Effect of Whole-body Vibration frequency on muscle tensile state during graded plantar flexor isometric contractions.

Background: Acute physiological and biomechanical alterations have been reported following whole-body vibration (WBV). Stiffening of muscles has only been anecdotally reported in response to WBV. Accordingly, this study investigated active plantar flexor muscle stiffness in response to a single WBV bout at four mechanical vibration frequencies.

Associations between long-term exercise participation and lower limb joint and whole-bone geometry in young and older adults.

Features of lower limb bone geometry are associated with movement kinematics and clinical outcomes including fractures and osteoarthritis. Therefore, it is important to identify their determinants. Lower limb geometry changes dramatically during development, partly due to adaptation to the forces experienced during physical activity.

Impaired Physical Performance in X-linked Hypophosphatemia Is not Caused by Depleted Muscular Phosphate Stores.

Context: X-linked hypophosphatemia (XLH) is a rare genetic disease, characterized by renal phosphate wasting and complex musculoskeletal manifestations including decreased physical performance.

Objective: To characterize muscular deficits in patients with XLH and investigate phosphate stores in muscles.

Methods: Case-control study (Muscle fatigability in X-linked Hypophosphatemia [MuXLiH]) with a 1-time assessment at the German Aerospace Center (DLR), Cologne, from May to December 2019, including patients with XLH cared for at the Osteology Department, University of Wuerzburg.

External to internal cranial perfusion shifts during simulated weightlessness: Results from a randomized cross-over trial.

The exact pathophysiology of the spaceflight-associated neuro-ocular syndrome (SANS) has so far not been completely elucidated. In this study we assessed the effect of acute head-down tilt position on the mean flow of the intra- and extracranial vessels. Our results suggest a shift from the external to the internal system that might play an important role in the pathomechanism of SANS.

Case Report: Muscle Wasting during Severe Sustained Hypoxia in Two Professional Mountaineers.

Purpose: Chronic exposure to hypoxia can induce muscle wasting in unaccustomed individuals. Detailed assessment of the effects of hypoxia on muscle tissue adaptation in elite mountaineers has not been performed. This study aims to assess muscle volume after exposure to normobaric hypoxia.

Effects of Aging and Fitness on Hopping Biomechanics.

Physical exercise promotes healthy aging and is associated with greater functionality and quality of life. Muscle strength and power are established factors in the ability to perform daily tasks and live independently. Stiffness, for mechanical reasons, is another important constituent of running performance and locomotion.

The Effects of Reconditioning Exercises Following Prolonged Bed Rest on Lumbopelvic Muscle Volume and Accumulation of Paraspinal Muscle Fat.

Reduced muscle size and accumulation of paraspinal muscle fat content (PFC) have been reported in lumbopelvic muscles after spaceflights and head-down tilt (HDT) bed rest. While some information is available regarding reconditioning programs on muscle atrophy recovery, the effects on the accumulation of PFC are unknown. Recently, a device (the Functional Re-adaptive Exercise Device-FRED) has been developed which aims to specifically recruit lumbopelvic muscles.

Lower limb bone geometry in adult individuals with X-linked hypophosphatemia: an observational study.

Unlabelled: We assessed lower-limb geometry in adults with X-linked hypophosphatemia (XLH) and controls. We found large differences in multiple measures including femoral and tibial torsion, bowing and cross-sectional area and acetabular version and coverage which may contribute to clinical problems such as osteoarthritis, fractures and altered gait common in XLH.

Purpose: Individuals with X-linked hypophosphatemia (XLH) are at risk of lower-limb deformities and early onset of osteoarthritis.

Gluteal Muscle Atrophy and Increased Intramuscular Lipid Concentration Are Not Mitigated by Daily Artificial Gravity Following 60-Day Head-Down Tilt Bed Rest.

Exposure to spaceflight and head-down tilt (HDT) bed rest leads to decreases in the mass of the gluteal muscle. Preliminary results have suggested that interventions, such as artificial gravity (AG), can partially mitigate some of the physiological adaptations induced by HDT bed rest. However, its effect on the gluteal muscles is currently unknown.

Intramuscular lipid concentration increased in localized regions of the lumbar muscles following 60 day bedrest.

Background Context: Prolonged bedrest induces accumulation of intramuscular lipid concentration (ILC) in the lumbar musculature; however, spatial distribution of ILC has not been determined. Artificial gravity (AG) mitigates some adaptations induced by 60 day bedrest by creating a head-to-feet force while participants are in a supine position.

Purpose: To quantify the spatial distribution of accumulation of ILC in the lumbar musculature after 60 day bedrest, and whether this can be mitigated by AG exposure.

Effects of Six-Week Resistance Training with or without Vibration on Metabolic Markers of Bone Metabolism.

Acute and protracted effects of resistive exercise (RE) and resistive exercise with whole-body vibration (RVE) on metabolic markers of bone metabolism were investigated. Twenty-six men participated in a randomized training program including RE ( = 13; age = 23.4 ± 1.

Lumbar muscle atrophy and increased relative intramuscular lipid concentration are not mitigated by daily artificial gravity after 60-day head-down tilt bed rest.

Exposure to axial unloading induces adaptations in paraspinal muscles, as shown after spaceflights. This study investigated whether daily exposure to artificial gravity (AG) mitigated lumbar spine flattening and muscle atrophy associated with 60-day head-down tilt (HDT) bed rest (Earth-based space analog). Twenty-four healthy individuals participated in the study: 8 received 30-min continuous AG; 8 received 6 × 5-min AG interspersed with rest periods; and 8 received no AG exposure (control group).

Quantitative assessment of the lumbar intervertebral disc via T2 shows excellent long-term reliability.

Methodologies for the quantitative assessment of the spine tissues, in particular the intervertebral disc (IVD), have not been well established in terms of long-term reliability. This is required for designing prospective studies. 1H water T2 in the IVD ("T2") has attained wider use in assessment of the lumbar intervertebral discs via magnetic resonance imaging.

Daily 30-min exposure to artificial gravity during 60 days of bed rest does not maintain aerobic exercise capacity but mitigates some deteriorations of muscle function: results from the AGBRESA RCT.

Purpose: Spaceflight impairs physical capacity. Here we assessed the protective effect of artificial gravity (AG) on aerobic exercise capacity and muscle function during bed rest, a spaceflight analogue.

Methods: 24 participants (33 ± 9 years, 175 ± 9 cm, 74 ± 10 kg, 8 women) were randomly allocated to one of three groups: continuous AG (cAG), intermittent AG (iAG) or control (CTRL).

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system.

Although acute hypoxia is of utmost pathophysiologic relevance in health and disease, studies on its effects on both the macro- and microcirculation are scarce. Herein, we provide a comprehensive analysis of the effects of acute normobaric hypoxia on human macro- and microcirculation. 20 healthy participants were enrolled in this study.

Enhanced Blood Supply Through Lower Body Negative Pressure During Slow-Paced, High Load Leg Press Exercise Alters the Response of Muscle AMPK and Circulating Angiogenic Factors.

Lower body negative pressure (LBNP) is an established method of simulating the gravitational effects of orthostasis on the cardiovascular system during space flight or at supine body position on Earth. We hypothesized that LBNP added onto leg press exercise would promote leg muscle perfusion, stimulate oxygen consumption, and modify acute molecular responses. Eighteen subjects performed fifteen slow-paced concentric (4 s) and eccentric contractions (4 s) without or with 40 mmHg LBNP.

Whey protein supplementation with vibration exercise ameliorates lumbar paraspinal muscle atrophy in prolonged bed rest.

Optimizing countermeasures for musculoskeletal deterioration during spaceflight is a priority for space agencies. We examined the impact of adding whey protein supplementation to resistive vibration exercise (RVE) on lumbar deconditioning during prolonged bed rest. Participants ( = 12) were enrolled in a crossover design study of 21 days of bed rest with RVE (2 days/wk, 2-4 min/session time under tension), whey protein supplementation plus RVE (NeX), and no-intervention control (CNT).

Effects of 21 days of bed rest and whey protein supplementation on plantar flexor muscle fatigue resistance during repeated shortening contractions.

Purpose: Space flight and bed rest (BR) lead to a rapid decline in exercise capacity. Whey protein plus potassium bicarbonate diet-supplementation (NUTR) could attenuate this effect by improving oxidative metabolism. We evaluated the impact of 21-day BR and NUTR on fatigue resistance of plantar flexor muscles (PF) during repeated shortening contractions, and whether any change was related to altered energy metabolism and muscle oxygenation.

Changes in motor unit activity and respiratory oxygen uptake during 6 weeks of progressive whole-body vibration combined with progressive, high intensity resistance training.

Objectives: We hypothesized that the additional activation of motor units (MU) and the elevation of metabolic energy turnover resulting from whole-body vibration (WBV) superimposed to high intensity resistance training on a smith machine persist after 6 weeks of training with progressively increasing loads and vibration frequencies.

Methods: Two groups of healthy male subjects performed either 6 weeks of Resistive Vibration Exercise (RVE, squats and heel raises with WBV, n=13) or Resistive Exercise (RE using the same protocol, n=13). During the first (pre) and the last training session (post), we determined the oxygen uptake changes normalized to total training weight (∆V'O/ttw) and the normalized MU activity from rectus femoris (squats) and gastrocnemius lateralis (heel raise) muscles filtered for vibration frequencies and harmonics (EMG/ttw).

Sleep Is Compromised in -12° Head Down Tilt Position.

Recent studies are elucidating the interrelation between sleep, cranial perfusion, and cerebrospinal fluid (CSF) circulation. Head down tilt (HDT) as a simulation of microgravity reduces cranial perfusion. Therefore, our aim was to assess whether HDT is affecting sleep (clinicaltrials.

Lower body negative pressure enhances oxygen availability in the knee extensor muscles during intense resistive exercise in supine position.

Purpose: During exercise in supine posture or under microgravity in space, the gravity-dependent component of local blood pressure in leg muscles at upright posture can be simulated by lower body negative pressure (LBNP). We hypothesized that during resistive exercise LBNP favors oxygen availability in lower extremities, benefiting energy levels and performance of working muscles.

Methods: In permutated crossover design, nine subjects performed a series of fifteen slow-paced concentric (4 s) and eccentric contractions (4 s) without or with 40 mmHg LBNP and 4 s pause between repetitions.

A Comparison of Squatting Exercise on a Centrifuge and With Earth Gravity.

Long-duration space missions require countermeasures against the muscular wasting and cardiovascular deconditioning associated with microgravity. Replacing gravitational acceleration by means of centrifugation is a promising alternative as it challenges all physiological systems at once. The aim of this study is to examine the metabolic energy costs of squatting on a centrifuge in comparison with squatting in an upright standing posture under natural gravity.

Vibration-related extrusion of capillary blood from the calf musculature depends upon directions of vibration of the leg and of the gravity vector.

Purpose: In this study, we investigated the effects of vibration of the whole lower leg on the content and the oxygenation of hemoglobin in the unloaded relaxed lateral gastrocnemius muscle. Vibration was applied orthogonal to and in parallel with leg axis to examine whether the extrusion of blood depends on an alignment of main vessel direction, axis of vibration and gravity.

Method: The blood volume in the muscles was altered by horizontal and 30° upright body posture.

Using the Hephaistos orthotic device to study countermeasure effectiveness of neuromuscular electrical stimulation and dietary lupin protein supplementation, a randomised controlled trial.

Purpose: The present study investigated whether neuromuscular electrical stimulation for 20 min twice a day with an electrode placed over the soleus muscle and nutritional supplementation with 19 g of protein rich lupin seeds can reduce the loss in volume and strength of the human calf musculature during long term unloading by wearing an orthotic unloading device.

Methods: Thirteen healthy male subjects (age of 26.4 ± 3.

Short-arm centrifugation as a partially effective musculoskeletal countermeasure during 5-day head-down tilt bed rest--results from the BRAG1 study.

Purpose: Human centrifugation, also called artificial gravity (AG), is proposed as a combined strategy against detrimental effects of microgravity in long-term space missions. This study scrutinized human short-arm centrifugation as countermeasure against musculoskeletal de-conditioning.

Method: Eleven healthy male subjects [mean age of 34 (SD 7) years] completed the cross-over trial, including three campaigns of -6° head-down tilt bed rest (HDT) for 5 days, with preceding baseline data collection and recovery phases.