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Acute effects of sustained isometric knee extension on cerebral and muscle oxygenation responses
Author(s) -
Pereira Marta Inez R.,
Gomes Paulo Sergio C.,
Bhambhani Yagesh N.
Publication year - 2009
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/j.1475-097x.2009.00870.x
Subject(s) - isometric exercise , medicine , cardiology , oxygenation , anaerobic exercise , vastus lateralis muscle , contraction (grammar) , anesthesia , physical therapy , skeletal muscle
Summary Cerebral contra‐lateral frontal lobe and the dominant vastus lateralis muscle oxygenation (Cox, Mox) and blood volume (Cbv, Mbv) were recorded simultaneously using near infrared spectroscopy (NIRS) in 12 healthy volunteers (37·4 ± 9·9 years; 72·3 ± 16·1 kg; 171·0 ± 9·6 cm) during 2 min resting baseline, an isometric knee extension with the 1 RM load sustained to the point of fatigue, and 3 min recovery. The mean exercise duration was 19·1 ± 2·6 s. During the contraction, Cox and Cbv increased systematically with no sign of levelling off until the point of fatigue. In contrast, Mox and Mbv declined continuously until the termination of exercise. Qualitative analysis of these NIRS profiles suggested that maximal isometric performance under normoxic conditions was most likely not limited by central neuronal activation, but rather, was due to factors within the exercising muscle. It is likely that depletion of intramuscular stores of high energy phosphates and oxymyoglobin, as well as the accumulation of metabolites from anaerobic pathways, were implicated in fatigue during this sustained high intensity isometric contraction.