Leg Muscle Mass Research Articles

Intermittent Claudication: New Targets for Drug Development

Peripheral artery disease (PAD) is the result of extensive atherosclerosis in the arterial supply to the lower extremities. PAD is associated with increased systemic cardiovascular morbidity and mortality as well as substantial disability due to walking impairment. Claudication is the classic symptom of leg pain with walking that is relieved by rest, but patients with PAD without typical claudication also have a walking limitation. Treatment of the patient with PAD is directed towards reducing cardiovascular risk and improving exercise capacity. The pathophysiology of the physical impairment is complex as changes in the muscle distal to the arterial stenoses contribute to the limitations. Current treatment options to improve exercise performance have limitations emphasizing the need for new pharmacotherapies for this highly prevalent condition. The multifactorial contributors to the exercise impairment in PAD suggest potential targets for novel drug therapies. Advances in understanding angiogenesis make pharmacologic revascularization possible. However, ensuring that new blood vessels develop in a distribution relevant to the clinical impairment remains a challenge. Skeletal muscle metabolism and its regulation are altered in patients with PAD and strategies to improve the efficient oxidation of fuel substrates may improve muscle function. PAD is associated with increased oxidative stress which may result in injury to the muscle microvasculature and myocyte. Minimizing this oxidative stress by enhancing cellular defense mechanisms, administration of anti-inflammatory agents or by providing antioxidants, could prevent oxidative injury. Given the central role of atherosclerosis in the flow limitation, therapies to induce regression of atherosclerotic lesions could result in improved blood flow and oxygen delivery. Drugs targeting the distribution of blood flow in the microcirculatory environment of the muscle have the potential to better match oxygen delivery with working myocytes. The physical disability and flow limitations contribute to a loss of leg muscle mass in patients with PAD. Drugs to increase muscle mass and strength could enhance walking ability in these patients. Pharmacotherapies that recapitulate the muscle adaptations induced by preconditioning may result in improved physical performance in patients with PAD. Adjunctive therapies combined with exercise training or revascularization may be important given the complexity of integrative muscle function and the multiple pathologic changes induced by PAD. New research into the pathophysiology of the physical impairment associated with PAD has identified potential new targets for drug therapy, and will likely continue to do so in the years to come. Translation of these opportunities into effective therapeutics will be important as the already high prevalence of PAD is expected to increase as the population ages.

LEG muscle mass and foot pain, structure and function: the Johnston County Osteoarthritis Project

LEG muscle mass and foot pain, structure and function: the Johnston County Osteoarthritis Project

Low appendicular skeletal muscle mass (ASM) with limited mobility and poor health outcomes in middle‐aged African Americans

BackgroundRecent efforts to provide a consensus definition propose that sarcopenia be considered a clinical syndrome associated with the loss of both skeletal muscle mass and muscle function that occurs with aging. Validation of sarcopenia definitions that include both low muscle mass and poor muscle function is needed.MethodsIn the population-based African American Health (AAH) study (N = 998 at baseline/wave 1), muscle mass and mobility were evaluated in a clinical testing center in a subsample of N = 319 persons (ages 52–68) at wave 4 (2004). Muscle mass was measured using dual energy x-ray absorptiometry and mobility by a 6-min walk test and 4-m gait walk test. Height corrected appendicular skeletal mass (ASM; 9.0 ± 1.5 in n = 124 males, 8.3 ± 2.2 in n = 195 females) was computed as total lean muscle mass in arms and legs (kilograms) divided by the square of height (meters). Cross-sectional and longitudinal (6-year) associations of low ASM (bottom 25 % AAH sample; <7.96 males and <7.06 females) and low ASM with limited mobility (4-m gait walk ≤1 m/s or 6-min walk <400 m) were examined for basic activities of daily living (ADL) difficulties, instrumental activities of daily living (IADL) difficulties, frailty, falls, and mortality (longitudinal only).ResultsLow ASM with limited mobility was associated with IADL difficulties (p = .008) and frailty (p = .040) but not with ADL difficulties or falls in cross-sectional analyses; and with ADL difficulties (p = .022), IADL difficulties (p = .006), frailty (p = .039), and mortality (p = .003) but not with falls in longitudinal analyses adjusted for age and gender. Low ASM alone was marginally associated with mortality (p = .085) but not with other outcomes in cross-sectional or longitudinal analyses.ConclusionLow ASM with limited mobility is associated with poor health outcomes among late middle-aged African Americans.

Thigh muscle attenuation measured by computed tomography was associated with the risk of low bone density in community‐dwelling elderly population

Although muscle mass has been shown to be positively related with bone mineral density (BMD), there are only a few studies that investigated the association between muscle strength or muscle quality and BMD. We investigated the effects of muscle strength and muscle fat infiltration, as a measure of muscle quality, adjusted for muscle mass on femoral neck BMD in Korean elderly cohort. We recruited 242 men and 231 women aged over 65 years who participated in the Korean Longitudinal Study on Health and Ageing. Leg muscle mass and femoral neck BMD were measured by dual-energy X-ray absorptiometry. Isokinetic strength of knee extensors was measured as a peak torque value by an isokinetic device. Computed tomography scan of the mid-thigh measured the mean Hounsfield unit (HU) of the lean tissue. Low bone density was defined as femoral neck T-score ≤-2·0. Leg muscle mass, knee extensor strength and thigh muscle HU values were significantly positively correlated with femoral neck BMD in both men and women. However, muscle strength was not a significant determinant for the presence of low bone mass after adjusting for muscle mass in multiple logistic regression analyses. Notably, thigh muscle HU values were strong and independent determinant for the risk of low bone density. Decreased thigh muscle HU values, a measure of fatty infiltration of muscle, were independently associated with increased risk of low bone density in the elderly population.

Protein Supplementation during Resistance-Type Exercise Training in the Elderly

Resistance training has been well established as an effective treatment strategy to increase skeletal muscle mass and strength in the elderly. We assessed whether dietary protein supplementation can further augment the adaptive response to prolonged resistance-type exercise training in healthy elderly men and women. Healthy elderly men (n = 31, 70 ± 1 yr) and women (n = 29, 70 ± 1 yr) were randomly assigned to a progressive, 24-wk resistance-type exercise training program with or without additional protein supplementation (15 g·d-1). Muscle hypertrophy was assessed on a whole-body Dual-energy X-ray absorptiometry (DXA), limb (computed tomography), and muscle fiber (biopsy) level. Strength was assessed regularly by 1-repetition maximum (RM) strength testing. Functional capacity was assessed with a sit-to-stand and handgrip test. One-RM strength increased by 45% ± 6% versus 40% ± 3% (women) and 41% ± 4% versus 44% ± 3% (men) in the placebo versus protein group, respectively (P < 0.001), with no differences between groups. Leg muscle mass (women, 4% ± 1% vs 3% ± 1%; men, 3% ± 1% vs 3% ± 1%) and quadriceps cross-sectional area (women, 9% ± 1% vs 9% ± 1%; men, 9% ± 1% vs 10% ± 1%) increased similarly in the placebo versus protein groups (P < 0.001). Type II muscle fiber size increased over time in both placebo and protein groups (25% ± 13% vs 30% ± 9% and 23% ± 12% vs 22% ± 10% in the women and men, respectively). Sit-to-stand improved by 18% ± 2% and 19% ± 2% in women and men, respectively (P < 0.001). Prolonged resistance-type exercise training increases skeletal muscle mass and strength, augments functional capacity, improves glycemia and lipidemia, and reduces blood pressure in healthy elderly men and women. Additional protein supplementation (15 g·d-1) does not further increase muscle mass, strength, and/or functional capacity.

Evaluation of a dual-scales method to measure weight-bearing through the legs, and effects of weight-bearing inequalities on hip bone mineral density and leg lean tissue mass

To investigate: the accuracy of measuring relative left/right weight-bearing using two identically calibrated weighing scales; the short-term weight-bearing tendencies in a general population of 9 participants and long-term in 42 females; the effect weight-bearing inequalities on hip bone mineral density and leg lean tissue mass. Participants were measured standing astride two scales. Short-term volunteers were measured 10 times on one visit, with repositioning between measurements and the long-term group were measured on three visits at 6 month intervals. Baseline bilateral hip and total body Dual X-ray Absorptiometry scans were performed on the long-term group. The short-term Coefficient of Variation is 5.41% and long-term 7.01%. No significant correlations were found between hip bone density differences and weight-bearing inequalities, although a weak correlation of r = 0.31 (p = 0.047) was found for differences in leg lean tissue mass. Left/right weight-bearing measured using two scales is a consistent method for evaluating weight distribution through the legs. The short- and long-term weight-bearing tendencies showed a similar degree of variation. Weight-bearing inequalities were not associated with any significant left/right differences in bone mineral density at the hip, but were weakly associated with left-right differences in leg muscle mass.

Whole-body electromyostimulation as a means to impact muscle mass and abdominal body fat in lean, sedentary, older female adults: subanalysis of the TEST-III trial

BackgroundThe primary aim of this study was to determine the effect of 12 months of whole-body electromyostimulation (WB-EMS) exercise on appendicular muscle mass and abdominal fat mass in subjects specifically at risk for sarcopenia and abdominal obesity, but unable or unwilling to exercise conventionally.MethodsForty-six lean, nonsportive (<60 minutes of exercise per week), elderly women (aged 75 ± 4 years) with abdominal obesity according to International Diabetes Federation criteria were randomly assigned to either a WB-EMS group (n=23) which performed 18 minutes of intermittent, bipolar WB-EMS (85 Hz) three sessions in 14 days or an “active” control group (n=23). Whole-body and regional body composition was assessed by dual energy X-ray absorptiometry to determine appendicular muscle mass, upper leg muscle mass, abdominal fat mass, and upper leg fat mass. Maximum strength of the leg extensors was determined isometrically by force plates.ResultsAfter 12 months, significant intergroup differences were detected for the primary end-points of appendicular muscle mass (0.5% ± 2.0% for the WB-EMS group versus −0.8% ± 2.0% for the control group, P=0.025) and abdominal fat mass (−1.2% ± 5.9% for the WB-EMS group versus 2.4% ± 5.8% for the control group, P=0.038). Further, upper leg lean muscle mass changed favorably in the WB-EMS group (0.5% ± 2.5% versus −0.9% ± 1.9%, in the control group, P=0.033), while effects for upper leg fat mass were borderline nonsignificant (−0.8% ± 3.5% for the WB-EMS group versus 1.0% ± 2.6% for the control group, P=0.050). With respect to functional parameters, the effects for leg extensor strength were again significant, with more favorable changes in the WB-EMS group (9.1% ± 11.2% versus 1.0% ± 8.1% in the control group, P=0.010).ConclusionIn summary, WB-EMS showed positive effects on the parameters of sarcopenia and regional fat accumulation. Further, considering the good acceptance of this technology by this nonsportive elderly cohort at risk for sarcopenia and abdominal obesity, WB-EMS may be a less off-putting alternative to impact appendicular muscle mass and abdominal fat mass, at least for subjects unwilling or unable to exercise conventionally.

Inflammation in HIV-Infected Patients: Impact of HIV, Lifestyle, Body Composition, and Demography – A Cross Sectional Cohort Study

ObjectivesTo examine mechanisms underlying the increased inflammatory state of HIV-infected patients, by investigating the association of HIV-related factors, demography, lifestyle, and body composition with the inflammatory marker soluble urokinase plasminogen activator receptor (suPAR).MethodssuPAR was measured in EDTA-plasma and associated with HIV-related factors (HIV-duration, combination antiretroviral treatment (cART), nadir CD4+ cell count, CD4+ cell count, and HIV RNA); demography; lifestyle; and body composition determined by Dual energy X-ray Absorptiometry (DXA) scan, in multiple linear regression analyses adjusted for biological relevant covariates, in a cross-sectional study of 1142 HIV-infected patients.ResultsIncreased suPAR levels were significantly associated with age, female sex, daily smoking, metabolic syndrome and waist circumference. cART was associated with 17% lower suPAR levels. In cART-treated patients 10-fold higher HIV RNA was associated with 21% higher suPAR, whereas there was no association in untreated patients. Patients with CD4+ cell count<350 cells/µL had 7% higher suPAR, but we found no association with nadir CD4+ cell count or with duration of HIV-infection. Finally, suPAR was not associated with adipose tissue distribution, but strongly associated with low muscle mass. In patients infected through intravenous drug use (IDU), CD4+ cell counts<350 cells/µL were associated with 27% lower suPAR (p = 0.03), and suPAR was 4% lower pr. year during treatment (p = 0.05); however, there was no association with HIV RNA, duration of HIV-infection, nor cART.ConclusionWe found elevated suPAR levels in untreated patients compared to patients on cART. Moreover, we observed a significant positive association between suPAR and HIV RNA levels in cART-treated patients. Age, HIV-transmission through IDU, metabolic syndrome, smoking, and low leg muscle mass were also significantly associated with suPAR levels. Our study therefore indicates, that also other aspects of living with HIV than virologic and immunologic markers add to the increased inflammation in HIV-infected patients.

Gender Differences in Anthropometric Predictors of Physical Performance in Older Adults

Both high body fat and low muscle mass have been associated with physical disability in older adults. However, men and women differ markedly in body composition; men generally have more absolute and relative lean muscle mass and less fat mass than women. It is not known how these anthropometric differences differentially affect physical ability in men and women. This study examines differences in anthropometric predictors of physical performance in older women and men. Participants were 470 older women and men 72.9 (7.9) years of age. Body composition was measured using dual-energy x-ray absorptiometry. Maximum leg strength and power were measured using a leg press. Muscle quality (MQ) was calculated as relative strength (leg press strength per kilogram of leg muscle mass). Gait speed and chair rise were used to assess mobility performance and functional strength. Body mass index (BMI), age, and MQ emerged as predictors (P < 0.05) of functional strength and mobility in men and women somewhat differently. After accounting for age and sample, leg MQ was related to chair rise time and gait speed in men but not women. BMI was related to gait speed in both men and women, but BMI was related to chair rise time only in women. Results implicate the prioritized importance of healthy weight and muscle maintenance in older women and men for maintained physical functioning with aging.

Effect of tumor burden and subsequent surgical resection on skeletal muscle mass and protein turnover in colorectal cancer patients

Cachexia is a consequence of tumor burden caused by ill-defined catabolic alterations in muscle protein turnover. We aimed to explore the effect of tumor burden and resection on muscle protein turnover in patients with nonmetastatic colorectal cancer (CRC), which is a surgically curable tumor that induces cachexia. We recruited the following 2 groups: patients with CRC [n = 13; mean ± SEM age: 66 ± 3 y; BMI (in kg/m(2)): 27.6 ± 1.1] and matched healthy controls (n = 8; age: 71 ± 2 y; BMI: 26.2 ± 1). Control subjects underwent a single study, whereas CRC patients were studied twice before and ~6 wk after surgical resection to assess muscle protein synthesis (MPS), muscle protein breakdown (MPB), and muscle mass by using dual-energy X-ray absorptiometry. Leg muscle mass was lower in CRC patients than in control subjects (6290 ± 456 compared with 7839 ± 617 g; P < 0.05) and had an additional decline after surgery (5840 ± 456 g; P < 0.001). Although postabsorptive MPS was unaffected, catabolic changes with tumor burden included the complete blunting of postprandial MPS (0.038 ± 0.004%/h in the CRC group compared with 0.065 ± 0.006%/h in the control group; P < 0.01) and a trend toward increased MPB under postabsorptive conditions (P = 0.09). Although surgical resection exacerbated muscle atrophy (-7.2%), catabolic changes in protein metabolism had normalized 6 wk after surgery. The recovery in postprandial MPS after surgery was inversely related to the degree of muscle atrophy (r = 0.65, P < 0.01). CRC patients display reduced postprandial MPS and a trend toward increased MPB, and tumor resection reverses these derangements. With no effective treatment of cancer cachexia, future therapies directed at preserving muscle mass should concentrate on alleviating proteolysis and enhancing anabolic responses to nutrition before surgery while augmenting muscle anabolism after resection.

Effects of exercise and tea catechins on muscle mass, strength and walking ability in community‐dwelling elderly Japanese sarcopenic women: A randomized controlled trial

To investigate the effects of exercise and/or tea catechin supplementation on muscle mass, strength and walking ability in elderly Japanese women with sarcopenia. A total of 128 women aged over 75 years were defined as sarcopenic and randomly assigned into four groups: exercise and tea catechin supplementation (n = 32), exercise (n = 32), tea catechin supplementation (n = 32) or health education (n = 32). The exercise group attended a 60-min comprehensive training program twice a week and the tea catechin supplementation group ingested 350 mL of a tea beverage fortified with catechin daily for 3 months. Body composition was determined by bioelectrical impedance analysis. Interview data and functional fitness measurements, such as muscle strength, balance and walking ability, were collected at baseline and after the 3-month intervention. There were significant group × time interactions observed in timed up & go (P < 0.001), usual walking speed (P = 0.007) and maximum walking speed (P < 0.001). The exercise + catechin group showed a significant effect (odds ratio 3.61, 95% confidence interval 1.05-13.66) for changes in the combined variables of leg muscle mass and usual walking speed compared with the health education group. The combination of exercise and tea catechin supplementation had a beneficial effect on physical function measured by walking ability and muscle mass.

Sex differences in response to maximal exercise stress test in trained adolescents

BackgroundSex comparisons between girls and boys in response to exercise in trained adolescents are missing and we investigated similarities and differences as a basis for clinical interpretation and guidance.MethodsA total of 24 adolescent females and 27 adolescent males aged 13–19 years underwent a maximal bicycle exercise stress test with measurement of cardiovascular variables, cardiac output, lung volumes, metabolic factors/lactate concentrations and breath-by-breath monitoring of ventilation, and determination of peak VO2.ResultsMaximum heart rate was similar in females (191 ± 9 bpm) and males (194 ± 7 bpm), cardiac index at maximum exercise was lower in females (7.0 ± 1.0 l/min/m2) than in males (8.3 ± 1.4 l/min/m2, P < 0.05). Metabolic responses and RQ at maximum exercise were similar (females: 1.04 ± 0.06 vs. males: 1.05 ± 0.05). Peak VO2 was lower in females (2.37 ± 0.34 l/min) than in males (3.38 ± 0.49 l/min, P < 0.05). When peak VO2 was normalized to leg muscle mass sex differences disappeared (females: 161 ± 21 ml/min/kg vs. males: 170 ± 23 ml/min/kg). The increase in cardiac index during exercise is the key factor responsible for the greater peak VO2 in adolescent boys compared to girls.ConclusionsDifferences in peak VO2 in adolescent boys and girls disappear when peak VO2 is normalized to estimated leg muscle mass and therefore provide a tool to conduct individual and intersex comparisons of fitness when evaluating adolescent athletes in aerobic sports.

Reply to Millet

Letters to the EditorReply to MilletG. Y. Millet, M. D. Hoffman, and J. B. MorinG. Y. MilletUniversité de Lyon, Saint-Etienne, France; and , M. D. HoffmanDepartment of Veterans Affairs, Northern California Health Care System, and University of California Davis Medical Center, Sacramento, California, and J. B. MorinUniversité de Lyon, Saint-Etienne, France; and Published Online:15 Aug 2012https://doi.org/10.1152/japplphysiol.00740.2012MoreSectionsPDF (27 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat SACRIFICING ECONOMY DOES NOT MEAN ENERGY COST ON A TREADMILL WILL BE HIGHto the editor: Determining factors of running performance are quite complex. G. P. Millet (1) suggests that ultramarathons are no different from shorter distance running events with regards to the importance of energy cost (Cr) and that the suggested specificities of ultramarathon running are due to the fact that “elite” athletes in this relatively new nonprofessional sport are not comparable with elite marathon runners. We fully agree that the number of runners at the elite level is lower in ultramarathons than in shorter distances, and we also agree that this may explain some of the published characteristics of ultramarathon runners.We contend that certain physiological and mechanical characteristics related to ultra-endurance running are specific to such extreme distances, independently of the “youth” of the sport and its localization mostly in the United States and Europe. For instance, it is true that athletes specializing in ultradistance running may have been less successful in the shorter distances where larger leg muscle mass may be a hindrance, and it is true that European/North American runners may have been more likely to run in ultramarathons than African runners who have thinner thighs/calves. Still, large thighs and calves are less detrimental at low speeds compared with high speeds based upon basic mechanics that internal work increases with speed and step frequency. In other words, velocity is much lower in ultramarathons and this has several mechanical and physiological consequences that were detailed in our original article. This is mostly due to the fact that leg and equipment mass is not as critical as is the importance of minimizing lower limb damage to improve endurance. In this context, it is correct that ultratrail runners should be light and should, in particular, have a very low percentage of body fat, but lower limb muscle mass may help to “support” long downhill sections requiring substantial eccentric work. This is not the case for mountain bike or road cycling uphill specialists.In our paper (2), we did not write that ultramarathon runners necessarily have a high Cr, as suggested by G. P. Millet. Instead, we argued that athletes may make adjustments that increase Cr during races. In other words, one may have a “normal” Cr when measured under laboratory conditions but not attempt to achieve such economy during competitions. Finally, although performance is only considered among elite athletes in his letter, our paper relates to performance of all runners, whatever their competitive level. We believe that considering the entire performance spectrum makes our arguments even more appropriate.In conclusion, it is apparent that there is a smaller number of elite-level participants in ultramarathons compared with shorter running events and this may explain some—but not all—results found in the literature. We proposed that certain measures to actually increase Cr under real race conditions may be more than offset through gains in endurance in ultramarathon running, and such a balance is essential for performance optimization, performance being viewed not only for elite athletes but among all runners.DISCLOSURESNo conflicts of interest, financial or otherwise, are declared by the authors.AUTHOR CONTRIBUTIONSAuthor contributions: G.Y.M. drafted manuscript; G.Y.M., M.D.H., and J.-B.M. edited and revised manuscript; G.Y.M., M.D.H., and J.-B.M. approved final version of manuscript.REFERENCES1. Millet GP. Economy is not sacrificed in ultramarathon runners. J Appl Physiol; doi:10.1152/japplphysiol.00642.2012.ISI | Google Scholar2. Millet GY , Hoffman MD , Morin JB. Viewpoint: Sacrificing economy to improve running performance—a reality in the ultramarathon? J Appl Physiol; doi:10.1152/japplphysiol.00016.2012.ISI | Google ScholarAUTHOR NOTESAddress for reprint requests and other correspondence: G. Y. Millet, Université de Lyon, F-42023, Saint-Etienne, France (e-mail: guillaume.[email protected]fr). Download PDF Previous Back to Top FiguresReferencesRelatedInformationRelated ArticlesEconomy is not sacrificed in ultramarathon runners 15 Aug 2012Journal of Applied Physiology More from this issue > Volume 113Issue 4August 2012Pages 687-687 https://doi.org/10.1152/japplphysiol.00740.2012History Published online 15 August 2012 Published in print 15 August 2012 Metrics

High prevalence of sarcopenia and reduced leg muscle mass in Japanese patients immediately after a hip fracture

Sarcopenia-related falls and fractures are becoming an emerging problem as a result of rapid aging worldwide. We aimed to investigate the prevalence of sarcopenia by estimating the muscle mass of the arms and legs of patients with and without hip fracture. This cross-sectional study examined 357 patients immediately after a hip fracture (the HF group) and in 2511 patients from an outpatient clinic who did not have a hip fracture (the NF group) at single institution in Japan. We carried out whole-body dual energy X-ray absorptiometry to analyze body composition with skeletal muscle mass index (SMI; lean mass/height(2)) and bone mineral density (BMD). We carried out stepwise logistic regression analysis to determine the factors associated with a hip fracture. Lower appendicular SMI (P < 0.001), leg SMI (P < 0.001), and higher prevalence of sarcopenia (P < 0.001) were observed in the HF group after controlling for age and sex. The arm SMI was similar in both groups (P > 0.95). In multivariate analysis, the presence of sarcopenia, older age and lower BMD were associated with the occurrence of a hip fracture (OR 1.476, P = 0.002; OR 1.103, P < 0.001; OR 0.082, P < 0.001; respectively). This study showed a higher prevalence of sarcopenia and more reduced leg muscle mass in patients after a hip fracture than in the outclinic patients who did not have hip fractures. The results imply sarcopenia can be a risk factor for a hip fracture.

Sacrificing economy to improve running performance—a reality in the ultramarathon?

ultramarathons have become increasingly popular in recent years. Although complex tactical and psychological-motivational factors play important roles in performance ([Fig. 1][1]), running velocity sustained over a prolonged time is directly proportional to maximal sustainable Vo2 and inversely

Pedometer-Based Behavioral Change Program Can Improve Dependency in Sedentary Older Adults: A Randomized Controlled Trial.

Recent studies suggested that pedometer-based walking programs are applicable to older adults. The purpose of this study was to evaluate the use of pedometer in sedentary older adults to improve physical activity, fear of falling, physical performance, and leg muscle mass. This was a pilot randomized controlled trial (RCT). Eighty-seven community dwelling sedentary older adults living in Japan. The intervention group (n=43) received a pedometer-based behavioural change program for 6 months, while the control group (n=44) did not. The participants in the intervention group were instructed to increase their mean daily steps by 10% each month. Thus, at the end of 6 months, participants in the intervention group were expected to have 77 % more daily steps than their baseline step counts. Written activity logs were monthly averaged to determine whether the participants were achieving their goal. Outcome measures were physical activity, fear of falling, physical performances, and leg muscle mass. In this 6-month trial 40 older adults (93%) completed the pedometer protocol with good adherence. In the intervention group, average daily steps were increased by 83.4% (from 20311323 to 3726 1607) during the study period, but not in the control group (from 20471698 to 22671837). The pedometer-based behavioral change program was more effective to improve their physical activity, fear of falling, locomotive function, and leg muscle mass than control (P<0.05). These results suggested that the pedometer-based behavioral change program can effectively improve the physical activity, fear of falling, physical performance, and leg muscle mass in sedentary older adults.

4．虚弱・サルコペニアへの介入研究

To investigate the effectiveness of exercise alone in improving frailty, and exercise with nutritional supplementation in improving sarcopenia. Frailty: 131 community-dwelling elderly people over 75 years of age were randomly assigned to either the exercise group (n=66) or the control group (n=65). The exercise group was provided with a 60-minute comprehensive exercise program twice a week for 3 months. Sarcopenia: 155 community-dwelling elderly people over 75 years of age were randomly assigned to the exercise + amino acid group (n=39), exercise group (n=39), amino acid group (n=39) or control group (n=38). The exercise intervention included a comprehensive training program for 60 minutes, provided twice a week for 3 months. The amino acid group ingested a leucine-rich essential amino acid supplementation (6 g/day) for 3 months. Frailty: in comparison to the non-frail elderly, muscle mass, bone mineral density, knee extension strength, and walking speed were significantly lower in the frail elderly; however, pain, fall rate, and osteoporosis history were greater in the frail elderly. The exercise intervention significantly improved bone mineral content and grip strength. Sarcopenia: appendicular skeletal muscle mass and walking speed were significantly improved by exercise or amino acid supplementation. However, muscle strength improved significantly only in the exercise + amino acid intervention. In the frail elderly, exercise was effective in enhancing bone mineral content and muscle strength; however, in order to increase leg muscle mass and strength in sarcopenic elderly, both exercise and amino acid supplementation may be necessary.

Effects of Exercise and Amino Acid Supplementation on Body Composition and Physical Function in Community‐Dwelling Elderly Japanese Sarcopenic Women: A Randomized Controlled Trial

To evaluate the effectiveness of exercise and amino acid supplementation in enhancing muscle mass and strength in community-dwelling elderly sarcopenic women. Randomized controlled trial. Urban community in Tokyo, Japan. One hundred fifty-five women aged 75 and older were defined as sarcopenic and randomly assigned to one of four groups: exercise and amino acid supplementation (exercise+AAS; n=38), exercise (n=39), amino acid supplementation (AAS; n=39), or health education (HE; n=39). The exercise group attended a 60-minute comprehensive training program twice a week, and the AAS group ingested 3 g of a leucine-rich essential amino acid mixture twice a day for 3months. Body composition was determined using bioelectrical impedance analysis. Data from interviews and functional fitness parameters such as muscle strength and walking ability were collected at baseline and after the 3-month intervention. A significant group×time interaction was seen in leg muscle mass (P=.007), usual walking speed (P=.007), and knee extension strength (P=.017). The within-group analysis showed that walking speed significantly increased in all three intervention groups, leg muscle mass in the exercise+AAS and exercise groups, and knee extension strength only in the exercise+AAS group (9.3% increase, P=.01). The odds ratio for leg muscle mass and knee extension strength improvement was more than four times as great in the exercise+AAS group (odds ratio=4.89, 95% confidence interval=1.89-11.27) as in the HE group. The data suggest that exercise and AAS together may be effective in enhancing not only muscle strength, but also combined variables of muscle mass and walking speed and of muscle mass and strength in sarcopenic women.

Cardiopulmonary Response and Body Composition Changes after Prolonged High Altitude Exposure in Women

Weight loss in men is commonly observed during prolonged high altitude exposure as a result of a daily negative energy balance. Its amount depends mainly on duration of exposure, altitude reached, and level of physical activity. This reduction in body weight often comes with a loss of muscular mass, likely contributing to the decreased physical performance generally reported. Limited data is, however, available on body composition, functional capacity, and cardiopulmonary response to exercise after high altitude exposure in women. The aim of this study was to evaluate the effects of prolonged high altitude exposure on body composition and on cardiopulmonary response to maximal exercise in a group of young, moderately active women. Twelve female subjects, aged 21.5 ± 3.1 (mean ± SD), BMI 22.1 ± 1.9 kg · m(-2) and Vo(2max) 33.8 ± 3.5 mL · kg(-1) · min(-1), participated in this study, by residing for 21 days at high altitude (5050 m, Pyramid, EV-K(2)-CNR laboratory). Before and after high altitude exposure, all subjects underwent both a body composition evaluation using two methods (bioimpedance analysis and DEXA) and a functional evaluation based on a maximal exercise test on a cycle ergometer with breath-by-breath gas analysis. After high altitude exposure, data showed a slight, nonsignificant reduction in body weight, with an average 3:2 reduction ratio between fat and fat-free mass evaluated by DEXA, in addition to a significant decrease in Vo(2max) on the cycle ergometer test (p<0.01). Changes in Vo(2max) correlated to changes of leg muscle mass, evaluated by DEXA (r(2) = 0.72; p<0.0001). No changes were observed in the maximal heart rate, work capacity, and ventilatory thresholds, while the Vo(2)/W slope was significantly reduced (p<0.05). Finally, Ve/Vo(2) and VE/Vco(2max) slopes were increased (p<0.01), suggesting a possible long-term modulation of the exercise ventilatory response after prolonged high altitude exposure.

Exercise intervention soon after stroke onset to prevent muscle atrophy

Objective: To investigate the effects of nurse-led exercise interventions, in addition to standard rehabilitation, on patients suffering from hemiplegia soon after stroke onset. Methods: Interventions involved a series of hip bridges. Efficacy was evaluated by monitoring leg muscle mass. Participants were divided into control, intervention and terminated intervention groups. In addition to standard rehabilitation, the intervention group performed a series of hip bridges once a day. Leg muscle mass was evaluated using dual-energy X-ray absorptiometry (DXA). Measurements were taken 3–5 days after stroke onset, then again 7 days after initial measurement. Results: During the first week, the mean decrease in leg muscle mass on the paralyzed side was 417 g (7%) for the control group, 304 g (6%) for the terminated intervention group and 108 g (2%) for the intervention group. Only the difference between control and intervention groups was significant (P=0.008). Conclusions: Exercise interventions comprising a series of hip bridges soon after stroke onset, in addition to standard rehabilitation, can reduce leg muscle atrophy on the paralyzed side in stroke patients.