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Titolo:
ADAPTIVE RESPONSES TO MUSCLE LENGTHENING AND SHORTENING IN HUMANS
Autore:
HORTOBAGYI T; HILL JP; HOUMARD JA; FRASER DD; LAMBERT NJ; ISRAEL RG;
Indirizzi:
E CAROLINA UNIV,BIOMECH LAB GREENVILLE NC 27858 E CAROLINA UNIV,HUMAN PERFORMANCE LAB GREENVILLE NC 27858 E CAROLINA UNIV,DEPT MED GREENVILLE NC 27858 E CAROLINA UNIV,DEPT PHYS THERAPY GREENVILLE NC 27858
Titolo Testata:
Journal of applied physiology
fascicolo: 3, volume: 80, anno: 1996,
pagine: 765 - 772
SICI:
8750-7587(1996)80:3<765:ARTMLA>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
HUMAN MOTOR UNITS; QUADRICEPS FEMORIS; ECCENTRIC ACTIONS; STRENGTH; CONTRACTION; EXERCISE; TORQUE; ANTERIOR; FORCE;
Keywords:
ECCENTRIC EXERCISE; MUSCLE FIBERS; ELECTROMYOGRAPHY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
T. Hortobagyi et al., "ADAPTIVE RESPONSES TO MUSCLE LENGTHENING AND SHORTENING IN HUMANS", Journal of applied physiology, 80(3), 1996, pp. 765-772

Abstract

We tested the hypothesis that exercise training with maximal eccentric (lengthening) muscle actions results in greater gains in muscle strength and size than training with concentric (shortening) actions. Changes in muscle strength, muscle fiber size, and surface electromyographic (EMG) activity of the quadriceps muscle were compared after 36 sessions of isokinetic concentric (n = 8) or eccentric (n = 7) exercise training over 12 wb with use of a one-leg model. Eccentric training increased eccentric strength 3.5 times more (pre/post 46%, P < 0.05) than concentric training increased concentric strength (pre/post 13%). Eccentric training increased concentric strength and concentric training increased eccentric strength by about the same magnitude (5 and 10%, respectively, P > 0.05). Eccentric training increased EMG activity seventimes more during eccentric testing (pre/post 86%, P < 0.05) than concentric training increased EMG activity during concentric testing (pre/post 12%). Eccentric training increased the EMC activity measured during concentric tests and concentric training increased the EMG activity measured during eccentric tests by about the same magnitude (8 and 11%, respectively, P > 0.05). Type I muscle fiber percentages did not change significantly, but type IIa fibers increased and type IIb fibersdecreased significantly (P < 0.05) in both training groups. Type I fiber areas did not change significantly (P > 0.05), but type II fiber area increased similar to 10 times more (P < 0.05) in the eccentric than in the concentric group. It is concluded that adaptations to training with maximal eccentric contractions are specific to eccentric muscleactions that are associated with greater neural adaptation and musclehypertrophy than concentric exercise.

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Documento generato il 03/12/20 alle ore 05:08:33