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Delayed Reoxygenation in the Anterior Tibialis Muscle Following Maximum Voluntary Contraction
Author(s) -
Damon Bruce M.,
Maguire Maria,
Weaver Timothy
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a802-d
Subject(s) - supine position , oxygenation , tibialis anterior muscle , contraction (grammar) , medicine , muscle contraction , isometric exercise , anatomy , cardiology , hemoglobin , anesthesia , skeletal muscle
The purpose of this study was to characterize the time course of tissue reoxygenation following brief dorsiflexion maximal voluntary contractions (MVCs). Because the anterior tibialis (AT) muscle has a high oxidative capacity, we hypothesized that there would be a transient fall in tissue oxygenation prior to restoration of normal tissue oxygenation. Methods 18 healthy subjects (9 male) lay supine and performed two or more 3s dorsiflexion MVCs. Total hemoglobin (THb), deoxyhemoglobin (HHb), and oxyhemoglobin saturation ( Y ) were measured continuously using near‐infrared spectroscopy (NIRS). The NIRS data from the two highest MVCs were fit to multi‐component exponential models containing sequential growth and decay terms. The kinetic parameters and values at specified time points were compared using ANOVA. Results Figure 1 shows group‐averaged fit NIRS data. [THb] fell during the contraction, rose above the baseline, and then decayed back to the pre‐exercise level. [HHb] was constant during the contraction, grew immediately following the contraction, decreased below the pre‐exercise level, and then returned to the pre‐exercise level. Y decreased during the contraction, decreased further during the first 11s after the contraction, grew above the pre‐exercise level, and then returned to baseline. Discussion There are three phases to the post‐MVC hemodynamic time course, as indicated by the vertical lines in Figure 1: 1) oxygen demand exceeding supply; 2) oxygen supply exceeding demand; and 3) restoration of normal oxygen supply‐demand matching.