Previous short-term disuse dictates muscle gene expression and physiological adaptations to subsequent resistance exercise.

Short-term unloading experienced following injury or hospitalisation induces muscle atrophy and weakness. The effects of exercise following unloading have been scarcely investigated. We investigated the functional and molecular adaptations to a resistance training (RT) programme following short-term unloading.

Reduced ATP turnover during hibernation in relaxed skeletal muscle.

Hibernating brown bears, due to a drastic reduction in metabolic rate, show only moderate muscle wasting. Here, we evaluate if ATPase activity of resting skeletal muscle myosin can contribute to this energy sparing. By analyzing single muscle fibers taken from the same bears, either during hibernation or in summer, we find that fibers from hibernating bears have a mild decline in force production and a significant reduction in ATPase activity.

Mobility Medicine: A call to unify hyper-fragmented specialties by abstracts sent to 2025Pdm3, and typescripts to Ejtm3, and .

Mega scientific conferences increasingly suffer from the need for short and poster presentations without discussion. An alternative is to organize workshops in hotels large enough to accommodate all participants. This significantly increases the opportunities for constructive discussion during breakfasts, lunches, dinners and long evenings that can bring together experts of scientific and clinical sub-specialties and young fellows.

Impact of ageing and disuse on neuromuscular junction and mitochondrial function and morphology: Current evidence and controversies.

Inactivity and ageing can have a detrimental impact on skeletal muscle and the neuromuscular junction (NMJ). Decreased physical activity results in muscle atrophy, impaired mitochondrial function, and NMJ instability. Ageing is associated with a progressive decrease in muscle mass, deterioration of mitochondrial function in the motor axon terminals and in myofibres, NMJ instability and loss of motor units.

Neuromuscular impairment at different stages of human sarcopenia.

Background: Degeneration of the motoneuron and neuromuscular junction (NMJ) and loss of motor units (MUs) contribute to age-related muscle wasting and weakness associated with sarcopenia. However, these features have not been comprehensively investigated in humans. This study aimed to compare neuromuscular system integrity and function at different stages of sarcopenia, with a particular focus on NMJ stability and MU properties.

Lessons for Flying Astronauts with Disabilities Drawn from Experience in Aviation.

Accessible spaceflight may seem a distant concept. As part of a diverse European Space Agency funded Topical Team, we are working on the physiological feasibility of space missions being undertaken by people with physical disabilities. Here, the first activity of this team is presented in the form of key lessons learned from aviation to inform new work on space missions.

Plasma C-terminal agrin fragment concentrations across adulthood: Reference values and associations with skeletal muscle health.

Background: Increasing interest surrounds the utility of blood-based biomarkers for diagnosing sarcopenia. C-terminal agrin fragment (CAF), a marker of neuromuscular junction stability, is amongst the most promising candidates; however, a dearth of reference data impedes the incorporation of its use in public health settings. This study aimed to establish reference values for plasma CAF concentrations across adulthood in a large, well-characterized cohort of healthy adults; and comprehensively examine the association between plasma CAF levels and skeletal muscle health.

Spaceflight on the ISS changed the skeletal muscle proteome of two astronauts.

Skeletal muscle undergoes atrophy and loss of force during long space missions, when astronauts are persistently exposed to altered gravity and increased ionizing radiation. We previously carried out mass spectrometry-based proteomics from skeletal muscle biopsies of two astronauts, taken before and after a mission on the International Space Station. The experiments were part of an effort to find similarities between spaceflight and bed rest, a ground-based model of unloading, focused on proteins located at the costameres.

Retinal venular vessel diameters are smaller during ten days of bed rest.

Older individuals experience cardiovascular dysfunction during extended bedridden hospital or care home stays. Bed rest is also used as a model to simulate accelerated vascular deconditioning occurring during spaceflight. This study investigates changes in retinal microcirculation during a ten-day bed rest protocol.

Handgrip strength asymmetry as a new biomarker for sarcopenia and individual sarcopenia signatures.

Background: Although handgrip strength (HGS) asymmetry has clinical screening utility, its relevance to sarcopenia is unknown. This study examined the relationship between HGS asymmetry and sarcopenia signatures, and explored the relevance of circulating neural/neuromuscular markers.

Methods: 9403 individuals aged 18-92 years participated in this study.

Lower limb suspension induces threshold-specific alterations of motor units properties that are reversed by active recovery.

Purpose: This study aimed to non-invasively test the hypothesis that (a) short-term lower limb unloading would induce changes in the neural control of force production (based on motor units (MUs) properties) in the vastus lateralis muscle and (b) possible changes are reversed by active recovery (AR).

Methods: Ten young males underwent 10 days of unilateral lower limb suspension (ULLS) followed by 21 days of AR. During ULLS, participants walked exclusively on crutches with the dominant leg suspended in a slightly flexed position (15°-20°) and with the contralateral foot raised by an elevated shoe.

Sarcopenia parameters in active older adults - an eight-year longitudinal study.

Backgroud: Sarcopenia is a common skeletal muscle syndrome that is common in older adults but can be mitigated by adequate and regular physical activity. The development and severity of sarcopenia is favored by several factors, the most influential of which are a sedentary lifestyle and physical inactivity. The aim of this observational longitudinal cohort study was to evaluate changes in sarcopenia parameters, based on the EWGSOP2 definition in a population of active older adults after eight years.

Pathophysiological mechanisms of reduced physical activity: Insights from the human step reduction model and animal analogues.

Physical inactivity represents a heavy burden for modern societies and is spreading worldwide, it is a recognised pandemic and is the fourth cause of global mortality. Not surprisingly, there is an increasing interest in longitudinal studies on the impact of reduced physical activity on different physiological systems. This narrative review focuses on the pathophysiological mechanisms of step reduction (SR), an experimental paradigm that involves a sudden decrease in participants' habitual daily steps to a lower level, mimicking the effects of a sedentary lifestyle.

Upregulation of Sarcolemmal Hemichannels and Inflammatory Transcripts with Neuromuscular Junction Instability during Lower Limb Unloading in Humans.

Human skeletal muscle atrophy and a disproportionate force loss occur within a few days of unloading in space and on Earth, but the underlying mechanisms are not fully understood. Disruption of neuromuscular junction homeostasis has been proposed as one of the possible causes. Here, we investigated the potential mechanisms involved in this neuromuscular disruption induced by a 10-day unilateral lower limb suspension (ULLS) in humans.

Abstracts of the 2023 Padua Days of Muscle and Mobility Medicine (2023Pdm3) to be held March 29 - April 1 at the Galileian Academy of Padua and at the Petrarca Hotel, Thermae of Euganean Hills, Padua, Italy.

At the end of the 2022 Padua Days of Muscle and Mobility Medicine (Pdm3) the next year's meeting was scheduled from 29 March to 1 April 2023. Despite the worsening evolution of the crisis in Eastern Europe, the program was confirmed in autumn 2022 with Scientific Sessions that will take place over three full days in the Aula Guariento of the Galileian Academy of Arts, Letters and Sciences of Padua (March 29, 2023) and then at the Conference Room of the Hotel Petrarca, Thermae of Euganean Hills (Padua), Italy. Collected during autumn and early winter, many titles and abstracts where submitted (about 100 Oral presentations are listed in the preliminary Program by January 31, 2023) confirming attractiveness of the 2023 Pdm3.

C-terminal agrin fragment as a biomarker of muscle wasting and weakness: a narrative review.

Ageing is accompanied by an inexorable loss of muscle mass and functionality and represents a major risk factor for numerous diseases such as cancer, diabetes and cardiovascular and pulmonary diseases. This progressive loss of muscle mass and function may also result in the insurgence of a clinical syndrome termed sarcopenia, exacerbated by inactivity and disease. Sarcopenia and muscle weakness yield the risk of falls and injuries, heavily impacting on health and social costs.

Signatures of muscle disuse in spaceflight and bed rest revealed by single muscle fiber proteomics.

Astronauts experience dramatic loss of muscle mass, decreased strength, and insulin resistance, despite performing daily intense physical exercise that would lead to muscle growth on Earth. Partially mimicking spaceflight, prolonged bed rest causes muscle atrophy, loss of force, and glucose intolerance. To unravel the underlying mechanisms, we employed highly sensitive single fiber proteomics to detail the molecular remodeling caused by unloading and inactivity during bed rest and changes of the muscle proteome of astronauts before and after a mission on the International Space Station.

Age-related changes in gait biomechanics and their impact on the metabolic cost of walking: Report from a National Institute on Aging workshop.

Changes in old age that contribute to the complex issue of an increased metabolic cost of walking (mass-specific energy cost per unit distance traveled) in older adults appear to center at least in part on changes in gait biomechanics. However, age-related changes in energy metabolism, neuromuscular function and connective tissue properties also likely contribute to this problem, of which the consequences are poor mobility and increased risk of inactivity-related disease and disability. The U.

Genes encoding agrin (AGRN) and neurotrypsin (PRSS12) are associated with muscle mass, strength and plasma C-terminal agrin fragment concentration.

Although physiological data suggest that neuromuscular junction (NMJ) dysfunction is a principal mechanism underpinning sarcopenia, genetic studies have implicated few genes involved in NMJ function. Accordingly, we explored whether genes encoding agrin (AGRN) and neurotrypsin (PRSS12) were associated with sarcopenia phenotypes: muscle mass, strength and plasma C-terminal agrin fragment (CAF). PhenoScanner was used to determine if AGRN and/or PRSS12 variants had previously been implicated with sarcopenia phenotypes.

Plasma proteome profiling of healthy subjects undergoing bed rest reveals unloading-dependent changes linked to muscle atrophy.

Background: Inactivity and unloading induce skeletal muscle atrophy, loss of strength and detrimental metabolic effects. Bed rest is a model to study the impact of inactivity on the musculoskeletal system. It not only provides information for bed-ridden patients care, but it is also a ground-based spaceflight analogue used to mimic the challenges of long space missions for the human body.

2023 On-site Padua Days on Muscle and Mobiliy Medicine: Call for speakers.

The winter of 2022 approaches with the need to finalize our plans for next year. This is urgent for the 2023 Meeting of the Padua Days of Muscle and Mobility Medicine (Pdm3) to be held March 29th to April 1st, 2023 at the Hotel Petrarca in the Thermae of Euganean Hills (Padua), Italy. A preliminary Pdm3 Program is almost ready with sessions, organzers and keynote speakers, but ther is still rooms for many interesting and interested young speakers.