.5 % ( 0.8-Ratio ) , and 7.5 and 6 % ( 1.25-Ratio ) . The carbohydrates were ingested at 1.8 g/min and naturally (13)C-enriched to permit evaluation of oxidation rate by mass spectrometry and indirect calorimetry . Mean exogenous carbohydrate oxidation rates were 1.04 , 1.14 , and 1.05 g/min ( coefficient of variation 20 % ) in 0.5- , 0.8- , and 1.25-Ratios , respectively , representing likely small increases in 0.8-Ratio of 11 % ( 90 % confidence limits ; ± 4 % ) and 10 % ( ± 4 % ) relative to 0.5- and 1.25-Ratios , respectively . Comparisons of fat and total and endogenous carbohydrate oxidation rates between solutions were unclear . Relative to 0.5-Ratio , there were moderate improvements to peak power with 0.8- ( 3.6 % ; 99 % confidence limits ± 3.5 % ) and 1.25-Ratio ( 3.0 % ; ± 3.7 % ) but unclear with water ( 0.4 % ; ± 4.4 % ) . Increases in stomach fullness , abdominal cramping , and nausea were lowest with the 0.8- followed by the 1.25-Ratio solution . At high carbohydrate-ingestion rate , greater benefits to endurance performance may result from ingestion of 0.8- to 1.25-Ratio fructose-maltodextrin solutions . Small perceptible improvements in gut comfort favor the 0.8-Ratio and provide a clearer suggestion of mechanism than the relationship with exogenous carbohydrate oxidation The effects of menstrual cycle phase and carbohydrate ( CHO ) supplementation were investigated during prolonged exercise . Nine healthy , moderately trained women cycled at 70 % peak O(2 ) consumption until exhaustion . Two trials were completed during the follicular ( Fol ) and luteal ( Lut ) phases of the menstrual cycle . Subjects consumed 0.6 g CHO . kg body wt(-1 ) . h(-1 ) ( 5 ml/kg of a 6 % CHO solution every 30 min beginning at min 30 of exercise ) or a placebo drink ( Pl ) during exercise .  Time to exhaustion during CHO  increased from Pl values ( P < 0.05 ) by 14.4 + /- 8.5 ( Fol ) and 11.4 + /- 7.1 % ( Lut ) ; no differences were observed between menstrual cycle phases .  CHO  attenuated ( P < 0.05 ) the decrease in plasma glucose and insulin and the increase in plasma free fatty acids , tryptophan , epinephrine , and cortisol observed during Pl for both phases . Plasma alanine , glutamine , proline , and isoleucine were lower ( P < 0.05 ) in Lut than in Fol phase .  CHO  result ed in lower ( P < 0.05 ) plasma tyrosine , valine , leucine , isoleucine , and phenylalanine . These results indicate that the menstrual cycle phase does not alter the effects of CHO supplementation on performance and plasma levels of related substrates during prolonged exercise This study was undertaken to determine the effects of ingesting either glucose ( trial G ) or glucose plus branched-chain amino acids ( BCAA : trial B ) , compared with placebo ( trial P ) , during prolonged exercise . Nine well-trained cyclists with a maximal oxygen uptake of 63.1 + /- 1.5 ml O2 . min-1.kg-1 performed three laboratory trials consisting of 100 km of cycling separated by 7 days between each trial . During these trials , the subjects were encouraged to complete the 100 km as fast as possible on their own bicycles connected to a magnetic brake . No differences in performance times were observed between the three trials ( 160.1 + /- 4.1 , 157.2 + /- 4.5 , and 159.8 + /- 3.7 min , respectively ) . In trial B , plasma BCAA levels increased from 339 + /- 28 microM at rest to 1,026 + /- 62 microM after exercise ( P < 0.01 ) 
    Output:
    
The data support that ingestion of CHO between 30 and 80 g/h enhances endurance exercise performance in adults