***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 Athletes often use weight training to prepare for sprint events , but the effectiveness of different types of weight training for sprinting is unclear . We have therefore investigated the effect of slow and explosive weight training on kayak sprint performance . METHODS Twenty-seven male and 11 female experienced sprint kayakers were r and omized to slow weight training , explosive weight training , or control ( usual training ) groups . Weight training consisted of two sessions per week for 6 wk ; in each session the athletes performed 3 - 4 sets of two sport-specific exercises with a load of 80 % 1-repetition-maximum . The two training programs differed only in the time taken to complete the concentric phase of the exercises : slow , 1.7 s ; explosive , < 0.85 s. To determine the effects of training on sprint acceleration and speed maintenance , the athletes performed 15-m kayaking sprints  pre- and posttraining ; an electronic timing system provided sprint times at 3.75- , 7.5- , and 15-m marks . RESULTS Relative to control , both types of weight training substantially improved strength and sprint performance . The improvements in mean sprint time over 15 m in each group were : slow , 3.4 % ; explosive , 2.3 % ; control , -0.2 % ( 90 % confidence limits for pairwise differences , approximately + /-1.4 % ) . Over the first 3.75 m , the improvements were : slow , 7.1 % ; explosive , 3.2 % ; control , 1.4 % ( approximately + /-2.6 % ) . Over the last 7.5 m , the improvements were : slow , 2.1 % ; explosive , 3.0 % ; control , -0.8 % ( approximately + /-1.9 % ) . CONCLUSIONS Slow weight training is likely to be more effective than explosive training for improving the acceleration phase of sprinting , when force is high throughout the length of the stroke . Explosive weight training may be more effective in speed maintenance , when forces are developed rapidly over a short period at the start of the stroke Sayers , SP and Gibson , K. A comparison of high-speed power training and traditional slow-speed resistance training in older men and women . J Strength Cond Res 24(12 ) : 3369 - 3380 , 2010-Muscle power , the product of force × velocity , is a critical determinant of function in older adults . Resistance training ( RT ) at high speed has been shown to improve peak muscle power in this population ; however , different functional tasks may benefit from the improvement of power at values other than “ peak ” values , for example , tasks that require a greater velocity component or a greater force component . This study compared the effect of high-speed RT on muscle performance ( peak power [ PP ] and its components [ PP force and PP velocity ] and overall peak velocity [ VEL ] ) across a broad range of external resistances . Thirty-eight older men and women were r and omized  to high-speed power training at 40 % of the 1-repetition maximum ( 1RM ) ( n = 13 [ 74.1 ± 6.4 years ] ) ; traditional RT at 80 % 1RM ( n = 13 [ 70.1 ± 7.0 years ] ) ; or control ( n = 12 [ 72.8 ± 4.1 years ] ) . Measures of muscle performance were obtained at baseline and after the 12-week training intervention . Muscle power and 1RM strength improved similarly with both high-speed and traditional slow-speed RT . However , speed-related muscle performance characteristics , PP velocity and overall VEL , were most positively impacted by high-speed power training , especially at lower external resistances . Because gains in speed-related measures with high-speed training compared to traditional RT do not come at the expense of other muscle performance outcomes , we recommend using an RT protocol in older adults that emphasizes high-speed movements at low external resistances OBJECTIVE To determine the effect of training intensity on the contributions of force and velocity to improvements in peak power ( PP ) after explosive resistance training in older adults . METHODS 112 healthy older adults ( 69 + /- 6 yr ) were r and omized to explosive resistance training at 20 % ( G20 ) , 50 % ( G50 ) , or 80 % ( G80 ) maximal strength ( 1-repetition maximum ) for 8 - 12 wk ( twice weekly , 5 exercises , 3 sets of 8 explosive concentric/slow eccentric repetitions ) using pneumatic resistance machines or a nontraining control group ( CON ) . RESULTS Force at peak power ( FPP ) increased significantly and similarly among training groups compared with CON . Velocity at peak power ( VPP ) did not improve significantly and remained similar between all groups . Force contributed significantly more to PP production in G80 and G50 than in CON . The change in PP was independently predicted by changes in fat-free mass in G80 and by changes in both FPP and VPP in G50 and G20 . CONCLUSION Explosive resistance training in older adults results in the ability to produce higher PP outputs with heavier loads without loss of movement velocity . Moderate- to high-intensity training induced a greater relative contribution of force to PP production in this cohort The purpose of this investigation was to examine the effect of an 8-week training program with heavy- vs. light-load jump squats on various physical performance measures and electromyography ( EMG ) .  Twenty-six athletic men with varying levels of resistance training experience performed sessions of jump squats with either 30 % ( JS30 , n = 9 ) or 80 % ( JS80 , n = 10 ) of their one repetition maximum in the squat ( 1RM ) or served as a control ( C , n = 7 ) . An agility test , 20-m sprint , and jump squats with 30 % ( 30J ) , 55 % ( 55J ) , and 80 % ( 80J ) of their 1RM were performed before and after training . Peak force , peak velocity ( PV ) , peak power ( PP ) , jump height , and average EMG ( concentric phase ) were calculated for the jumps . There were significant increases in PP and PV in the 30J , 55J , and 80J for the JS30 group ( p < 0.05 ) . The JS30 group also significantly increased in the 1RM with a trend towards improved 20-m sprint times . In contrast , the JS80 group significantly increased both PF and PP in the 55J and 80J and significantly increased in the 1RM but ran significantly slower in the 20-m sprint . In the 30J the JS30 group 's percentage increase in EMG activity was significantly different from the C group . In the 80J the JS80 group 's percentage increase in EMG activity was significantly different from the C group . This investigation indicates that training with light-load jump squats results in increased movement velocity capabilities and that velocity-specific changes in muscle activity may play a key role in this adaptation The authors investigated the effects of low-intensity resistance training on muscle size and strength in older men and women . Thirty-five participants ( age 59 - 76 yr ) were r and omly assigned to 2 groups and performed low-intensity ( 50 % of 1-repetition maximum ) knee-extension and -flexion exercises with either slow movement and tonic force generation ( LST ; 3-s eccentric , 3-s concentric , and 1-s isometric actions with no rest between repetitions ) or normal speed ( LN ; 1-s concentric and 1-s eccentric actions with 1-s rests between repetitions ) twice a week for 12 wk ( 2-wk preparation and 10-wk intervention ) . The LST significantly increased thigh-muscle thickness , as well as isometric knee-extension and -flexion strength . The LN significantly improved strength , but its hypertrophic effect was limited . These results indicate that even for older individuals , the LST can be an effective method for gaining muscle mass and strength Initial strength gains were examined in the context of learning a new skill . Forty female volunteers were r and omly assigned to one of four groups : a bench-press training group utilizing heavy loads in its training , a bench-press training group utilizing almost no load , an alternative training group using different exercises , or a control group that did not train . Training period was 6 wk , with three training sessions per week . Emphasis was put on keeping the coordination and muscular adaptation dem and s in the bench-press groups as invariant as possible . Bench-press training with a light or with a heavy weight was shown to be equally effective in improving the maximal velocity of contraction for a given absolute resistance . Mean velocity with loads of 0.37 , 6.6 , 16.6 , and 20 kg improved by 21.1 , 15.8 , 16.9 , and 19.5 % , respectively . No significant differences in the percent improvement at the four different loads were apparent , indicating that no significant velocity-specific adaptations were present . The bench-press training group , utilizing heavy loads in its training , was the only group with improved one repetition maximum . Overall , findings point to the development of coordination as the determining factor in early velocity-specific strength gains OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity PURPOSE To compare effects on strength in the early phase of resistance training with one or three sets and fast or slow speeds . METHODS A total of 115 healthy , untrained subjects were r and omized to a control group or one of four training groups : one set fast ( approximately 140 degrees.s(-1 ) ) , three sets fast , one set slow ( approximately 50 degrees.s(-1 ) ) , or three sets slow . All subjects attended training 3 x wk(-1 ) for 6 wk . Subjects in the training groups performed unilateral elbow flexion contractions with a target six- to eight-repetition maximum load . Control subjects sat at the training bench but did not train . One repetition maximum strength , arm circumference , and biceps skinfold thickness were measured before and after training . RESULTS One slow set increased strength by 25 % ( 95 % CI 13 - 36 % , P < 0.001 ) . Three sets of training produced greater increases in strength than one set ( difference = 23 % of initial strength , 95 % CI 12 - 34 % , P < 0.001 ) and fast training result ed in a greater increase in strength than slow training ( difference = 11 % , 95 % CI 0.2 - 23 % , P = 0.046 ) . The interaction between sets and speed was negative ( -15 % ) and of borderline significance ( P = 0.052 ) , suggesting there is a benefit of training with three sets or fast speeds , but there is not an additive benefit of training with both . CONCLUSIONS Three sets of exercise produce twice the strength increase of one set in the early phase of resistance training . Training fast produces greater strength increases than training slow ; however , there does not appear to be any additional benefit of training with both three sets and fast contractions We previously reported that low‐intensity [ 50 % of one repetition maximum ( 1RM ) ] resistance training with slow movement and tonic force generation ( LST ) causes muscle hypertrophy and strength gain in older participants . The aim of this study was to determine whether resistance training with slow movement and much more reduced intensity ( 30%1RM ) increases muscle size and strength in older adults . Eighteen participants ( 60–77 years ) were r and omly assigned to two groups . One group performed very low‐intensity ( 30 % 1RM ) knee extension exercise with continuous muscle contraction ( LST : 3‐s eccentric , 3‐s concentric , and 1‐s isometric actions with no rest between each repetition ) twice a week for 12 weeks . The other group underwent intermitted muscle contraction ( CON : 1‐s concentric and 1‐s eccentric actions with 1‐ 
    Output:
    
Strength gains between conditions were not influenced by training status and age .
Conclusions Overall , the results suggest that fast and moderate-slow resistance training  improve dynamic muscular strength similarly in individuals within a wide range of training statuses and ages .
Resistance training performed at fast movement velocities using moderate intensities showed a trend for superior muscular strength gains as compared to moderate-slow resistance training .