***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: Abstract The aim of this study was to examine physical , physiological , and motor responses and perceived exertion during different soccer drills . In small-sided games , the individual playing area ( ∼275 m2 , ∼175 m2 , and ∼75 m2 ) was varied while the number of players per team was kept constant : 5 vs. 5 plus goal keepers .  Participants were ten male youth soccer players . Each session comprised three small-sided game formats , which lasted 8 min each with a 5-min passive rest period between them . A range of variables was recorded and analysed for the three drills performed over three training sessions : ( a ) physiological , measured using Polar Team devices ; ( b ) physical , using GPS SPI elite devices ; ( c )  perceived exertion  , rated using the CR-10 scale ; and ( d ) motor response , evaluated using an observational tool that was specially design ed for this study . Significant differences were observed for most of the variables studied . When the individual playing area was larger , the effective playing time , the physical ( total distance covered ; distances covered in low-intensity running , medium-intensity running , and high-intensity running ; distance covered per minute ; maximum speed ; work-to-rest ratio ; sprint frequency ) and physiological workload ( percent maximum heart rate ; percent mean heart rate ; time spent above 90 % maximum heart rate ) , and the rating of perceived exertion were all higher , while certain motor behaviours were observed less frequently ( interception , control and dribble , control and shoot , clearance , and putting the ball in play ) . The results show that the size of the pitch should be taken into account when planning training drills , as it influences the intensity of the task and the motor response of players A Comparison Of Physiological Responses To Various Intermittent And Continuous Small-Sided Games In Young Soccer Players The purpose of this study was to investigate physiological responses to various intermittent and continuous small-sided games ( SSGs ) - including 2-a-side , 3-a-side , and 4-a-side games - in young soccer players . Twenty soccer players ( average age 16.6±0.5 years ; mean body height 176.2±4.6 cm ; mean body mass 65.9±5.6 kg ) voluntarily participated in this study . The subjects underwent anthropometric measurements  followed by the YoYo intermittent recovery test . Then , they played intermittent ( SSGint ) and continuous ( SSGcon ) 2-a-side , 3-a-side , and 4-a-side soccer-specific SSGs in r and om order at 2-day intervals . Paired t-tests were used to assess differences between the training regimens ( intermittent and continuous ) in terms of heart rate ( HR ) , percentage of maximum HR ( % HRmax ) , and blood lactate concentration ( LA ) . The differences in LA , HR and % HRmax between the 2-a-side , 3-a-side and 4-a-side SSGint or the 2-a-side , 3-a-side and 4-a-side SSGcon were identified using a one-way analysis of variance with repeated measures . The results demonstrated that the 3-a-side SSGint and SSGcon measurements were significantly higher than the 2-a-side and 4-a-side games in terms of HR and % HRmax , whereas the 2-a-side SSGint and SSGcon result ed in higher LA responses compared to other SSG types . The study results also demonstrated that SSGint and SSGcon are similar in terms of physiological responses except for 2-a-side game LA responses . The results of this study suggest that both SSGint and SSGcon could be used for the physiological adaptations required for soccer specific aerobic endurance Abstract Sanchez-Sanchez , J , Hernández , D , Casamichana , D , Martínez-Salazar , C , Ramirez-Campillo , R , and Sampaio , J. Heart rate , technical performance , and session-RPE in elite youth soccer small-sided games played with wildcard players . J Strength Cond Res 31(10 ) : 2678–2685 , 2017—The aim of this study was to compare heart rate ( HR ) , rating of perceived exertion ( RPE ) , and technical-tactical actions during  small-sided games ( SSGs ) played without ( CTR ) , with internal ( IW ) , and with IW and external ( IEW ) wildcard players . A total of 22 young male soccer players ( age 17.2 ± 0.9 years ) r and omly completed six 4vs4 SSG situations . The control conditions occurred with goals scored without goal keeper ( 4vs4-NO ) and with goal keeper ( 4vs4-GK ) . During the experimental conditions , the situations incorporated 2 IW ( 4vs4 + 2IW-NO , 4vs4 + 2IW-GK ) and 2 IEW ( 4vs4 + 2IW+2IEW-NO , 4vs4 + 2IW+2IEW-GK ) . Processed results did not include data from goal keepers , IW , and IEW players . The HR was divided in intensity-zones ( Z1 , Z2 , and Z3 , for < 80 % , 80–90 % , and > 90 % of maximal HR , respectively ) and the analyzed technical-tactical actions were the pass , dribbling , collective success , and pause . The effects of IW and IEW were analyzed through repeated measures analysis of variance . During 4vs4 + 2IW+2IEW-NO , greater time was recorded in Z1 ( p ⩽ 0.05 ) compared with 4vs4-NO and 4s4 + 2IW-NO . During 4vs4 + 2IW+2IEW-GK , greater time was recorded in Z1 and less in Z3 ( p ⩽ 0.05 ) compared with 4vs4-GK . Greater RPE was reported in 4vs4-NO ( p < 0.01 ) and 4vs4 + 2IW-NO ( p < 0.01 ) compared with 4vs4 + 2IW+2IEW-NO , and during 4vs4-GK ( p < 0.01 ) than 4vs4 + 2IW+2IEW-GK . Greater number of dribbling situations were recorded during 4vs4-NO ( p ⩽ 0.05 ) compared with 4vs4 + 2IW+2IEW-NO . In conclusion , compared with the control condition of 4vs4 , the incorporation of IEW reduced HR , RPE , and dribbling actions Abstract The purpose of the present study was to examine the effects of additional in-season speed endurance production versus speed endurance maintenance training regimes on performance in competitive male soccer players . In a r and omised controlled trial 18 male sub-elite players were exposed to additional speed endurance production ( SEP ) or speed endurance maintenance ( SEM ) training ( two additional sessions/wk for 4 weeks ) during the competitive season . Players performed the Yo-Yo intermittent recovery level 2 test ( YYIR2 ) and a repeated sprint test ( RST ) pre- and post-intervention .  Yo-Yo IR2 performance increased ( p<0.001 ) by 50 ± 8 % and 26 ± 5 % in SEP and SEM , respectively , with greater ( p=0.03 ) improvement in SEP . RST performance improved by 2.1 ± 0.3 % and 1.3 ± 0.4 % in SEP and SEM , respectively , while the RST fatigue index decreased ( 4.4 ± 0.8 to 3.4 ± 0.5 % ; p<0.04 ) in SEP only . Peak and average speed during training were higher ( p<0.001 ) in SEP than in SEM ( 24.5 ± 0.3 vs 19.2 ± 0.3 and 15.5 ± 0.1 km·h-1 vs 9.4 ± 0.1 km·h-1 ) . Additional in-season anaerobic speed endurance production and maintenance training improves high-intensity exercise performance in competitive soccer players with superior effects of speed endurance production training The aim of this study was to compare the effects of specific ( small-sided games ) vs. generic ( running ) aerobic interval training on physical fitness and objective measures of match performance in soccer . Forty junior players were r and omly assigned to either generic ( n=20 ) or specific ( n=20 ) interval training consisting of 4 bouts of 4 min at 90 - 95 % of maximum heart rate with 3 min active rest periods , completed twice a week . The following outcomes were measured at baseline ( Pre ) , after 4 weeks of pre-season training ( Mid ) , and after a further 8 weeks of training during the regular season ( Post ) : maximum oxygen uptake , lactate threshold ( Tlac ) , running economy at Tlac , a soccer-specific endurance test ( Ekblom 's circuit ) , and indices of physical performance during soccer matches ( total distance and time spent st and ing , walking , and at low- and high-intensity running speed ) . Training load , as quantified by heart rate and rating of perceived exertion , was recorded during all training sessions and was similar between groups . There were significant improvements in aerobic fitness and match performance in both groups of soccer players , especially in response to the first 4 weeks of pre-season training . However , no significant differences between specific and generic aerobic interval training were found in any of the measured variables including soccer specific tests . The results of this study showed that both small-sided games and running are equally effective modes of aerobic interval training in junior soccer players OBJECTIVES To compare time-motion variables , heart rate and players ' tactical behaviour according to game pace ( slow , normal or fast ) , status ( winning and losing ) and team unbalance ( superiority and inferiority ) in football 5-a-side small-sided games .  To identify the most discriminating variables in classifying performances according to these constraints . DESIGN Cross-sectional field study . METHODS The data were gathered using global positioning systems ( 5 Hz ) in 5-a-side small-sided games ( 7 × 5 min ) played by twenty-four footballers .  The tactical performance was measured using dynamical  positioning variables , processed by non-linear signal processing techniques ( approximate entropy ) . ANOVA models were used to compare between constraints and discriminant analyses to identify the variables that best discriminate between pacing and status × unbalance constraints . RESULTS The fast paced games had the highest mean speed value , followed by normal and slow paced games ( 8.2 ± 0.6 km h(-1 ) , 7.8 ± 0.5 km h(-1 ) and 6.2 ± 0.4 km h(-1 ) , respectively ) . The stronger predictor variables of pacing were the r and omness in distance to team centroid and the distances covered above 13 km h(-1 ) . The results also changed according to game status and team unbalance . The strongest predictor variables were the distance covered below 6.9 km h(-1 ) , distance and r and omness to team centroid , with higher values when winning in superiority conditions . CONCLUSIONS Practice task design manipulating game pace , status and team unbalance significantly influenced the emergent behavioural dynamics . Collective positioning variables were more accurate in discriminating these constraints and , therefore , need to be considered when planning and monitoring performance BACKGROUND The aim of the study was to compare the effects of high-intensity intermittent training ( HIIT ) versus small-sided games ( SSG ) in soccer on both the physiological responses and the mood state of players . METHODS Sixteen professional soccer players took part in the study ( age : 24.1±0.9 years ) . Testing of players was conducted on separate days in a r and omized and counter-balanced order ( each training session : 28 minutes : 4x4 minutes work with 3 minutes of passive recovery in-between ) . Effort : HIIT : intermittent 15-s runs at 110 % maximal aerobic speed with 15 seconds of passive recovery in-between . SSG : 4 versus 4 players on a 25x35 meter pitch size with full-involvement play . Psychological responses before and after each training-session were assessed using the profile of mood-state ( POMS : Tension , Depression , Anger , Vigor , Fatigue , and Confusion ) . The players ' heart rate ( HR ) was continuously measured , whereas ratings of perceived exertion ( RPE ) and blood lactate concentration ( [ La ] ) were collected ~3-min after each training-session . RESULTS HIIT and SSG showed no significant difference in HR , RPE and [ La ] responses . The HIIT compared with SSG result ed in : an increased total mood disturbance ( P<0.001 ) , tension ( P<0.05 ) , fatigue ( P<0.01 ) and a decreased vigor ( P<0.001 ) . CONCLUSIONS Both HIIT and SSG sessions induced similar physiological responses , in contrast , HIIT produced a mood disturbance while SSG ensured mood balance . Practitioners could choose between these two exercises according to the objective of their training , keeping in mind the mood-related advantages of the SSG shown in the present study The purpose of this study was to compare the effects of Small-Sided Games ( SSG ) vs. Interval Training ( IT ) in soccer training on aerobic fitness and physical enjoyment in youth elite soccer players during the last 8 weeks of the season . Seventeen U-16 male soccer players ( age = 15.5 ± 0.6 years , and 8.5 years of experience ) of a Spanish First Division club academy were r and omized to 2 different groups for 6 weeks : SSG group ( n = 9 ) and IT group ( n = 8) . In addition to the usual technical and tactical sessions and competitive games , the SSG group performed 11 sessions with different SSGs , whereas the IT group performed the same number of sessions of IT . Players were tested before and after the 6-week training intervention with a 
    Output:
    
SSG-based football plans ( 2 to 4 SSG sessions per week ) show athletic performance improvements in football players by improving sprint , repeated sprint ability ( RSA ) and change of direction ( COD ) along with muscular and physiological adaptation