Muscle size, neuromuscular activation, and rapid force characteristics in elderly men and women:effects of unilateral long-term disuse due to hip-osteoarthritis

Udgivelsesdato: 2007-MarSubstantial evidence exists for the age-related decline in muscle strength and neural function, but the effect of long-term disuse in the elderly is largely unexplored. The present study examined the effect of unilateral long-term limb disuse on maximal voluntary quadriceps contraction (MVC), lean quadriceps muscle cross-sectional area (LCSA), contractile rate of force development (RFD, Delta force/Delta time), impulse (integral force dt), muscle activation deficit (interpolated twitch technique), maximal neuromuscular activity [electromyogram (EMG)], and antagonist muscle coactivation in elderly men (M: 60-86 yr; n = 19) and women (W: 60-86 yr; n = 20) with unilateral chronic hip-osteoarthritis. Both sides were examined to compare the effect of long-term decreased activity on the affected (AF) leg with the unaffected (UN) side. AF had a significant lower MVC (W: 20%; M: 20%), LCSA (W: 8%; M: 10%), contractile RFD (W: 17-26%; M: 15-24%), impulse (W: 10-19%, M: 19-20%), maximal EMG amplitude (W: 22-25%, M: 22-28%), and an increased muscle activation deficit (-18%) compared with UN. Furthermore, women were less strong (AF: 40%; UN: 39%), had less muscle mass (AF: 33%; UN: 34%), and had a lower RFD (AF: 38-50%; UN: 41-48%) compared with men. Similarly, maximum EMG amplitude was smaller for both agonists (AF: 51-63%; UN: 35-61%) and antagonist (AF: 49-64%; UN: 36-56%) muscles in women compared with men. However, when MVC and RFD were normalized to LCSA, there were no differences between genders. The present data demonstrate that disuse leads to a marked loss of muscle strength and muscle mass in elderly individuals. Furthermore, the data indicate that neuromuscular activation and contractile RFD are more affected by long-term disuse than maximal muscle strength, which may increase the future risk for falls

Applying both the 30-s and the 5-repetition sit-to-stand tests captures dissimilar groups and a broader spectrum of physical abilities in mobility-limited older individuals:results from the BIOFRAIL study

PURPOSE: We aimed to assess differences among older patients demonstrating low STS performance in the 30 s-STS and/or the 5r-STS.METHODS: 30 s-STS and 5r-STS were used to assess lower limb muscle strength and function in older adults. Analysis involved 376 patients (≥ 65 years) from a geriatric outpatient clinic for fall assessment.RESULTS: The mean age of patients was 79.8 (± 6.1) years (67% female). In total, 40.6% had low STS performance with 9.3% presenting only low 30 s-STS, 9.8% only low 5r-STS, and 21.5% low STS performance in both tests. Patients with low STS performance in both tests had lower gait speed, were more often frail, and had more prior falls compared to patients with low STS performance in one test only.CONCLUSION: The two STS tests are not interchangeable, and the use of both STS tests capture a wider range of physical abilities in mobility-limited older adults.CLINICAL TRIAL REGISTRATION: NCT05795556.</p

Frailty is associated with a history of falls among mobility-limited older adults—cross-sectional multivariate analysis from the BIOFRAIL study

Aim: Key summary points: To identify differences in characteristics between mobility-limited older adults with a history of falls and those at risk of falling but who have not yet fallen. Findings: Frailty and muscle strength were characteristics distinguishing between older adults with a history of falls and those absent of falls despite an increased risk of falling. Message: Frailty should be incorporated alongside handgrip strength (HGS) and sit-to-stand (STS) tests into routine evaluations of mobility-limited older adults referred for fall assessment. Purpose: Abstract: We aimed to identify differences in characteristics between mobility-limited older adults with a history of falls and those at risk of falling, and to identify the parameter with the strongest predictive value on the risk of falling. Methods: Data included anthropometry, HGS, 30-s and 5-reps STS tests, maximal isometric knee extensor strength, gait speed (6 m), postural balance (tandem test), and muscle mass (BIA). Frailty was assessed using the Clinical Frailty Scale (CFS) and sarcopenia was evaluated according to the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) guidelines. Outcomes of falls (past year), and depression (Geriatric Depression Scale 15) were self-reported. Results: Totally, 505 mobility-limited older adults (mean age 79.7 ± 6.3 years, 64.8% females) were included. Of these, 400 (79.2%) had experienced one or more falls within the past year (fallers), while 105 (20.8%) had not experienced a fall (at risk). Patients with experienced falls were more likely to feel depressed, had reduced handgrip strength, and reduced performance in both STS tests compared to those who had not fallen. Frailty was the strongest individual parameter associated with a history of prior falls, even after adjusting for covariates such as depression and 30-s STS (aOR 3.80; 95% CI 1.70–8.50). Conclusions: Present study identified frailty as a key factor independently associated with a history of falls in this population. Additionally, handgrip strength and STS performance were key characteristics distinguishing between older adults with a history of falls within the past 12 months and those at risk of falling.</p

Relative sit-to-stand power: aging trajectories, functionally relevant cut-off points, and normative data in a large European cohort

Background: A validated, standardized, and feasible test to assess muscle power in older adults has recently been reported: the sit-to-stand (STS) muscle power test. This investigation aimed to assess the relationship between relative STS power and age and to provide normative data, cut-off points, and minimal clinically important differences (MCID) for STS power measures in older women and men. Methods: A total of 9320 older adults (6161 women and 3159 men) aged 60–103 years and 586 young and middle-aged adults (318 women and 268 men) aged 20–60 years were included in this cross-sectional study. Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to legs muscle mass) muscle power values were assessed by the 30 s STS power test. Body composition was evaluated by dual energy X-ray absorptiometry and bioelectrical impedance analysis, and legs skeletal muscle index (SMI; normalized to height squared) was calculated. Habitual and maximal gait speed, timed up-and-go test, and 6 min walking distance were collected as physical performance measures, and participants were classified into two groups: well-functioning and mobility-limited older adults. Results: Relative STS power was found to decrease between 30–50 years (-0.05 W·kg-1·year-1; P &gt; 0.05), 50–80 years (-0.10 to -0.13 W·kg-1·year-1; P &lt; 0.001), and above 80 years (-0.07 to -0.08 W·kg-1·year-1; P &lt; 0.001). A total of 1129 older women (18%) and 510 older men (16%) presented mobility limitations. Mobility-limited older adults were older and exhibited lower relative, allometric, and specific power; higher body mass index (BMI) and legs SMI (both only in women); and lower legs SMI (only in men) than their well-functioning counterparts (all P &lt; 0.05). Normative data and cut-off points for relative, allometric, and specific STS power and for BMI and legs SMI were reported. Low relative STS power occurred below 2.1 W·kg-1 in women (area under the curve, AUC, [95% confidence interval, CI] = 0.85 [0.84–0.87]) and below 2.6 W·kg-1 in men (AUC [95% CI] = 0.89 [0.87–0.91]). The age-adjusted odds ratios [95% CI] for mobility limitations in older women and men with low relative STS power were 10.6 [9.0–12.6] and 14.1 [10.9–18.2], respectively. MCID values for relative STS power were 0.33 W·kg-1 in women and 0.42 W·kg-1 in men. Conclusions: Relative STS power decreased significantly after the age of 50 years and was negatively and strongly associated with mobility limitations. Our study provides normative data, functionally relevant cut-off points, and MCID values for STS power for their use in daily clinical practice. © 2021 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders

Relative sit-to-stand power: aging trajectories, functionally relevant cut-off points, and normative data in a large European cohort

Background: A validated, standardized, and feasible test to assess muscle power in older adults has recently been reported: the sit-to-stand (STS) muscle power test. This investigation aimed to assess the relationship between relative STS power and age and to provide normative data, cut-off points, and minimal clinically important differences (MCID) for STS power measures in older women and men. Methods: A total of 9320 older adults (6161 women and 3159 men) aged 60–103 years and 586 young and middle-aged adults (318 women and 268 men) aged 20–60 years were included in this cross-sectional study. Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to legs muscle mass) muscle power values were assessed by the 30 s STS power test. Body composition was evaluated by dual energy X-ray absorptiometry and bioelectrical impedance analysis, and legs skeletal muscle index (SMI; normalized to height squared) was calculated. Habitual and maximal gait speed, timed up-and-go test, and 6 min walking distance were collected as physical performance measures, and participants were classified into two groups: well-functioning and mobility-limited older adults. Results: Relative STS power was found to decrease between 30–50 years (-0.05 W·kg-1·year-1; P &gt; 0.05), 50–80 years (-0.10 to -0.13 W·kg-1·year-1; P &lt; 0.001), and above 80 years (-0.07 to -0.08 W·kg-1·year-1; P &lt; 0.001). A total of 1129 older women (18%) and 510 older men (16%) presented mobility limitations. Mobility-limited older adults were older and exhibited lower relative, allometric, and specific power; higher body mass index (BMI) and legs SMI (both only in women); and lower legs SMI (only in men) than their well-functioning counterparts (all P &lt; 0.05). Normative data and cut-off points for relative, allometric, and specific STS power and for BMI and legs SMI were reported. Low relative STS power occurred below 2.1 W·kg-1 in women (area under the curve, AUC, [95% confidence interval, CI] = 0.85 [0.84–0.87]) and below 2.6 W·kg-1 in men (AUC [95% CI] = 0.89 [0.87–0.91]). The age-adjusted odds ratios [95% CI] for mobility limitations in older women and men with low relative STS power were 10.6 [9.0–12.6] and 14.1 [10.9–18.2], respectively. MCID values for relative STS power were 0.33 W·kg-1 in women and 0.42 W·kg-1 in men. Conclusions: Relative STS power decreased significantly after the age of 50 years and was negatively and strongly associated with mobility limitations. Our study provides normative data, functionally relevant cut-off points, and MCID values for STS power for their use in daily clinical practice. © 2021 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders

Exercise conditioning in old mice improves skeletal muscle regeneration

Skeletal muscle possesses the ability to regenerate after injury, but this ability is impaired or delayed with aging. Regardless of age, muscle retains the ability to positively respond to stimuli, such as exercise. We examined whether exercise is able to improve regenerative response in skeletal muscle of aged mice. Twenty‐two‐month‐old male C57Bl/6J mice (n = 20) underwent an 8‐wk progressive exercise training protocol [old exercised (O‐Ex) group]. An old sedentary (O‐Sed) and a sedentary young control (Y‐Ctl) group were included. Animals were subjected to injections of cardiotoxin into the tibialis anterior muscle. The tibialis anterior were harvested before [O‐Ex/O‐Sed/ Y‐Ctl control (CTL); n = 6], 10 d (O‐Ex/O‐Sed/Y‐Ctl d 10; n = 8), and 28 d (O‐Ex/O‐Sed/Y‐Ctl d 28; n = 6) postinjection. Average fiber cross‐sectional area was reduced in all groups at d 10 (CTL: O‐Ex: 2499 ± 140; O‐Sed: 2320 ± 165; Y‐Ctl: 2474 ± 269; d 10: O‐Ex: 1191 ± 100; O‐Sed: 1125 ± 99; Y‐Ctl: 1481 ± 167 μm2; P 0.05). Satellite cell content was greater at CTL in O‐Ex (2.6 ± 0.4 satellite cells/100 fibers) compared with O‐Sed (1.0 ± 0.1% satellite cells/100 fibers; P < 0.05). Exercise conditioning appears to improve ability of skeletal muscle to regenerate after injury in aged mice.—Joanisse, S., Nederveen, J. P., Baker, J. M., Snijders, T., Iacono, C., Parise, G. Exercise conditioning in old mice improves skeletal muscle regeneration. FASEB J. 30, 3256–3268 (2016)

Designing a Compressive Sensing Demonstrator of an Earth Observation Payload in the Visible and Medium Infrared: Instrumental Concept and Main Features †

Increased spatial resolution and revisit time of payloads operating in the infrared spectral region can offer unprecedented advantages to Earth Observation. This, however, poses several technological challenges, such as large array detector availability and data bandwidth. In this paper, we present a super-resolved demonstrator—based on a compressive sensing architecture—which is being developed to address enhanced performance in terms of at-ground spatial resolution, on-board data processing and encryption functionalities for Earth Observation payloads. The demonstrator’s architecture is here presented, together with its working principle, main features and the approach used for image reconstruction