***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: The purpose of this study was to determine the effect of an acute static stretching bout of the biceps brachii on torque , electromyography ( EMG ) , and mechanomyography ( MMG )  during concentric isokinetic muscle actions . Eighteen ( men , n = 10 ; women , n = 8) adult subjects ( M ± SD age = 22.7 ± 2.8 years ; weight = 78.0 ± 17.0 kg ; height = 177.9 ± 11.0 cm ) performed maximal isokinetic ( 30 and 270 ° ·s−1 ) forearm flexion strength testing on 2 occasions while EMG and MMG were recorded . Subjects were r and omly assigned to stretching ( STR ) or nonstretching ( NSTR ) protocol s before strength testing . Two-way ANOVAs with repeated measures revealed significantly ( p ≤ 0.05 ) greater torque for NSTR ( M ± SEM = 36.9 ± 3.3 N·m ) vs. STR ( 35.2 ± 3.3 N·m ) , significantly greater MMG amplitude for STR vs. NSTR for 30 ° ·s−1 ( STR = 93.5 ± 14.4 mV ; NSTR = 63.1 ± 10.6 mV ) and 270 ° ·s−1 ( STR = 207.6 ± 35.6 mV ; NSTR = 136.4 ± 31.7 mV ) , and no difference in EMG amplitude . These results indicate that a greater ability to produce torque without prior stretching is related to the musculotendinous stiffness of the muscle rather than the number of motor units activated . This suggests that performing activities that reduce muscle stiffness ( such as stretching ) , may be detrimental to performance Gurjão , ALD , Gonçalves , R , de Moura , RF , and Gobbi , S. Acute effect of static stretching on rate of force development and maximal voluntary contraction in older women . J Strength Cond Res 23(7 ) : 2149 - 2154 , 2009-The purpose of this study was to investigate , in older women , the acute effect of static stretching ( SS ) on both muscle activation and force output . Twenty-three older women ( 64.6 ± 7.1 yr ) participated in the study . The maximal voluntary contraction ( MVC ) , rate of force development ( RFD ) ( 50 , 100 , 150 , and 200 ms relative to onset of muscular contraction ) , and peak RFD ( PRFD ) ( the steepest slope of the curve during the first 200 ms ) were tested under 2 r and omly separate conditions : SS and control ( C )  . Electromyographic ( EMG ) activity of the vastus medialis ( VM ) , vastus lateralis ( VL ) , and biceps femoris ( BF ) muscles also was assessed . The MVC was significantly lower ( p < 0.05 ) in the 3 trials of SS when compared with the C condition ( control : 925.0 ± 50.9 N ; trial 1 : 854.3 ± 55.3 N ; trial 2 : 863.1 ± 52.2 N ; and trial 3 : 877.5 ± 49.9 N ) . PRFD showed a significant decrease only for the first 2 trials of SS when compared with the C condition ( control : 2672.3 ± 259.1 N/s ; trial 1 : 2296.6 ± 300.7 N/s ; and trial 2 : 2197.9 ± 246.3 N/s ) . However , no difference was found for RFD ( 50 , 100 , 150 , and 200 ms relative to onset of muscular contraction ) . The EMG activity for VM , VL , and BF was not significantly different between the C and SS conditions . In conclusion , the  older women 's capacity to produce muscular force decreased after their performance of SS exercises . The mechanisms responsible for this effect do not appear to be related to muscle activation . Thus , if flexibility is to be trained , it is recommended that SS does not occur just before the performance of activities that require high levels of muscular force This perspective provides an overview of the r and omized controlled trials , systematic review s , and evidence -based clinical practice guidelines in physical therapy . Data from the Physiotherapy Evidence Data base ( PEDro ) are used to describe key events in the history of physical therapy research and the growth of evidence of effects of interventions used in the various subdisciplines of physical therapy . The 11,494 records that were identified reveal a rich history of physical therapy research dating back to the first trial in 1929 . Most of the r and omized controlled trials , systematic review s , and evidence -based clinical practice guidelines in physical therapy have been published since the year 2000 . This rapid growth presents a challenge for physical therapists who want to keep up to date in clinical practice The purpose of this study was to determine the effect of different static and dynamic stretch protocol s on 20-m sprint performance . The 97 male rugby union players were assigned r and omly to 4 groups : passive static stretch ( PSS ; n = 28 ) , active dynamic stretch ( ADS ; n = 22 ) , active static stretch ( ASST ; n = 24 ) , and static dynamic stretch ( SDS ; n = 23 ) . All groups performed a st and ard 10-minute jog warm-up , followed by two 20-m sprints . The 20-m sprints were then repeated after subjects had performed different stretch protocol s. The PSS and ASST groups had a significant increase in sprint time ( p ≤ 0.05 ) , while the ADS group had a significant decrease in sprint time ( p ≤ 0.05 ) . The decrease in sprint time , observed in the SDS group , was found to be nonsignificant ( p ≥ 0.05 ) . The decrease in performance for the 2 static stretch groups was attributed to an increase in the musculotendinous unit ( MTU ) compliance , leading to a decrease in the MTU ability to store elastic energy in its eccentric phase . The reason why the ADS group improved performance is less clear , but could be linked to the rehearsal of specific movement patterns , which may help increase coordination of subsequent movement . It was concluded that static stretching as part of a warm-up may decrease short sprint performance , whereas active dynamic stretching seems to increase 20-m sprint performance PURPOSE To examine the time course ( immediate , 10 , 20 , and 30 min ) for the acute effects of 2 , 4 , and 8 min of passive stretching ( PS ) on isometric peak torque ( PT ) , percent voluntary activation ( % VA ) , EMG amplitude , peak twitch torque ( PTT ) , rate of twitch torque development ( RTD ) , and range of motion ( ROM ) of the plantarflexors . METHODS Thirteen volunteers ( mean + /- SD age , 22 + /- 3 yr ) participated in four r and omly ordered experimental trials : control ( CON ) with no stretching , 2 min ( PS2 ) , 4 min ( PS4 ) , and 8 min ( PS8 ) of PS . Testing was conducted before ( pre ) , immediately after ( post ) , and at 10 , 20 , and 30 min poststretching . The PS trials involved varied repetitions of 30-s passive stretches , whereas the CON trial included 15 min of resting . PT , % VA , EMG amplitude , PTT , and RTD were assessed during the twitch interpolation technique , whereas ROM was quantified as the maximum tolerable angle of passive dorsiflexion . RESULTS PT decreased ( P < or = 0.05 ) immediately after all conditions [ CON ( 4 % ) , PS2 ( 2 % ) , PS4 ( 4 % ) , and PS8 ( 6 % ) ] but returned to baseline at 10 , 20 , and 30 min poststretching . % VA and EMG amplitude were unaltered ( P > 0.05 ) after all conditions . PTT and RTD decreased ( P < or = 0.05 ) immediately after the PS4 ( 7 % ) and the PS8 ( 6 % ) conditions only ; however , these changes were not sufficient to alter voluntary force production . There were also increases ( P < or = 0.05 ) in ROM after the PS2 ( 8 % ) , the PS4 ( 14 % ) , and the PS8 ( 13 % ) conditions that returned to baseline after 10 min . CONCLUSION Practical duration s of stretching ( 2 , 4 , or 8 min ) of the plantarflexors did not decrease isometric PT compared with the CON but caused temporary improvements in the ROM , thereby question ing the overall detrimental influence of PS on performance Curry , BS , Chengkalath , D , Crouch , GJ , Romance , M , and Manns , PJ . Acute effects of dynamic stretching , static stretching and light aerobic activity on muscular performance in women . J Strength Cond Res 23(6 ) : 1811 - 1819 , 2009-The purpose of this study was to compare three warm-up protocol s-static stretching , dynamic stretching , and light aerobic activity-on selected measures of range of motion and power in untrained females and to investigate the sustained effects at 5 and 30 minutes after warm-up . A total of 24 healthy females ( ages 23 - 29 years ) attended one familiarization session and three test sessions on nonconsecutive days within 2 weeks . A within-subject design protocol with the testing investigators blinded to the subjects ' warm-up was followed . Each session started with 5 minutes of light aerobic cycling followed by pretest baseline measures . Another 5 minutes of light aerobic cycling was completed and followed by one of the three r and omly selected warm-up interventions ( static stretching , dynamic stretching , or light aerobic activity ) . The following posttest outcome measures were collected 5 and 30 minutes following the intervention : modified Thomas test , countermovement jump , and isometric time to peak force knee extension measured by dynamometer . Analysis of the data revealed significant time effects on range of motion and countermovement jump changes . No significant differences ( p > 0.05 ) were found between the warm-up conditions on any of the variables . The variation in responses to warm-up conditions emphasizes the unique nature of individual reactions to different warm-ups ; however , there was a tendency for warm-ups with an active component to have beneficial effects . The data suggests dynamic stretching has greater applicability to enhance performance on power outcomes compared to static stretching Context : Stretching is commonly used as a technique for injury prevention in the clinical setting . Our findings may improve the underst and ing of the neuromuscular responses to stretching and help clinicians make decisions for rehabilitation progression and return to play . Objective : To examine the short-term effects of static and proprioceptive neuromuscular facilitation stretching on peak torque ( PT ) , mean power output ( MP ) , active range of motion ( AROM ) , passive range of motion ( PROM ) , electromyographic ( EMG ) amplitude , and mechanomyographic ( MMG ) amplitude of the vastus lateralis and rectus femoris muscles during voluntary maximal concentric isokinetic leg extensions at 60 and 300 degrees .s . Design : A r and omized , counterbalanced , cross-sectional , repeated- measures design . Setting : A university human research laboratory . Patients or Other Participants : Ten female ( age , 23 + /- 3 years ) and 9 male ( age , 21 + /- 3 years ) apparently healthy and recreationally active volunteers . Intervention(s ) : Four static or proprioceptive neuromuscular facilitation stretching exercises to stretch the leg extensor muscles of the dominant limb during 2 separate , r and omly ordered laboratory visits . Main Outcome Measure(s ) : The PT and MP were measured at 60 and 300 degrees .s , EMG and MMG signals were recorded , and AROM and PROM were measured at the knee joint before and after the stretching exercises . Results : Static and proprioceptive neuromuscular facilitation stretching reduced PT ( P = .051 ) , MP ( P = .041 ) , and EMG amplitude ( P = .013 ) from prestretching to poststretching at 60 and 300 degrees .s ( P < .05 ) . The AROM ( P < .001 ) and PROM ( P = .001 ) increased as a result of the static and proprioceptive neuromuscular facilitation stretching . The MMG amplitude increased in the rectus femoris muscle in response to the static stretching at 60 degrees .s ( P = .031 ) , but no other changes in MMG amplitude were observed ( P > .05 ) . Conclusions : Both static and proprioceptive neuromuscular facilitation stretching caused similar deficits in strength , power output , and muscle activation at both slow ( 60 degrees .s ) and fast ( 300 degrees .s ) velocities . The effect sizes , however , corresponding to these stretching-induced changes were small , which suggests the need for practitioners to consider a risk-to-benefit ratio when incorporating static or proprioceptive neuromuscular facilitation stretching AIM The interaction between running , stretching and practice jumps during warm-up for jumping tests has not been investigated . The purpose of the present study was to compare the effects of running , static stretching of the leg extensors and practice jumps on explosive force production and jumping performance . METHODS Sixteen volunteers ( 13 male and 3 female ) participated in five different warm-ups in a r and omised order prior to the performance of two jumping tests . The warm-ups were control , 4 min run , static stretch , run + stretch , and run + stretch + practice jumps . After a 2 min rest , a concentric jump and a drop jump were performed , which yielded 6 variables expressing fast force production and jumping performance of the leg extensor muscles ( concentric jump height , peak force , 
    Output:
    
A sigmoidal dose-response effect was evident between stretch duration and both the likelihood and magnitude of significant decrements , with a significant reduction likely to occur with stretches ≥ 60 s. This strong evidence for a dose-response effect was independent of performance task , contraction mode , or muscle group .
Studies have only examined changes in eccentric strength when the stretch duration s were > 60 s , with limited evidence for an effect on eccentric strength .
The detrimental effects of static stretch are mainly limited to longer duration s ( ≥ 60 s ) , which may not be typically used during preexercise routines in clinical , healthy , or athletic population s. Shorter duration s of stretch ( < 60 s ) can be performed in a preexercise routine without compromising maximal muscle performance