MEASUREMENT BY LASER-DOPPLER FLOWMETRY OF MICROCIRCULATION IN LOWER LEG MUSCLE AT DIFFERENT BLOOD FLUXES IN RELATION TO ELECTROMYOGRAPHICALLY DETERMINED CONTRACTION AND ACCUMULATED FATIGUE
Se. Larsson et al., MEASUREMENT BY LASER-DOPPLER FLOWMETRY OF MICROCIRCULATION IN LOWER LEG MUSCLE AT DIFFERENT BLOOD FLUXES IN RELATION TO ELECTROMYOGRAPHICALLY DETERMINED CONTRACTION AND ACCUMULATED FATIGUE, European journal of applied physiology and occupational physiology, 70(4), 1995, pp. 288-293
Single-fibre percutaneous laser-Doppler flowmetry (LDF) of the tibiali
s anterior muscle was performed continuously for measurement of the mi
crocirculation during different blood fluxes. as well as in relation t
o different muscle activities and fatigue determined electromyographic
ally (EMG). The laser-Doppler power spectrum density function was stud
ied in a frequency range of 0-8.2 Hz as representing the blood flow mo
st selectively. Reduced blood flow from tourniquet inflation caused a
decrease in signal power density, compared to that of intact blood flo
w at rest. During postocclusion reactive hyperaemia an increased signa
l power was recorded. This reached its maximum within 4.4 (SD 1.88) s
after deflation of the tourniquet. The different fluxes were recorded
at high sensitivity and disturbances were small. Periods of 1-min stat
ic dorsi-flexion of the foot at 10, 20, 30, 40, and 50% MVC (maximal v
oluntary contraction) with 1-min rest between were associated with a s
ignificant increase in LDF, the recordings obtained during the rest pe
riods showing a tendency towards an increase. A decrease in the EMG me
an power frequency (MPF) indicated accumulated fatigue. The LDF for th
e rest periods that followed upon continuous contractions up to the sa
me MVC levels showed a tendency towards an increase but variability wa
s large. With further development, these techniques may be useful in t
he evaluation of insufficiency of the peripheral circulation.