Muscle blood volume assessment during exercise with Power Doppler Ultrasound

Assessment of perfusion adaptation in muscle during exercise can provide diagnostic information on cardiac and endothelial diseases. Power Doppler Ultrasound (PDUS) is known for its feasibility in the non-invasive measurement of moving blood volume (MBV), a perfusion related parameter. In this study, we show how PDUS can be used to assess the MBV kinetics in muscle, before, during, and after exercise. In a volunteer study, PDUS signal was obtained continuously on the gastrocnemius muscle and rectus femoris muscle, during calf raise (N=11) and leg extension exercises (N=11), respectively. To test reproducibility, the measurements were repeated on two different days. A clear increase of PDUS signal was obtained in both exercises. MBV kinetics during leg extension and after calf raise are assessed by linear and mono-exponential fitting of the data. The reproducibility of the obtained slope and time constants of the signal increase and decay were moderate to good between measurement days, with intra-class correlations (ICC) values of 0.6 - 0.8. Future studies will focus on protocol standardization and the monitoring of muscle perfusion during whole body exercise.