Muscle metabolic economy is inversely related to exercise intensity and type II myofiber distribution

Citation
Gr. Hunter et al., Muscle metabolic economy is inversely related to exercise intensity and type II myofiber distribution, MUSCLE NERV, 24(5), 2001, pp. 654-661
Citations number
32
Categorie Soggetti
da verificare
Journal title
MUSCLE & NERVE
ISSN journal
0148639X → ACNP
Volume
24
Issue
5
Year of publication
2001
Pages
654 - 661
Database
ISI
SICI code
0148-639X(200105)24:5<654:MMEIIR>2.0.ZU;2-8
Abstract
It is not known what causes the well-established inverse relationship betwe en whole-body exercise economy and exercise intensity. The purpose of this study was to: (1) evaluate muscle exercise economy at 45%, 70%, and maximum isometric strength using P-31 magnetic resonance spectroscopy (P-31-MRS); and (2) determine the relationship between percent type II muscle fiber cro ss-section, whole-body exercise economy, and muscle exercise economy. Subje cts included 32 premenopausal women. Muscle exercise economy was significan tly different across the three exercise intensities (28.1 +/- 10,4, 24.8 +/ - 8,2, and 20.2 +/- 7.5 N/cm(2) mmol/L adenosine triphosphate [ATP] for the 45%, 70%, and maximum intensities, respectively). Percent type II muscle a rea was significantly related to whole-body metabolic economy during activi ties of daily living (r = -0.68) and P-31-MRS muscle metabolic economy duri ng isometric plantar flexion (r = -0.53), These data suggest that skeletal muscle becomes less economical as force production increases, and that thes e decreases in metabolic economy may be related to increased dependence on inefficient type II muscle. (C) 2001 John Wiley & Sons, Inc.