***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: We determined myofibrillar and mitochondrial protein fractional synthesis rates ( FSR ) , intramuscular signaling protein phosphorylation , and mRNA expression responses after isolated bouts of resistance exercise ( RE ) , aerobic exercise ( AE ) , or in combination [ termed concurrent exercise ( CE ) ] in sedentary middle-aged men . Eight subjects ( age = 53.3 ± 1.8 yr ; body mass index = 29.4 ± 1.4 kg·m(2 ) ) r and omly completed 8 × 8 leg extension repetitions at 70 % of one repetition-maximum , 40 min of cycling at 55 % peak aerobic power output ( AE ) , or ( consecutively ) 50 % of the RE and AE trials ( CE ) . Biopsies were obtained ( during a primed , constant infusion of l-[ring-(13)C(6)]phenylalanine ) while fasted , and at 1 and 4 h following postexercise ingestion of 20 g of protein . All trials increased mitochondrial FSR above fasted rates ( RE = 1.3-fold ; AE = 1.5 ; CE = 1.4 ; P < 0.05 ) , although only CE ( 2.2 ) and RE ( 1.8 ) increased myofibrillar FSR ( P < 0.05 ) . At 1 h postexercise , phosphorylation of Akt on Ser(473 ) ( CE = 7.7 ; RE = 4.6 ) and Thr(308 ) ( CE = 4.4 ; RE = 2.9 ) , and PRAS40 on Thr(246 ) ( CE = 3.8 ; AE = 2.5 ) increased ( P < 0.05 ) , with CE greater than AE for Akt Ser(473)-Thr(308 ) and greater than RE for PRAS40 ( P < 0.05 ) . Despite increased phosphorylation of Akt-PRAS40 , phosphorylation of mammalian target of rapamycin ( Ser(2448 ) ) remained unchanged ( P > 0.05 ) , while rpS6 ( Ser(235/236 ) ) increased only in RE ( 10.4 ) ( P < 0.05 ) . CE and AE both result ed in increased peroxisome proliferator receptor-γ coactivator 1-α ( PGC1α ) expression at 1 h ( CE = 2.9 ; AE = 2.8 ; P < 0.05 ) and 4 h ( CE = 2.6 ; AE = 2.4 ) and PGC1β expression at 4 h ( CE = 2.1 ; AE = 2.6 ; P < 0.05 ) . These data suggest that CE-induced acute stimulation of myofibrillar and mitochondrial FSR , protein signaling , and mRNA expression are equivalent to either isolate mode ( RE or AE ) . These results occurred without an interference effect on muscle protein subfractional synthesis rates , protein signaling , or mRNA expression This study was design ed to evaluate the effects of enriching an essential amino acid ( EAA ) mixture with leucine on muscle protein metabolism in elderly and young individuals . Four ( 2 elderly and 2 young ) groups were studied before and after ingestion of 6.7 g of EAAs . EAAs were based on the composition of whey protein [ 26 % leucine ( 26 % Leu ) ] or were enriched in leucine [ 41 % leucine ( 41 % Leu ) ] . A primed , continuous infusion of L-[ring-2H5]phenylalanine was used together with vastus lateralis muscle biopsies and leg arteriovenous blood sample s for the determinations of fractional synthetic rate ( FSR ) and balance of muscle protein . FSR increased following amino acid ingestion in both the 26 % ( basal : 0.048 + /- 0.005%/h ; post-EAA : 0.063 + /- 0.007%/h ) and the 41 % ( basal : 0.036 + /- 0.004%/h ; post-EAA : 0.051 + /- 0.007%/h ) Leu young groups ( P < 0.05 ) . In contrast , in the elderly , FSR did not increase following ingestion of 26 % Leu EAA ( basal : 0.044 + /- 0.003%/h ; post-EAA : 0.049 + /- 0.006%/h ; P > 0.05 ) but did increase following ingestion of 41 % Leu EAA ( basal : 0.038 + /- 0.007%/h ; post-EAA : 0.056 + /- 0.008%/h ; P < 0.05 ) . Similar to the FSR responses , the mean response of muscle phenylalanine net balance , a reflection of muscle protein balance , was improved ( P < 0.05 ) in all groups , with the exception of the 26 % Leu elderly group . We conclude that increasing the proportion of leucine in a mixture of EAA can reverse an attenuated response of muscle protein synthesis in elderly but does not result in further stimulation of muscle protein synthesis in young subjects Objectives To examine associations between sarcopenia , obesity , and sarcopenic obesity and risk of cardiovascular disease ( CVD ) and all-cause mortality in older men . Design Prospect i ve cohort study . Setting British Regional Heart Study . Participants Men aged 60–79 years ( n = 4,252 ) . Measurements Baseline waist circumference ( WC ) and midarm muscle circumference ( MAMC ) measurements  were used to classify participants into four groups : sarcopenic , obese , sarcopenic obese , or optimal WC and MAMC . The cohort was followed for a mean of 11.3 years for CVD and all-cause mortality . Cox regression analyses assessed associations between sarcopenic obesity groups and all-cause mortality , CVD mortality , CVD events , and coronary heart disease ( CHD ) events . Results There were 1,314 deaths , 518 CVD deaths , 852 CVD events , and 458 CHD events during follow-up . All-cause mortality risk was significantly greater in sarcopenic ( HR = 1.41 , 95 % CI = 1.22–1.63 ) and obese ( HR = 1.21 , 95 % CI = 1.03–1.42 ) men than in the optimal reference group , with the highest risk in sarcopenic obese ( HR = 1.72 , 95 % CI = 1.35–2.18 ) , after adjustment for lifestyle characteristics . Risk of CVD mortality was significantly greater in sarcopenic and obese but not sarcopenic obese men . No association was seen between sarcopenic obesity groups and CHD or CVD events . Conclusion Sarcopenia and central adiposity were associated with greater cardiovascular mortality and all-cause mortality . Sarcopenic obese men had the highest risk of all-cause mortality but not CVD mortality . Efforts to promote healthy aging should focus on preventing obesity and maintaining muscle mass 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 We recently demonstrated that muscle protein synthesis was stimulated to a similar extent in young and elderly subjects during a 3-h amino acid infusion . We sought to determine if a more practical bolus oral ingestion would also produce a similar response in young ( 34 + /- 4 yr ) and elderly ( 67 + /- 2 yr ) individuals . Arteriovenous blood sample s and muscle biopsies were obtained during a primed ( 2.0 micromol/kg ) constant infusion ( 0.05 micromol.kg(-1).min(-1 ) ) of L-[ring-2H5]phenylalanine .  Muscle protein kinetics and mixed muscle fractional synthetic rate ( FSR ) were calculated before and after the bolus ingestion of 15 g of essential amino acids ( EAA ) in young ( n = 6 ) and elderly ( n = 7 ) subjects . After EAA ingestion , the rate of increase in femoral artery phenylalanine concentration was slower in elderly subjects but remained elevated for a longer period . EAA ingestion increased FSR in both age groups by approximately 0.04%/h ( P < 0.05 ) . However , muscle intracellular ( IC ) phenylalanine concentration remained significantly higher in elderly subjects at the completion of the study ( young : 115.6 + /- 5.4 nmol/ml ; elderly : 150.2 + /- 19.4 nmol/ml ) . Correction for the free phenylalanine retained in the muscle IC pool result ed in similar net phenylalanine uptake values in the young and elderly . EAA ingestion increased plasma insulin levels in young ( 6.1 + /- 1.2 to 21.3 + /- 3.1 microIU/ml ) but not in elderly subjects ( 3.0 + /- 0.6 to 4.3 + /- 0.4 microIU/ml ) . Despite differences in the time course of plasma phenylalanine kinetics and a greater residual IC phenylalanine concentration , amino acid supplementation acutely stimulated muscle protein synthesis in both young and elderly individuals The ability to maintain skeletal muscle mass appears to be impaired in insulin-resistant conditions , such as type 2 diabetes , that are characterized by muscle lipid accumulation . The current study investigated the effect of acutely increasing lipid availability on muscle protein synthesis .  Seven healthy young male volunteers underwent a 7-h intravenous infusion of l-[ring-2H5]phenylalanine on two r and omized occasions combined with 0.9 % saline or 10 % Intralipid at 100 mL/h . After a 4-h “ basal ” period , a 21-g bolus of amino acids was administered and a 3-h hyperinsulinemic-euglycemic clamp was commenced ( “ fed ” period ) . Muscle biopsy specimens were obtained from the vastus lateralis at 1.5 , 4 , and 7 h. Lipid infusion reduced fed whole-body glucose disposal by 20 % . Furthermore , whereas the mixed muscle fractional synthetic rate increased from the basal to the fed period during saline infusion by 2.2-fold , no change occurred during lipid infusion , despite similar circulating insulin and leucine concentrations . This “ anabolic resistance ” to insulin and amino acids with lipid infusion was associated with a complete suppression of muscle 4E-BP1 phosphorylation . We propose that increased muscle lipid availability may contribute to anabolic resistance in insulin-resistant conditions by impairing translation initiation Maximizing anabolic responses to feeding and exercise is crucial for muscle maintenance and adaptation to exercise training . We hypothesized that enriching a protein drink with leucine would improve anabolic responses to resistance exercise ( RE : 6 × 8 knee-extension repetitions at 75 % of 1-RM ) in both young and older adults . Groups ( n = 9 ) of young ( 24 ± 6 y , BMI 23 ± 2 kg m-2 ) and older men ( 70 ± 5 y , BMI 25 ± 2 kg m-2 ) were r and omized to either : ( i ) RE followed by Slim-Fast Optima ( SFO 10 g PRO ; 24 g CHO ) with 4.2 g of leucine ( LEU ) or , ( ii ) RE + SFO with 4.2 g of alanine ( ALA ; isonitrogenous control ) . Muscle biopsies were taken before , immediately after , and 1 , 2 and 4 h after RE and feeding . Muscle protein synthesis ( MPS ) was measured by incorporation of [ 1 , 2 - 13C2 ] leucine into myofibrillar proteins and the phosphorylation of p70S6K1 by immunoblotting . In young men , both area under the curve ( AUC ; FSR 0 - 4 h P < 0.05 ) and peak FSR ( 0. 
    Output:
    
Our results highlight that optimization of exercise and amino acid-based nutrition is sufficient to induce a comparable MPS response between young and older individuals .
However , the exercise volume completed and /or the amino acid/protein dose and leucine content must exceed a certain threshold to stimulate equivalent MPS rates in young and older adults , below which age-related muscle anabolic resistance may become apparent