Changes in lower extremity muscle function after 56 days of bed rest

Preservation of muscle function, known to decline in microgravity and simulation (bed rest), is important for successful spaceflight missions. Hence, there is great interest in developing interventions to prevent musclefunction loss. In this study, 20 males underwent 56 days of bed rest. Ten volunteers were randomized to do resistive vibration exercise (RVE). The other 10 served as controls. RVE consisted of muscle contractions against resistance and concurrent whole-body vibration. Main outcome parameters were maximal isometric plantar-flexion force (IPFF), electromyography (EMG)/force ratio, as well as jumping power and height. Measurements were obtained before and after bed rest, including a morning and evening assessment on the first day of recovery from bed rest. IPFF (-17.1%), jumping peak power (-24.1%), and height (-28.5%) declined (P < 0.05) in the control group. There was a trend to EMG/force ratio decrease (-20%; P < 0.051). RVE preserved IPFF and mitigated the decline of countermovement jump performance (peak power -12.2%; height -14.2%). In both groups, IPFF was reduced between the two measurements of the first day of reambulation. This study indicates that bed rest and countermeasure exercises differentially affect the various functions of skeletal muscle. Moreover, the time course during recovery needs to be considered more thoroughly in future studies, as IPFF declined not only with bed rest but also within the first day of reambulation. RVE was effective in maintaining IPFF but only mitigated the decline in jumping performance. More research is needed to develop countermeasures that maintain muscle strength as well as other muscle functions including power

In vivo bone remodeling rates determination and compressive stiffness variations before, during 60 days bed rest and two years follow up: A micro-FE-analysis from HR-pQCT measurements of the berlin Bed Rest Study-2

Bed rest studies are used for simulation and study of physiological changes as observed in unloading/non-gravity environments. Amongst others, bone mass reduction, similar as occurring due to aging osteoporosis, combined with bio-fluids redistribution and muscle atrophy have been observed and analyzed. Advanced radiological methods of high resolution such as HR-pQCT (XtremeCT) allow 3D-visualizing in vivo bone remodeling processes occurring during absence/reduction of mechanical stimuli (0 to &lt;1&nbsp;g) as simulated by bed rest. Induced bone micro-structure (e.g. trabecular number, cortical thickness, porosity) and density variations can be quantified. However, these parameters are average values of each sample and important information regarding bone mass distribution and within bone mechanical behaviour is lost. Finite element models with hexa-elements of identical size as the HR-pQCT measurements (0.082&nbsp;mm&times;0.082&nbsp;mm&times;0.082&nbsp;mm, ca. 7E6 elements/sample) can be used for subject-specific in vivo stiffness calculation. This technique also allows quantifying if bone microstructural changes represent a risk of mechanical bone collapse (fracture). Materials and methods In the Berlin Bed Rest Study-2, 23 male subjects (20&ndash;50 YO) were maintained 60 days under restricted bed rest (6&deg; HDT) aiming to test a - for this study specifically designed - vibration resistive exercise regime for maintenance of bone mass and muscle functionality at normal levels (base line measurements). For comparison a resistive exercise without vibration and a control group were included. Base line HR-pQCT measurements (3 days before bed rest: base line), as well as during 30 days bed rest (BR30 and BR59, 3 days of recovery (R3), R15, R30, R90, R180, R360, and R720 were performed. CT-scan voxels were converted into finite elements (hexa-82&nbsp;&micro;m edge length) for calculating in vivo compressive stiffness during the experiment duration. Histograms of stresses and strains distributions as well as anatomical regions susceptible for mechanical failure were identified and compared. Results: Resistive vibration exercises (RVE) were able to maintain in the majority of the subjects compressive bone strength as determined after modelling a compressive test using finite element models. Compressive bone stiffness using FEA was monitored through analysis of the internal deformation on the trabecular structures and cortical bone, reaction forces, and minimum principal strains on the in vivo CT measured bone regions during the experiment duration. Stress distributions (main stresses) and von Mises stress distribution remained comparable with those determined in the base line measurements for the RVE-group. However, no major differences were found in the group with resistive exercise training alone. Without mechanical stimuli an increment of bone regions with high stress concentration was observed and a reduction of up to 10% of bone compressive stiffness was quantified by using subject-specific finite-element analysis. Anatomically von Mises stress concentrations, thus bone regions susceptible to fail mechanically, were observed at the center of the cancellous bone and at the antero- posterior region of the cortical bone. Conclusions: Finite element simulations from bed rest studies are an invaluable tool to determine subject-specific in vivo compressive stiffness and anatomical mechanically compromised regions under controlled mechanical conditions (unloading) which - until now - are not possible to be determined with any other method. Vibration exercise combined with a resistive compressive force was able to maintain bone structure and density even during 60 days of bed rest

Plyometrics can preserve peak power during 2 months of physical inactivity: an RCT including a one-year follow-up

Objective: Inactivity results in a marked loss of muscle function, especially in movements requiring high power, force, and rate of force development. The aim of the present study was to evaluate if jump training can prevent these deteriorating effects of physical inactivity. Methods: Performance and muscle activity during several types of jumps was assessed directly before and after 60 days of bed rest as well as during follow-up visits in 23 male participants. Participants in the jump training group (JUMP, 12 participants) trained 5-6x per week during the bed rest period in a sledge jump system that allows jumps in a horizontal position, whereas the control group (CTRL, 11 participants) did not train. Results: Performance and muscle activity considerably decreased after bed rest in the control group but not in the training group, neither for countermovement jumps (peak power CTRL -31%, JUMP +0%, group &times; time interaction effect p &lt; 0.001), nor for squat jumps (peak power CTRL -35%, JUMP +1%, p &lt; 0.001) and repetitive hops (peak force CTRL -35%, JUMP -2%, p &lt; 0.001; rate of force development CTRL -53%, JUMP +4%, p &lt; 0.001). The control group\u27s performance had returned to baseline 3 months after bed rest. Conclusion: Despite the short exercise duration, the jump training successfully prevented power and strength losses throughout 2 months of bed rest.Thus, plyometrics can be recommended as an effective and efficient type of exercise for sedentary populations, preventing the deterioration of neuromuscular performance during physical inactivity

Systematic review of countermeasures to minimise physiological changes and risk of injury to the lumbopelvic area following long-term microgravity

publisher: Elsevier articletitle: Systematic review of countermeasures to minimise physiological changes and risk of injury to the lumbopelvic area following long-term microgravity journaltitle: Musculoskeletal Science and Practice articlelink: http://dx.doi.org/10.1016/j.msksp.2016.12.009 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved

Boosting treatment outcomes via the patient-practitioner relationship, treatment-beliefs or therapeutic setting. A systematic review with meta-analysis of contextual effects in chronic musculoskeletal pain.

Objective: To ascertain whether manipulating contextual effects (e.g. interaction with patients, or beliefs about treatments) boosted the outcomes of non-pharmacological and non-surgicaltreatments for chronic primary musculoskeletal pain.Design: Systematic review of randomized controlled trialsData Sources: We searched for trials in six databases, citation tracking, and clinical trials registers. We included trials that compared treatments with enhanced contextual effects with the same treatments without enhancement in adults with chronic primary musculoskeletal pain.Data synthesis: The outcomes of interest were pain intensity, physical functioning, global ratings of improvement, quality of life, depression, anxiety, and sleep. We evaluated risk of bias and certainty of the evidence using Cochrane Risk of Bias tool 2.0 and the GRADE approach, respectively.Results: Of 17637 records, we included 10 trials with 990 participants and identified 5 ongoing trials. The treatments were acupuncture, education, exercise training, and physical therapy. The contextual effects that were improved in the enhanced treatments were patient-practitioner relationship, patient beliefs and characteristics, therapeutic setting/environment, and treatment characteristics. Our analysis showed that improving contextual effects in non-pharmacological and non-surgical treatments may not make much difference on pain intensity (mean difference [MD] : -1.77, 95%-CI: [-8.71; 5.16], k = 7 trials, N = 719 participants, Scale: 0-100, GRADE: Low)) or physical functioning (MD: -0.27, 95%-CI: [-1.02; 0.49], 95%-PI: [-2.04; 1.51], k = 6 , N = 567, Scale: 0-10, GRADE: Low) in the short-term and at later follow-ups. Sensitivity analyses revealed similar findings.Conclusion: Whilst evidence gaps exist, per current evidence it may not be possible to achieve meaningful benefit for patients with chronic musculoskeletal pain by manipulating the context of non-pharmacological and non-surgical treatments

Domains of chronic low back pain and assessing treatment effectiveness : a clinical perspective

Nonspecific chronic low back pain (CLBP) is a common clinical condition that has impacts at both the individual and societal level. Pain intensity is a primary outcome used in clinical practice to quantify the severity of CLBP and the efficacy of its treatment; however, pain is a subjective experience that is impacted by a multitude of factors. Moreover, differences in effect sizes for pain intensity are not observed between common conservative treatments, such as spinal manipulative therapy, cognitive behavioral therapy, acupuncture, and exercise training. As pain science evolves, the biopsychosocial model is gaining interest in its application for CLBP management. The aim of this article is to discuss our current scientific understanding of pain and present why additional factors should be considered in conservative CLBP management. In addition to pain intensity, we recommend that clinicians should consider assessing the multidimensional nature of CLBP by including physical (disability, muscular strength and endurance, performance in activities of daily living, and body composition), psychological (kinesiophobia, fear-avoidance, pain catastrophizing, pain self-efficacy, depression, anxiety, and sleep quality), social (social functioning and work absenteeism), and health-related quality-of-life measures, depending on what is deemed relevant for each individual. This review also provides practical recommendations to clinicians for the assessment of outcomes beyond pain intensity, including information on how large a change must be for it to be considered "real" in an individual patient. This information can guide treatment selection when working with an individual with CLBP

J Musculoskelet Neuronal Interact

Long-term bed-rest is used to simulate the effect of spaceflight on the human body and test different kinds of countermeasures. The 2nd Berlin BedRest Study (BBR2-2) tested the efficacy of whole-body vibration in addition to high-load resisitance exercise in preventing bone loss during bed-rest. Here we present the protocol of the study and discuss its implementation. Twenty-four male subjects underwent 60-days of six-degree head down tilt bed-rest and were randomised to an inactive control group (CTR), a high-load resistive exercise group (RE) or a high-load resistive exercise with whole-body vibration group (RVE). Subsequent to events in the course of the study (e.g. subject withdrawal), 9 subjects participated in the CTR-group, 7 in the RVE-group and 8 (7 beyond bed-rest day-30) in the RE-group. Fluid intake, urine output and axiallary temperature increased during bed-rest (p or = .17). Body weight changes differed between groups (p < .0001) with decreases in the CTR-group, marginal decreases in the RE-group and the RVE-group displaying significant decreases in body-weight beyond bed-rest day-51 only. In light of events and experiences of the current study, recommendations on various aspects of bed-rest methodology are also discussed

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. The reliability of IVD T2 measurements are yet to be established. IVD T2 was assessed nine times at regular intervals over 368 days on six anatomical slices centred at the lumbar spine using a spin-echo multi-echo sequence in 12 men. To assess repeatability, intra-class correlation co-efficients (ICCs), standard error of the measurement, minimal detectable difference and co-efficients of variation (CVs) were calculated along with their 95% confidence intervals. Bland-Altman analysis was also performed. ICCs were above 0.93, with the exception of nuclear T2 at L5/S1, where the ICC was 0.88. CVs of the central-slice nucleus sub-region ranged from 4.3% (average of all levels) to 10.1% for L5/S1 and between 2.2% to 3.2% for whole IVD T2 (1.8% for the average of all levels). Averaging between vertebral levels improved reliability. Reliability of measurements was least at L5/S1. ICCs of degenerated IVDs were lower. Test-retest reliability was excellent for whole IVD and good to excellent for IVD subregions. The findings help to establish the long-term repeatability of lumbar IVD T2 for the implementation of prospective studies and determination of significant changes within individuals

Influence of Habitual Physical Behavior – Sleeping, Sedentarism, Physical Activity – On Bone Health in Community-Dwelling Older People

Sedentary behavior (SB) has emerged as an independent public-health risk and may contribute to the lower bone mineral density (BMD) in old (>60 years of age) than young adults. The purpose of this study was to quantify SB and habitual physical behavior (PB) in community-dwelling older adults and how this correlates with BMD. In 112 relatively healthy and independent-living individuals aged 72.5 ± 6.4 years, BMD, PB and SB were determined using dual energy X-ray absorptiometry and 7-day three-dimensional accelerometry, respectively. In men, only healthy and osteopenic BMDs were found, whereas in women, osteoporotic BMD classifications also occurred. Our sample spent ∼61%, 7%, 12% and 19% of daily waking hours in SB, standing, LIPA [light intensity physical activity (PA)] and MVPA (medium-to-vigorous intensity PA), respectively. In men, after accounting for covariates (BMI, total fat, android:gynoid ratio), sleeping (hours/day), number of breaks in SB, number of SB ≥ 5 min, number of PA bouts, total duration of PA bouts (min), mean PA bouts duration (min), LIPA (%PA bout time) and MVPA (%PA bout time) were all predictors of BMD. In women, after accounting for covariates (age, BMI, total fat, android:gynoid ratio), SB (hours/day), SB (% waking hours), LIPA (hours/day), LIPA (% waking hours), MVPA (% waking hours) and number of short SB (i.e., <5 min), total time spent in PA (min) significantly correlated with BMD. In conclusion, the PB predictors of bone health in older persons include: night time sleeping duration, number of short bouts of SB, number and duration of bouts of PA relative to total waking hours. While radar graphs of PB patterns for healthy, osteopenic, osteoporotic individuals highlighted significant differences in PB between them, they were not consistent with the expectations from the Mechanostat Theory: i.e., more loading leads to better bone. Rather, our results suggest that a balance of activities must be maintained across the PB spectrum, where certain PB parameters are especially impactful in each sex, supporting the recently coined multifactorial-based variations in the Mechanostat threshold