***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: PURPOSE The aim of this study was to compare the effects of isometric training performed with progressive versus rapid rate of contraction on the knee extensor neuromuscular properties over a 7-wk period . METHODS Sixteen healthy male subjects trained quadriceps femoris muscle in a leg extension machine three times a week during 7 wk . The training sessions consisted of six sets of six maximal isometric contractions . A first group trained by performing progressive contractions lasting 4 s , whereas a second group performed contractions with a rapid rate of contraction ( i.e. , ballistic contractions ) lasting about 1 s. RESULTS Both groups significantly increased the isometric and isokinetic voluntary torque , and the respective absolute or relative gains were comparable . Isometric training performed with progressive rate of contraction affected the evoked action potential ( M wave ) of the vastus lateralis muscle and not the related twitch properties . On the other h and , the isometric training completed with ballistic contractions significantly modified the twitch contractile properties of the knee extensors and not the associated M waves of both vastus medialis and vastus lateralis . CONCLUSION Knee extensors adapted specifically their neuromuscular properties to the type of rate of contraction performed during 7-wk isometric resistance training . Progressive isometric contractions produced modifications of the nervous system at peripheral level ( i.e. , muscle membrane electrical activity ) , whereas ballistic isometric contractions affected the knee extensor contractile muscle properties ( i.e. , excitation-contraction coupling ) INTRODUCTION We used transcranial magnetic stimulation ( TMS ) to investigate 3 weeks of unilateral leg strength training on ipsilateral motor cortex ( iM1 ) excitability , and short-latency intracortical inhibition ( SICI ) . METHODS Right leg dominant participants ( n = 14 ) were r and omly divided into either a  strength training ( ST )  or  control group . The ST group completed 9 training sessions ( 4 sets of 6 to 8 repetitions of single right leg squats ) . RESULTS We observed a 41 % increase in right leg strength , and a 35 % increase in strength of the untrained left leg ( P < 0.01 ) . There was a significant increase in motor evoked potential ( MEP ) amplitude recruitment curve for the untrained left leg ( P < 0.01 ) . SICI of the iM1 decreased by 21 % for the untrained left leg ( P < 0.01 ) . CONCLUSIONS The findings provide evidence for corticomotor adaptation for unilateral leg strength training within the iM1 that is modulated by changes in interhemispheric inhibition Abstract The present study investigated the effects of different intensities of  resistance training ( RT ) on elbow flexion and leg press one-repetition maximum ( 1RM ) and muscle cross-sectional area ( CSA ) .  Thirty men volunteered to participate in an RT programme  , performed twice a week for 12 weeks . The study employed a within-subject design , in which one leg and arm trained at 20 % 1RM ( G20 ) and the contralateral limb was r and omly assigned to one of the three conditions : 40 % ( G40 ) ; 60 % ( G60 ) , and 80 % 1RM ( G80 ) . The G20 started RT session with three sets to failure . After G20 training , the number of sets was adjusted for the other contralateral limb conditions with volume-matched . CSA and 1RM were assessed at pre , post-6 weeks , and post-12 weeks . There was time effect for CSA for the vastus lateralis ( VL ) ( 8.9 % , 20.5 % , 20.4 % , and 19.5 % ) and elbow flexors ( EF ) ( 11.4 % , 25.3 % , 25.1 % , and 25 % ) in G20 , G40 , G60 , and G80 , respectively ( p > .05 ) . G80 showed higher CSA than G20 for VL ( 19.5 % vs. 8.9 % ) and EF ( 25 % vs. 11.4 % ) at post-12 weeks ( p < .05 ) . There was time effect for elbow flexion and unilateral leg press strength for all groups post-12 weeks ( p < .05 ) . However , the magnitude of increase was higher in G60 and G80 . In conclusion , when low to high intensities of RT are performed with volume-matched , all intensities were effective for increasing muscle strength and size ; however , 20 % 1RM was suboptimal in this regard , and only the heavier RT intensity ( 80 % 1RM ) was shown superior for increasing strength and CSA compared to low intensities Objective To assess whether three-dimensional imaging of the Achilles tendon by ultrasonographic tissue characterisation ( UTC ) can differentiate between symptomatic and asymptomatic tendons . Design Case-control study . Setting Sports Medical Department of the Hague Medical Centre . Patients Twenty-six tendons from patients with chronic midportion Achilles tendinopathy were included . The “ matched ” control group consisted of 26 asymptomatic tendons . Interventions Symptomatic and asymptomatic tendons were scanned using the UTC procedure . One research er performed the ultrasonographic data collection . These blinded data were r and omised , and outcome measures were determined by two independent observers . Main outcome measurements The raw ultrasonographic images were analysed with a custom design ed algorithm that quantifies the three-dimensional stability of echo patterns , qua intensity and distribution over contiguous transverse images . This threedimensional stability was related to tendon structure in previous studies . UTC categorises four different echotypes that represent ( I ) highly stable ; ( II ) medium stable ; ( III ) highly variable and ( IV ) constantly low intensity and variable distribution . The percentages of echo-types were calculated , and the maximum tendon thickness was measured . Finally , the inter-observer reliability of UTC was determined . Results Symptomatic tendons showed less pixels in echo-types I and II than asymptomatic tendons ( 51.5 % vs 76.6 % , p<0.001 ) , thus less three-dimensional stability of the echo pattern . The mean maximum tendon thickness was 9.2 mm in the symptomatic group and 6.8 mm in the asymptomatic group ( p<0.001 ) . The Intraclass Correlation Coefficient ( ICC ) for the interobserver reliability of determining the echo-types I+II was 0.95 . The ICC for tendon thickness was 0.84 . Conclusion UTC can quantitatively evaluate tendon structure and thereby discriminate symptomatic and asymptomatic tendons . As such , UTC might be useful to monitor treatment protocol Objective : This study aim ed to compare the immediate analgesic effects of 2 resistance programs in in-season athletes with patellar tendinopathy ( PT ) .  Resistance training is noninvasive , a principle stimulus for corticospinal and neuromuscular adaptation , and may be analgesic . Design : Within-season r and omized clinical trial . Data analysis was conducted blinded to group . Setting : Subelite volleyball and basketball competitions . Participants : Twenty jumping athletes aged more than 16 years , participating in games/trainings 3 times per week with clinical ly diagnosed PT . Interventions : Two quadriceps resistance protocol s were compared ; ( 1 ) isometric leg extension holds at 60 degrees knee flexion ( 80 % of their maximal voluntary isometric contraction ) or ( 2 ) isotonic leg extension ( at 80 % of their 8 repetition maximum ) 4 times per week for 4 weeks . Time under load and rest between sets was matched between groups . Main Outcome Measures : ( 1 ) Pain ( 0 - 10 numerical rating score ) during single leg decline squat ( SLDS ) , measured preintervention and postintervention sessions . ( 2 ) VISA-P , a question naire about tendon pain and function , completed at baseline and after 4 weeks . Results : Twenty athletes with PT ( 18 men , mean 22.5 ± 4.7 years ) participated ( isotonic n = 10 , isometric n = 10 ) . Baseline median SLDS pain was 5/10 for both groups ( isotonic range 1 - 8 , isometric range 2 - 8 ) . Isometric contractions produced significantly greater immediate analgesia ( P < 0.002 ) . Week one analgesic response positively correlated with improvements in VISA-P at 4 weeks ( r2 = 0.64 ) . Conclusions : Both protocol s appear efficacious for in-season athletes to reduce pain , however , isometric contractions demonstrated significantly greater immediate analgesia throughout the 4-week trial . Greater analgesia may increase the ability to load or perform Abstract The eccentric contraction mode was proposed to be the primary stimulus for optimum angle ( angle at which peak torque occurs ) shift . However , the training range of motion ( or muscle excursion range ) could be a stimulus as important . The aim of this study was to assess the influence of the training range of motion stimulus on the hamstring optimum length . It was hypothesised that performing a single set of concentric contractions beyond optimal length ( seated at 80 ° of hip flexion ) would lead to an immediate shift of the optimum angle to longer muscle length while performing it below ( supine at 0 ° of hip flexion ) would not provide any shift . Eleven male participants were assessed on an isokinetic dynamometer .  In both positions , the test consisted of 30 consecutive knee flexions at 4.19 rad · s−1 . The optimum angle was significantly shifted by ∼15 ° in the direction of longer muscle length after the contractions at 80 ° of hip flexion , while a non-significant shift of 3 ° was found at 0 ° . The hamstring fatigability was not influenced by the hip position . It was concluded that the training range of motion seems to be a relevant stimulus for shifting the optimum angle to longer muscle length . Moreover , fatigue appears as a mechanism partly responsible for the observed shift BACKGROUND AND PURPOSE The purpose of this study was to examine the effect of isometric training of the quadriceps femoris muscles , at different joint angles , on torque production and electromyographic ( EMG ) activity . SUBJECTS One hundred seven women were r and omly assigned to one of four groups . Three groups trained with isometric contractions three times per week at a knee flexion angle of 30 , 60 , or 90 degrees . The fourth group , which served as a control , did not exercise . METHODS  Isometric torque  was measured using a dynamometer , and  EMG activity  was measured using a multichannel EMG system .  Measurements were obtained during maximal isometric contraction of the quadriceps femoris muscles at 15-degree increments from 15 to 105 degrees of knee flexion . Measurements were taken before and after 8 weeks of training . RESULTS Following isometric exercise , increased torque and EMG activity occurred not only at the angle at which subjects exercised , but also at angles in the range of motion at which exercise did occur . Further analyses indicated that exercising in the lengthened position for the quadriceps femoris muscles ( 90 degrees of knee flexion ) produced increased torque across all angles measured and appeared to be the more effective position for transferring strength and EMG activity to adjacent angles following isometric training as compared with the shorter positions of the muscle ( 30 degrees and 60 degrees of knee flexion ) . CONCLUSION AND DISCUSSION These findings suggest that an efficient method for increasing isometric knee extension torque and EMG activity throughout the entire range of motion is to exercise with the quadriceps femoris muscles in the lengthened position Background Few interventions reduce patellar tendinopathy ( PT ) pain in the short term . Eccentric exercises are painful and have limited effectiveness during the competitive season . Isometric and isotonic muscle contractions may have an immediate effect on PT pain . Methods This single-blinded , r and omised cross-over study compared immediate and 45 min effects following a bout of isometric and isotonic muscle contractions . Outcome measures were PT pain during the  single-leg decline squat  ( SLDS , 0–10 ) , quadriceps strength on maximal voluntary isometric contraction ( MVIC ) , and measures of corticospinal excitability and inhibition . Data were analysed using a split-plot in time-repeated measures analysis of variance ( ANOVA ) . Results 6 volleyball players with PT participated . Condition effects were detected with greater pain relief immediately from isometric contractions : isometric contractions reduced SLDS ( mean±SD ) from 7.0±2.04 to 0.17±0.41 , and isotonic contractions reduced SLDS ( mean±SD ) from 6.33±2.80 to 3.75±3.28 ( p<0.001 ) . Isometric contractions released cortical inhibition ( ratio mean±SD ) from 27.53%±8.30 to 54.95%±5.47 , but isotonic contractions had no significant effect on inhibition ( pre 30.26±3.89 , post 31.92±4.67 ; p=0.004 ) . Condition by time analysis showed pain reduction was sustained at 45 min postisometric but not isotonic condition ( p<0.001 ) . The mean reduction in pain scores postisometric was 6.8/10 compared with 2.6/10 postisotonic . MVIC increased significantly following the isometric condition by 18.7±7.8 % , and was significantly higher than baseline ( p<0.001 ) and isotonic condition ( p<0.001 ) , and at 45 min ( p<0.001 ) . Conclusions A single resistance training bout of isometric contractions reduced tendon pain immediately for at least 45 min postintervention and increased MVIC . The reduction in pain was paralleled by a reduction in cortical inhibition , providing insight into potential mechanisms . Isometric contractions can be completed without pain for people with PT . The clinical implication s are that isometric muscle contra 
    Output:
    
Substantial improvements in muscular hypertrophy and maximal force production were reported regardless of training intensity .
High-intensity ( ≥70 % ) contractions are required for improving tendon structure and function .
Additionally , long muscle length training results in greater transference to dynamic performance .
Despite relatively few studies meeting the inclusion criteria , this review provides practitioners with insight into which isometric training variables ( eg , joint angle , intensity , intent ) to manipulate to achieve desired morphological and neuromuscular adaptations