***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: 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 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 PURPOSE Five days of a high-fat diet produce metabolic adaptations that increase the rate of fat oxidation during prolonged exercise . We investigated whether enhanced rates of fat oxidation during submaximal exercise after 5 d of a high-fat diet would persist in the face of increased carbohydrate ( CHO ) availability before and during exercise . METHODS Eight well-trained subjects consumed either a high-CHO ( 9.3 g x kg(-1 ) x d(-1 ) CHO , 1.1 g x kg(-1 ) x d(-1 ) fat ; HCHO ) or an isoenergetic high-fat diet ( 2.5 g x kg(-1 ) x d(-1 ) CHO , 4.3 g x kg(-1 ) x d(-1 ) fat ; FAT-adapt ) for 5 d followed by a high-CHO diet and rest on day 6 . On day 7 , performance testing ( 2 h steady-state ( SS ) cycling at 70 % peak O(2 ) uptake [ VO(2peak ) ] + time trial [ TT ] ) of 7 kJ x kg(-1 ) ) was undertaken after a CHO breakfast ( CHO 2 g x kg(-1 ) ) and intake of CHO during cycling ( 0.8 g x kg(-1 ) x h(-1 ) ) . RESULTS FAT-adapt reduced respiratory exchange ratio ( RER ) values before and during cycling at 70 % VO(2peak ) ; RER was restored by 1 d  CHO  and  CHO  intake during cycling ( 0.90 + /- 0.01 , 0.80 + /- 0.01 , 0.91 + /- 0.01 , for days 1 , 6 , and 7 , respectively ) . RER values were higher with HCHO ( 0.90 + /- 0.01 , 0.88 + /- 0.01 ( HCHO > FAT-adapt , P < 0.05 ) , 0.95 + /- 0.01 ( HCHO > FAT-adapt , P < 0.05 ) ) . On day 7 , fat oxidation remained elevated ( 73 + /- 4 g vs 45 + /- 3 g , P < 0.05 ) , whereas CHO oxidation was reduced ( 354 + /- 11 g vs 419 + /- 13 g , P < 0.05 ) throughout SS in FAT-adapt versus HCHO . TT performance was similar for both trials ( 25.53 + /- 0.67 min vs 25.45 + /- 0.96 min , NS ) . CONCLUSION Adaptations to a short-term high-fat diet persisted in the face of high CHO availability before and during exercise , but failed to confer a performance advantage during a TT lasting approximately 25 min undertaken after 2 h of submaximal cycling We evaluated the effect of carbohydrate ( CHO ) loading on cycling performance that was design ed to be similar to the dem and s of competitive road racing . Seven well-trained cyclists performed two 100-km time trials ( TTs ) on separate occasions , 3 days after either a CHO-loading ( 9 g CHO . kg body mass(-1 ) . day(-1 ) ) or placebo-controlled moderate-CHO diet ( 6 g CHO . kg body mass(-1 ) . day(-1 ) ) . A CHO breakfast ( 2 g CHO/kg body mass ) was consumed 2 h before each TT , and a CHO drink ( 1 g CHO . kg(.)body mass(-1 ) . h(-1 ) ) was consumed during the TTs to optimize CHO availability . The 100-km TT was interspersed with four 4-km and five 1-km sprints . CHO loading significantly increased muscle glycogen concentrations ( 572 + /- 107 vs. 485 + /- 128 mmol/kg dry wt for CHO loading and placebo , respectively ; P < 0.05 ) . Total muscle glycogen utilization did not differ between trials , nor did time to complete the TTs ( 147.5 + /- 10.0 and 149.1 + /- 11.0 min ; P = 0.4 ) or the mean power output during the TTs ( 259 + /- 40 and 253 + /- 40 W , P = 0.4 ) . This placebo-controlled study shows that CHO loading did not improve performance of a 100-km cycling TT during which CHO was consumed . By preventing any fall in blood glucose concentration , CHO ingestion during exercise may offset any detrimental effects on performance of lower preexercise muscle and liver glycogen concentrations . Alternatively , part of the reported benefit of CHO loading on subsequent athletic performance could have result ed from a placebo effect 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 This study investigated the effect of carbohydrate ( CHO ) ingestion on postexercise glycogen re synthesis , measured simultaneously in liver and muscle ( n = 6 ) by (13)C magnetic resonance spectroscopy , and subsequent exercise capacity ( n = 10 ) . Subjects cycled at 70 % maximal oxygen uptake for 83 + /- 8 min on six separate occasions . At the end of exercise , subjects ingested 1 g/kg body mass ( BM ) glucose , sucrose , or placebo ( control ) . Re synthesis of glycogen over a 4-h period after treatment ingestion was measured on the first three occasions , and subsequent exercise capacity was measured on occasions four through six . No glycogen was resynthesized during the control trial . Liver glycogen re synthesis was evident after glucose ( 13 + /- 8 g ) and sucrose ( 25 + /- 5 g ) ingestion , both of which were different from control ( P < 0.01 ) . No significant differences in muscle glycogen re synthesis were found among trials . A relationship between the CHO load ( g ) and change in liver glycogen content ( g ) was evident after 30 , 90 , 150 , and 210 min of recovery ( r = 0.59 - 0 . 79 , P < 0.05 ) . Furthermore , a modest relationship existed between change in liver glycogen content ( g ) and subsequent exercise capacity ( r = 0.53 , P < 0.05 ) . However , no significant difference in mean exercise time was found ( control : 35 + /- 5 , glucose : 40 + /- 5 , and sucrose : 46 + /- 6 min ) . Therefore , 1 g/kg BM glucose or sucrose is sufficient to initiate postexercise liver glycogen re synthesis , which contributes to subsequent exercise capacity , but not muscle glycogen re synthesis This study examined the effect of carbohydrate ingestion on metabolic and performance-related responses during and after a simulated 1 h cycling time trial . Eight trained male cyclists ( VO2 peak = 66.5 ml kg-1 min-1 ) rode their own bicycles mounted on a windload simulator to imitate real riding conditions . At a self-selected maximal pace , the cyclists performed two 1 h rides ( separated by 7 days ) and were fed either an 8 % carbohydrate or placebo solution . The beverages were administered 25 min before ( 4.5 ml kg-1 ) and at the end ( 4.5 ml kg-1 ) of the ride . With carbohydrate feeding , plasma glucose tended ( P = 0.21 ) to rise before the time trial . Compared with rest , the plasma glucose concentration decreased significantly ( P < 0.05 ) at the end of both rides , with no statistically significant difference being observed between treatments . Thereafter , plasma glucose increased significantly ( P < 0.05 ) at 15 and 30 min into recovery and was significantly higher at 30 min during the carbohydrate trial compared with the placebo trial . No significant changes in plasma free fatty acids were observed during the ride . However , a significant increase ( P < 0.05 ) in free fatty acids was found at 15 and 30 min into recovery , with no difference between trials . Mean power output was significantly ( P < 0.05 ) greater during the carbohydrate compared with the placebo trial ( mean + /- S.E. : 277 + /- 3 and 269 + /- 3 W , respectively ) . The greater distance covered in the carbohydrate compared with the placebo trial ( 41.5 + /- 1.06 and 41.0 + /- 1.06 km , respectively ; P < 0.05 ) was equivalent to a 44 s improvement . We conclude that pre-exercise carbohydrate ingestion significantly increases endurance performance in trained cyclists during a 1 h simulated time trial . Although the mechanism for this enhancement in performance with carbohydrate ingestion can not be surmised from the present results , it could be related to a higher rate of carbohydrate oxidation , or to favourable effects of carbohydrate ingestion on the central component of fatigue The purpose of this study was to compare the effects of a carbohydrate-electrolyte plus caffeine , carnitine , taurine , and B vitamins solution ( CE+ ) and a carbohydrate-electrolyte-only solution ( CE ) vs. a placebo solution ( PLA ) on cycling performance and maximal voluntary contraction ( MVC ) . In a r and omized , double-blind , crossover , repeated- measures design , 14 male cyclists ( M + /- SD age 27 + /- 6 yr , VO2max 60.4 + /- 6.8 ml x kg-1 x min(-1 ) ) cycled for 120 min submaximally ( alternating 61 % + /- 5 % and 75 % + /- 5 % VO2max ) and then completed a 15-min performance trial ( PT ) . Particip 
    Output:
    
Thus , when considering only studies with a setting mimicking real-life competition , there is a mixed general picture about the ergogenic effect of carbohydrates ingested in the proximity of or during a performance bout with an unlikely effect with bouts up to perhaps 70 min and a possible but not compelling ergogenic effect with performance duration s longer than about 70 min