Biomaterial Database

Influence of 120-days 6 degrees head-down tilt bed rest on the functional properties of the neuromuscular system in man. 1998

Y A Koryak

Department of Neurophysiology, Institute of Biomedical Problems, Moscow, Russia.

The effect of a 120-d 6 degrees head-down tilt bed rest on the functional properties of the human triceps surae muscle have been studied in a group of male volunteers (n = 6), mean age 38 +/- 2 yr. According to tendometry measurements, maximum voluntary contraction and maximum strength in response to a nerve stimulation at a frequency of 150 impulses s(-1) after head-down tilt decreased by 45.5% and 33.7%, respectively (p < 0.05-0.01), and maximal twitch declined by 36.7% (p < 0.05). The magnitude of force deficiency increased by 60.2% (p < 0.001). Time to peak tension, half-relaxation time and total contraction time of twitch increased (p < 0.05-0.001); the maximum rate of rise of isometric tetanic tension as absolute tension exerted by the triceps surae muscle in response to an electrical stimulation of the motor nerve and during voluntary contraction performed on command to contract quickly and strongly decreased. With force expressed as a percentage of the maximum developed, the force-time curves did not alter significantly. A post head-down tilt fatigability index of the triceps surae muscle was to 0.61 +/- 0.02 as opposed to 0.80 +/- 0.03 prior to an exposure (p < 0.05). It is postulated that changes of contractile properties of the triceps surae muscle head-down tilt are linked to the atrophic processes, alterations of muscle length and the state of sarcoplasmic reticulum on the one hand, and to the altered state of the central nervous system, on the other.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D002490	Central Nervous System	The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges.	Cerebrospinal Axis,Axi, Cerebrospinal,Axis, Cerebrospinal,Central Nervous Systems,Cerebrospinal Axi,Nervous System, Central,Nervous Systems, Central,Systems, Central Nervous
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D001510	Bed Rest	Confinement of an individual to bed for therapeutic or experimental reasons.	Bedrest,Bed Rests,Bedrests,Rest, Bed,Rests, Bed
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014893	Weightlessness	Condition in which no acceleration, whether due to gravity or any other force, can be detected by an observer within a system. It also means the absence of weight or the absence of the force of gravity acting on a body. Microgravity, gravitational force between 0 and 10 -6 g, is included here. (From NASA Thesaurus, 1988)	Microgravity,Zero Gravity,Gravity, Zero
D018482	Muscle, Skeletal	A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.	Anterior Tibial Muscle,Gastrocnemius Muscle,Muscle, Voluntary,Plantaris Muscle,Skeletal Muscle,Soleus Muscle,Muscle, Anterior Tibial,Muscle, Gastrocnemius,Muscle, Plantaris,Muscle, Soleus,Muscles, Skeletal,Muscles, Voluntary,Skeletal Muscles,Tibial Muscle, Anterior,Voluntary Muscle,Voluntary Muscles