PHYSIOLOGICAL VARIABILITY OF FEMORAL ARTERY BLOOD FLOW DURING STEADY-STATE ONE- LEGGED DYNAMIC KNEE EXTENSOR EXERCISE

Abstract

PURPOSE To determine the physiological variation in femoral arterial blood flow (FABF) during steady-state, one-legged, dynamic, knee-extensor exercise (1L-KEE), and the sampling duration needed to access accurate steady-state FABF measurements. METHODS Eleven healthy subjects performed 1L-KEE in the sitting position at external work rates of 10, 20, 30 and 40 W, at 60 contractions per minute (cpm). FABF (Doppler ultrasound) and muscle force (F, strain gauge; representing the intra-muscular pressure variations) were continuously measured. The coefficients of variation for FABF (CVFABF) were determined for 1-, 2-, 5-, 10-, 15-, 20- and 30-contraction-relaxation duty cycles (CRcycles) during 1L-KEE. RESULTS During 1L- KEE, at 60 cpm, the CVFABF (mean) was higher (P < 0.05) for 1-CRcycle (15.5%) and 2-CRcycle (11.8%) compared to for 30-CRcycle (5.3%). The CVFABF for 10-, 15-, 20- and 30-CRcycle were, however, similar (p = NS) for all work rates. During 1L-KEE, the CVFABF was linearly related to the CVmean-F at 60 cpm. The CVmean-F (range, 10–20 %) was higher (p < 0.0001) than the CVmean- BP (range, 5 %) at each work rate. BPpeak was linearly related (r = 0.981, P < 0.05) to Fpeak at each contraction rate. CONCLUSION The magnitude of the physiological variation in FABF for each contraction-relaxation duty cycle was ∼373–536 ml/min during incremental 1L-KEE. The FABF variability seems to depend on the intramuscular pressure variations, with the superimposed influence of the perfusion pressure variations. A collective influence on FABF of BPpeak and Fpeak is supported by that they are interrelated. At least 10-CRcycles are needed to obtain accurate steady-state FABF measurements during 1L-KEE.