Article Text
Abstract
Aims To investigate differential muscle atrophy during bed-rest, the impact of a high-intensity concentric-eccentric (flywheel) resistance exercise countermeasure and muscle recovery after bed-rest.
Methods Twenty-five healthy male subjects underwent 90 dayshead-down tilt bed-rest. Volume of individual lower-limb muscles was measured via MRI before, twice during and four times up to 1 year after bed-rest. Subjects were either inactive (n=16) or performed flywheel exercise every third day of bed-rest (n=9). Functional performance was assessed via countermovement jump.
Results On ‘intent-to-treat’ analysis, flywheel prevented atrophy in the vasti (p<0.001) and reduced atrophy in the hip adductor/extensor adductor magnus (p=0.001) and ankle dorsiflexors/toe flexors (soleus (p<0.001), gastrocnemius medialis (p<0.001), gastrocnemius lateralis (p=0.02), and tibialis posterior with flexor digitorum longus (p=0.04)). Flywheel exercise was not effective for the hamstrings, gracilis, sartorius, peroneals and anterior tibial muscles. Muscle atrophy in vasti, soleus, gastrocnemius medialis, gastrocnemius lateralis and adductor magnus correlated with losses in countermovement jump performance. Muscle volume recovered within 90 days after bed-rest, however long-term after bed-rest, the inactive subjects only showed significantly increased muscle volume versus prebed-rest in a number of muscles including soleus (+4.3%), gastrocnemius medialis (+3.9%) and semimembranosus (+4.3%). This was not associated with greater countermovement jump performance.
Conclusion The exercise countermeasure was effective in preventing or reducing atrophy in the vasti, adductor magnus and ankle dorsiflexors/toe flexors but not the hamstrings, medial thigh muscles or peroneals and dorsiflexor muscles.
Trial registration number NCT00311571; results.
- Muscle
- Exercise
- Exercise rehabilitation
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Footnotes
Acknowledgements The authors thank the subjects for their participation in the study. Centre National d’Etudes Spatiales (CNES) was the ‘Promoteur’ of the study according to French law and the LTBR study has been performed by MEDES, Institute for Space Physiology and Medicine. The results of the present study do not constitute endorsement by ACSM.
Contributors DLB: analysis of MRI data, statistical analyses, drafting of manuscript.
HO: conception and design of the experiments, secured funding, approved final version of the manuscript.
JR: conception and design of the experiments, organised data acquisition, secured funding, interpretation of results, revision of manuscript.
DF: conception and design of the experiments, secured funding, revision of manuscript.
Funding The participation of Rittweger/Felsenberg in the LTBR study was supported by the German Aerospace Center with grant number 50 WB 0156. The analyses of the image data were supported by grant number 50 WB 1220 from the German Aerospace Center (DLR). The LTBR study was sponsored by the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA) and the Centre National d’Etudes Spatiales (CNES).
Competing interests None declared.
Ethics approval Toulouse I ethics committee (CCPPRB Toulouse I) of the Rangueil University Hospital as well as the ethical committee of the Free University of Berlin.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This paper has been amended since it was published Online First. Owing to a scripting error, some of the publisher names in the references were replaced with 'BMJ Publishing Group'. This only affected the full text version, not the PDF. We have since corrected these errors and the correct publishers have been inserted into the references.