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BACKGROUND Wrist worn consumer-grade activity trackers are popular devices, developed mainly for personal use, but with the potential to be used also for clinical and research purposes. OBJECTIVE The objective of this study was to explore the validity, reliability and sensitivity to change of movement behaviours metrics from three popular activity trackers (POLAR Vantage M, Garmin Vivosport and Garmin Vivoactive 4s) in controlled and free-living conditions when worn by older adults. METHODS Participants (n = 28; 74 ± 5 years) underwent a videotaped laboratory protocol while wearing all three activity trackers. On a separate occasion, participants wore one (randomly assigned) activity tracker and a research grade physical activity monitor ActiGraph wGT3X-BT simultaneously for six consecutive days for comparisons. RESULTS Both Garmin activity trackers showed excellent performance for step counts, with mean absolute percentage error (MAPE) below 20 % and intraclass correlation coefficient (ICC2,1) above 0.90 (P < .05), while Polar Vantage M substantially over counted steps (MAPE = 84 % and ICC2,1 = 0.37 for free-living conditions). MAPE for sleep time was within 10 % for all the trackers tested, while far beyond 20 % for all the physical activity and calories burned outputs. Both Garmin trackers showed fair agreement (ICC2,1 = 0.58–0.55) for measuring calories burned when compared with ActiGraph. CONCLUSIONS Garmin Vivoactive 4s showed overall best performance, especially for measuring steps and sleep time in healthy older adults. Minimal detectible change was consistently lower for an average day measures than for a single day measure, but still relatively high. The results provided in this study could be used to guide choice on activity trackers aiming for different purposes – individual use/care, longitudinal monitoring or in clinical trial setting.

To evaluate progression of skin atrophy during 8 years of complete Conus-Cauda Syndrome and its recovery after 2 years of surface Functional Electrical Stimulation a cohort study was organized and implemented. Functional assessments, tissue biopsies, and follow-up were performed at the Wilhelminenspital, Vienna, Austria; skin histology and immunohistochemistry at the University of Padova, Italy on 13 spinal cord injury persons suffering up to 10 years of complete conus/cauda syndrome. Skin biopsies (n. 52) of both legs were analyzed before and after 2 years of home-based Functional Electrical Stimulation delivered by large anatomically shaped surface electrodes placed on the skin of the anterior thigh. Using quantitative histology we analyzed: 1. Epidermis atrophy by thickness and by area; 2. Skin flattening by computing papillae per mm and Interdigitation Index of dermal-epidermal junctions; 3. Presence of Langerhans cells. Linear regression analyses show that epidermal atrophy and flattening worsen with increasing years post- spinal cord injury and that 2 years of skin electrostimulation by large anatomically shaped electrodes reverses skin changes (pre-functional Electrical Stimulation vs post-functional Electrical Stimulation: thickness 39%, P

Many factors contribute to the decline of skeletal muscle that occurs as we age. This is a reality that we may combat, but not prevent because it is written into our genome. The series of records from World Master Athletes reveals that skeletal muscle power begins to decline at the age of 30 years and continues, almost linearly, to zero at the age of 110 years. Here we discuss evidence that denervation contributes to the atrophy and slowness of aged muscle. We compared muscle from lifelong active seniors to that of sedentary elderly people and found that the sportsmen have more muscle bulk and slow fiber type groupings, providing evidence that physical activity maintains slow motoneurons which reinnervate muscle fibers. Further, accelerated muscle atrophy/degeneration occurs with irreversible Conus and Cauda Equina syndrome, a spinal cord injury in which the human leg muscles may be permanently disconnected from the nervous system with complete loss of muscle fibers within 5-8 years. We used histological morphometry and Muscle Color Computed Tomography to evaluate muscle from these peculiar persons and reveal that contraction produced by home-based Functional Electrical Stimulation (h-bFES) recovers muscle size and function which is reversed if h-bFES is discontinued. FES also reverses muscle atrophy in sedentary seniors and modulates mitochondria in horse muscles. All together these observations indicate that FES modifies muscle fibers by increasing contractions per day. Thus, FES should be considered in critical care units, rehabilitation centers and nursing facilities when patients are unable or reluctant to exercise.

Purpose: Low back and/or pelvic girdle pain is common during pregnancy and may persist after delivery. Therapeutic methods to alleviate pain, with no side effects for mother and child, are of high clinical importance. The consensus statement expresses the position of the Working Group on Evidence-Based Medicine in Physical and Rehabilitation Medicine, the Austrian Society of Physical Medicine and Rehabilitation and the Austrian Pain Society, for the treatment of low back and/or pelvic girdle pain by transcutaneous electrical nerve stimulation (TENS) during pregnancy. Materials and Methods: The literature was reviewed followed by a subsequent interdisciplinary discussion. Results: Diagnostic investigations, therapeutic options, mode of application as well as efficacy and side effects of the method are presented. Conclusion: TENS is a safe therapy for low back and/or pelvic girdle pain in the last trimester of pregnancy with no side effects, low costs and the possibility of home application.

Physical activity plays an important role in preventing muscle atrophy and chronic diseases in adults and in the elderly. Calcium (Ca 2+ ) cycling and activation of specific molecular pathways are essential in contraction-induced muscle adaptation. This study attains human muscle sections and total homogenates prepared from biopsies obtained before (control) and after 9 weeks of training by electrical stimulation (ES) on a group of volunteers. The aim of the study was to investigate about the molecular mechanisms that support functional muscle improvement by ES. Evidences of kinase/phosphatase pathways activation after ES were obtained. Moreover, expression of Sarcalumenin, Calsequestrin and sarco/endoplasmic reticulum Ca 2+ -ATPase (Serca) isoforms was regulated by training. In conclusion, this work shows that neuromuscular ES applied to vastus lateralis muscle of sedentary seniors combines fiber remodeling with activation of Ca 2+ -Calmodulin molecular pathways and modulation of key Ca 2+ -handling proteins.

All progressive muscle contractile impairments (including age-related muscle weakness) need permanent management. We discuss evidence that subclinical denervation contributes to atrophy and slowness of aged muscle, and we provide stimulation protocols for aged and denervated skeletal muscles. We describe in Sect. 11.1 the effects of home-based neuromuscular FES in elderly persons and then in Sect. 11.2 the diagnostics, training protocols, and clinical results of home-based functional electrical stimulation (h-b FES) for denervated–degenerated skeletal muscle tissue. Using molecular analyses, histological morphometry, and Muscle Color Computed Tomography, we evaluated muscles of elderly persons, showing that increased levels of muscle contractions induced by h-b FES reverse muscle weakness and atrophy both in sedentary seniors and in conus and cauda equina complete syndrome.

Long-term lower motor neuron denervation of skeletal muscle is known to result in degeneration of muscle with replacement by adipose and fibrotic tissues. However, long-term survival of a subset of skeletal myofibers also occurs.We performed transverse and longitudinal studies of patients with spinal cord injury (SCI), patients specifically complete Conus and Cauda Equina Syndrome and also of active and sedentary seniors which included analyses of muscle biopsies from the quadriceps m.Surprisingly, we discovered that human denervated myofibers survive years of denervation after full and irreversible disconnection from their motor neurons. We found that atrophic myofibers could be rescued by home-based Functional Electrical Stimulation (h-bFES), using purpose developed stimulators and electrodes. Although denervated myofibers quickly lose the ability to sustain high-frequency contractions, they respond to very long impulses that are able to allow for re-emergence of tetanic contractions. A description of the early muscle changes in humans are hampered by a paucity of patients suffering complete Conus and Cauda Equina Syndrome, but the cohort enrolled in the EU RISE Project has shown that even five years after SCI, severe atrophic myofibers with a peculiar cluster reorganization of myonuclei are present in human muscles and respond to h-bFES.Human myofibers survive permanent denervation longer than generally accepted and they respond to h-bFES beyond the stage of simple atrophy. Furthermore, long-term denervation/reinnervation events occur in elderly people and are part of the mechanisms responsible for muscle aging and again h-bFES was beneficial in delaying aging decay.

Histochemistry, immuno-histochemistry, gel electrophoresis of single muscle fibers and electromyography of aging muscles and nerves suggest that: i) denervation contributes to muscle atrophy, ii) impaired mobility accelerates the process, and iii) lifelong running protects against loss of motor units. Recent corroborating results on the muscle effects of Functional Electrical Stimulation (FES) of aged muscles will be also mentioned, but we will in particular discuss how and why a lifelong increased physical activity sustains reinnervation of muscle fibers. By analyzing distribution and density of muscle fibers co-expressing fast and slow Myosin Heavy Chains (MHC) we are able to distinguish the transforming muscle fibers due to activity related plasticity, to those that adapt muscle fiber properties to denervation and reinnervation. In muscle biopsies from septuagenarians with a history of lifelong high-level recreational activity we recently observed in comparison to sedentary seniors: 1. decreased proportion of small-size angular myofibers (denervated muscle fibers); 2. considerable increase of fiber-type groupings of the slow type (reinnervated muscle fibers); 3. sparse presence of muscle fibers co-expressing fast and slow MHC. Immuno-histochemical characteristics fluctuate from those with scarce fiber-type modulation and groupings to almost complete transformed muscles, going through a process in which isolated fibers co-expressing fast and slow MHC fill the gaps among fiber groupings. Data suggest that lifelong high-level exercise allows the body to adapt to the consequences of the age-related denervation and that it preserves muscle structure and function by saving otherwise lost muscle fibers through recruitment to different slow motor units. This is an opposite behavior of that described in long term denervated or resting muscles. These effects of lifelong high level activity seems to act primarily on motor neurons, in particular on those always more active, i.e., on the slow motoneurons. The preferential reinnervation that follows along decades of increased activity maintains neuron and myofibers. All together the results open interesting perspectives for applications of FES and electroceuticals for rejuvenation of aged muscles to delay functional decline and loss of independence that are unavoidable burdens of advanced aging. Trial Registration: ClinicalTrials.gov: NCT01679977.

Literature confirms the effects of vision and stance on body sway and indicates possible interactions between the two. However, no attempts have been made to systematically compare the effect of vision on the different types of stance which are frequently used in clinical and research practice. The biomechanical changes that occur after changing shape and size of the support surface suggest possible sensory re-weighting might take place. The purpose of this study was to assess the effect of vision on body sway in relation to different stance configurations and width. Thirty-eight volunteers performed four quiet stance configurations (parallel, semi-tandem, tandem and single leg), repeating them with open and closed eyes. Traditional parameters, recurrence quantification analysis and sample entropy were analyzed from the CoP trajectory signal. Traditional and recurrence quantification analysis parameters were affected by vision removal and stance type. Exceptions were frequency of oscillation, entropy and trapping time. The most prominent effect of vision elimination on traditional parameters was observed for narrower stances. A significant interaction effect between vision removal and stance type was present for most of the parameters observed (p

The centre of pressure (COP) movement during stance maintenance on a stable surface is commonly used to describe and evaluate static balance. The aim of our study was to test sensitivity of individual COP parameters to different stance positions which were used to address size specific changes in the support surface. Twenty-nine subjects participated in the study. They carried out three 60-second repetitions of each of the five balance tasks (parallel stance, semi-tandem stance, tandem stance, contra-tandem stance, single leg stance). Using the force plate, the monitored parameters included the total COP distance, the distance covered in antero-posterior and medio-lateral directions, the maximum oscillation amplitude in antero-posterior and medio-lateral directions, the total frequency of oscillation, as well as the frequency of oscillation in antero-posterior and medio-lateral directions. The parameters which describe the total COP distance were the most sensitive to changes in the balance task, whereas the frequency of oscillation proved to be sensitive to a slightly lesser extent. Reductions in the support surface size in each of the directions resulted in proportional changes of antero-posterior and medio- lateral directions. The frequency of oscillation did not increase evenly with the increase in the level of difficulty of the balance task, but reached a certain value, above which it did not increase. Our study revealed the monitored parameters of the COP to be sensitive to the support surface size manipulations. The results of the study provide an important source for clinical and research use of the body sway measurements. Key pointsTesting static balance with body sway related center of pressure (COP) parameters;Testing sensitivity of COP sub-components to manipulations of the stance position;Analytical approach to the study of COP parameters that enable the insight to the frequency/amplitude and direction-dependency relationships;Adding to the basic knowledge of static balance which can be applied to testing and training routines.

To examine the effects of a time-saving leg-press training program with moderate vibration on strength parameters, pain, and functional outcomes of patients after total knee arthroplasty (TKA) in comparison with functional physiotherapy.Randomized controlled trial.Outpatient rehabilitation department at a university teaching hospital.Patients (N=55) with TKA were randomly allocated into 2 rehabilitation groups.Six weeks after TKA, participants either underwent isokinetic leg-press training combined with moderate vibration (n=26) of 15 minutes per session or functional physiotherapy (n=29) of 30 minutes per session. Both groups received therapy twice a week for a period of 6 weeks. Participants were evaluated at baseline (6wk after TKA) and after the 6-week rehabilitation program.The main outcome measure was maximal voluntary contraction (MVC) of the involved leg. Secondary outcome measures were pain assessed with a visual analog scale (VAS), range of motion, stair test, timed Up and Go test, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).Both groups showed statistically significant improvements in MVC of knee extensors measured on the knee dynamometer (leg-press group: from 0.8±.06 to 1±.09Nm/kg body weight [BW], physiotherapy group: from 0.7±.06 to 0.9±.06Nm/kg BW; P.05) and in closed kinetic chain on the leg press (leg-press group: from 8.9±.77 to 10.3±1.06N/kg BW, physiotherapy group: from 6.7±.54 to 9.1±.70N/kg BW; P.05) and in pain at rest (leg-press group: from 2±.36 to 1.3±.36 on the VAS, physiotherapy group: from 1.2±.28 to 1.1±.31; P.05), WOMAC scores, and functional measurements after 6 weeks of training. There was no significant difference between the 2 groups concerning strength, pain, and functional outcomes after training (P.05).Isokinetic leg-press training with moderate vibration and functional physiotherapy are both effective in regaining muscle strength and function after TKA; however, isokinetic leg-press training is considerably less time consuming.

Summary Mitochondrial dysfunction occurs during aging, but its impact on tissue senescence is unknown. Here, we find that sedentary but not active humans display an age-related decline in the mitochondrial protein, optic atrophy 1 (OPA1), that is associated with muscle loss. In adult mice, acute, muscle-specific deletion of Opa1 induces a precocious senescence phenotype and premature death. Conditional and inducible Opa1 deletion alters mitochondrial morphology and function but not DNA content. Mechanistically, the ablation of Opa1 leads to ER stress, which signals via the unfolded protein response (UPR) and FoxOs, inducing a catabolic program of muscle loss and systemic aging. Pharmacological inhibition of ER stress or muscle-specific deletion of FGF21 compensates for the loss of Opa1, restoring a normal metabolic state and preventing muscle atrophy and premature death. Thus, mitochondrial dysfunction in the muscle can trigger a cascade of signaling initiated at the ER that systemically affects general metabolism and aging., Graphical Abstract, Highlights • OPA1 is a physical activity sensor that is downregulated during aging sarcopenia • Muscle OPA1 controls general metabolism and epithelial senescence via FGF21 • Inhibition of muscle OPA1 induces a systemic pro-inflammatory status • OPA1 controls protein breakdown/synthesis, muscle stem cells and fiber innervation, Aging has been reported to be accompanied by changes in mitochondrial dynamics, but the impact on tissue senescence is unknown. Tezze et al. show that deletion of Opa1 impacts muscle mass, metabolic homeostasis, systemic inflammation, and epithelial senescence and identify FGF21 as the culprit of precocious aging and premature death.

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.

Home based training by using neuromuscular electrical stimulation requires sufficient monitoring to guar- antee optimal training results. In a clinical study elderly subjects should follow a specific training of both anterior thighs. The schedule consists of 24 training days within 9 weeks where each training session consists of 3 series of 6 or 10 minutes. The compliance of five subjects (4 females) were evaluated based on an evaluation software programmed in Visual Studio C#. The training device is a custom-built volt- age-controlled stimulator where the stimulation parameters are monitored. The average stimulation voltage of all sub- jects was 18,81 V with an average current of 57,33 mA. The monitoring of the training demonstrates the importance for evaluation for the study success. Trial Registration: ClinicalTrials.gov NCT01679977

Spinal cord injury (SCI) causes muscle atrophy, which is particularly severe, due to inability to perform tetanic contractions, when lower motor neurons (LMN) are involved. We performed a longitudinal study in 25 Europeans suffering from complete conus cauda syndrome from 0.7 to 8.7 years comparing functional and structural thigh muscle properties before and after 2 years of home-based daily training by functional electrical stimulation (FES). The mid-term results after 1 year and preliminary muscle biopsy observations at project end-point from a subset of subjects are here reported.Muscles were electrically stimulated at home by means of large surface electrodes and a custom-designed stimulator. The poor excitability of the LMN denervated muscles was first improved by twitch-contraction training. Then, tetanic contractions against progressively increased loading were elicited. Finally, standing-up exercises were daily performed. The bulk of thigh muscle was estimated by transverse computer tomography (CT) scan and force measurements. Needle biopsies of vastus lateralis were harvested before and after 2 years of FES.The 1 year home-based daily FES training induced: (1) very similar increases in muscle excitability and contractility in right and left legs; (2) feasibility to elicit tetanic contractions by means of train-stimulation with about ten times improvement of muscle force; (3) increase in the 26% of muscle bulk, as shown by CT scan analyses, improving appearance of limbs and muscle cushioning; (4) myofiber size increase (+94%) in a small series of muscle biopsies obtained after 2 years of FES. None of the subjects that performed 1 year home-based daily FES training (20 persons) had worsened their functional class, while 20% (4/20) improved to functional class 4, that is, the ability to stand.The European Union (EU) Project Rise shows that 'home-based daily FES training' is a safe and effective therapy that may maintain life-long physical exercise by active muscle contraction (FES is the only option for denervated muscle) as a procedure to recover the early-lost tetanic contractility of denervated muscle, and to counteract muscle atrophy in order to prevent clinical complications.

There is something in our genome that dictates life expectancy and there is nothing that can be done to avoid this; indeed, there is not yet any record of a person who has cheated death. Our physical prowess can vacillate substantially in our lifetime according to our activity levels and nutritional status and we may fight aging, but we will inevitably lose. We have presented strong evidence that the atrophy which accompanies aging is to some extent caused by loss of innervation. We compared muscle biopsies of sedentary seniors to those of life long active seniors, and show that these groups indeed have a different distribution of muscle fiber diameter and fiber type. The senior sportsmen have many more slow fiber-type groupings than the sedentary people which provides strong evidence of denervation-reinnervation events in muscle fibers. It appears that activity maintains the motoneurons and the muscle fibers. Premature or accelerated aging of muscle may occur as the result of many chronic diseases. One extreme case is provided by irreversible damage of the Conus and Cauda Equina, a spinal cord injury (SCI) sequela in which the human leg muscles may be completely and permanently disconnected from the nervous system with the almost complete disappearance of muscle fibers within 3-5 years from SCI. In cases of this extreme example of muscle degeneration, we have used 2D Muscle Color CT to gather data supporting the idea that electrical stimulation of denervated muscles can retain and even regain muscle. We show here that, if people are compliant, atrophy can be reversed. A further example of activity-related muscle adaptation is provided by the fact that mitochondrial distribution and density are significantly changed by functional electrical stimulation in horse muscle biopsies relative to those not receiving treatment. All together, the data indicate that FES is a good way to modify behaviors of muscle fibers by increasing the contraction load per day. Indeed, it should be possible to defer the muscle decline that occurs in aging people and in those who have become unable to participate in physical activities. Thus, FES should be considered for use in rehabilitation centers, nursing facilities and in critical care units when patients are completely inactive even for short periods of time.

Different dynamic balance tests help to identify specific balance deficits in elderly and various population groups. In addition, dynamic balance tests have proved useful in identifying potential locomotor-system injury risk factors. These tests differ in the quality of their metric characteristics which could influence their applicability to measure balance in different clinical groups. Reliability, validity, sensitivity and objectivity define metric characteristics of an individual test. This paper provides an overview of the available scientific literature regarding measurement characteristics of the most commonly used dynamic balance tests. Reliability (intra-session, inter-session, inter-tester and intra-tester), sensitivity, validity and ability to predict possible balance impairing trauma and disease are presented. Clinical balance tests (balance assessed by analogue scales), functional reach, star excursion tests and out step tests were most frequently studied for their metric characteristics. In general intra-session reliability proved to be slightly higher than inter-session reliability. On the contrary there is a lack of reports on inter-tester and intra-tester reliability, especially for star excursion tests and for the tests performed on an unstable surface. Tests differ in the validity; possibly resulting from use of different reference standards. In addition factors such as age, fatigue, learning, and anthropometric characteristics have been shown to affect dynamic balance. Majority of tests were successfully implemented in the process of identifying fall prone individuals. However the reports on potential of dynamic balance tests to help predict other lower extremity injury or sports performance are sparse. In general dynamic balance measuring tests (not all parameters) proved to have sufficient metric characteristics for their practical application. However individual parameters and goals of balance assessment should be considered, when choosing the most appropriate test.

Summary The cellular basis of age-related tissue deterioration remains largely obscure. The ability to activate compensatory mechanisms in response to environmental stress is an important factor for survival and maintenance of cellular functions. Autophagy is activated both under short and prolonged stress and is required to clear the cell of dysfunctional organelles and altered proteins. We report that specific autophagy inhibition in muscle has a major impact on neuromuscular synaptic function and, consequently, on muscle strength, ultimately affecting the lifespan of animals. Inhibition of autophagy also exacerbates aging phenotypes in muscle, such as mitochondrial dysfunction, oxidative stress, and profound weakness. Mitochondrial dysfunction and oxidative stress directly affect acto-myosin interaction and force generation but show a limited effect on stability of neuromuscular synapses. These results demonstrate that age-related deterioration of synaptic structure and function is exacerbated by defective autophagy., Graphical Abstract, Highlights • Autophagy in muscle decreases with age, and rescue prevents muscle loss • Autophagy inhibition in muscles shortens animal lifespan • Autophagy is required to maintain a normal muscle-nerve interaction • Autophagy impairment induces oxidation of contractile proteins, causing weakness, The cellular basis of age-related tissue deterioration remains largely obscure. Autophagy is often activated under stress conditions and declines with age. Carnio et al. now report that specific autophagy inhibition in muscle has a major impact on neuromuscular synaptic function and consequently on muscle strength, ultimately affecting the lifespan of animals. Autophagy inhibition also exacerbates several aging phenotypes, confirming that autophagy is required for healthy aging.