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Titolo:
MECHANICAL-BEHAVIOR OF SKELETAL-MUSCLE DURING INTERMITTENT VOLUNTARY ISOMETRIC CONTRACTIONS IN HUMANS
Autore:
VOLLESTAD NK; SEJERSTED I; SAUGEN E;
Indirizzi:
UNIV OSLO,SECT POSTGRAD STUDIES HLTH SCI,BOX 1153 BLINDERN N-0316 OSLO NORWAY NATL INST OCCUPAT HLTH,SECT POSTGRAD STUDIES HLTH SCI N-0316 OSLO NORWAY NATL INST OCCUPAT HLTH,DEPT PHYSIOL N-0316 OSLO NORWAY
Titolo Testata:
Journal of applied physiology
fascicolo: 5, volume: 83, anno: 1997,
pagine: 1557 - 1565
SICI:
8750-7587(1997)83:5<1557:MOSDIV>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
REPEATED SUBMAXIMAL CONTRACTIONS; METABOLIC HEAT-PRODUCTION; HUMAN ADDUCTOR POLLICIS; RELAXATION RATE; MOTOR UNITS; QUADRICEPS MUSCLE; FATIGUE; TEMPERATURE; FORCE; RECRUITMENT;
Keywords:
ENERGY COST; FATIGUE; RELAXATION RATE; SKELETAL MUSCLE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
N.K. Vollestad et al., "MECHANICAL-BEHAVIOR OF SKELETAL-MUSCLE DURING INTERMITTENT VOLUNTARY ISOMETRIC CONTRACTIONS IN HUMANS", Journal of applied physiology, 83(5), 1997, pp. 1557-1565

Abstract

Changes in contractile speed and force-fusion properties were examined during repetitive isometric contractions with the knee extensors at three different target force levels. Seven healthy subjects were studied at target force levels of 30, 45, and 60% of their maximal voluntary contraction (MVC) force. Repeated 6-s contractions followed by 4-s rest were continued until exhaustion. Contractile speed was determined for contractions elicited by electrical stimulation at 1-50 Hz given during exercise and a subsequent 27-min recovery period. Contraction time remained unchanged during exercise and recovery, except for an initial rapid shift in the twitch properties. Half relaxation time (RT1/2)decreased gradually by 20-40% during exercise at 30 and 45% of MVC. In the recovery period, RT1/2 values were not fully restored to preexercise levels. During exercise at 60% MVC, the RT1/2 decreased for twitches and increased for the 50-Hz stimulation. In the recovery period after 60% MVC, RT1/2 values declined toward those seen after the 30 and 45% MVC exercise. The force oscillation amplitude in unfused tetani relative to the mean force increased during exercise at 30 and 45% MVC but remained unaltered during the 60% MVC exercise. This altered force-fusion was closely associated with the changes in RT1/2. The faster relaxation may at least partly explain the increased energy cost of contraction reported previously for the same type of exercise.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/04/20 alle ore 19:15:47