***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 effects of 18 weeks ' intensive strength and endurance training on fibre characteristics of the vastus lateralis muscle were studied in 76- to 78-year-old women . Type I and type IIa fibres constituted over 90 % of the cell population and were almost equally represented . No changes were observed in the proportions of the different fibre types . When comparing the baseline and the 18-week measurements within the groups , the strength group showed a mean increase of 34 % ( P = 0.028 ) in mean type I fibre area . The frequency histograms showed an increased proportion of larger type I fibres after strength training and a decreased proportion of smaller type IIa fibres after endurance training . In the control subjects , the proportion of smaller type I and type IIa fibres increased during the experimental period . The results indicate that intensive strength training induces type I fibre hypertrophy , whereas the effects of endurance training are less evident . The considerable variation found in the change in muscle fibre cross-sectional areas is also noteworthy OBJECTIVES To determine the independent and combined effects of progressive resistance muscle strength training ( PRMST ) and megestrol acetate ( MA ) on strength , muscle mass , and function in older recuperative care patients . DESIGN Double-blind , r and omized , controlled intervention using a two-by-two factorial design and conducted between 1999 and 2001 . SETTING University-affiliated Department of Veterans Affairs hospital . PARTICIPANTS Twenty-nine patients ( mean age 79.4 + /- 7.4 , 90 % white ) aged 65 and older and had recent functional decline . INTERVENTIONS After r and omization to one of four treatment groups ( low-resistance exercises plus 800 mg per day of MA or a placebo or high-intensity PRMST plus 800 mg/d of MA or placebo ) , subjects received training and the drug or placebo for 12 weeks . MEASUREMENTS Change in muscle strength , mid-thigh muscle area , and aggregate functional performance score as assessed using analysis of covariance . RESULTS Five subjects withdrew from the study before its completion . Based on intent-to-treat analyses , subjects who received high-intensity PRMST and placebo experienced the greatest strength gains . The addition of MA was associated with worse outcomes than with high-intensity exercise training alone , especially with regard to the leg exercises . Post hoc analysis demonstrated that subjects who received high-intensity PRMST and placebo experienced significantly greater percentage increases in leg strength than subjects in either of the MA treatment groups ( P<.05 for each comparison ) . There was also a significant negative effect of MA on physical function . In general , subjects who received MA experienced a deterioration in aggregate physical function scores , whereas the remaining subjects improved ( -0.80+/-0.40 vs 0.48+/-0.41 , P=.04 ) . There was not a significant interaction between exercise and MA for any outcome . CONCLUSION High-intensity PRMST is a safe and well-tolerated exercise regimen for frail elderly patients . The addition of MA appears to blunt the beneficial effects of PRMST , result ing in less muscle strength and functional performance gains The " Hybrid training " ( HYBT ) method utilizing combined electrical stimulation and voluntary muscle contraction has been developed as a muscle training method . It has already been shown that the method is technically sound and clinical ly effective in healthy young subjects . The purpose of this study was to investigate the effect of the HYBT method on the knee extensor strength considering safety for elderly people . Twenty subjects were r and omly divided into two groups : the HYBT group and the weight machine training ( WMT ) group . All the subjects performed knee flexion and extension for 19 min per session , twice a week for 12 weeks . At the baseline and after the training , the subjects ' maximal isometric torque of knee extension and cross-sectional area ( CSA ) of quadriceps femoris muscle were measured . The subjects completed the study without adverse effects . The knee extension torque significantly increased in both groups ( 39 % in HYBT group and 42 % in WMT group , P < 0.05 ) . The CSA of quadriceps whole significantly increased in both groups ( 9 % in HYBT group and 14 % in WMT group , P < 0.05 ) . These results indicate that the HYBT method increases muscle strength and mass , and that this method is as effective as the WMT . In addition , unlike the WMT , the HYBT device , which is portable and not large in size , is so easy to h and le that it can be placed at the bedside . Therefore , the HYBT has potential to become a safe , effective method of muscle training for elderly people To determine whether 10 weeks of whole-body vibration ( WBV ) training has a significant effect on strength , muscle mass , muscle power , and mobility in older women , 26 subjects were r and omly assigned to a  WBV training group ( n=13 ; mean age 79 years ) and a control ( CON ) group ( n=13 ; mean age 76 years ) . Maximal voluntary isometric contraction ( MVIC ) increased 38.8 % in the WBV group , without changes in the CON group . Electromyographic activity of the vastus medialis ( VM ) , the vastus lateralis , and the biceps femoris ( BF ) did not change in either group . Thigh muscle cross-sectional area increased significantly after training in VM ( 8.7 % ) and BF ( 15.5 % ) . Muscle power at 20 % , 40 % , and 60 % MVIC decreased from pre-test to post-test in the CON group ; however , WBV training prevented the decrease in the WBV group . Consequently , mobility , measured by the Timed Up and Go test , increased significantly after training ( 9.0 % ) only in the WBV group . Ten weeks of lower limb WBV training in older women produces a significant increase in muscle strength induced by thigh muscle hypertrophy , with no change in muscle power . The adaptations to WBV found in the present study may be of use in counteracting the loss of muscle strength and mobility associated with age-induced sarcopenia Research indicates that lower extremity muscle weakness in the elderly is consistently related to impaired mobility and fall risk . Reversible components of the muscle weakness of aging include underuse syndromes and undernutrition , both of which are prevalent in nursing home population s. The Boston FICSIT study is a nursing home-based intervention to improve muscle strength through progressive resistance training of the lower extremities and /or multi-nutrient supplementation in chronically institutionalized subjects aged 70 - 100 . Baseline measurements of falls , medical status , psychological variables , functional status , nutritional intake and status , body composition , muscle mass and morphology , muscle function , and gait and balance are taken . The nursing home residents are then r and omly assigned to one of four treatment groups for 10 weeks : ( 1 ) high intensity progressive resistance training of the hip and knee extensors 3 days per week ; ( 2 ) multi-nutrient supplementation with a 360-kcal high carbohydrate , low fat liquid supplement every day ; ( 3 ) a combination of groups ( 1 ) and ( 2 ) ; and ( 4 ) a control group . Both non-supplemented groups receive a liquid placebo every day , and both non-exercising groups attend three sessions of " leisure activities " every week in order to control for the attentional aspects of the exercise and nutritional interventions . At the end of the 10-week period , all baseline measurements are re-assessed Considerable evidence suggests that the loss of strength and muscle mass appear to be inevitable consequences of aging . Moreover , aging is associated with an increase in body fat . This study examined whether increased physical activity could prevent or reverse the losses of strength and skeletal muscle mass as well as the gain in  fat in older adults . Eleven men and 31 women completed a r and omized trial consisting of either a physical activity ( PA ; n = 22 ) or successful aging health educational control ( SA ; n = 20 ) group . Isokinetic knee extensor strength and computed tomography-derived midthigh skeletal muscle and adipose tissue cross-sectional areas ( CSA ) were assessed at baseline and at 12 mo following r and omization .  Total body weight and muscle CSA decreased in both groups , but these losses were not different between groups . Strength adjusted for muscle mass decreased ( -20.1 + /- 9.3 % , P < 0.05 ) in SA . The loss of strength was completely prevented in PA ( + 2.5 + /- 8.3 % ) . In addition , there was a significant increase ( 18.4 + /- 6.0 % ) in muscle fat infiltration in SA , but this gain was nearly completely prevented in PA ( 2.3 + /- 5.7 % ) . In conclusion , regular physical activity prevents both the age-associated loss of muscle strength and increase in muscle fat infiltration in older adults with moderate functional limitations The plasma levels of dehydroepi and rosterone ( DHEA ) and its sulfated form ( DHEAS ) decline approximately 80 % between the ages of 25 and 75 yr . Muscle mass and strength also decrease with aging . Published data on the effects of DHEA replacement on muscle mass and strength are conflicting . The goals of this study were to determine whether DHEA replacement increases muscle mass and strength and /or enhances the effects of heavy resistance exercise in elderly women and men . We conducted a r and omized , double-blind , placebo-controlled study of the effects of 10 mo of DHEA replacement therapy with the addition of weightlifting exercise training during the last 4 mo of the study  ( DHEA + exercise group , n = 29 ; placebo + exercise group , n = 27 ) .  DHEA alone for 6 mo did not significantly increase strength or thigh muscle volume . However , DHEA therapy potentiated the effect of 4 mo of weightlifting training on muscle strength , evaluated by means of one-repetition maximum measurement and Cybex dynamometry , and on thigh muscle volume , measured by magnetic resonance imaging . Serum insulin-like growth factor concentration increased in response to DHEA replacement . This study provides evidence that DHEA replacement has the beneficial effect of enhancing the increases in muscle mass and strength induced by heavy resistance exercise in elderly individuals The purpose of this study was to investigate whole muscle and single muscle fiber adaptations in very old men in response to progressive resistance training ( PRT ) .  Six healthy independently living old men ( 82 + /- 1 yr ; range 80 - 86 yr , 74 + /- 4 kg )  resistance-trained the knee extensors ( 3 sets , 10 repetitions ) at approximately 70 % one repetition maximum 3 days/wk for 12 wk . Whole thigh muscle cross-sectional area ( CSA ) was assessed before and after PRT using computed tomography ( CT ) . Muscle biopsies were obtained from the vastus lateralis before and after the PRT program . Isolated myosin heavy chain ( MHC ) I and IIa single muscle fibers ( n = 267 ; 142 pre ; 125 post ) were studied for diameter , peak tension , shortening velocity , and power . An additional set of isolated single muscle fibers ( n = 2,215 ; 1,202 pre ; 1,013 post ) was used to identify MHC distribution . One repetition maximum knee extensor strength increased ( P < 0.05 ) 23 + /- 4 kg ( 56 + /- 4 to 79 + /- 7 kg ; 41 % ) . Muscle CSA increased ( P < 0.05 ) 3 + /- 1 cm2 ( 120 + /- 7 to 123 + /- 7 cm2 ; 2.5 % ) . Single muscle fiber contractile function and MHC distribution were unaltered with PRT . These data indicate limited muscle plasticity at the single-muscle fiber level with a resistance-training program among the very old . The minor increases in whole muscle CSA coupled with the static nature of the myocellular profile indicate that the strength gains were primarily neurological . These data contrast typical muscle responses to resistance training in young ( approximately 20 yr ) and old ( approximately 70 yr ) humans and indicate that the physiological regulation of muscle remodeling is adversely modified in the oldest old The short- and long-term effects of heavy-resistance training ( 85 % of one-repetition maximum ( RM ) ) on elbow flexion and knee extension dynamic and isokinetic strength and on morphology in the biceps brachii and vastus lateralis muscles were evaluated during 1 year in 35 Sc and inavian men and women , aged 70 - 77 years , 12 of whom formed a control group . After the first 11 weeks of training ( n = 23 ; 3 times/week )  elbow flexion and knee extension dynamic strength ( 1 RM ) had increased [ mean + /- SD ] 49 % + /- 16 and 163 % + /- 75 , respectively , with no significant difference between men and women . For the following 27 weeks , strength was maintained with one training session per week ( n = 12 ) but dropped without training ( n = 11 ) . After the final 11 weeks of training ( n = 11 ; 3 times/week ) , strength had further increased 32 % + /- 16 in both the arm and the leg . Isokinetic strength measurements ( Cybex II ; 30 degrees/s ) revealed similar but smaller gains than for dynamic strength . Muscle biopsies ( n = 20 ) taken at the start and after the first 11 weeks of training showed a significant increase in the area of both type 1 and type 2 fibers in the biceps brachii muscle and a positive significant correlation between the percentage increase in the proportional area of type 2 fibers in the vastus lateralis muscle and the percentage increase in knee extension dynamic muscle strength . In conclusion , 
    Output:
    
Physical training when delivered as resistance training has the ability to elicit hypertrophy and increase muscle strength in very elderly muscle