***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: Consuming carbohydrate- and antioxidant-rich fruits during exercise as a means of supporting and enhancing both performance and health is of interest to endurance athletes .  Watermelon ( WM ) contains carbohydrate , lycopene , l-citrulline , and l-arginine . WM may support exercise performance , augment antioxidant capacity , and act as a countermeasure to exercise-induced inflammation and innate immune changes . Trained cyclists ( n = 20 , 48 ± 2 years ) participated in a r and omized , placebo controlled , crossover study . Subjects completed two 75 km cycling time trials after either 2 weeks ingestion of 980 mL/day WM puree or no treatment . Subjects drank either WM puree containing 0.2 gm/kg carbohydrate or a 6 % carbohydrate beverage every 15 min during the time  trials . Blood sample s were taken pre- study and pre- , post- , 1 h post-exercise . WM ingestion versus no treatment for 2-weeks increased plasma l-citrulline and l-arginine concentrations ( p < 0.0125 ) . Exercise performance did not differ between WM puree or carbohydrate beverage trials ( p > 0.05 ) , however , the rating of perceived exertion was greater during the WM trial ( p > 0.05 ) . WM puree versus carbohydrate beverage result ed in a similar pattern of increase in blood glucose , and greater increases in post-exercise plasma antioxidant capacity , l-citrulline , l-arginine , and total nitrate ( all p < 0.05 ) , but without differences in systemic markers of inflammation or innate immune function . Daily WM puree consumption fully supported the energy dem and s of exercise , and increased post-exercise blood levels of WM nutritional components ( l-citrulline and l-arginine ) , antioxidant capacity , and total nitrate , but without an influence on post-exercise inflammation and changes in innate immune function ABSTRACT Citrulline-malate ( CM ) has been proposed to provide an ergogenic effect during resistance exercise ; however , there is a paucity of research investigating these cl aims . Therefore , we investigated the impact that CM supplementation would have on repeated bouts of resistance exercise . Fourteen resistance-trained males participated in a r and omized , counterbalanced , double-blind study . Subjects were r and omly assigned to placebo ( PL ) or CM ( 8 g ) and performed three sets each of chin-ups , reverse chin-ups , and push-ups to failure . One week later , subjects ingested the other supplement and performed the same protocol . Blood lactate ( BLa ) , heart rate ( HR ) , and blood pressure ( BP ) were measured preexercise , with BLa measured a second time immediately following the last set , while HR and BP were measured 5 and 10 min postexercise . Citrulline-malate ingestion significantly increased the amount of repetitions performed for each exercise ( chin-ups : PL = 28.4 ± 7.1 , CM = 32.2 ± 5.6 , p = .003 ; reverse chin-ups : PL = 26.6 ± 5.6 , CM = 32.1 ± 7.1 , p = .017 ; push-ups : PL = 89.1 ± 37.4 , CM = 97.7 ± 36.1 , p < .001 ) . Blood lactate data indicated a time effect ( p < .001 ) , but no treatment differences ( p = .935 ) . Systolic BP data did not show differences for time ( p = .078 ) or treatment ( p = .119 ) . Diastolic BP data did not show differences for time ( p = .069 ) , but indicated treatment differences ( p = .014 ) for subjects ingesting CM . Collectively , these findings suggests that CM increased upper-body resistance performance in trained college-age males BACKGROUND L-arginine is a semi-essential amino acid involved in nitric oxide production . As nitric oxide is an important vasodilator , L-arginine supplementation would increase blood perfusion and , subsequently , muscle performance during exercises . The aim of this study was to determine the acute effect of L-arginine supplementation on strength performance and nitric oxide levels in healthy trained individuals . METHODS In a double-blind , placebo-controlled , cross-over study , 12 men were r and omly assigned to L-arginine or placebo supplementation . Subjects received 6 g of L-arginine or placebo 60 minutes before strength test ( maximum number of repetitions , 3 sets at 70 % of one repetition maximum on bench press and at 80 % of one repetition maximum on knee extensions , 2 minutes of rest between sets and exercises ) .  Blood sample s  were collected before supplementation and 6 min after exercise .  RESULTS Plasma nitrite levels did not significantly change after L-arginine or placebo supplementation and strength-training exercise ( placebo , from 13.01±1.18 to 11.83±2.81 mM ; L-arginine , from 10.95±4.09 to 11.99±2.5 mM ) . There was a significant reduction in the number of repetitions performed from set 1 to set 3 in each set of both bench press and knee extension , but no significant interactions were observed between placebo and L-arginine . CONCLUSIONS These results do not support the use of L-arginine as an ergogenic aid for strength performance , at least in context of acute use immediately before resistance exercise performance Supplementation with l-citrulline ( Cit ) has been shown to improve muscle oxygenation and oxygen uptake kinetics during moderate- to high-intensity cycling in young men . The aim of this study was to test the hypothesis that Cit would improve oxygen uptake kinetics during walking in older and young adults . In a r and omized , double-blind study , 26 ( 15 women , 11 men ) adults between the ages of 20 - 35 years ( n = 15 ) and 64 - 86 years ( n = 11 ) completed 7-day periods of taking placebo and Cit ( 6 g/day ) in a crossover manner . Participants walked on a treadmill at 40 % heart rate reserve while pulmonary oxygen uptake was measured using indirect calorimetry . Net oxygen cost , mean response time ( MRT ) , and the oxygen deficit were calculated before and after each supplement period . There was no significant change ( P > 0.05 ) in net oxygen cost , MRT , or the oxygen deficit  after Cit in older adults , while young adults showed a decrease ( P = 0.05 ) in the oxygen deficit  after Cit that tended ( P = 0.053 ) to be different than the change after placebo . Sex-stratified analysis revealed that Cit  decreased MRT ( P = 0.04 , Cohen 's d = 0.41 ) and the oxygen deficit ( P < 0.01 , Cohen 's d = 0.56 ) in men with the change after Cit being greater than the change after placebo ( MRT : -4.5 ± 2.1 vs. 3.4 ± 2.1 s , P = 0.01 ; deficit : -0.15 ± 0.05 vs. 0.01 ± 0.05 L , P = 0.02 ) . All oxygen uptake parameters were unchanged ( P > 0.05 ) following Cit and placebo in women . Cit does not alter the oxygen cost of moderate-intensity walking in young or older adults , but Cit improved the rate of rise in oxygen uptake at exercise onset in men Background Many human studies report that nitric oxide ( NO ) improves sport performance . This is because NO is a potential modulator of blood flow , muscle energy metabolism , and mitochondrial respiration during exercise . L-Citrulline is an amino acid present in the body and is a potent endogenous precursor of L-arginine , which is a substrate for NO synthase . Here , we investigated the effect of oral L-citrulline supplementation on cycling time trial performance in humans . Methods A double-blind r and omized placebo-controlled 2-way crossover study was employed . Twenty-two trained males consumed 2.4 g/day of L-citrulline or placebo orally for 7 days . On Day 8 they took 2.4 g of L-citrulline or placebo 1 h before a 4-km cycling time trial .  Time taken to complete the 4 km cycle , along with power output/VO2 ratio ( PO/VO2 ) , plasma nitrite and nitrate ( NOx ) and amino acid levels , and visual analog scale ( VAS ) scores , was evaluated . Results L-Citrulline supplementation significantly increased plasma L-arginine levels and reduced completion time by 1.5 % ( p < 0.05 ) compared with placebo . Moreover , L-citrulline significantly improved subjective feelings of muscle fatigue and concentration immediately after exercise . Conclusions Oral L-citrulline supplementation reduced the time take to complete a cycle ergometer exercise trial . Trial registration Current Controlled Trials UMIN000014278 Abstract Citrulline-malate ( CM ) is a precursor to nitric-oxide ( NO ) in the NO synthase ( NOS ) pathway and is suggested to increase exercise performance in younger individuals . With age , NO production decreases and augmented NO production may provide beneficial effects on sports performance among masters athletes ( MAs ) . Purpose : To examine the effects of acute CM supplementation on grip strength , vertical power , and anaerobic cycling performance in female , MA tennis players . Methods : Seventeen female MA ( 51 ± 9 years ) completed two double-blind , r and omized trials consuming CM ( 12 g dextrose + 8 g CM ) and placebo ( PLA ) ( 12 g dextrose ) . One hour after consumption , subjects completed grip strength , vertical power , and Wingate anaerobic cycling assessment s in respective order . Maximal and average grip strength , peak and average vertical power , anaerobic capacity , peak power , explosive power , and ability to sustain anaerobic power were calculated from the tests . Results : When consuming CM , participants exhibited greater maximal ( p = .042 ) and average ( p = .045 ) grip strength compared to PLA . No differences existed between trials for peak ( p = .51 ) or average ( p = .51 ) vertical power . For the Wingate , peak power ( p < .001 ) and explosive power ( p < .001 ) were significantly greater when consuming CM compared to PLA . For the ability to sustain power , a significant effect ( p < .001 ) was observed for time within trials , but no significant differences were observed between trials regarding supplement consumed . Conclusions : These data suggest that consuming CM before competition has the potential to improve tennis match-play performance in masters tennis athletes . However , this study utilized a controlled laboratory environment and research evaluating direct application to on-court performance is warranted The extent to which dietary supplementation with the nitric oxide synthase ( NOS ) substrate , l-arginine ( ARG ) , impacts on NO production and NO-mediated physiological responses is controversial . This r and omised , double blinded , cross-over study investigated the effects of acute ARG supplementation on NO biomarkers , O2 cost of exercise and exercise tolerance  in humans . In one experiment , 15 subjects completed moderate- and severe-intensity running bouts after acute supplementation with 6 g ARG or placebo ( PLA ) . In another experiment , eight subjects completed moderate- and severe-intensity cycling bouts after acute supplementation with 6 g ARG plus 25 g of carbohydrate ( ARG + CHO ) or an energy-matched dose of carbohydrate alone ( CHO ) . The plasma nitrite concentration was not different after ARG ( Pre : 204 ± 79 ; Post : 241 ± 114 nM ; P > 0.05 ) or ARG + CHO consumption ( Pre : 304 ± 57 ; Post : 335 ± 116 nM ; P > 0.05 ) . During moderate-intensity exercise , the steady-state pulmonary $ $ \dot{V}{\text{O}}_{2 } $ $ was not different , relative to the respective placebo conditions , after ARG ( PLA : 2,407 ± 318 , ARG : 2,422 ± 333 mL min−1 ) or ARG + CHO ( CHO : 1,695 ± 304 , ARG + CHO : 1,712 ± 312 mL min−1 ) ingestion ( P > 0.05 ) . The tolerable duration of severe exercise was also not significantly different ( P > 0.05 ) after ingesting ARG ( PLA : 551 ± 140 , ARG : 552 ± 150 s ) or ARG + CHO ( CHO : 457 ± 182 , ARG + CHO : 441 ± 221 s ) . In conclusion , acute dietary supplementation with ARG or ARG + CHO  did not alter biomarkers of NO synthesis , O2 cost of exercise or exercise tolerance in healthy subjects Camic , CL , Housh , TJ , Zuniga , JM , Hendrix , CR , Mielke , M , Johnson , GO , and Schmidt , RJ . Effects of arginine-based supplements on the physical working capacity at the fatigue threshold . J Strength Cond Res 24(5 ) : 1306 - 1312 , 2010-The purpose 
    Output:
    
there is evidence that L-citr works better as ergogenic than L-arg does on physical performance , since L-citr showed a positive effect on the rate of perceived exertion and muscular pain , in addition to a decrease in lactate concentrations and time in maximum tests .
However , there is not enough evidence to establish a beneficial L-citr dosage for physical performance