Age-related decline in muscle mass and muscle function in Flemish Caucasians: a 10-year follow-up

Aging is a complex process that is accompanied with changes in both muscle mass and muscle function (strength and performance). Therefore, the current longitudinal study aimed to provide a better insight in 10-year aging-related changes in whole-body muscle mass and strength performance of the leg extensors during the adult life span. Data were gathered within the framework of the first- (2002–2004: baseline) and third-generation Flemish Policy Research Center Sport (2012–2014: follow-up). Results are based on muscle characteristics data of 591 Flemish Caucasian adults (19–73 years, 381 men). Skeletal muscle mass (SMM) was determined with bioelectrical impedance analysis. Biodex Medical System 3® dynamometer was used to measure isometric (PT_static120°) and isokinetic (PT_dynamic60° and PT_dynamic240°) strength, ballistic movement speed (S _20 %), and muscular endurance (work) of the knee extensors. Overall strength performance was higher at both evaluation moments in men compared to women (p?<?0.01). But only S _20 % declined significantly faster in men compared to women (p?<?0.01). Age and baseline strength performance were negatively related with the change in strength performance, even when corrected for SMM, protein intake, and energy expenditure during sports (E _sport). In conclusion, strength performance was not associated with E _sport in this study, but protein intake was associated with isometric strength in men, and with ballistic and isokinetic strength in women. Changes in S _20 % were significantly greater in men compared to women. Baseline values of strength performance and age were associated with changes in strength performance parameters, even after correction for SMM, protein intake, and E _sport.     

Validation of keratan sulfate level in mucopolysaccharidosis type IVA by liquid chromatography–tandem mass spectrometry

Mucopolysaccharidosis type IVA (MPS IVA, Morquio A disease), a progressive lysosomal storage disease, causes skeletal chondrodysplasia through excessive storage of keratan sulfate (KS). KS is synthesized mainly in cartilage and released to the circulation. The excess storage of KS disrupts cartilage, consequently releasing more KS into circulation, which is a critical biomarker for MPS IVA. Thus, assessment of KS level provides a potential screening strategy and determines clinical course and efficacy of therapies. We have recently developed a tandem mass spectrometry liquid chromatography [LC/MS/MS] method to assay KS levels in blood. Forty-nine blood specimens from patients with MPS IVA [severe (n?=?33), attenuated (n?=?11) and undefined (n?=?5)] were analyzed for comparison of blood KS concentration with that of healthy subjects and for correlation with clinical severity. Plasma samples were digested by keratanase II to obtain disaccharides of KS. Digested samples were assayed by LC/MS/MS. We found that blood KS levels (0.4–26 µg/ml) in MPS IVA patients were significantly higher than those in age-matched controls (0.67–4.6 µg/ml; P?<?0.0001). It was found that blood KS level varied with age and clinical severity in the patients. Blood KS levels in MPS IVA peaked between 2 years and 5 years of age (mean 11.4 µg/ml). Blood KS levels in severe MPS IVA (mean 7.3 µg/ml) were higher than in the attenuated form (mean 2.1 µg/ml) (P?=?0.012). We also found elevated blood KS levels in other types of MPS. These findings indicate that the new KS assay for blood is suitable for early diagnosis and longitudinal assessment of disease severity in MPS IVA.     

Age-related maintenance of eccentric strength: a study of temperature dependence

With adult aging, eccentric strength is maintained better than isometric strength leading to a higher ratio of eccentric/isometric force production (ECC/ISO) in older than younger adults. The purpose was to investigate the ECC/ISO during electrical activation of the adductor pollicis during lengthening (20–320° s^?1) contractions in 24 young (n = 12, ～24 years) and old (n = 12, ～72 years) males across muscle temperatures (cold ～19 °C; normal ～30 °C; warm ～35 °C). For isometric force, the old were 20–30 % weaker in the normal and cold conditions (P < 0.05) with no difference for the warm condition compared to young (P > 0.05). Half-relaxation time (HRT) did not differ across age for the normal and warm temperatures (P > 0.05), but it slowed significantly for old in the cold condition compared with young (～15 %; P < 0.05), as well, there was a 20 and 40 % increase in muscle stiffness for the young and old, respectively. ECC/ISO was 50–60 % greater for the cold condition than the normal and warm conditions. There was no age difference in ECC/ISO across ages for the normal and warm conditions (P > 0.05), but for the cold, the old exhibited a 20–35 % higher ECC/ISO than did the young for velocities above 60° s^?1 (P < 0.05). A contributing factor to the elevated ECC/ISO is an increased proportion of weakly compared to strongly bound crossbridges. These findings highlight the relationship (r = 0.70) between intrinsic muscle contractile speed (HRT) and eccentric strength in old age.     

Predicting sarcopenia from functional measures among community-dwelling older adults

Sarcopenia is defined as age-related lean tissue mass (LTM) loss resulting in reduced muscular strength, physical function, and mobility. Up to 33 % of older adults currently are sarcopenic, with likely many more undiagnosed. The purpose of this investigation was to predict sarcopenia status from easily accessible functional measures of community-dwelling older adults. Forty-three community-dwelling older adults (n?=?32 females and n?=?11 males) participated in the present investigation. Inclusion criteria included ≥65 years of age, mini-mental state examination score ≥24, and no falls within previous 12 months. All subjects completed their appendicular skeletal mass (ASM) assessment via dual-energy X-ray absorptiometry (DXA) and were categorized as either sarcopenic or non-sarcopenic. Physical assessments included 10-m usual walk, hand-grip (HG) strength, 6-min walk, 8-ft up-and-go, 30-s chair stand, 30-s arm curl, and sit-to-stand muscular power. A forward, stepwise multiple regression analysis revealed that age, sex, weight, height, 10-m walk, HG, and sit-to-stand muscular power account for 96.1 % of the variance in ASM. The area under the curve was 0.92 for correctly identifying sarcopenic participants compared to their actual classification. This is the first prediction model used to identify sarcopenia based on parameters of demographic and functional fitness measures in community-dwelling older adults. The ability to accurately identify sarcopenia in older adults is imperative to their quality of life and ability to perform activities of daily living.     

A Pilot Study of the Head Extension Swallowing Exercise: New Method for Strengthening Swallowing-Related Muscle Activity

This pilot study examined the effect of a new head extension swallowing exercise (HESE) on submental muscle activity and tongue strength in healthy volunteers. Fifteen young adults (10 females and 5 males) were instructed to extend their head backwards as much as possible, and while watching the ceiling, swallowed their saliva every 10 s for a duration of 20 min. Twenty-four treatments were performed over 8 weeks. The outcome variables evaluated at baseline, 4 and 8 weeks of training, and 12-week follow-up included mean and peak submental muscle activation amplitudes during normal and effortful swallowing measured via surface electromyography, and anterior and posterior isometric tongue pressures were measured with the Iowa Oral Performance Instrument. Results indicated that the muscle activation amplitudes during effortful swallowing increased significantly at 4 and 8 weeks compared to baseline (p < 0.025). However, the increases in amplitudes during normal swallowing were minor (nonsignificant) after 8 weeks compared to baseline. The isometric pressures of the tongue tip and the posterior part of the oral tongue were significantly higher at 8 weeks compared to baseline (p < 0.025). Thus, the 8-week HESE protocol significantly improved suprahyoid muscle activity during effortful swallowing as well as the isometric tongue pressures. The HESE appears effective in exercising and strengthening the suprahyoid muscles and tongue muscles in healthy participants. Although encouraging, these results need to be replicated in clinical trials for testing the therapeutic effects of the HESE in older adults and patients with dysphagia who present with decreased hyolaryngeal elevation.     

Associations between dietary nutrient intake and muscle mass and strength in community-dwelling older adults: the Tasmanian Older Adult Cohort Study

OBJECTIVES: To describe associations between dietary nutrient intake and progression of sarcopenia, the age‐related loss of muscle mass and strength. DESIGN: Prospective cohort study of community‐dwelling older adults. SETTING: Southern Tasmania, Australia. PARTICIPANTS: Seven hundred forty noninstitutionalized older adults (50% female; mean age 62±7) randomly sampled from electoral rolls. MEASUREMENTS: Dietary nutrient intake was examined at baseline and follow‐up (2.6±0.4 years later) using The Cancer Council Victoria's Food Frequency Questionnaire (FFQ). Appendicular lean mass (aLM) was assessed using dual X‐ray absorptiometry and muscle strength of the knee extensors using a dynamometer. RESULTS: Failing to meet the recommended dietary intake for protein was associated with significantly lower aLM at baseline (?0.81 kg, 95% confidence interval (CI)=?1.54 to ?0.08) and follow‐up (?0.79 kg, 95%CI=?1.42 to ?0.17). Energy‐adjusted protein intake was a positive predictor of change in aLM over 2.6 years (β=0.10, P=.003). Energy‐adjusted intake of iron (β=0.07, P=.02), magnesium (β=0.07, P=.02), phosphorus (β=0.07, P=.047), and zinc (β=0.08, P=.02) were positive predictors of change in aLM, whereas retinol (β=?0.09, P=.005) was a negative predictor of change in aLM after adjustment for protein intake. No significant associations were observed between nutrient intake and muscle strength. CONCLUSION: Protein and several other dietary nutrients are associated with muscle mass and rate of muscle loss (but not strength) in older adults, suggesting that multiple dietary components may ameliorate the progression of sarcopenia.     

Effect of traditional resistance and power training using rated perceived exertion for enhancement of muscle strength,power, and functional performance

The present study compared the effects of 12 weeks of traditional resistance training and power training using rated perceived exertion (RPE) to determine training intensity on improvements in strength, muscle power, and ability to perform functional task in older women. Thirty healthy elderly women (60–75 years) were randomly assigned to traditional resistance training group (TRT; n = 15) or power training group (PT; n = 15). Participants trained twice a week for 12 weeks using six exercises. The training protocol was designed to ascertain that participants exercised at an RPE of 13–18 (on a 6–20 scale). Maximal dynamic strength, muscle power, and functional performance of lower limb muscles were assessed. Maximal dynamic strength muscle strength leg press (≈58 %) and knee extension (≈20 %) increased significantly (p < 0.001) and similarly in both groups after training. Muscle power also increased with training (≈27 %; p < 0.05), with no difference between groups. Both groups also improved their functional performance after training period (≈13 %; p < 0.001), with no difference between groups. The present study showed that TRT and PT using RPE scale to control intensity were significantly and similarly effective in improving maximal strength, muscle power, and functional performance of lower limbs in elderly women.     

Effect of resistance training on muscular strength and indicators of abdominal adiposity,metabolic risk,and inflammation in postmenopausal women: controlled and randomized clinical trial of efficacy of training volume

This study evaluated the effect of resistance training (RT) volume on muscular strength and on indicators of abdominal adiposity, metabolic risk, and inflammation in post-menopausal women (PW). Thirty-two volunteers were randomly allocated into the following three groups: control (CT, no exercise, n = 11), low-volume RT (LV, three sets/exercise, n = 10), and high-volume RT (HV, six sets/exercise, n = 11). The LV and HV groups performed eight exercises at 70 % of one maximal repetition, three times a week, for 16 weeks. Muscular strength and indicators of abdominal adiposity, metabolic risk, and inflammation were measured at baseline and after 16 weeks. No differences were found in baseline measures between the groups. The PW showed excess weight and fat percentage (F%), large waist circumference (WC), high waist-hip ratio (WHR), and hypercholesterolemia and borderline values of glycated hemoglobin (HbA1c%). Following the RT, a similar increase in muscle strength and reduction in F% from baseline were found in both trained groups. In HV, a decrease in total cholesterol, LDL-c, WC, and WHR was noted. Moreover, the HV showed a lower change (delta%) of interleukin-6 (IL-6) when compared to CT (HV = 11.2 %, P _25–75 = ?7.6–28.4 % vs. CT = 99.55 %, P _25–75 = 18.5–377.0 %, p = 0.049). In LV, a decrease was noted for HbA1c%. There were positive correlations (delta%) between WHR and IL-6 and between IL-6 and TC. These results suggest that while a low-volume RT improves HbA1c%, F%, and muscular strength, a high-volume RT is necessary to improve indicators of abdominal adiposity and lipid metabolism and also prevent IL-6 increases in PW.     

A retrospective analysis of the impact of telephonic counseling on dietary and lifestyle modifications in Indian patients with type 2 diabetes mellitus

Dietary and lifestyle modifications are critical in the management of type 2 diabetes mellitus (T2DM). However, in a resource-constrained setting, providing physical counseling for dietary and lifestyle modifications is a challenge. Therefore, SPARSH, a call center based, telephonic counseling program was set up for patients with T2DM. In this study, effect of SPARSH services on dietary and lifestyle parameters of patients with T2DM was analyzed. Adult patients who received counseling regularly for at least 14 months were selected. At the end of 14 months, change from baseline in various dietary and lifestyle parameters was evaluated using t test and McNemar’s test at 5% significance level. Overall, 1283 patients were included. At the end of 14 months, change in dietary parameters was as follows: total calories, carbohydrates, and fat consumption decreased significantly by 169.1 kcal/day, 16.2 g/day, and 3.1 g/day, respectively (p?<?0.0001); proteins intake increased by 1.0 g/day (p?=?0.0043); cereals, alcohol, and junk food consumption decreased by 1.1 exchanges/day, 34.9 kcal/day, and 46.0 kcal/day, respectively (p?<?0.0001); fruits and vegetable consumption increased by 0.2 and 0.4 exchanges/day, respectively (p?<?0.0001); dietary fiber intake increased by 0.9 g/day (p?=?0.0207). Change in lifestyle parameters was as follows: increase in frequency and duration of exercise by 1.2 days/week and 1.3 h/week, respectively; self-inspection of feet and footwear by 1.5 and 1.0 times/week, respectively; and decrease in smoking by 2 cigarettes/day (p?<?0.0001). Regular telephonic counseling significantly improved dietary and lifestyle parameters in T2DM patients.     

Exercise and nutritional interventions for improving aging muscle health

Skeletal muscle mass declines with age (i.e., sarcopenia) resulting in muscle weakness and functional limitations. Sarcopenia has been associated with physiological changes in muscle morphology, protein and hormonal kinetics, insulin resistance, inflammation, and oxidative stress. The purpose of this review is to highlight how exercise and nutritional intervention strategies may benefit aging muscle. It is well known that resistance exercise training increases muscle strength and size and evidence also suggests that resistance training can increase mitochondrial content and decrease oxidative stress in older adults. Recent findings suggest that fast-velocity resistance exercise may be an effective intervention for older adults to enhance muscle power and functional capacity. Aerobic exercise training may also benefit aging skeletal muscle by enhancing mitochondrial bioenergetics, improving insulin sensitivity, and/or decreasing oxidative stress. In addition to exercise, creatine monohydrate, milk-based proteins, and essential fatty acids all have biological effects which could enhance some of the physiological adaptations from exercise training in older adults. Additional research is needed to determine whether skeletal muscle adaptations to increased activity in older adults are further enhanced with effective nutritional interventions and whether this is due to enhanced muscle protein synthesis, improved mitochondrial function, and/or a reduced inflammatory response.     

Balance Exercises Circuit improves muscle strength,balance, and functional performance in older women

This study introduces the Balance Exercises Circuit (BEC) and examines its effects on muscle strength and power, balance, and functional performance in older women. Thirty-five women aged 60+ (mean age = 69.31, SD = 7.35) were assigned to either a balance exercises group (BG, n = 14) that underwent 50-min sessions twice weekly, of a 12-week BEC program, or a wait-list control group (CG, n = 21). Outcome measures were knee extensor peak torque (PT), rate of force development (RFD), balance, Timed Up & Go (TUG), 30-s chair stand, and 6-min walk tests, assessed at baseline and 12 weeks. Twenty-three participants completed follow-up assessments. Mixed analysis of variance models examined differences in outcomes. The BG displayed improvements in all measures at follow-up and significantly improved compared with CG on, isokinetic PT60, PT180 (p = 0.02), RFD (p < 0.05), balance with eyes closed (p values range .02 to <.01) and TUG (p = 0.03), all with medium effect sizes. No changes in outcome measures were observed in the CG. BEC improved strength, power, balance, and functionality in older women. The BEC warrants further investigation as a fall prevention intervention.     

Intramuscular fat and physical performance at the Framingham Heart Study

Intramuscular fat may mediate associations between obesity and physical disability. We examined the associations between muscle attenuation, a proxy for intramuscular fat, and physical function. Paraspinous muscle computed tomography attenuation was obtained on a Framingham Heart Study subgroup (n?=?1152, 56 % women, mean age 66 years). Regressions modeled cross-sectional associations between muscle attenuation and mobility disability, grip strength, and walking speed with standard covariates; models additionally adjusted for body mass index (BMI) and visceral adipose tissue (VAT). Separate models investigated associations between VAT and subcutaneous adipose tissue (SAT) and physical function. Per 1 standard deviation decrement in muscle attenuation (i.e., more muscle fat), we observed 1.29 (95 % CI?=?1.11, 1.50; p?=?0.0009) increased odds of walking speed ≤1 m/s in women and men. This persisted after separate BMI and VAT adjustments (p?<?0.02). In men, there was a 1.29 kg (95 % CI?=?0.57, 2.01; p?=?0.0005) decrement in grip strength, which persisted after BMI and VAT adjustments (p?≤?0.0004). For VAT and SAT, similar associations were not observed. Intramuscular fat is associated with increased odds of walking speed ≤1 m/s in both sexes and lower grip strength in men. There were no similar associations for VAT and SAT, highlighting the specificity of intramuscular fat in association with physical function.     

The acute physiological effects of high- and low-velocity resistance exercise in older adults

The aim of the present study was to determine if workload matched, high-velocity (HVE) and low-velocity (LVE) resistance exercise protocols, elicit differing acute physiological responses in older adults. Ten older adults completed three sets of eight exercises on six separate occasions (three HVE and three LVE sessions). Systolic blood pressure, diastolic blood pressure and blood lactate were measured pre- and post-exercise, heart rate was measured before exercise and following each set of each exercise. Finally, a rating of perceived exertion was measured following each set of each exercise. There were no significant differences in blood lactate (F_(1,9) = 0.028; P = 0.872; \(\eta_{\text{P}}^{ 2}\) = 0.003), heart rate (F_(1,9) = 0.045; P = 0.837; \(\eta_{\text{P}}^{ 2}\) = 0.005), systolic blood pressure (F_(1,9) = 0.023; P = 0.884; \(\eta_{\text{P}}^{ 2}\) = 0.003) or diastolic blood pressure (F_(1,9) = 1.516; P = 0.249; \(\eta_{\text{P}}^{ 2}\) = 0.144) between HVE and LVE. However, LVE elicited significantly greater ratings of perceived exertion compared to HVE (F_(1,9) = 13.059; P = 0.006; \(\eta_{\text{P}}^{ 2}\) = 0.592). The present workload matched HVE and LVE protocols produced comparable physiological responses, although greater exertion was perceived during LVE.     

Alcohol intake and the risk of osteonecrosis of the femoral head in Japanese populations: a dose-response meta-analysis of case-control studies

Studies examining the association between alcohol intake and the risk of osteonecrosis of the femoral head (ONFH) have inconsistent results. The purpose of this study was to examine and summarize the evidence regarding the association between alcohol intake and ONFH based on results from case-control studies. This analysis included five case-control studies reporting data from 1251 individuals. Alcohol intake habits (never, former, or current), average drinking consumption (g/week), and cumulative drinking consumption (drink-years) were extracted. The risk of ONFH was evaluated, and a two-stage dose-response meta-analysis was performed using restricted cubic splines with four knots at fixed percentiles of 5, 35, 65, and 95% of the distribution. Former alcohol intake increased the risk of ONFH with a marginal significance (odds ratio [OR], 2.62; p = 0.055). Current alcohol intake was associated with an increased risk of ONFH (OR, 3.63; p < 0.001 in occasional drinkers, OR, 5.90; p < 0.001 in daily drinkers). The dose-response meta-analysis revealed that the risk of ONFH increased by 35.3% for every 100 g/week (95% confidence interval [CI], 1.24–1.47; p < 0.001) and by 44.1% for every 500 g drink-years (95% CI, 1.295–1.601; p < 0.001). Current intake and the dose of alcohol were positively associated with an increased risk of ONFH in a non-linear pattern.     

The Effect of a Community-Based Exercise Program on Inflammation,Metabolic Risk,and Fitness Levels Among Persons Living with HIV/AIDS

The human immunodeficiency virus (HIV) pandemic remains a top national health priority. Chronic inflammation may be a critical component in the disease course of HIV as C-reactive protein (CRP) is elevated and associated with increased mortality. This study examined the effect of 3 months of combined aerobic and resistance exercise training among a diverse cohort of HIV-infected men and women. The fixed effect of time for CRP was found to be non-significant (F[1,57.3] = 1.7, p = 0.19). There was a significant fixed effect for time for upper body (F[1,51.6] = 18.1, p < 0.05) and lower body strength (F[1,48.0] = 15.7, p < 0.05) and significant declines in diastolic blood pressure (p = 0.002) and waist circumference (p = 0.027). Though levels of CRP were not impacted after 3 months training, participants demonstrated a significant increase in muscular strength as well as beneficial changes in metabolic risk factors. Future studies should focus on determining the optimal exercise intervention length and mode to reduce inflammation among individuals living with HIV.     

Socio-demographic correlates of physical activity among European older people

From a public health perspective, identifying factors related to attaining the physical activity (PA) recommendations is important in order to identify subgroups for intervention programs. The aim of this study is to identify the socio-demographic correlates of attaining the recommended levels of PA in the older European population. Using data from the European Social Survey round 6, PA and socio-demographic characteristics were collected from 10,148 participants (4556 men, 5592 women), aged 65 years and over, from 28 countries in 2012. PA was accessed using the question “On how many of the last seven days did you walk quickly, do sports, or other PA for 30 min or longer?” and meeting PA guidelines was assessed using World Health Organization criteria. Overall, 59.7% of the participants attained the PA-recommended levels. The likelihood of attaining PA recommendations was higher among older people with higher education levels (p < 0.05; p < 0.01; p < 0.001). Men who lived in a town or small city (p < 0.05) and lived in a rural area (p < 0.001) were more likely to attain the PA recommendations. Women who lived with a partner were more likely to attain the PA recommendations (p < 0.001). Promotion of PA is critical to health among older people; therefore, intervention programs must consider these socio-demographic factors when planning an increase in PA.     

Newborn screening for mucopolysaccharidoses: a pilot study of measurement of glycosaminoglycans by tandem mass spectrometry

Background

Mucopolysaccharidoses (MPS) are a group of inborn errors of metabolism that are progressive and usually result in irreversible skeletal, visceral, and/or brain damage, highlighting a need for early diagnosis.

Methods

This pilot study analyzed 2862 dried blood spots (DBS) from newborns and 14 DBS from newborn patients with MPS (MPS I, n?=?7; MPS II, n?=?2; MPS III, n?=?5). Disaccharides were produced from polymer GAGs by digestion with chondroitinase B, heparitinase, and keratanase II. Heparan sulfate (0S, NS), dermatan sulfate (DS) and mono- and di-sulfated KS were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Median absolute deviation (MAD) was used to determine cutoffs to distinguish patients from controls. Cutoffs were defined as median?+?7× MAD from general newborns.

Results

The cutoffs were as follows: HS-0S?>?90 ng/mL; HS-NS?>?23 ng/mL, DS?>?88 ng/mL; mono-sulfated KS?>?445 ng/mL; di-sulfated KS?>?89 ng/mL and ratio di-KS in total KS?>?32 %. All MPS I and II samples were above the cutoffs for HS-0S, HS-NS, and DS, and all MPS III samples were above cutoffs for HS-0S and HS-NS. The rate of false positives for MPS I and II was 0.03 % based on a combination of HS-0S, HS-NS, and DS, and for MPS III was 0.9 % based upon a combination of HS-0S and HS-NS.

Conclusions

Combination of levels of two or more different GAGs improves separation of MPS patients from unaffected controls, indicating that GAG measurements are potentially valuable biomarkers for newborn screening for MPS.

     

A reduced activity model: a relevant tool for the study of ageing muscle

Skeletal muscle mass is in a constant state of turnover, and atrophy is the result of a shift in the balance of muscle protein synthesis and breakdown resulting in net muscle protein loss. Total disuse of skeletal muscle quickly leads to muscle atrophy and loss of strength, and this has been repeatedly demonstrated in studies employing bed rest and lower limb immobilisation methodologies in young healthy participants. Fewer studies have focused on older participants (>65 years of age), but those that have provide evidence that advancing age brings increased vulnerability to rapid and marked loss of muscle size and strength during period of total muscle unloading. Increased systemic inflammation and reduced protein synthetic responses to protein feeding and muscle contraction might influence the severity of muscle protein loss during periods of total unloading compared with younger individuals. Less extreme reductions in muscle loading (e.g., 2 weeks of reducing daily ambulation to <1500 steps/day) have also been shown to result in decreases in muscle mass. This step-reduction model may be more relevant than total bed rest or limb immobilisation for examining real-world scenarios that present a physiological challenge to the maintenance of skeletal muscle mass in older individuals.     

Creatine supplementation enhances isometric strength and body composition improvements following strength exercise training in older adults

We sought to determine whether creatine monohydrate (CrM) supplementation would enhance the increases in strength and fat-free mass that develop during resistance exercise training in older adults. Twenty-eight healthy men and women over the age of 65 years participated in a whole-body resistance exercise program 3 days per week for 14 weeks. The study participants were randomly allocated, in a double-blind fashion, to receive either CrM (5 g/d + 2 g of dextrose; n = 14) or placebo (7 g of dextrose; n = 14). The primary outcome measurements included the following: total body mass, fat-free mass, one-repetition maximum strength for each body part, isometric knee extension, handgrip, and dorsiflexion strength, chair stand performance, 30-m walk test, 14-stair climb performance, muscle fiber type and area, and intramuscular total creatine. Fourteen weeks of resistance exercise training resulted in significant increases in all measurements of strength and functional tasks and muscle fiber area for both groups (p <.05). CrM supplementation resulted in significantly greater increases in fat-free mass and total body mass, as compared with placebo (p <.05). The CrM group also showed a greater increase in isometric knee extension strength in men and women, as compared with placebo (p <.05), and also greater gains in isometric dorsiflexion strength (p <.05), but in men only. There was a significant increase in intramuscular total creatine in the CrM group (p <.05). Finally, there were no significant side effects of treatment or exercise training. This study confirms that supervised heavy resistance exercise training can safely increase muscle strength and functional capacity in older adults. The addition of CrM supplementation to the exercise stimulus enhanced the increase in total and fat-free mass, and gains in several indices of isometric muscle strength.     

Older age is associated with greater central aortic blood pressure following the exercise stress test in subjects with similar brachial systolic blood pressure

Brachial systolic pressure (BSP) is often monitored during exercise by the stress test; however, central systolic pressure (CSP) is thought to be a more direct measure of cardiovascular events. Although some studies reported that exercise and aging may play roles in changes of both BSP and CSP, the relationship between BSP and CSP with age following the exercise stress test remains unclear. The aim of this study was to evaluate the effect of age on the relationship between BSP and CSP measured after exercise. Ninety-six subjects underwent the diagnostic treadmill exercise stress test, and we retrospectively divided them into the following 3 groups by age: the younger age group (43 ± 4 years), middle age group (58 ± 4 years), and older age group (70 ± 4 years). Subjects exercised according to the Bruce protocol, to achieve 85 % of their age-predicted maximum heart rate or until the appearance of exercise-associated symptoms. BSP, CSP, and pulse rate (PR) were measured using a HEM-9000AI (Omron Healthcare, Japan) at rest and after exercise. BSP, CSP, and PR at rest were not significantly different among the 3 groups (p = 0.92, 0.21, and 0.99, respectively). BSP and PR immediately after exercise were not significantly different among the groups (p = 0.70 and 0.38, respectively). However, CSP immediately after exercise was 144 ± 18 mmHg (younger age), 149 ± 17 mmHg (middle age), and 158 ± 19 mmHg (older age). CSP in the older age group was significantly higher than that in the younger age group (p < 0.01). Despite similar BSPs in all age groups after exercise, CSP was higher in the older age group. Therefore, older subjects have a higher CSP after exercise, which is not readily assessed by conventional measurements of BSP.