human
***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: Muscle mass decreases with age , leading to " sarcopenia , " or low relative muscle mass , in elderly people . Sarcopenia is believed to be associated with metabolic , physiologic , and functional impairments and disability . Methods of estimating the prevalence of sarcopenia and its associated risks in elderly population s are lacking . Data from a  population -based survey of 883 elderly Hispanic and non-Hispanic white men and women living in New Mexico ( the New Mexico Elder Health Survey , 1993 - 1995 ) were analyzed to develop a method for estimating the prevalence of sarcopenia . An anthropometric equation for predicting appendicular skeletal muscle mass was developed from a r and om sub sample ( n = 199 ) of participants and was extended to the total sample . Sarcopenia was defined as appendicular skeletal muscle mass (kg)/height2 ( m2 ) being less than two st and ard deviations below the mean of a young reference group . Prevalences increased from 13 - 24 % in persons under 70 years of age to > 50 % in persons over 80 years of age , and were slightly greater in Hispanics than in non-Hispanic whites . Sarcopenia was significantly associated with self-reported physical disability in both men and women , independent of ethnicity , age , morbidity , obesity , income , and health behaviors . This study provides some of the first estimates of the extent of the public health problem posed by sarcopenia Previous studies have shown that low-intensity resistance training with restricted muscular venous blood flow ( Kaatsu ) causes muscle hypertrophy and strength gain . To investigate the effects of daily physical activity combined with Kaatsu , we examined the acute and chronic effects of walk training with and without Kaatsu on MRI-measured muscle size and maximum dynamic ( one repetition maximum ) and isometric strength , along with blood hormonal parameters . Nine men performed Kaatsu-walk training , and nine men performed walk training alone ( control-walk ) . Training was conducted two times a day , 6 days/wk , for 3 wk using five sets of 2-min bouts ( treadmill speed at 50 m/min ) , with a 1-min rest between bouts .  Mean oxygen uptake during Kaatsu-walk and control-walk exercise was 19.5 ( SD 3.6 ) and 17.2 % ( SD 3.1 ) of treadmill-determined maximum oxygen uptake , respectively . Serum growth hormone was elevated ( P < 0.01 ) after acute Kaatsu-walk exercise but not in control-walk exercise .  MRI-measured thigh muscle cross-sectional area and muscle volume increased by 4 - 7 % , and one repetition maximum and maximum isometric strength increased by 8 - 10 % in the Kaatsu-walk group . There was no change in muscle size and dynamic and isometric strength in the control-walk group . Indicators of muscle damage ( creatine kinase and myoglobin ) and resting anabolic hormones did not change in both groups . The results suggest that the combination of leg muscle blood flow restriction with slow-walk training induces muscle hypertrophy and strength gain , despite the minimal level of exercise intensity . Kaatsu-walk training may be a potentially useful method for promoting muscle hypertrophy , covering a wide range of the population , including the frail and elderly Background We aim ed to determine the effect of resistance exercise intensity ( % 1 repetition maximum—1RM ) and volume on muscle protein synthesis , anabolic signaling , and myogenic gene expression . Methodology /Principal Findings Fifteen men ( 21±1 years ; BMI = 24.1±0.8 kg/m2 ) performed 4 sets of unilateral leg extension exercise at different exercise loads and /or volumes : 90 % of repetition maximum ( 1RM ) until volitional failure ( 90FAIL ) , 30 % 1RM work-matched to 90%FAIL ( 30WM ) , or 30 % 1RM performed until volitional failure ( 30FAIL ) . Infusion of [ ring-13C6 ] phenylalanine with biopsies was used to measure rates of mixed ( MIX ) , myofibrillar ( MYO ) , and sarcoplasmic ( SARC ) protein synthesis at rest , and 4 h and 24 h after exercise . Exercise at 30WM induced a significant increase above rest in MIX ( 121 % ) and MYO ( 87 % ) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only . The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM , with no difference between these conditions ; however , MYO remained elevated ( 199 % ) above rest at 24 h only in 30FAIL . There was a significant increase in AktSer473 at 24h in all conditions ( P = 0.023 ) and mTORSer2448 phosphorylation at 4 h post-exercise ( P = 0.025 ) . Phosporylation of Erk1/2Tyr202/204 , p70S6KThr389 , and 4E-BP1Thr37/46 increased significantly ( P<0.05 ) only in the 30FAIL condition at 4 h post-exercise , whereas , 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL ( 237 % ) and 30FAIL ( 312 % ) conditions . Pax7 mRNA expression increased at 24 h post-exercise ( P = 0.02 ) regardless of condition . The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition . Conclusions / Significance These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes This study identified factors associated with exercise participation  and  adherence  in a sample of 102 sedentary , functionally limited , community-dwelling adults aged 60 to 94 years who participated in a home-based resistance training program .  Stepwise regression analyses revealed that baseline physical factors ( i.e. , higher levels of mobility , weaker muscle strength , and fewer numbers of new medical conditions ) were associated with higher rates of participation in the home program .  Positive attitudes and a sense of control toward exercise , lower levels of confusion and depressive moods , and the development of fewer new medical problems during the program were related to higher levels of adherence to the program . Findings revealed that although physical health variables were the primary indicators of an older person 's overall participation in the program , it was the psychological factors that were most important to adherence to this home-based program OBJECTIVES To assess the extent to which physical activity and leg strength are associated with change in mobility  in older persons . DESIGN Prospect i ve , observational cohort study . SETTING Retirement communities across the Chicago metropolitan area participating in the Rush Memory and Aging Project . PARTICIPANTS Eight hundred eighty-six ambulatory older persons without dementia . MEASUREMENT Rate of change in mobility . RESULTS In a linear mixed-effects model that controlled for age , sex , education , and a term for baseline physical activity , a higher level of physical activity was associated with a slower rate of mobility decline ( estimate=0.006 , st and ard error (SE)=0.003 , P=.03 ) ; each additional hour of physical activity at baseline was associated with an approximately 3 % decrease in the rate of mobility decline . In a similar model , a higher level of baseline leg strength was associated with a slower rate of mobility decline ( estimate=0.031 , SE=0.132 , P=.02 ) ; each additional unit of leg strength at baseline was associated with an approximately 20 % decrease in the rate of mobility decline . In a final model , which included terms for physical activity and leg strength together , both were associated with decline in mobility . Furthermore , both remained associated with mobility even after controlling for body composition , balance , pulmonary function , cognition , history of joint pain , cardiovascular diseases and risk factors , and medications . CONCLUSION Physical activity and leg strength are relatively independent predictors of mobility decline  in older persons . Although physical activity may improve strength , the beneficial effect of physical activity on mobility is likely to involve other pathways We have reported that the acute postexercise increases in muscle protein synthesis rates , with differing nutritional support , are predictive of longer-term training-induced muscle hypertrophy . Here , we aim ed to test whether the same was true with acute exercise-mediated changes in muscle protein synthesis . Eighteen men ( 21 ± 1 yr , 22.6 ± 2.1 kg/m(2 ) ; means ± SE ) had their legs r and omly assigned to two of three training conditions that differed in contraction intensity [ % of maximal strength ( 1 repetition maximum ) ] or contraction volume ( 1 or 3 sets of repetitions ) : 30%-3 , 80%-1 , and 80%-3 . Subjects trained each leg with their assigned regime for a period of 10 wk , 3 times/wk . We made pre- and posttraining measures of strength , muscle volume by magnetic resonance ( MR ) scans , as well as pre- and posttraining biopsies of the vastus lateralis , and a single postexercise ( 1 h ) biopsy following the first bout of exercise , to measure signaling proteins . Training-induced increases in MR-measured muscle volume were significant ( P < 0.01 ) , with no difference between groups : 30%-3 = 6.8 ± 1.8 % , 80%-1 = 3.2 ± 0.8 % , and 80%-3= 7.2 ± 1.9 % , P = 0.18 . Isotonic maximal strength gains were not different between 80%-1 and 80%-3 , but were greater than 30%-3 ( P = 0.04 ) , whereas training-induced isometric strength gains were significant but not different between conditions ( P = 0.92 ) . Biopsies taken 1 h following the initial resistance exercise bout showed increased phosphorylation ( P < 0.05 ) of p70S6 K only in the 80%-1 and 80%-3 conditions . There was no correlation between phosphorylation of any signaling protein and hypertrophy . In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure result ed in similar hypertrophy as a heavy load lifted to failure BACKGROUND This study tested the hypothesis that a home-based exercise program would improve functional performance in elderly people . METHODS We conducted a 6-month , single-blinded , r and omized controlled trial . 72 community dwelling men and women ( aged > /=70 years ) with self-reported and laboratory-based functional impairment were recruited for the study . Participants were r and omly assigned to either a home-based progressive strength , balance , and general physical activity intervention or an attention-control group that received home-based nutrition education .  Functional performance was measured in the laboratory using the Physical Performance Test ( PPT ) and the Established Population s for Epidemiologic Studies of the Elderly ( EPESE ) short physical performance battery . Physiologic capacity was measured by strength ( one repetition maximum ) , dynamic balance ( t and em walk ) , gait speed ( 2-meter walk ) , and cardiovascular endurance ( 6-minute walk ) . RESULTS 70 participants ( 97 % ) completed the 6-month trial . Compliance with study interventions within each group ranged from 75 % in controls to 82 % in exercisers . PPT increased by 6.1 + /- 13.4 % in exercisers and decreased by 2.8 + /- 13.6 % in controls ( p = .02 ) . EPESE improved by 26.2 + /- 37.5 % in exercisers and decreased by 1.2 + /- 22.1 % in controls ( p = .001 ) . Dynamic balance improved by 33.8 + /- 14.4 % in exercisers versus 11.5 + /- 23.7 % in controls ( p = .0002 ) . There were no differences between groups in the change in strength , gait speed , or cardiovascular endurance . CONCLUSIONS Minimally supervised exercise is safe and can improve functional performance  in elderly individuals . The improvements in functional performance occurred along with improvements in balance but without a significant change in muscle strength or endurance BACKGROUND Identification of the physiologic factors most relevant to functional independence in the elderly population is critical for the design of effective interventions . It has been suggested that muscle power may be more directly related to impaired physical performance than muscle strength in elderly persons . We tested the hypothesis that peak muscle power is closely associated with self-reported functional status in sedentary elderly community-dwelling women . METHODS We used baseline data that were collected as part of a 1-year r and omized controlled clinical trial of a combined program of strength , power , and endurance training in 80 elderly women ( mean age 74.8 + /- 5.0 years ) with 3.2 + /- 1.9 chronic diseases , selected for baseline functional impairment and /or falls . RESULTS Functional status at baseline was related in univariate analyses to physiologic capacity , habitual physical activity level , neuropsychological status , and medical diagnoses . Leg power had the strongest univariate correlation to self-reported functional status ( r = -.47 , p < .0001 ) of any of the physiologic factors we tested . In a forward stepwise regression model , leg press power and habitual physical activity level were the only two factors that contributed independently to functional status ( r = .6 
    Output:
    
agent
Overall , home-based resistance exercise  can improve both strength and functional ability , but the improvements are generally small .
The intensity of the exercises might not progress sufficiently enough to produce large improvements in strength as a result of less supervision or a lack of motivation to increase the intensity further
***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: Muscle mass decreases with age , leading to " sarcopenia , " or low relative muscle mass , in elderly people . Sarcopenia is believed to be associated with metabolic , physiologic , and functional impairments and disability . Methods of estimating the prevalence of sarcopenia and its associated risks in elderly population s are lacking . Data from a  population -based survey of 883 elderly Hispanic and non-Hispanic white men and women living in New Mexico ( the New Mexico Elder Health Survey , 1993 - 1995 ) were analyzed to develop a method for estimating the prevalence of sarcopenia . An anthropometric equation for predicting appendicular skeletal muscle mass was developed from a r and om sub sample ( n = 199 ) of participants and was extended to the total sample . Sarcopenia was defined as appendicular skeletal muscle mass (kg)/height2 ( m2 ) being less than two st and ard deviations below the mean of a young reference group . Prevalences increased from 13 - 24 % in persons under 70 years of age to > 50 % in persons over 80 years of age , and were slightly greater in Hispanics than in non-Hispanic whites . Sarcopenia was significantly associated with self-reported physical disability in both men and women , independent of ethnicity , age , morbidity , obesity , income , and health behaviors . This study provides some of the first estimates of the extent of the public health problem posed by sarcopenia Previous studies have shown that low-intensity resistance training with restricted muscular venous blood flow ( Kaatsu ) causes muscle hypertrophy and strength gain . To investigate the effects of daily physical activity combined with Kaatsu , we examined the acute and chronic effects of walk training with and without Kaatsu on MRI-measured muscle size and maximum dynamic ( one repetition maximum ) and isometric strength , along with blood hormonal parameters . Nine men performed Kaatsu-walk training , and nine men performed walk training alone ( control-walk ) . Training was conducted two times a day , 6 days/wk , for 3 wk using five sets of 2-min bouts ( treadmill speed at 50 m/min ) , with a 1-min rest between bouts .  Mean oxygen uptake during Kaatsu-walk and control-walk exercise was 19.5 ( SD 3.6 ) and 17.2 % ( SD 3.1 ) of treadmill-determined maximum oxygen uptake , respectively . Serum growth hormone was elevated ( P < 0.01 ) after acute Kaatsu-walk exercise but not in control-walk exercise .  MRI-measured thigh muscle cross-sectional area and muscle volume increased by 4 - 7 % , and one repetition maximum and maximum isometric strength increased by 8 - 10 % in the Kaatsu-walk group . There was no change in muscle size and dynamic and isometric strength in the control-walk group . Indicators of muscle damage ( creatine kinase and myoglobin ) and resting anabolic hormones did not change in both groups . The results suggest that the combination of leg muscle blood flow restriction with slow-walk training induces muscle hypertrophy and strength gain , despite the minimal level of exercise intensity . Kaatsu-walk training may be a potentially useful method for promoting muscle hypertrophy , covering a wide range of the population , including the frail and elderly Background We aim ed to determine the effect of resistance exercise intensity ( % 1 repetition maximum—1RM ) and volume on muscle protein synthesis , anabolic signaling , and myogenic gene expression . Methodology /Principal Findings Fifteen men ( 21±1 years ; BMI = 24.1±0.8 kg/m2 ) performed 4 sets of unilateral leg extension exercise at different exercise loads and /or volumes : 90 % of repetition maximum ( 1RM ) until volitional failure ( 90FAIL ) , 30 % 1RM work-matched to 90%FAIL ( 30WM ) , or 30 % 1RM performed until volitional failure ( 30FAIL ) . Infusion of [ ring-13C6 ] phenylalanine with biopsies was used to measure rates of mixed ( MIX ) , myofibrillar ( MYO ) , and sarcoplasmic ( SARC ) protein synthesis at rest , and 4 h and 24 h after exercise . Exercise at 30WM induced a significant increase above rest in MIX ( 121 % ) and MYO ( 87 % ) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only . The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM , with no difference between these conditions ; however , MYO remained elevated ( 199 % ) above rest at 24 h only in 30FAIL . There was a significant increase in AktSer473 at 24h in all conditions ( P = 0.023 ) and mTORSer2448 phosphorylation at 4 h post-exercise ( P = 0.025 ) . Phosporylation of Erk1/2Tyr202/204 , p70S6KThr389 , and 4E-BP1Thr37/46 increased significantly ( P<0.05 ) only in the 30FAIL condition at 4 h post-exercise , whereas , 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL ( 237 % ) and 30FAIL ( 312 % ) conditions . Pax7 mRNA expression increased at 24 h post-exercise ( P = 0.02 ) regardless of condition . The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition . Conclusions / Significance These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes This study identified factors associated with exercise participation  and  adherence  in a sample of 102 sedentary , functionally limited , community-dwelling adults aged 60 to 94 years who participated in a home-based resistance training program .  Stepwise regression analyses revealed that baseline physical factors ( i.e. , higher levels of mobility , weaker muscle strength , and fewer numbers of new medical conditions ) were associated with higher rates of participation in the home program .  Positive attitudes and a sense of control toward exercise , lower levels of confusion and depressive moods , and the development of fewer new medical problems during the program were related to higher levels of adherence to the program . Findings revealed that although physical health variables were the primary indicators of an older person 's overall participation in the program , it was the psychological factors that were most important to adherence to this home-based program OBJECTIVES To assess the extent to which physical activity and leg strength are associated with change in mobility  in older persons . DESIGN Prospect i ve , observational cohort study . SETTING Retirement communities across the Chicago metropolitan area participating in the Rush Memory and Aging Project . PARTICIPANTS Eight hundred eighty-six ambulatory older persons without dementia . MEASUREMENT Rate of change in mobility . RESULTS In a linear mixed-effects model that controlled for age , sex , education , and a term for baseline physical activity , a higher level of physical activity was associated with a slower rate of mobility decline ( estimate=0.006 , st and ard error (SE)=0.003 , P=.03 ) ; each additional hour of physical activity at baseline was associated with an approximately 3 % decrease in the rate of mobility decline . In a similar model , a higher level of baseline leg strength was associated with a slower rate of mobility decline ( estimate=0.031 , SE=0.132 , P=.02 ) ; each additional unit of leg strength at baseline was associated with an approximately 20 % decrease in the rate of mobility decline . In a final model , which included terms for physical activity and leg strength together , both were associated with decline in mobility . Furthermore , both remained associated with mobility even after controlling for body composition , balance , pulmonary function , cognition , history of joint pain , cardiovascular diseases and risk factors , and medications . CONCLUSION Physical activity and leg strength are relatively independent predictors of mobility decline  in older persons . Although physical activity may improve strength , the beneficial effect of physical activity on mobility is likely to involve other pathways We have reported that the acute postexercise increases in muscle protein synthesis rates , with differing nutritional support , are predictive of longer-term training-induced muscle hypertrophy . Here , we aim ed to test whether the same was true with acute exercise-mediated changes in muscle protein synthesis . Eighteen men ( 21 ± 1 yr , 22.6 ± 2.1 kg/m(2 ) ; means ± SE ) had their legs r and omly assigned to two of three training conditions that differed in contraction intensity [ % of maximal strength ( 1 repetition maximum ) ] or contraction volume ( 1 or 3 sets of repetitions ) : 30%-3 , 80%-1 , and 80%-3 . Subjects trained each leg with their assigned regime for a period of 10 wk , 3 times/wk . We made pre- and posttraining measures of strength , muscle volume by magnetic resonance ( MR ) scans , as well as pre- and posttraining biopsies of the vastus lateralis , and a single postexercise ( 1 h ) biopsy following the first bout of exercise , to measure signaling proteins . Training-induced increases in MR-measured muscle volume were significant ( P < 0.01 ) , with no difference between groups : 30%-3 = 6.8 ± 1.8 % , 80%-1 = 3.2 ± 0.8 % , and 80%-3= 7.2 ± 1.9 % , P = 0.18 . Isotonic maximal strength gains were not different between 80%-1 and 80%-3 , but were greater than 30%-3 ( P = 0.04 ) , whereas training-induced isometric strength gains were significant but not different between conditions ( P = 0.92 ) . Biopsies taken 1 h following the initial resistance exercise bout showed increased phosphorylation ( P < 0.05 ) of p70S6 K only in the 80%-1 and 80%-3 conditions . There was no correlation between phosphorylation of any signaling protein and hypertrophy . In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure result ed in similar hypertrophy as a heavy load lifted to failure BACKGROUND This study tested the hypothesis that a home-based exercise program would improve functional performance in elderly people . METHODS We conducted a 6-month , single-blinded , r and omized controlled trial . 72 community dwelling men and women ( aged > /=70 years ) with self-reported and laboratory-based functional impairment were recruited for the study . Participants were r and omly assigned to either a home-based progressive strength , balance , and general physical activity intervention or an attention-control group that received home-based nutrition education .  Functional performance was measured in the laboratory using the Physical Performance Test ( PPT ) and the Established Population s for Epidemiologic Studies of the Elderly ( EPESE ) short physical performance battery . Physiologic capacity was measured by strength ( one repetition maximum ) , dynamic balance ( t and em walk ) , gait speed ( 2-meter walk ) , and cardiovascular endurance ( 6-minute walk ) . RESULTS 70 participants ( 97 % ) completed the 6-month trial . Compliance with study interventions within each group ranged from 75 % in controls to 82 % in exercisers . PPT increased by 6.1 + /- 13.4 % in exercisers and decreased by 2.8 + /- 13.6 % in controls ( p = .02 ) . EPESE improved by 26.2 + /- 37.5 % in exercisers and decreased by 1.2 + /- 22.1 % in controls ( p = .001 ) . Dynamic balance improved by 33.8 + /- 14.4 % in exercisers versus 11.5 + /- 23.7 % in controls ( p = .0002 ) . There were no differences between groups in the change in strength , gait speed , or cardiovascular endurance . CONCLUSIONS Minimally supervised exercise is safe and can improve functional performance  in elderly individuals . The improvements in functional performance occurred along with improvements in balance but without a significant change in muscle strength or endurance BACKGROUND Identification of the physiologic factors most relevant to functional independence in the elderly population is critical for the design of effective interventions . It has been suggested that muscle power may be more directly related to impaired physical performance than muscle strength in elderly persons . We tested the hypothesis that peak muscle power is closely associated with self-reported functional status in sedentary elderly community-dwelling women . METHODS We used baseline data that were collected as part of a 1-year r and omized controlled clinical trial of a combined program of strength , power , and endurance training in 80 elderly women ( mean age 74.8 + /- 5.0 years ) with 3.2 + /- 1.9 chronic diseases , selected for baseline functional impairment and /or falls . RESULTS Functional status at baseline was related in univariate analyses to physiologic capacity , habitual physical activity level , neuropsychological status , and medical diagnoses . Leg power had the strongest univariate correlation to self-reported functional status ( r = -.47 , p < .0001 ) of any of the physiologic factors we tested . In a forward stepwise regression model , leg press power and habitual physical activity level were the only two factors that contributed independently to functional status ( r = .6 
    Output:
    