Effects of Therapeutic Physical Agents on Achilles Tendon Microcirculation

Controlled laboratory study. To measure Achilles tendon microcirculation (total hemoglobin [THb] and oxygen saturation [StO2]) before and after the application of a physical agent in asymptomatic participants, and to compare differences between application location and physical agent dosage. Tendon microcirculation can be altered by superficial heating or cryotherapy. Fifty-one healthy adults (median age, 22 years; range, 20-34 years) were recruited and randomly assigned into 1 of 4 groups. Participants in each group received an intervention consisting of 1 of the following 4 physical agents: ultrasound (n = 12), interferential current (n = 14), low-level laser (n = 11), or vibration massage (n = 14). In each group, the selected intervention was applied at 2 different doses (ultrasound, 0.8 or 1.2 W/cm(2); laser, 5.4 or 18 J) or target locations (vibration and electrostimulation, calf muscle or Achilles tendon). For each participant, each dose or target location was randomly applied to 1 randomly selected lower leg (each leg receiving only 1 of the 2 options). The StO2 values significantly increased after ultrasound at both doses (P