Theodore Towse
Last active: 4/25/2016

Effect of physical activity on MRI-measured blood oxygen level-dependent transients in skeletal muscle after brief contractions.

Towse TF, Slade JM, Meyer RA
J Appl Physiol (1985). 2005 99 (2): 715-22

PMID: 15802369 · DOI:10.1152/japplphysiol.00272.2005

The signal intensity (SI) in gradient-echo, echo-planar magnetic resonance images (repetition time/echo time = 1,000/40) of anterior tibialis muscle in active [estimated energy expenditure 42.4 +/- 3.7 (SD), n = 8] vs. sedentary (32.3 +/- 0.6, n = 8) young adult (18-34 yr old) human subjects was measured after single, 1-s-duration maximum voluntary ankle dorsiflexion contractions. There was no difference between groups in anterior tibial muscle cross-sectional area or peak force. In both groups there was a transient increase in anterior tibialis muscle SI, which peaked 5-7 s after the end of each contraction. The magnitude of the SI transient was over threefold greater [5.5 +/- 1.0 (SE) vs. 1.5 +/- 0.4%] and persisted twice as long (half-recovery time 5.4 +/- 0.4 vs. 2.7 +/- 0.3 s) in the active subjects. In the same subjects, blood flow in popliteal, anterior tibial, and posterior tibial arteries was measured by cardiac-gated CINE magnetic resonance angiography before and after 2 min of dynamic, repetitive ankle dorsiflexion exercise. There was no difference between groups in resting or postexercise flow in anterior tibial artery, although popliteal and posterior tibial artery flow after exercise tended to be greater in the active group. The results indicate that transient hyperemia and oxygenation in muscle after single contractions are enhanced by chronic physical activity to a greater extent than peak muscle blood flow.

MeSH Terms (15)

Adolescent Adult Ankle Joint Female Humans Image Interpretation, Computer-Assisted Magnetic Resonance Imaging Male Motor Activity Muscle, Skeletal Muscle Contraction Oxygen Oxygen Consumption Physical Exertion Time Factors

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