***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 Saeterbakken , AH and Fiml and , MS . Electromyographic activity and 6RM strength in bench press on stable and unstable surfaces . J Strength Cond Res 27(4 ) : 1101–1107 , 2013—The purpose of the study was to compare 6-repetition maximum ( 6RM ) loads and muscle activity in bench press on 3 surfaces , namely , stable bench , balance cushion , and Swiss ball .  Sixteen healthy , resistance-trained men ( age 22.5 ± 2.0 years , stature 1.82 ± 6.6 m , and body mass 82.0 ± 7.8 kg ) volunteered for 3 habituation/strength testing sessions and 1 experimental session . In r and omized order on the 3 surfaces , 6RM strength and electromyographic activity of pectoralis major , deltoid anterior , biceps brachii , triceps brachii , rectus abdominis , oblique external and erector spinae were assessed . Relative to stable bench , the 6RM strength was approximately 93 % for balance cushion ( p ⩽ 0.001 ) and approximately 92 % for Swiss ball ( p = 0.008 ) ; the pectoralis major electromyographic ( EMG ) activity was approximately 90 % using the balance cushion ( p = 0.080 ) and approximately 81 % using Swiss ball ( p = 0.006 ) ; the triceps EMG was approximately 79 % using the balance cushion ( p = 0.028 ) and approximately 69 % using the Swiss ball ( p = 0.002 ) . Relative to balance cushion , the EMG activity in pectoralis , triceps , and erector spinae using Swiss ball was approximately 89 % ( p = 0.016 ) , approximately 88 % ( p = 0.014 ) and approximately 80 % ( p = 0.020 ) , respectively . In rectus abdominis , the EMG activity relative to Swiss ball was approximately 69 % using stable bench ( p = 0.042 ) and approximately 65 % using the balance cushion ( p = 0.046 ) . Similar EMG activities between stable and unstable surfaces were observed for deltoid anterior , biceps brachii , and oblique external . In conclusion , stable bench press had greater 6RM strength and triceps and pectoralis EMG activity compared with the unstable surfaces . These findings have implication s for athletic training and rehabilitation , because they demonstrate an inferior effect of unstable surfaces on muscle activation of prime movers and strength in bench press . If an unstable surface in bench press is desirable , a balance cushion should be chosen instead of a Swiss ball Antagonistic muscle pairs can not be fully activated simultaneously , even with maximal effort , under conditions of voluntary co-contraction , and their muscular activity levels are always below those during agonist contraction with maximal voluntary effort ( MVE ) . Whether the muscular activity level during the task has trainability remains unclear . The present study examined this issue by comparing the muscular activity level during maximal voluntary co-contraction for highly experienced bodybuilders , who frequently perform  voluntary co-contraction in their training programs , with that for untrained individuals ( nonathletes ) .  The electromyograms ( EMGs ) of biceps brachii and triceps brachii muscles during maximal voluntary co-contraction of elbow flexors and extensors were recorded in 11 male bodybuilders and 10 nonathletes , and normalized to the values obtained during the MVE of agonist contraction for each of the corresponding muscles ( % EMGMVE ) . The involuntary coactivation level in antagonist muscle during the MVE of agonist contraction was also calculated . In both muscles , % EMGMVE values during the co-contraction task for bodybuilders were significantly higher ( P<0.01 ) than those for nonathletes ( biceps brachii : 66±14 % in bodybuilders vs. 46±13 % in nonathletes , triceps brachii : 74±16 % vs. 57±9 % ) . There was a significant positive correlation between a length of bodybuilding experience and muscular activity level during the co-contraction task ( r = 0.653 , P = 0.03 ) . Involuntary antagonist coactivation level during MVE of agonist contraction was not different between the two groups . The current result indicates that long-term participation in voluntary co-contraction training progressively enhances muscular activity during maximal voluntary co-contraction Abstract The purpose of this study was to compare one-repetition maximum ( 1-RM ) and muscle activity in three chest-press exercises with different stability requirements ( Smith machine , barbell , and dumbbells ) . Twelve healthy , resistance-trained males ( age 22.7 ± 1.7 years , body mass 78.6 ± 7.6 kg , stature 1.80 ± 0.06 m ) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3–5 days of rest between the exercises . One-repetition maximum and electromyographic activity of the pectoralis major , deltoid anterior , biceps , and triceps brachii were recorded in the exercises . The dumbbell load was 14 % less than that for the Smith machine ( P ≤ 0.001 , effect size [ ES ] = 1.05 ) and 17 % less than that for the barbell ( P ≤ 0.001 , ES = 1.11 ) . The barbell load was ∼3 % higher than that for the Smith machine ( P = 0.016 , ES = 0.18 ) . Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts . Electrical activity in the biceps brachii increased with stability requirements ( i.e. Smith machine < barbell < dumbbells ; P ≤ 0.005 ; ES = 0.57 , 1.46 , and 2.00 , respectively ) , while triceps brachii activity was reduced using dumbbells versus barbell ( P = 0.007 , ES = 0.73 ) and dumbbells versus Smith machine ( P = 0.003 , ES = 0.62 ) . In conclusion , high stability requirements in the chest press ( dumbbells ) result in similar ( pectoralis major and anterior deltoid ) , lower ( triceps brachii ) or higher ( biceps brachii ) muscle activity . These findings have implication s for athletic training and rehabilitation The purpose s of this study were to assess : ( i ) the effects of 8-week training programs with constrained-path and unconstrained-path chest press machines on 1-RM ; ( ii ) the different activity patterns of selected arm and shoulder girdle muscles during push movement performed on the different machines ; ( iii ) the transfer of the training effects from one machine to the other . Twenty healthy , sedentary women ( mean+/-SD age , 24.8+/-1.0yrs ) , r and omized to either the FM or CM strength training protocol s were evaluated before and after the strength training program .  Muscular activity signals were recorded by surface electromyography ( sEMG ) from eight muscles while each subject performed the exercise on each machine . Muscle strength was defined by a 1 repetition maximum ( 1-RM ) test for each subject on each machine . Both machines were effective in improving 1-RM , but the 1-RM increased more in the  FM  than the CM . Adaptive change in the sEMG was observed in all muscles after training on the FM machine , but not within the stabilizers when training on the CM machine . The results suggest that training in an unconstrained condition provides a more effective method for improving inter-muscular coordination via adaptation of the motor strategy aim ed at optimising muscular efforts Abstract Flanagan , SD , Mills , MD , Sterczala , AJ , Mala , J , Comstock , BA , Szivak , TK , DuPont , WH , Looney , DP , McDermott , DM , Hooper , DR , White , MT , Dunn-Lewis , C , Volek , JS , Maresh , CM , and Kraemer , WJ . The relationship between muscle action and repetition maximum on the squat and bench press in men and women . J Strength Cond Res 28(9 ) : 2437–2442 , 2014—The relationship between muscle action and fatigue is not well understood , especially in terms of potential sex-specific differences . The purpose of this investigation was to determine whether a different number of repetitions could be performed on the individual muscle actions of the bench press and squat in men and women . Ten resistance-trained men ( n = 10 ; age , 25.2 ± 1.2 years ; height , 178.6 ± 8.8 cm ; weight , 91.4 ± 18.1 kg ; body fat , 12.7 ± 3.6 % ) and women ( n = 10 ; age , 25.4 ± 2.4 years ; height , 164 ± 4.0 cm ; weight , 58.45 ± 3.3 kg ; body fat , 20.8 ± 1.5 % ) participated in this balanced and r and omized within-group study . Using 85 % of a 1 repetition maximum , over the course of 3 visits , subjects performed 1 eccentric ( ECC ) , concentric ( CON ) , or combined ( COMB ) set to failure on the squat and bench press . Differences in muscle action and sex-specific number of repetitions to failure were compared on the squat and bench press , where significance was p ⩽ 0.05 . Across both exercises and sex , we observed significant differences between each of the 3 muscle actions , where the number of repetitions decreased from ECC to COMB to CON . While no sex-specific differences were observed in the squat , women performed significantly more repetitions on the ECC and CON muscle actions of the bench press . Men performed more combined repetitions , however , indicating a greater reliance on the stretch-shortening cycle . Different muscle actions contribute uniquely to the successful performance of a lift and fatigue . These contributions appear to differ in men and women Clark , RA , Humphries , B , Hohmann , E , and Bryant , AL . The influence of variable range of motion training on neuromuscular performance and control of external loads . J Strength Cond Res 25(3 ) : 704 - 711 , 2011-Resistance training programs that emphasize high force production in different regions of the range of motion ( ROM ) may provide performance benefits . This study examined whether variable ROM ( VROM ) training , which consists of partial ROM training with countermovements performed in a different phase of the ROM for each set , results in improved functional performance .  Twenty-two athletes ( age 22.7 ± 2.4 years , height 1.81 ± 0.07 m , and body mass 94.6 ± 14.5 kg ) with extensive resistance training background s performed either a VROM or full ROM control ( CON ) 5-week , concentric work-matched training program . The participants were assigned to a group based on stratified r and omization incorporating their strength levels and performance gains in preceding training microcycles . Testing consisted of assessing the force-ROM relationship during isokinetic and isometric bench press and ballistic bench throws , with normalized electromyography amplitude assessed during the isometric tests . Repeated-measure analyses of variance revealed that the VROM intervention significantly ( p < 0.05 ) increased both full ROM bench throw displacement ( + 15.5 % ) and half ROM bench throw peak force ( + 15.7 % ) , in addition to isokinetic peak force in the terminal ROM ( 13.5 % increase ) . No significant differences were observed in the CON group or between groups for any other outcome measures . Analysis of the force-ROM relationship revealed that that the VROM intervention enhanced performance at shorter muscle lengths . These findings suggest that VROM training improves terminal and midrange performance gains , result ing in the athlete possessing an improved ability to control external loading and produce dynamic force Abstract Calatayud , J , Borreani , S , Colado , JC , Martin , F , Tella , V , and And ersen , LL . Bench press and push-up at comparable levels of muscle activity results in similar strength gains . J Strength Cond Res 29(1 ) : 246–253 , 2015—Electromyography ( EMG ) exercise evaluation is commonly used to measure the intensity of muscle contraction . Although research ers assume that biomechanically comparable resistance exercises with similar high EMG levels will produce similar strength gains over the long term , no studies have actually corroborated this hypothesis . This study evaluated EMG levels during 6 repetition maximum ( 6RM ) bench press and push-up , and subsequently performed a 5-week training period where subjects were r and omly divided into 3 groups ( i.e. , 6RM bench press group , 6RM elastic b and push-up group , or control group ) to evaluate muscle strength gains . Thirty university students with advanced resistance training experience participated in the 2-part study . During the training period , exercises were performed using the same loads and variables that were used during the EMG data collection . At baseline , EMG amplitude showed no significant difference between 6RM bench press and b and push-up . Significant differences among the groups were found for percent change ( & Dgr ; ) between pretest and posttest for 6RM ( p = 0.017 ) and for 1 repetition maximum ( 1RM ) ( p < 0.001 ) . Six repetition maximum bench press group and 6RM elastic b and push-up group improved their 1RM and 6RM ( & Dgr ; ranging from 13.65 to 22.21 ) tests significantly with similar gains , whereas control group remains unchanged . Thus , when the EMG values are comparable and the same conditions are reproduced , the aforementioned exercises can 
    Output:
    
The triceps brachii ( TB ) and pectoralis major ( PM ) muscles were found to have similar activity during the BP , which was significantly higher than the activity of the anterior deltoid .
During the BP movement , muscle activity changes with exercise intensity , velocity of movement , fatigue , mental focus , movement phase and stability conditions , such as bar vibration or unstable surfaces .
Under these circumstances , TB is the most common object of activity change .
PM and TB EMG activity is more dominant and shows greater EMG amplitude than anterior deltoid during the BP .
There are six factors that can influence muscle activity during the BP ; however , the most important factor is exercise intensity , which interacts with all other factors .