The increasingly popular ultrasound therapy used for sports injuries is also one of the most misunderstood and misused therapies, a Brigham Young University physical education professor says.
Ultrasound therapy uses sound waves to increase blood flow and provide heat in muscles up to 5 centimeters below the skin.For the past three years, David O. Draper has been studying the effectiveness and use of ultrasound therapy in physical therapy and sports medicine.
One popular therapy Draper observed involves applying ultrasound after an ice treatment. "Some clinicians will ice massage or apply an ice pack to a body part for 15 minutes and then immediately apply ultrasound," he said. "Their theory is that the ice make the tissue more dense and the ultrasound will penetrate deeper."
When he tested this theory, Draper found that ice therapy penetrated about 3 centimeters and lowered muscle temperature 6 degrees. "When ultrasound was applied immediately after the ice, the tissue temperature rose slightly but still remained lower than the original muscle temperature. Therefore, despite what the therapists believe, ultrasound applied after an ice treatment is ineffective."
A recent study Draper conducted for Physio Technology Inc. (PTI), a leading manufacturer of ultrasound equipment, illustrated that many therapy textbooks give incorrect information on how long an ultrasound treatment should last.
"Most authors agree that an ultrasound treatment need take only five minutes," he said. "However, I discovered that significant heating - an increase of 4 degrees - takes nearly 10 minutes."
New ultrasound technology will help deliver ultrasound therapy faster. Draper is the first researcher to study the rate of temperature increase using the newest ultrasound equipment capable of 3 megahertz (MHz) frequency.
"After World War II, when ultrasound first became a popular deep-heating treatment, the only frequency available was 1 MHz, which focused its energy deep into muscles lying near the bone," explained Draper.
Around 1990, 3 MHz came onto the scene. During his research, Draper discovered that 3 MHz ultrasound heats tissues more than three times faster than 1 MHz. "Where significant heating may take 10 minutes for 1 MHz ultrasound, it can occur in about three minutes during 3 MHz ultrasound," he said.
PTI has installed this information in a microchip housed in its latest generation machine, which will automatically shut off when the treated tissue reaches the desired temperature, added Draper, whose next project involves testing the machine to further validate his findings.