Fig. 3.

(a) Dynamometer recordings (plantar flexion torque, footplate position and angular velocity) and DCS signals (αD_B) during 10 isotonic exercises. Data are presented with different colors and symbols based on the exercise status of muscle fibers; i.e., no-exercise (pre- and post-exercises without muscle fiber motion, ■), non-contracting (muscle relaxation at 90° without fiber motion, ▼), PF-120° (muscle contraction at an angle of 120° without fiber motion, ◇), PF (footplate moving forward with muscle fiber motions,★) and DF (footplate moving backward with muscle fiber motions, ●). The muscle exercise status was determined by the footplate position and angular velocity. Note that several motion-induced spikes appeared in DCS measurements before and after exercise when the angle of footplate was adjusted (i.e., 90° → 120° or 120° → 90°) for setting up the dynamometer. Those artifacts were excluded from our data analysis. (b) Average increases [mean ± standard error, n = 10 (trials)] in DCS data (αD_B) during muscle fiber motion (PF or DF) and during static status of muscles (PF-120° or non-contracting). The muscle fiber motion (i.e., PF and DF) created higher αD_B than that without motion (i.e., PF-120° and Non-contracting), and muscle fiber contraction (PF-120°) caused an increase in blood flow compared to that without the muscle contracting.