The purpose of this study is to determine the rate of tissue temperature increase in the triceps surae during an ultrasound treatment using the Chattanooga Intelect Legend XT. The following parameters will be used: 3 MHz frequency, 1.0 W/cm2 intensity, 15 minute treatment time. Thermocouples will be inserted at 1.0, 1.75, and 2.5 cm depths to determine the heating rates. Most modality textbook recommendations for therapeutic ultrasound are based on studies performed with the Omnisound ultrasound machine. Previous research has shown variations in power output across manufacturers, producing differences in tissue temperature increases. No information has been published regarding the heating rates of the Chattanooga Intelect Legend XT machine for ultrasound treatments. By determining the heating rates for this machine, clinicians will be better able to utilize the Chattanooga Intelect Legend XT to help reach therapeutic goals.

Individual subjects will report to the research lab. They will be instructed to wear appropriate shorts or pants that can be rolled up to expose the gastrocnemius (calf) muscle. The subject will lay prone on the treatment table with the foot and lower leg off of the treatment table in a relaxed, comfortable position. The following procedures will be completed using universal precautions:

1. The investigator will prep the treatment area by having the subject flex the calf to determine the proper location for the ultrasound treatment in the middle of the medial gastrocnemius muscle belly at its largest girth.

   1. A carpenter's square with markings along the vertical arm at the three experimental depths (1.0, 1.75, 2.5 cm) will be used.
   2. The horizontal arm of the carpenter's square will be covered in tape. The carpenter's square is then placed just proximal to the treatment mark while the level on the horizontal arm is used to maintain a level measure.
   3. Marks will be made on the muscle belly parallel to the marks on the vertical axis at 1.0, 1.75 and 2.5 cm depths.
   4. A mark is also made on the horizontal arm tape in line with the treatment mark on the medial gastrocnemius.

2. The Terason uSmart 3300 diagnostic ultrasound unit will be used to measure the adipose thickness over the treatment area and look for abnormalities in the treatment and thermocouple insertion areas. Aquasonic® 100 ultrasound gel will be placed on the 15L4 transducer. The transducer with gel will be placed over the mark of the treatment area. Once the transducer is in place, the screen will be frozen and the skin and adipose thickness will be measured using the caliper tool.

3. The thermocouples will be removed from the MetriCide after sterilizing for a minimum of 12 hours prior to insertion.

   1. The distal aspect of the thermocouple will be wiped dry with sterile gauze.
   2. A mark with a sharpie will be made on each thermocouple just past the length marked on the horizontal arm of the carpenter's square. This allows the tip of each thermocouple to be directly below the treatment site. A second mark will be made at 5 cm to make sure the thermocouple does not go too deep into the tissue.
   3. The distal end of the thermocouple will be wiped clean again using a 70% isopropyl alcohol wipe up to the marks and then the thermocouple will be wrapped in sterile gauze until it is inserted.

4. The insertion areas will be shaved to remove any body hair (if necessary) and cleaned using Betadine.

   a. Once the Betadine dries, 70% isopropyl alcohol will be wiped over the insertion area and given time to dry.

5. The subject will be instructed to take two deep breaths, while the researcher lightly grasps the gastrocnemius to confirm muscle relaxation.

   1. During the second exhalation, the 1.16 in needle catheter will be placed into the subject's calf at the 1.0 cm depth insertion mark using the level to guide the needle in. The needle will be removed leaving the catheter in the tissue.
   2. The thermocouple will be threaded through the catheter to the appropriate depth marked on the thermocouple and the catheter will be removed.
   3. The thermocouple will be secured using medical tape to keep it from moving.
   4. This procedure will be performed 3 times, with one thermocouple placed at each respective depth: 1.0 cm, 1.75 cm, and 2.5 cm.

6. Each thermocouple will be attached to the Iso Thermex electronic thermometer (Columbus Instruments, Columbus, OH), which will measure and record intramuscular temperatures from the tips of the thermocouples.

7. An ultrasound treatment template will be applied at the treatment site and secured with tape to maintain consistent treatment size.

   a. This template will be twice the size of the transducer's Effective Radiating Area (ERA).

8. A metronome will be utilized to consistently move the transducer at a rate of 4 cm/s .

9. The ultrasound treatment will begin once the intramuscular temperature has remained the same for a minute.

10. Each subject will receive one ultrasound treatment at the following parameters: 3 MHz frequency, 1.0 W/cm2 intensity, and 100% duty cycle using the Chattanooga Intelect® Legend XT.

    a. Termination of treatment will result when any of the following occur: i. A 15-minute treatment time is obtained. ii. A 4°C temperature increase occurs at all three depths as this has been shown as the necessary temperature change to increase tissue extensibility.

    iii. A 45°C temperature is reached at any depth, due to concern of tissue damage at high temperatures.

    iv. The subject experiences any pain or discomfort during the treatment.

11. Following the treatment, the ultrasound gel will be wiped from the leg, the template and thermocouples will be removed, and the insertion sites will be cleaned with 70% isopropyl alcohol wipes and covered with a band aid.

12. The subject will then be instructed on the possibility of minor soreness for the next day or two and instructed on an icing schedule to decrease discomfort.

Inclusion Criteria:

• males and females between the ages of 18 - 35 years old
• able to speak English
• have less than 1 cm of adipose over the left medial gastrocnemius muscle.

Exclusion Criteria:

• any current lower extremity injury
• any lower extremity injuries within the last 6 months
• open wounds
• skin infections
• impaired circulation
• peripheral vascular disease
• deep vein thrombosis
• advanced arthritis
• poor thermal regulation
• anesthetic areas
• neoplasms/tumors
• thrombophlebitis
• closed infections
• any allergies or sensitivities to betadine
• any abnormalities observed in the medial gastrocnemius muscle determined by diagnostic ultrasound
• 1.0 cm or greater adipose over the left medial gastrocnemius muscle.

Once the data has been analyzed to determine the heating rates, a manuscript including the heating rates will be submitted for publication.

male and female 18-35 year olds with no injuries to the lower leg.

3 months