***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: Introduction Aging involves a progressive reduction of respiratory muscle strength as well as muscle strength . Purpose Compare the effects of resistance training volume on the maximum inspiratory pressure ( MIP ) , maximum expiratory pressure ( MEP ) , functional performance , and muscle strength in elderly women . Methods Thirty elderly women were r and omly assigned to a group performing either single sets ( 1-SET ) or three sets ( 3-SET ) of exercises . The sit-to-st and test , MIP , MEP , and muscle strength were assessed before and after 24 training sessions . Progressive resistance training was performed two times per week for a total of 8–12 repetitions , using the main muscle groups of the upper and lower limbs . Results The main results showed that the participants significantly increased their MEP ( P<0.05 ; 1-SET : 34.6 % ; 3-SET : 35.8 % ) and MIP ( P<0.05 ; 1-SET : 13.7 % ; 3-SET : 11.2 % ) . Both groups also improved in the sit-to-st and test ( P<0.05 ; 1-SET : 10.6 % ; 3-SET : 17.1 % ) . After 24 training sessions , muscle strength also significantly increased ( P<0.0001 ; 40%–80 % ) in both groups . An intergroup comparison did not show any statistically significant differences between the groups in any of the parameters analyzed . Conclusion Single- and multiple-set resistance training programs  increased MIP , MEP , muscle strength , and sit-to-st and test performance in elderly women after 24 sessions of training . In conclusion , our results suggested that elderly women who are not in the habit of physical activity may start with single-set resistance training programs as a short-term strategy for the maintenance of health The strength training has been shown to be effective for attenuating the age-related physiological decline . However , the adequate volume of strength training volume adequate to promote improvements , mainly during the initial period of training , still remains controversial . Thus , the purpose of this study was to compare the effects of a short-term strength training program with single or multiple sets in elderly women .  Maximal dynamic ( 1-RM ) and isometric strength , muscle activation , muscle thickness ( MT ) , and muscle quality ( MQ = 1-RM and MT quadriceps quotient ) of the knee extensors were assessed . Subjects were r and omly assigned into one of two groups : single set  ( SS ; n = 14 ) that performed one set per exercise or multiple sets  ( MS ; n = 13 ) that performed three-sets per exercise , twice weekly for 6 weeks . Following training , there were significant increases ( p ≤ 0.05 ) in knee extension 1-RM ( 16.1 ± 12 % for SS group and 21.7 ± 7.7 % for MS group ) , in all MT ( p ≤ 0.05 ; vastus lateralis , rectus femoris , vastus medialis , and vastus intermedius ) , and in MQ ( p ≤ 0.05 ) ; 15.0 ± 12.2 % for SS group and 12.6 ± 7.2 % for MS group ) , with no differences between groups . These results suggest that during the initial stages of strength training , single- and multiple-set training demonstrate similar capacity for increasing dynamic strength , MT , and MQ of the knee extensors in elderly women OBJECTIVE To determine the effect of frequency of resistive training on gain in muscle strength and neuromuscular performance in healthy older adults . DESIGN A r and omized controlled trial with subjects assigned either to high-intensity resistance training 1 ( EX1 ) , 2 ( EX2 ) , or 3 ( EX3 ) days per week for 24 weeks or to a control group ( CO ) . SETTING An exercise facility at an academic medical center . SUBJECTS Forty-six community-dwelling healthy men ( n = 29 ) and women ( n = 17 ) aged 65 to 79 years . INTERVENTION Progressive resistance training consisting of three sets of eight exercises targeting major muscle groups of the upper and lower body , at 80 % of one-repetition maximum ( 1-RM ) for eight repetitions , either 1 , 2 , or 3 days per week . MEASURES Dynamic muscle strength ( 1-RM ) using isotonic equipment every 4 weeks , bone mineral density and body composition by dual energy X-ray absorptiometry ( DXA ) , and neuromuscular performance by timed chair rise and 6-meter backward t and em walk . RESULTS For each of the eight exercises , muscle strength increased in the exercise groups relative to CO ( P < .01 ) , with no difference among EX1 , EX2 and EX3 groups at any measurement interval . Percent change averaged 3.9 + /- 2.4 ( CO ) , 37.0 + /- 15.2 ( EX1 ) , 41.9 + /- 18.2 ( EX2 ) , and 39.7 + /- 9.8 ( EX3 ) . The time to rise successfully from the chair 5 times decreased significantly ( P < .01 ) at 24 weeks , whereas improvement in the 6-meter backward t and em walk approached significance ( P = .10 ) in the three exercise groups compared with CO . Changes in chair rise ability were correlated to percent changes in quadriceps strength ( r = -0.40 , P < .01 ) and lean mass ( r = -0.40 , P < .01 ) . CONCLUSIONS A program of once or twice weekly resistance exercise achieves muscle strength gains similar to 3 days per week training in older adults and is associated with improved neuromuscular performance . Such improvement could potentially reduce the risk of falls and fracture in older adults Are meta-analyses the brave new world , or are the critics of such combined analyses right to say that the biases inherent in clinical trials make them uncombinable ? Negative trials are often unreported , and hence can be missed by meta-analysts . And how much heterogeneity between trials is acceptable ? A recent major criticism is that large r and omised trials do not always agree with a prior meta- analysis . Neither individual trials nor meta-analyses , reporting as they do on population effects , tell how to treat the individual patient . Here we take a more rounded approach to meta-analyses , arguing that their strengths outweigh their weaknesses , although the latter must not be brushed aside Age-related processes in the neuromuscular and the somatosensory system are responsible for decreases in maximal and explosive force production capacity and deficits in postural control . Thus , the objectives of this study were to investigate the effects of resistance training on strength performance and on postural control in seniors . Forty healthy seniors ( 67+/-1 yrs ) participated in this study . Subjects were r and omly assigned to a resistance training ( n=20 ) and a control group ( n=20 ) . Resistance training for the lower extremities lasted for 13 weeks at 80 % of the one repetition maximum . Pre and post tests included the measurement of maximal isometric leg extension force with special emphasis on the early part of the force-time-curve and the assessment of static ( functional reach test ) and dynamic ( t and em walk test , platform perturbation ) postural control .  Resistance training result ed in an enhanced strength performance with increases in explosive force exceeding those in maximal strength . Improved performances in the functional reach and in the t and em walk test were observed . Resistance training did not have an effect on the compensation of platform perturbations . Increases in strength performance can primarily be explained by an improved neural drive of the agonist muscles . The inconsistent effect of resistance training on postural control may be explained by heterogeneity of testing methodology or by the incapability of isolated resistance training to improve postural control BACKGROUND To study the effects of resistance training on muscle strength and size in older people , we enrolled 8 men and 17 women ( mean age 68.2 + /- 1 SEM ) into a one-year exercise trial . METHODS Subjects were r and omly assigned to exercise or control groups . Muscle biopsies were obtained from 11 subjects ( 8 exercisers/3 controls ) at baseline and after 15 weeks ; exercisers underwent another biopsy at 30 weeks . After testing maximum strength using the 1-RM method , the exercisers began a 12-exercise circuit ( 3 sets of 8 repetitions at 75 % of 1-RM ) , 3 times a week . The controls repeated the strength testing every 15 weeks . They were asked to continue usual activities and not to start any exercise program . RESULTS With exercise , muscle strength increased , average increases ranging from 30 % ( hip extensors ) to 97 % ( hip flexors ) . Strength increased rapidly over 3 months , then plateaued for the duration of the experiment . No strength changes were observed in sedentary controls . Cross-sectional area of type 1 muscle fibers increased in exercisers by 15 weeks ( 29.4 + /- 1 % , p < .02 ) and after 30 weeks ( 58.5 + /- 13.7 % , p < .002 ) compared to baseline . Type 2 fiber area did not change at 15 weeks , but increased by 30 weeks of training ( 66.6 + /- 9.5 % , p < .0002 ) . CONCLUSIONS These results suggest that prolonged moderate to high intensity resistance training may be carried out by healthy older adults with reasonable compliance , and that such training leads to sustained increases in muscle strength . These improvements are rapidly achieved and are accompanied by hypertrophy of both type 1 and type 2 muscle fibers The purpose of this study was to determine whether a high intensity ( HI ) versus a moderate ( MI ) or low-intensity ( LI ) training program would be more effective in improving the isokinetic knee extension muscular performance in healthy inactive men and women . Sixty-four participants , men and women , were r and omly assigned to one of four groups : control group ( C ) , LI ( 50 % of 1RM ) , the MI group ( 70 % of 1RM ) and the HI ( 90 % of 1RM ) . Participants exercised on three resistance exercise machines : leg extension , leg curls and leg press . The isokinetic testing method ( concentric mode ) applied prior to and at the end of the training period ( 16 weeks , three 3 times per week ) to assess the knee muscular performance . MANOVA repeated measures revealed that the HI group demonstrated the most strength gains following a speed specificity pattern ( most considerable improvement occurred at or near slow speeds from 7.3 % to 11.2 % for male and from 2.3 % to 15.2 % for female ) . In addition , males demonstrated a greater improvement of knee extension power output than females . In conclusion , HI strength training is proposed for elderly men and women as the most effective protocol . Furthermore only at low-velocity testing , women of the HI showed a greater change than men ( p < 0.05 ) . Regarding strength increase in relation to various testing velocities , a greater increase was found in HI at low velocities , with the other training groups exhibiting almost similar strength increase at all tested speeds ZusammenfassungHINTERGRUND : I m Alter kommt es sowohl zu einer Reduktion der Muskelmasse als auch zu metabolischen Veränderungen i m Skelettmuskel . Ein Großteil dieser Veränderungen ist auf Bewegungsmangel zurückzuführen und kann durch ein Ausdauertraining ( ET ) und Krafttraining ( RT ) verhindert werden . FRAGESTELLUNG : Welche Trainings method e ist die effektivste , um die physische Leistungsfähigkeit i m Alter zu verbessern ? Das Ziel dieser Studie ist es festzustellen , ob ein systematisches ET auch die Muskelkraft steigern kann und/oder ob ein systematisches RT auch die aerobe Kapazität von gesunden alten Menschen verbessern kann . UNTERSUCHUNGEN/ METHOD EN : 42 Prob and en ( 32 Frauen , 10 Männer ) wurden für die Studie rekrutiert und in 3 Gruppen r and omisiert : 13 Prob and en führten ein 6-monatiges ET Programm durch , 15 Prob and en ein 6-monatiges  RT Programm und 14 Prob and en wurden in die Kontrollgruppe gelost . Eine Belastungsspiroergometrie und eine Dynamometrie wurden zu Beginn und am Ende der Studie absolviert , um die aerobe Kapazität ( VO2max ) , die maximale Leistungsfähigkeit ( Wmax ) , sowie die Maximalkraft ( 1-RM ) zu testen . ERGEBNISSE : Die Maximalkraft verbesserte sich signifikant ( zwischen 15 % und 30 % ) nach 6 Monaten RT , während ET zu keiner signifikanten Veränderung der Maximalkraft führte . ET result ierte in einer hoch signifikanten Verbesserung der Wmax um 31 % , während RT nur eine moderate Verbesserung der Wmax um 6 % zeigte . ET result ierte zusätzlich in einer signifikanten Reduktion des Körperfettanteils , RT in einer Zunahme der fettfreien Magermasse . SCHLUSSFOLGERUNG : Sowohl ET , als auch RT wirken positiv auf die Gesundheit und Fitness gesunder alter Menschen , jedoch auf unterschiedliche Art und Weise : ET verbessert die aerobe Kapazität , jedoch nicht die Muskelkraft , und reduziert das kardiovaskuläre Risiko wahrscheinlich effektiver . RT verbessert die Muskelkraft und tendenziell das metabolische Risiko , das bei einer reduzierten Muskelmasse i m Alter erhöht ist . Wir empfehlen bei gesunden , alten Menschen vor allem ein Maximalkrafttraining mit einer Intensität von 60–80 % des EWM , 8–15 Wiederholungen pro Übung und einem Volumen von 3–6 Sätzen pro Muskelgruppe und Woche . ET sollte ergänzend 2-mal pro Woche mit einer Intensität von 60 % VO2max ( nach Karvonen ) und einer wöchentlichen 
    Output:
    
No single training volume variable significantly predicted RT effects on measures of muscle morphology .
While we were able to determine a dose – response relationship based on specific individual training variables with respect to muscle strength and morphology , it was not possible to ascertain any potential interactions between these variables .
Conclusions This systematic literature review and meta- analysis confirmed the effectiveness of RT on specific measures of upper and lower extremity muscle strength and muscle morphology in healthy old adults .
In addition , we were able to extract dose – response relationships for key training variables ( i.e. , volume , intensity , rest ) , informing clinicians and practitioners to design effective RTs for muscle strength and morphology .
Training period , intensity , time under tension , and rest in between sets play an important role in improving muscle strength and morphology and should be implemented in exercise training programs targeting healthy old adults .