***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: To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics , 10 experimental ( E ) and 8 control ( C ) endurance athletes trained for 9 wk . The total training volume was kept the same in both groups , but 32 % of training in E and 3 % in C was replaced by explosive-type strength training . A 5-km time trial ( 5 K ) , running economy ( RE ) , maximal 20-m speed ( V20 m ) , and 5-jump ( 5J ) tests were measured on a track . Maximal anaerobic ( MART ) and aerobic treadmill running tests were used to determine maximal velocity in the MART ( VMART ) and maximal oxygen uptake ( VO2 max ) . The 5 K time , RE , and VMART improved ( P < 0.05 ) in E , but no changes were observed in C. V20 m and 5J increased in E ( P < 0.01 ) and decreased in C ( P < 0.05 ) . VO2 max increased in C ( P < 0.05 ) , but no changes were observed in E. In the pooled data , the changes in the 5 K velocity during 9 wk of training correlated ( P < 0.05 ) with the changes in RE [ O2 uptake ( r = -0.54 ) ] and VMART ( r = 0.55 ) . In conclusion , the present simultaneous explosive-strength and endurance training improved the 5 K time in well-trained endurance athletes without changes in their VO2 max . This improvement was due to improved neuromuscular characteristics that were transferred into improved VMART and running economy Fifteen highly trained distance runners ( & OV0312;O2max 71.1 ± 6.0 ml·min−1·kg−1 , mean ± SD ) were r and omly assigned to a  plyometric training ( PLY ; n = 7 ) or control ( CON ; n = 8) group . In addition to their normal training , the PLY group undertook 3 × 30 minutes PLY sessions per week for 9 weeks . Running economy ( RE ) was assessed during 3 × 4 minute treadmill runs ( 14 , 16 , and 18 km·h−1 ) , followed by an incremental test to measure & OV0312;O2max . Muscle power characteristics were assessed on a portable , unidirectional ground reaction force plate . Compared with CON , PLY improved RE at 18 km·h−1 ( 4.1 % , p = 0.02 ) , but not at 14 or 16 km·h−1 . This was accompanied by trends for increased average power during a 5-jump plyometric test ( 15 % , p = 0.11 ) , a shorter time to reach maximal dynamic strength during a strength quality assessment test ( 14 % , p = 0.09 ) , and a lower & OV0312;O2-speed slope ( 14 % , p = 0.12 ) after 9 weeks of PLY . There were no significant differences in cardiorespiratory measures or & OV0312;O2max as a result of PLY . In a group of highly-trained distance runners , 9 weeks of PLY improved RE , with likely mechanisms residing in the muscle , or alternatively by improving running mechanics The purpose of this study was to determine if changes in triceps-surae tendon stiffness ( TST K ) could affect running economy ( RE ) in highly trained distance runners . The intent was to induce increased TST K in a subgroup of runners by an added isometric training program . If TST K is a primary determinant of RE , then the energy cost of running ( EC ) should decrease in the trained subjects . EC was measured via open-circuit spirometry in 12 highly trained male distance runners , and TST K was measured using ultrasonography and dynamometry . Runners were r and omly assigned to either a training or control group . The training group performed 4 × 20 s isometric contractions at 80 % of maximum voluntary plantarflexion moment three times per week for 8 weeks . All subjects ( mean $ $ \dot{V}{\text{O } } _ { 2 } { \max } $ $ = 67.4 ± 4.6 ml kg−1 min−1 ) continued their usual training for running . TST K was measured every 2 weeks . EC was measured in both training and control groups before and after the 8 weeks at three submaximal velocities , corresponding to 75 , 85 and 95 % of the speed at lactate threshold ( sLT ) . Isometric training did neither result in a mean increase in TST K ( 0.9 ± 25.8 % ) nor a mean improvement in RE ( 0.1 ± 3.6 % ) ; however , there was a significant relationship ( r2 = 0.43 , p = 0.02 ) between the change in TST K and change in EC , regardless of the assigned group . It was concluded that TST K and EC are somewhat labile and change together Berryman , N , Maurel , D , and Bosquet , L. Effect of plyometric vs. dynamic weight training on the energy cost of running . J Strength Cond Res 24(7 ) : 1818 - 1825 , 2010-The purpose of this study is to compare the effects of 2 strength training methods on the energy cost of running ( Cr ) .  Thirty-five moderately to well-trained male endurance runners were r and omly assigned to either a control group ( C ) or 2 intervention groups . All groups performed the same endurance-training program during an 8-week period . Intervention groups added a weekly strength training session design ed to improve neuromuscular qualities . Sessions were matched for volume and intensity using either plyometric training ( PT ) or purely concentric contractions with added weight ( dynamic weight training [ DWT ] ) . We found an interaction between time and group ( p < 0.05 ) and an effect of time ( p < 0.01 ) for Cr . Plyometric training induced a larger decrease of Cr ( 218 ± 16 to 203 ± 13 ml·kg−1·km−1 ) than DWT ( 207 ± 15 to 199 ± 12 ml·kg−1·km−1 ) , whereas it remained unchanged in C. Pre-post changes in Cr were correlated with initial Cr ( r = −0.57 , p < 0.05 ) . Peak vertical jump height ( VJHpeak ) increased significantly ( p < 0.01 ) for both experimental groups ( DWT = 33.4 ± 6.2 to 34.9 ± 6.1 cm , PT = 33.3 ± 4.0 to 35.3 ± 3.6 cm ) but not for C. All groups showed improvements ( p < 0.05 ) in Perf3000 ( C = 711 ± 107 to 690 ± 109 seconds , DWT = 755 ± 87 to 724 ± 77 seconds , PT = 748 ± 81 to 712 ± 76 seconds ) . Plyometric training were more effective than DWT in improving Cr in moderately to well-trained male endurance runners showing that athletes and coaches should include explosive strength training in their practice s with a particular attention on plyometric exercises . Future research is needed to establish the origin of this adaptation Abstract .Previous research has reported that plyometric training improves running economy ( RE ) and ultimately distance-running performance , although the exact mechanism by which this occurs remains unclear . This study examined whether changes in running performance result ing from plyometric training were related to alterations in lower leg musculotendinous stiffness ( MTS ) . Seventeen male runners were pre- and post-tested for lower leg MTS , maximum isometric force , rate of force development , 5-bound distance test ( 5BT ) , counter movement jump ( CMJ ) height , RE , V˙O2max , lactate threshold ( Thla ) , and 3-km time . Subjects were r and omly split into an experimental ( E ) group which completed 6 weeks of plyometric training in conjunction with their normal running training , and a control ( C ) group which trained as normal . Following the training period , the E group significantly improved 3-km performance ( 2.7 % ) and RE at each of the tested velocities , while no changes in V˙O2max or Thla were recorded . CMJ height , 5BT , and MTS also increased significantly . No significant changes were observed in any measures for the C group . The results clearly demonstrated that a 6-week plyometric programme led to improvements in 3-km running performance . It is postulated that the increase in MTS result ed in improved RE . We speculate that the improved RE led to changes in 3-km running performance , as there were no corresponding alterations in V˙O2max or Thla Abstract . Maximal strength-training with an emphasis on maximal mobilization during cross-country skiing increases exercise economy when double-poling . The aim of this experiment was to investigate whether the mechanism of this increase is a change in the force-velocity relationship and the mechanical power output . A group of 19 cross-country skiers having an average peak oxygen uptake of 255 ml·kg–0.67 body mass·min–1 or 61 ml·kg–1·min–1 were r and omly assigned to either a  high resistance-training group ( n=10 ) or a  control group ( n=9 )  . Upper body endurance was tested on a ski ergometer . The high-resistance-training group trained for 15 min on three occasions a week for 9 weeks . Training consisted of three series of five repetitions using 85 % of one repetition maximum ( 1RM ) , with emphasis on high velocity in the concentric part of the movement . Upper body exercise economy , 1RM and time to exhaustion increased significantly in the high resistance-training group , but was unchanged in the control group . Peak power and the velocities for a given load increased significantly , except for the two lowest loads . We conclude that the increased exercise economy after a period of upper body high resistance-training can be partly explained by a specific change in the force-velocity relationship and the mechanical power output PURPOSE It has been suggested that endurance training influences the running economy ( CR ) and the oxygen uptake ( .VO(2 ) ) kinetics in heavy exercise by accelerating the primary phase and attenuating the .VO(2 ) slow component . However , the effects of heavy weight training ( HWT ) in combination with endurance training remain unclear . The purpose of this study was to examine the influence of a concurrent HWT+endurance training on CR and the .VO(2 ) kinetics in endurance athletes . METHODS Fifteen triathletes were assigned to endurance+strength ( ES ) or endurance-only ( E ) training for 14 wk . The training program was similar , except ES performed two HWT sessions a week . Before and after the training period , the subjects performed 1 ) an incremental field running test for determination of .VO(2max ) and the velocity associated ( V(.VO2max ) ) , the second ventilatory threshold ( VT(2 ) ) ; 2 ) a 3000-m run at constant velocity , calculated to require 25 % of the difference between .VO(2max ) and VT(2 ) , to determine CR and the characteristics of the VO(2 ) kinetics ; 3 ) maximal hopping tests to determine maximal mechanical power and lower-limb stiffness ; 4 ) maximal concentric lower-limb strength measurements . RESULTS After the training period , maximal strength were increased ( P < 0.01 ) in ES but remained unchanged in E. Hopping power decreased in E ( P < 0.05 ) . After training , economy ( P < 0.05 ) and hopping power ( P < 0.001 ) were greater in ES than in E. .VO(2max ) , leg hopping stiffness and the .VO(2 ) kinetics were not significantly affected by training either in ES or E. CONCLUSION Additional HWT led to improved maximal strength and running economy with no significant effects on the .VO(2 ) kinetics pattern in heavy exercise We investigated the effects of strength maintenance training on thigh muscle cross-sectional area ( CSA ) , leg strength , determinants of cycling performance , and cycling performance . Well-trained cyclists completed either ( 1 ) usual endurance training supplemented with heavy strength training twice a week during a 12-week preparatory period followed by strength maintenance training once a week during the first 13 weeks of a competition period ( E + S ; n = 6 [ ♂ = 6 ] ) , or ( 2 ) usual endurance training during the whole intervention period ( E ; n = 6 [ ♂ = 5 , ♀ = 1 ] ) . Following the preparatory period , E + S increased thigh muscle CSA and 1RM ( p < 0.05 ) , while no changes were observed in E. Both groups increased maximal oxygen consumption and mean power output in the 40-min all-out trial ( p < 0.05 ) . At 13 weeks into the competition period , E + S had preserved the increase in CSA and strength from the preparatory period . From the beginning of the preparatory period to 13 weeks into the competition period , E + S increased peak power output in the Wingate test , power output at 2 mmol l−1 [ la− ] , maximal aerobic power output ( Wmax ) , and mean power output in the 40-min all-out trial ( p < 0.05 ) . The relative improvements in the last two measurements were larger than in E ( p < 0.05 ) . For E , Wmax and power output at 2 mmol l−1 [ la− ] remained unchanged . In conclusion , in well-trained cyclists  , strength maintenance training in a competition period preserved increases in thigh muscle CSA and leg strength attained in a preceding preparatory period and further improved cycling performance determinants and performance PURPOSE The present study investigated the effect of maximal strength training on running economy ( RE ) at 70 % of maximal oxygen consumption ( V[spacing dot above]O2max ) and time to exhaustion at maximal aerobic speed ( MAS ) . Responses in one repetition maximum ( 1RM ) and rate of force development ( RFD ) in half-squats , maximal oxygen consumption , RE , and time to 
    Output:
    
Results The results showed  that strength training  improved time-trial performance , economy , $ $ { \text{v}}\dot{V}{\text{O}}_{2 \ , \hbox{max } } /{\text{w}}\dot{V}{\text{O}}_{2 \ , \hbox{max } } $ $ vV˙O2max/wV˙O2max and vMART in competitive endurance athletes .
Conclusion The present research available supports the addition of strength training in an endurance athlete ’s programme for improved economy , $ $ { \text{v}}\dot{V}{\text{O}}_{2 \ , \hbox{max } } /{\text{w}}\dot{V}{\text{O}}_{2 \ , \hbox{max } } $ $ vV˙O2max/wV˙O2max , muscle power and performance .
Future investigations should include valid strength assessment s ( i.e. squats , jump squats , drop jumps ) through a range of velocities ( maximal-strength ↔ strength-speed ↔ speed-strength ↔ reactive-strength ) , and administer appropriate strength programmes ( exercise , load and velocity prescription ) over a long-term intervention period ( > 6 months ) for optimal transfer to performance