***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: Biopsy sample s were taken from the vastus lateralis of 18- to 84-yr-old male sprinters ( n = 91 ) . Fiber-type distribution , cross-sectional area , and myosin heavy chain ( MHC ) isoform content were identified using ATPase histochemistry and SDS-PAGE . Specific tension and maximum shortening velocity ( V(o ) ) were determined in 144 single skinned fibers from younger ( 18 - 33 yr , n = 8) and older ( 53 - 77 yr , n = 9 ) runners .  Force-time characteristics of the knee extensors were determined by using isometric contraction . The cross-sectional area of type I fibers was unchanged with age , whereas that of type II fibers was reduced ( P < 0.001 ) . With age there was an increased MHC I ( P < 0.01 ) and reduced MHC IIx isoform content ( P < 0.05 ) but no differences in MHC IIa . Specific tension of type I and IIa MHC fibers did not differ between younger and older subjects . V(o ) of fibers expressing type I MHC was lower ( P < 0.05 ) in older than in younger subjects , but there was no difference in V(o ) of type IIa MHC fibers . An aging-related decline of maximal isometric force ( P < 0.001 ) and normalized rate of force development ( P < 0.05 ) of knee extensors was observed . Normalized rate of force development was positively associated with MHC II ( P < 0.05 ) . The sprint-trained athletes experienced the typical aging-related reduction in the size of fast fibers , a shift toward a slower MHC isoform profile , and a lower V(o ) of type I MHC fibers , which played a role in the decline in explosive force production . However , the muscle characteristics were preserved at a high level in the oldest runners , underlining the favorable impact of sprint exercise on aging muscle Using a meta-analytic approach , we recently reported that the rate of decline in maximal oxygen uptake ( VO2 max ) with age in healthy women is greatest in the most physically active and smallest in the least active when expressed in milliliters per kilogram per minute per decade . We tested this hypothesis prospect ively under well-controlled laboratory conditions by study ing 156 healthy , nonobese women ( age 20 - 75 yr ) : 84 endurance-trained runners ( ET ) and 72 sedentary subjects ( S ) . ET were matched across the age range for age-adjusted 10-km running performance . Body mass was positively related with age in S but not in ET . Fat-free mass was not different with age in ET or S. Maximal respiratory exchange ratio and rating of perceived exertion were similar across age in ET and S , suggesting equivalent voluntary maximal efforts . There was a significant but modest decline in running mileage , frequency , and speed with advancing age in ET . VO2 max ( ml . kg-1 . min-1 ) was inversely related to age ( P < 0.001 ) in ET ( r = -0.82 ) and S ( r = -0.71 ) and was higher at any age in ET . Consistent with our meta-analysic findings , the absolute rate of decline in VO2 max was greater in ET ( -5.7 ml . kg-1 . min-1 . decade-1 ) compared with S ( -3.2 ml . kg-1 . min-1 . decade-1 ; P < 0 . 01 ) , but the relative ( % ) rate of decline was similar ( -9.7 vs -9 . 1%/decade ; not significant ) . The greater absolute rate of decline in VO2 max in ET compared with S was not associated with a greater rate of decline in maximal heart rate ( -5.6 vs. -6.2 beats . min-1 . decade-1 ) , nor was it related to training factors . The present cross-sectional findings provide additional evidence that the absolute , but not the relative , rate of decline in maximal aerobic capacity with age may be greater in highly physically active women compared with their sedentary healthy peers . This difference does not appear to be related to age-associated changes in maximal heart rate , body composition , or training factors Abstract The purpose of this study was to investigate the time course of skeletal muscle adaptations result ing from high-intensity , upper and lower body dynamic resistance training ( WT ) .  A group of 17 men and 20 women were recruited for WT , and 6 men and 7 women served as a control group . The WT group performed six dynamic resistance exercises to fatigue using 8–12 repetition maximum ( RM ) . The subjects trained 3 days a week for 12 weeks . One-RM knee extension ( KE ) and chest press ( CP ) exercises were measured at baseline and at weeks 2 , 4 , 6 , 8 , and 12 for the WT group . Muscle thickness ( MTH ) was measured by ultrasound at eight anatomical sites . One-RM CP and KE strength had increased significantly at week 4 for the female WT group . For the men in the WT group , 1 RM had increased significantly at week 2 for KE and at week 6 for CP . The mean relative increases in KE and CP strength were 19 % and 19 % for the men and 19 % and 27 % for the women , respectively , after 12 weeks of WT . Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes . There were non-significant trends for increases in quadriceps MTH for the WT groups . The relative increases in upper and lower body MTH were 12%–21 % and 7%–9 % in the men and 10%–31 % and 7%–8 % in the women respectively , after 12 weeks of WT . These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity , during the first 12 weeks of a total body WT programme . The time-course and proportions of the increase in strength and MTH were similar for both the men and the women Ageing has been proposed to be associated with increased levels of reactive oxygen species ( ROS ) that scavenge nitric oxide ( NO ) . In eight young sedentary ( 23 ± 1 years ; Y ) , eight older lifelong sedentary ( 66 ± 2 years ; OS ) and eight older lifelong physically active subjects ( 62 ± 2 years ; OA ) , we studied the effect of ROS on systemic and skeletal muscle NO bioavailability and leg blood flow by infusion of the antioxidant N-acetylcysteine ( NAC ) . Infusion of NAC  increased the bioavailability of NO in OS , as evidence d by an increased concentration of stable metabolites of NO ( NOx ) in the arterial and venous circulation and in the muscle interstitium . In OA , infusion of NAC only increased NOx concentrations in venous plasma whereas in Y , infusion of NAC did not affect NOx concentrations . Skeletal muscle protein levels of endothelial and neuronal NO synthase were 32 % and 24 % higher , respectively , in OA than in OS . Exercise at 12 W elicited a lower leg blood flow response that was associated with a lower leg oxygen uptake in OS than in Y. The improved bioavailability of NO in OS did not increase blood flow during exercise . These data demonstrate that NO bioavailability is compromised in the systemic circulation and in the musculature of sedentary ageing humans due to increased oxidative stress . Lifelong physical activity opposes this effect within the trained musculature and in the arterial circulation . The lower blood flow response to leg exercise in ageing humans is not associated with a reduced NO bioavailability PURPOSE Exercise-induced hypoxemia in highly trained athletes is associated with an increase in histamine release during exercise . The cells most implicated in blood histamine release are basophils . The aim of this study was to determine whether high-level endurance training induces modifications in histamine releasability from human basophils . METHODS Seven young highly trained athletes ( YA ) [ aged 26.1+/-1.3 yr ( mean + /- SEM ) ] and seven master athletes ( MA ) ( 64.4+/-4.1 yr ) , all known to develop exercise-induced hypoxemia , were respectively compared with seven young untrained men ( YC ) ( 23.0+/-1.5 yr ) and seven older untrained men ( OC ) ( 61.6+/-1.3 yr ) . During an incremental exhaustive exercise , blood sample s for measurement of anti-IgE-induced histamine release from leukocytes were drawn at rest , VO2max , and recovery . RESULTS Basophils from " leukocyte-rich " supernatant in YA and MA showed significantly higher histamine release induced by anti-IgE ( 1 microg x mL(-1 ) than , respectively , YC ( P<0.01 ) and OC ( P<0.05 ) at rest , VO2ax ( P<0.01 ) , and recovery ( P<0.01 ) . Basophils in YA and MA also showed a histamine release induced by anti-IgE that was higher at VO2max than at rest ( respectively . P<0.01 and P<0.05 ) , but this change was not found in the control groups . CONCLUSION In conclusion , the basophils in highly trained endurance athletes , both young and older , showed higher anti-IgE-induced histamine release than those of untrained men . This effect of high-level training seemed to be potentiated by exercise The histologic features of aging muscle suggest that denervation contributes to atrophy , that immobility accelerates the process , and that routine exercise may protect against loss of motor units and muscle tissue . Here , we compared muscle biopsies from sedentary and physically active seniors and found that seniors with a long history of high-level recreational activity up to the time of muscle biopsy had 1 ) lower loss of muscle strength versus young men ( 32 % loss in physically active vs 51 % loss in sedentary seniors ) ; 2 ) fewer small angulated ( denervated ) myofibers ; 3 ) a higher percentage of fiber-type groups ( reinnervated muscle fibers ) that were almost exclusive of the slow type ; and 4 ) sparse normal-size muscle fibers coexpressing fast and slow myosin heavy chains , which is not compatible with exercise-driven muscle-type transformation . The biopsies from the old physically active seniors varied from sparse fiber-type groupings to almost fully transformed muscle , suggesting that coexpressing fibers appear to fill gaps . Altogether , the data show that long-term physical activity promotes reinnervation of muscle fibers and suggest that decades of high-level exercise allow the body to adapt to age-related denervation by saving otherwise lost muscle fibers through selective recruitment to slow motor units . These effects on size and structure of myofibers may delay functional decline in late aging Objectives To explore the extent to which muscular strength in adolescence is associated with all cause and cause specific premature mortality ( < 55 years ) . Design Prospect i ve cohort study . Setting Sweden . Participants 1 142 599 Swedish male adolescents aged 16 - 19 years were followed over a period of 24 years . Main outcome measures Baseline examinations included  knee extension , h and grip , and elbow flexion strength tests  , as well as measures of  diastolic and systolic blood pressure and body mass index . Cox regression was used to estimate hazard ratios for mortality according to muscular strength categories ( tenths ) . Results During a median follow-up period of 24 years , 26 145 participants died . Suicide was a more frequent cause of death in young adulthood ( 22.3 % ) than was cardiovascular diseases ( 7.8 % ) or cancer ( 14.9 % ) . High muscular strength in adolescence , as assessed by knee extension and h and grip tests , was associated with a 20 - 35 % lower risk of premature mortality due to any cause or cardiovascular disease , independently of body mass index or blood pressure ; no association was observed with mortality due to cancer . Stronger adolescents had a 20 - 30 % lower risk of death from suicide and were 15 - 65 % less likely to have any psychiatric diagnosis ( such as schizophrenia and mood disorders ) . Adolescents in the lowest tenth of muscular strength showed by far the highest risk of mortality for different causes . All cause mortality rates ( per 100 000 person years ) ranged between 122.3 and 86.9 for the weakest and strongest adolescents ; corresponding figures were 9.5 and 5.6 for mortality due to cardiovascular diseases and 24.6 and 16.9 for mortality due to suicide . Conclusions Low muscular strength in adolescents is an emerging risk factor for major causes of death in young adulthood , such as suicide and cardiovascular diseases . The effect size observed for all cause mortality was equivalent to that for well established risk factors such as elevated body mass index or blood pressure AIM Regular exercise is a key component of cardiovascular risk prevention strategies , because it is associated with a variety of beneficial metabolic and vascular effects that reduce mortality and the incidence of cardiovascular adverse events . Endothelium plays an important role in the local regulation of vascular tone and structure , mainly by nitric oxide ( NO ) synthesis and action . Aim of the present study was to evaluate in elderly athletes the effect of regular aerobic exercise on arterial blood pressure ( BP ) and on endothelium-dependent flow-mediated dilation ( FMD ) of the brachial artery . METHODS The study population included 30 male subjects ( mean age 65.6+/-5.6 years ) , 
    Output:
    
Despite advancing age , this review suggests that chronic exercise training  preserves physical function , muscular strength and body fat levels similar to that of young , healthy individuals in an exercise mode-specific manner