Influence of long-term spaceflight on neuromechanical properties of muscles in humans
| Autor: | Daniel Lambertz, Francis Goubel, Chantal Pérot, Rustem Kaspranski |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Male
Reflex Stretch medicine.medical_specialty Time Factors Physiology Astronauta Musculotendinous stiffness Spaceflight law.invention H-Reflex law Isometric Contraction Physiology (medical) Internal medicine medicine Humans Nervous System Physiological Phenomena Stretch reflex Muscle Skeletal biology Weightlessness business.industry Anatomy Space Flight biology.organism_classification Elasticity medicine.anatomical_structure Endocrinology Reflex Stress Mechanical H-reflex business |
| Zdroj: | Journal of Applied Physiology. 94:490-498 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/japplphysiol.00666.2002 |
| Popis: | Reflex and elastic properties of the triceps surae (TS) were measured on 12 male cosmonauts 28–40 days before a 3- to 6-mo spaceflight, 2 or 3 days after return (R+2/+3) and a few days later (R+5/+6). H reflexes to electrical stimulations and T reflexes to tendon taps gave the reflex excitability at rest. Under voluntary contractions, reflex excitability was assessed by the stretch reflex, elicited by sinusoidal length perturbations. Stiffness measurements concerned the musculoarticular system in passive conditions and the musculotendinous complex in active conditions. Results indicated 1) no changes ( P > 0.05) in H reflexes, whatever the day of test, and 2) increase in T reflexes ( P < 0.05) by 57%, despite a decrease ( P < 0.05) in musculoarticular stiffness (11%) on R+2/+3. T reflexes decreased ( P < 0.05) between R+2/+3 and R+5/+6 (−21%); 3) increase in stretch reflexes ( P< 0.05) on R+2/+3 by 31%, whereas it decreased ( P < 0.05) between R+2/+3 and R+5/+6 (−29%). Musculotendinous stiffness was increased ( P < 0.05) whatever the day of test (25%). Links between changes in reflex and stiffness were also studied by considering individual data. At R+2/+3, correlated changes between T reflexes and musculoarticular stiffness suggested that, besides central adaptive phenomena, musculoarticular structures took part in the reflex adaptation. This mechanical contribution was confirmed when data collected at R+2/+3 and R+5/+6 were used because correlations between changes in stretch reflexes and musculotendinous stiffness were improved. In conclusion, the present study shows that peripheral influences take part in reflex changes in gravitational unloaded muscles, but can only be revealed when central influences are reduced. |
| Databáze: | OpenAIRE |
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