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Titolo:
EFFECT OF ACUTE HEAD-DOWN TILT ON SKELETAL-MUSCLE CROSS-SECTIONAL AREA AND PROTON TRANSVERSE RELAXATION-TIME
Autore:
CONLEY MS; FOLEY JM; PLOUTZSNYDER LL; MEYER RA; DUDLEY GA;
Indirizzi:
UNIV GEORGIA,RAMSEY CTR,DEPT EXERCISE SCI ATHENS GA 30602 UNIV GEORGIA,RAMSEY CTR,DEPT EXERCISE SCI ATHENS GA 30602 MICHIGAN STATE UNIV,DEPT PHYS EDUC E LANSING MI 48824 MICHIGAN STATE UNIV,DEPT PHYSIOL & RADIOL E LANSING MI 48824
Titolo Testata:
Journal of applied physiology
fascicolo: 4, volume: 81, anno: 1996,
pagine: 1572 - 1577
SICI:
8750-7587(1996)81:4<1572:EOAHTO>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
TEMPERATURE-DEPENDENCE; METABOLIC MYOPATHIES; EXERCISE INTENSITY; P-31 SPECTROSCOPY; FLUID SHIFTS; WATER; T2; IMAGES; MICROGRAVITY; SENSITIVITY;
Keywords:
SIMULATED MICROGRAVITY; MAGNETIC RESONANCE IMAGING; POSTURE; SKELETAL MUSCLE SIZE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
M.S. Conley et al., "EFFECT OF ACUTE HEAD-DOWN TILT ON SKELETAL-MUSCLE CROSS-SECTIONAL AREA AND PROTON TRANSVERSE RELAXATION-TIME", Journal of applied physiology, 81(4), 1996, pp. 1572-1577

Abstract

This study investigated changes in skeletal muscle cross-sectional area (CSA) evoked by fluid shifts that accompany short-term 6 degrees head-down tilt (HDT) or horizontal bed rest, the time course of the resolution of these changes after resumption of upright posture, and the effect of altered muscle CSA, in the absence of increased contractile activity, on proton transverse relaxation time (T-2). Average muscle CSA and T-2 were determined by standard spin-echo magnetic resonance imaging. Analyses were performed on contiguous transaxial images of the neck and calf. After a day of normal activity, 24 h of HDT increased neck muscle CSA 19 +/- 4 (SE)% (P < 0.05) while calf muscle CSA decreased 14 +/- 3% (P < 0.05). The horizontal posture (12 h) induced about one-half of these responses: an 11 +/- 2% (P < 0.05) increase in neck muscle CSA and an 8 +/- 2% decrease (P < 0.05) in the calf. Within 2 h after resumption of upright posture, neck and calf muscle CSA returned to within 0.5% (P > 0.05) of the values assessed after a day of normalactivity, with most of the change occurring within the first 30 min. No further change in muscle CSA was observed through 6 h of upright posture. Despite these large alterations in muscle CSA, T-2 was not altered by more than 1.1 +/- 0.6% (P > 0.05) and did not relate to muscle size. These results suggest that postural manipulations and subsequentfluid shifts modeling microgravity elicit marked changes in muscle size. Because these responses were not associated with alterations in muscle T-2, it does not appear that simple movement of water into musclecan explain the contrast shift observed after exercise.

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Documento generato il 03/12/20 alle ore 12:37:45