Effects of Therapeutic Physical Agents on Achilles Tendon Microcirculation.

The objective of this study was to measure Achilles tendon microcirculation (total hemoglobin [THb] and oxygen saturation [StO2]) prior to and following the application of a physical agent in asymptomatic participants and to compare differences between application location and physical agent dosage. The microcirculation in the tendon can be altered by superficial heating or cryotherapy. Fifty-one healthy adults (age: median 22; range 20-34 years) were recruited and randomly assigned to 1 of 4 groups. Participants in each group received an intervention comprised 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/cm2; 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 applied at random to 1 randomly selected lower leg (each leg receiving only 1 of the 2 options). The THb and StO2 values significantly increased after ultrasound at both doses (P<.008). Both THb and StO2 values were also significantly increased in response to vibration massage targeting the Achilles tendon (P<.008) and these values were greater than those resulting from the vibration massage applied to the calf muscle (P =.003 and .002 respectively). No significant THb and StO2 differences were found after the application of interferential current or low-level laser.

Tendon microcirculation is increased following ultrasound and vibration massage intervention concentrated on the Achilles tendon. These modalities may be considered for the purpose of temporarily increasing microcirculation in the tendon.