Resistive vibration exercise during bed-rest reduces motor control changes in the lumbo-pelvic musculature

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Abstract

To understand the effects of a resistive vibration exercise (RVE) countermeasure on changes in lumbo-pelvic muscle motor control during prolonged bed-rest, 20 male subjects took part in the Berlin Bed-Rest Study (in 2003–2005) and were randomised to a RVE group or an inactive control group. Surface electromyographic signals recorded from five superficial lumbo-pelvic muscles during a repetitive knee movement task. The task, which required stabilisation of the lumbo-pelvic region, was performed at multiple movement speeds and at multiple time points during and after bed-rest. After excluding effects that could be attributed to increases in subcutaneous fat changes and improvements in movement skill, we found that the RVE intervention ameliorated the generalised increases in activity ratios between movement speeds (p  0.012), reductions in lumbo-pelvic extensor and flexor co-contraction (p = 0.058) and increases in root-mean-square electromyographic amplitude (p = 0.001) of the lumbar erector spinae muscles. Effects of RVE on preventing increases in amplitude-modulation (p = 0.23) of the lumbar erector spinae muscles were not significant. Few significant changes in activation-timing were seen. The RVE intervention during bed-rest, with indirect loading of the spine during exercise, was capable of reducing some, but not all, motor control changes in the lumbo-pelvic musculature during and after bed-rest.

Introduction

Bed-rest represents a unique model of extreme musculoskeletal disuse, particularly of the lower quadrant (Booth and Gollnick, 1983). The methodology of prolonged bed-rest was originally developed to act as a simulation of the effects of spaceflight on the human body (Nicogossian and Dietlein, 1982). An additional aim of space agencies in implementing bed-rest studies is to better understand the effect of “inactivity” on the human body and in so doing aiming to improve our management of illness on Earth. Specifically in the musculature, the muscle groups most affected by bed-rest are those involved in upright posture and locomotion, such as the triceps surae, vasti and lumbar spine extensors (Belavý et al., 2011, Belavý et al., 2009b). In recent works, we have attempted to gain a better understanding of the effects of bed-rest on motor control at the lumbo-pelvic region (Belavý et al., 2010, Belavý et al., 2007a, Belavý et al., 2007b). Some of the findings have included development of generalised overactivity in the superficial lumbo-pelvic muscles, more phasic activation of the lumbar erector spinae and shift to higher median activation frequencies in this same muscle.

However, aside from gaining a better understanding of the effects of bed-rest on the human body, another goal of bed-rest studies is the development of countermeasures against the changes seen in spaceflight simulation. This information will help not only in the development of (exercise) programmes for preventing musculoskeletal deterioration in spaceflight, but may also better insight into treatment regimes on Earth for deconditioned patients. In the Berlin Bed-Rest Study (Armbrecht et al., 2010, Rittweger et al., 2006), a high-load resistive exercise programme with whole-body vibration (RVE) was implemented. This exercise programme was targeted predominately at the bones (Armbrecht et al., 2010, Rittweger et al., 2010) and muscles (Belavý et al., 2009c, Blottner et al., 2006, Mulder et al., 2006) of the lower limbs. Nonetheless, indirect loading of the lumbar spine occurred via shoulder straps. Magnetic resonance imaging investigations in these same subjects showed that the RVE subjects exhibited less atrophy of the short lumbar spine extensor muscles than in the control subjects (Belavý et al., 2008). Hence, we hypothesised that the RVE countermeasure would ameliorate the extent of motor control changes, as measured by electromyography, seen in the lumbo-pelvic muscles of the inactive control subjects.

Section snippets

Bed-rest protocol

The “Berlin Bed-Rest Study” was implemented by the Centre of Muscle and Bone Research at the Charité Benjamin Franklin Hospital in Berlin, Germany, from February 2003 to May 2005. Twenty male subjects underwent 8 weeks of strict bed-rest with a subsequent 6-month follow-up recovery period. The bed-rest protocol, as well as inclusion and exclusion criteria, is discussed in detail elsewhere (Rittweger et al., 2006). In brief, subjects were randomly allocated to either a group that remained

Results

Due to subject absence or technical difficulties, not all data from each subject on every scheduled testing day were available. The numbers of subjects able to be included in statistical analysis on each testing day are given in online Supplementary material.

Discussion

The current study examined the effect of a resistive vibration exercise (RVE) countermeasure on preventing motor control changes in the lumbo-pelvic musculature due to 56 days strict bed-rest. The loading of the spine during this exercise countermeasure occurred indirectly via shoulder straps. A number of differences were observed between the two subject groups, although not all were significant statistically on analysis of variance. These effects included an increase in activity-ratios (or

Acknowledgements

The authors wish to thank the subjects who participated in the study, and the staff of the Center of Muscle and Bone Research at the Charité Campus Benjamin Franklin Hospital, Berlin, Germany who helped implement the bed-rest study. The lead author wishes to thank Anne Diepgen, Björn Bühring and Franzi Luhn for their support during the lengthy data collection period. The IT-staff of the School of Information Technology and Electrical Engineering (Brisbane) are thanked for access to high-speed

Daniel L. Belavý is currently a post-doctoral research associate at the Charité University Medicine, Berlin. His interests are in musculoskeletal changes in weightlessness, countermeasures against these changes and he has also published in the fields of signal/data analysis. He enjoys his work but also enjoys taking it easy.

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    Daniel L. Belavý is currently a post-doctoral research associate at the Charité University Medicine, Berlin. His interests are in musculoskeletal changes in weightlessness, countermeasures against these changes and he has also published in the fields of signal/data analysis. He enjoys his work but also enjoys taking it easy.

    Stephen J. Wilson is a medically qualified engineer and medical doctor, is currently associate professor in the School of Information Technology and Electrical Engineering at the University of Queensland. Instrumentation and imaging for musculoskeletal measures is one theme of his research. He also participates in sleep and respiratory medicine based research projects and pursues interests in nonlinear biological signal analysis, biomedical instrumentation generally and engineering teaching at undergraduate level.

    Gabriele Armbrecht received her M.D. and Ph.D. at the Medical School, Free University, Berlin, Germany and is currently in her last year for board certification in radiology. Since 2004 she is vice-leader of the Centre for Muscle and Bone Research at the Charité University Medicine, Berlin. Her special interests are in radiological diagnostic techniques for detection of muscle and bone changes.

    Jörn Rittweger received his M.D. from the Ludwig-Maximilians University in Munich, Germany, and his Ph.D. in physiology from Charité University Medicine in Berlin. He is currently working as a Head of the division “Space Physiology” in the Institute of Aerospace Medicine at the German Aerospace Center (DLR) in Cologne, Germany.

    Dieter Felsenberg is leader of the Centre for Muscle and Bone Research and Professor at the Charité University Medicine, Berlin. His research focuses on osteoporosis, bone and muscle metabolism, bone biomechanics, diagnostics of bone metastases, sports medicine, rheumatoid arthritis, micro-CT technology and muscle and bone metabolism in weightlessness. He is a member of a number of European and American radiological and osteoporosis societies, is vice-president of the German Academy of Osteology and Rheumatology (DAdorW) and president of the German Society of Muscle and Bone Research.

    Carolyn A. Richardson focuses on into the most effective and efficient exercise treatment (and countermeasures) for musculoskeletal injuries, especially low back pain, which are linked to inadequate stabilisation and support of the joints. Current research has developed a new focus relating to the function of the human antigravity muscle system, which is severely affected when gravity is minimized (including in microgravity). These changes provide new information on the possible aetiology of low back pain, as well as other conditions such as osteoarthritis of the weightbearing joints and osteoporosis. This line of research has led to extensive research collaboration and consultancies with the European Space Agency (ESA), including scientific consultant to the Toulouse Bedrest study, member of the ESA Topical Team for Low Back Pain, Senior Collaborator and on the Board of the ESA project “Vibration Exercise in Space”, a Bedrest study, undertaken at the Free University of Berlin February 2003 to May 2005.

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