Facts and misfits in ultrasound therapy: steps to improve your treatment outcomes.

Ultrasound has been used as a therapeutic agent for decades. Unfortunately many treatments are ineffective because the wrong treatment parameters are used. In this paper I present much of my work over the past 20 years with the goal of improving ultrasound use. Seven steps to optimal ultrasound use are presented. These include: treatment size area; movement speed of the transducer; and the "stretching window".

Injuries restored to ROM using PSWD and mobilizations.

The purpose of this paper is to report the cases of 7 subjects who lacked full range of motion (ROM) in the elbow, and my treatment regimen of PSWD and joint mobilizations. 7 subjects presented with decreased elbow (ROM) due to extensive fractures and or dislocations from traumatic injuries. All subjects were post-surgical, 2 with internal fixation devices. Initial active extension for each patient was 17°, 23°, 28°, 25°, 45°, 30°, 26° respectively (range of 17-45 degrees). Treatment regimen consisted of PSWD to the anterior elbow for 20 min at 48 watts. Immediately after PSWD, mobilizations were administered to the elbow. Extension improved 19°, 21°, 25°, 23°, 20°, 30°, and 26°, respectively, after 6 or less treatments (range of 19-30 degrees). All but 1 patient returned to normal activities with functional ROM in all planes. Follow-up 4 weeks later indicated that all of the subjects maintained 85-100% of their extension. No negative effects were reported during the short-term follow-up. When precautions are taken, I propose PSWD (48 W) may be an appropriate adjunct to joint mobilizations to increase ROM in peripheral joints despite implanted metal.

Heat distribution in the lower leg from pulsed short-wave diathermy and ultrasound treatments.

OBJECTIVE: To compare tissue temperature rise and decay after 20-minute diathermy and ultrasound treatments. DESIGN AND SETTING: We inserted 3 26-gauge thermistor microprobes into the medial aspect of the anesthetized triceps surae muscle at a depth of 3 cm and spaced 5 cm apart. Eight subjects received the diathermy treatment first, followed by the ultrasound treatment. This sequence was reversed for the remaining 8 subjects. The diathermy was applied at a frequency of 27.12 MHz at the following settings: 800 bursts per second, 400-microsecond burst duration, 850-microsecond interburst interval, peak root mean square amplitude of 150 W per burst, and an average root mean square output of 48 W per burst. The ultrasound was delivered at a frequency of 1 MHz and an intensity of 1.5 W/cm(2) in the continuous mode for 20 minutes over an area of 40 times the effective radiating area. The study was performed in a ventilated research laboratory. SUBJECTS: Sixteen (11 men, 5 women) healthy subjects (mean age = 23.56 +/- 4.73 years) volunteered to participate in this study. MEASUREMENTS: We recorded baseline, final, and decay temperatures for each of the 3 sites. RESULTS: The average temperature increases over baseline temperature after pulsed short-wave diathermy were 3.02 degrees C +/- 1.02 degrees C in site 1, 4.58 degrees C +/- 0.87 degrees C in site 2, and 3.28 degrees C +/- 1.64 degrees C in site 3. The average temperature increases over baseline temperature after ultrasound were only 0.17 degrees C +/- 0.40 degrees C, 0.09 degrees C +/- 0.56 degrees C, and -0.43 degrees C +/- 0.41 degrees C in sites 1, 2, and 3, respectively. The temperature dropped only 1 degrees C in 7.65 +/- 4.96 minutes after pulsed short-wave diathermy. CONCLUSIONS: We conclude that pulsed short-wave diathermy was more effective than 1-MHz ultrasound in heating a large muscle mass and resulted in the muscles' retaining heat longer.

Ultrasonic enhancement of antibiotic action on Escherichia coli biofilms: an in vivo model.

Biofilm infections are a common complication of prosthetic devices in humans. Previous in vitro research has determined that low-frequency ultrasound combined with aminoglycoside antibiotics is an effective method of killing biofilms. We report the development of an in vivo model to determine if ultrasound enhances antibiotic action. Two 24-h-old Escherichia coli (ATCC 10798) biofilms grown on polyethylene disks were implanted subcutaneously on the backs of New Zealand White female rabbits, one on each side of the spine. Low-frequency (28.48-kHz) and low-power-density (100- and 300-mW/cm2) continuous ultrasound treatment was applied for 24 h with and without systemic administration of gentamicin. The disks were then removed, and the number of viable bacteria on each disk was determined. At the low ultrasonic power used in this study, exposure to ultrasound only (no gentamicin) caused no significant difference in bacterial viability. In the presence of antibiotic, there was a significant reduction due to 300-mW/cm2 ultrasound (P = 0.0485) but no significant reduction due to 100-mW/cm2 ultrasound. Tissue damage to the skin was noted at the 300-mW/cm2 treatment level. Further development of this technique has promise in treatment of clinical implant infections.

Temperature change in human muscle during and after pulsed short-wave diathermy.

STUDY DESIGN: A time series design was used, with the dependent variable being gastrocnemius muscle temperature at a depth of 3 cm. OBJECTIVES: To determine the rate of temperature rise and the rate of post-treatment temperature decline in skeletal muscle following the application of pulsed short-wave diathermy (PSWD). BACKGROUND: Data on PSWD rate and longevity of heating are 20 years old and outdated. With the recent introduction of advanced diathermy equipment, results of our study would provide clinicians with much needed information regarding treatment duration. METHODS AND MEASURES: A 23-gauge thermistor was inserted into the center of the medial head of the anesthetized gastrocnemius muscle, 3 cm below the skin's surface of 20 subjects. The PSWD (27.12 MHz frequency) was applied using the following parameters: 800 bursts per second; 400 microseconds burst duration; 850 microseconds interburst interval; with a peak root mean square (RMS) amplitude of 150 W per burst and an average RMS output of 48 W. Temperature changes were documented every 5 minutes during the treatment and additionally at 5 and 10 minutes following treatment. RESULTS: The average baseline and peak temperatures were 35.84 +/- 0.93 degrees C and 39.80 +/- 0.83 degrees C, respectively. Mean temperature increases were: 1.36 +/- 0.90 degrees C (5 min); 2.87 +/- 1.44 degrees C (10 min); 3.78 +/- 1.19 degrees C (15 min); 3.49 +/- 1.13 degrees C (20 min). After the treatment terminated, intramuscular temperature dropped 0.97 +/- 0.68 degree C in 5 minutes and 1.78 +/- 0.69 degrees C in 10 minutes. CONCLUSIONS: PSWD is an effective modality if temperature elevation of deep tissue over a large area is the clinical objective.

Hot-Pack and 1-MHz Ultrasound Treatments Have an Additive Effect on Muscle Temperature Increase.

OBJECTIVE: Therapeutic ultrasound is an effective deep heating modality commonly applied alone or after cooling or heating of the treatment area. The purpose of this study was to examine the tissue temperature rise in the human triceps surae muscle group after ultrasound with prior heating via a silicate gel hot pack. DESIGN AND SETTING: This study was designed as a 2 x 2 x 3 factorial with repeated measures on two factors (depth and time). Independent variables were temperature of pack (hot and room temperature), depth of measurement (1 cm and 3 cm), and time (beginning, after pack application, and after ultrasound). The dependent variable was tissue temperature. Subjects were assigned to one of two treatment groups: ultrasound preceded by a 15-minute hot pack treatment or ultrasound preceded by a 15-minute application with a silicate gel pack at room temperature. Measurements were taken while subjects were treated in a university training room. SUBJECTS: Twenty-one uninjured male and female college student volunteers were randomly assigned to one of the two pack groups. MEASUREMENTS: The hot packs were stored in 75 degrees C water. A 1-MHz ultrasound treatment was administered for 10 minutes at an intensity of 1.5 W/cm(2). Tissue temperature was measured every 30 seconds using 23-gauge hypodermic microprobes interfaced with a telethermometer and inserted 1 and 3 cm below the surface of anesthetized triceps surae muscle. RESULTS: At both tissue depths, there was a 0.8 degrees C greater increase in tissue temperature with hot packs and ultrasound. At 1 cm, ultrasound increased temperature 3.5 degrees C after a 0.5 degrees C rise during the room temperature-pack application, but only 0.6 degrees C after a 3.8 degrees C increase during hot-pack application. At 3 cm, ultrasound increased temperature 3.85 degrees C following a slight (-0.26 degrees C) decrease during the room temperature-pack application and 3.68 degrees C after a 0.74 degrees C increase during hot-pack application. CONCLUSIONS: Vigorous increases in deep muscle temperature (>/=4 degrees C) can be reached with 2 to 3 minutes less total sonation time when preheated with a hot pack. Thus, ultrasound and hot packs have an additive effect on intramuscular temperature, but the characteristics of the additive effect are different, primarily because there appears to be a tissue temperature plateau.

Temperature changes in human patellar tendon in response to therapeutic ultrasound.

OBJECTIVE: To determine the rate and magnitude of temperature change in response to ultrasound in human patellar tendon for two treatment sizes. DESIGN AND SETTING: A thermistor was inserted into the medial aspect of each subject's right patellar tendon, and the baseline temperature was recorded. Using stratified random sampling and using a transducer head with an effective radiating area (ERA) of 4.5 cm(2), we had eight subjects each undergo either the 2-or 4-ERA ultrasound treatment first. Each subject received a 3-MHz continuous ultrasound treatment at 1 W/cm(2) for both the 2-and 4-ERA treatment sizes. SUBJECTS: Sixteen subjects (8 males, 21.3 +/- 1.9 years, and 8 females, 21.0 +/- 2.8 years) participated. MEASUREMENTS: We moved the sound head at a speed of 2 to 3 cm/sec while recording the tendon temperature every 30 seconds during, and for 20 minutes after, the 4-minute treatment. Twenty minutes after the treatment, we applied the second treatment to the other ERA treatment size. RESULTS: At the end of the treatment, the mean temperature increase was significantly different (P = .006) between treatment sizes (8.3 degrees C +/- 1.7 degrees C (2 x ERA) and 5.0 degrees C +/- 1.0 degrees C (4 x ERA)). The rate of increase was also significantly different (P < .001). The heating rate per minute for the 2-ERA treatment was 2.1 degrees C +/- 0.4 degrees C and 1.3 degrees C +/- 0.3 degrees C for the 4-ERA treatment. There was a significant difference in the cooling between treatment sizes (P = .001). The rate of temperature decrease between treatment sizes was significantly different only during the first 5-minute interval post-treatment. CONCLUSION: Three-megahertz ultrasound at an intensity of 1 W/cm(2) significantly increased patellar tendon temperature at both 2 and 4 x ERA, but our results confirm that the 2-ERA treatment size provided higher and longer heating than the 4-ERA treatment size.

Temperature rise in human muscle during ultrasound treatments using flex-all as a coupling agent.

OBJECTIVE: To determine if Flex-all 454, as advertised, is effective as a thermal ultrasound couplant. DESIGN AND SETTING: Research design was a one-factor analysis of variance. Subjects received three (alternating order) ultrasound treatments (1 MHz at 1.5 W/cm(2) for 10 minutes) using the following couplants: 50% Flex-all mixed with 50% ultrasound gel; 100% ultrasound gel; and sham ultrasound with 100% Flex-all. Data were collected in a ventilated laboratory. SUBJECTS: Fifteen male and female students (mean age = 24.2 +/- 3.7 years). MEASUREMENTS: Muscle temperature was measured via hypodermic microprobes inserted 3 and 5 cm deep in the medial triceps surae. A visual analogue scale was used to measure perceived heat. RESULTS: At 3 cm, the increases for the gel, 50/50 mixture, and sham were 3.2 degrees C, 2.6 degrees C, and -0.82 degrees C, respectively. At 5 cm, the increases were 2.17 degrees C, 1.80 degrees C, and -0.50 degrees C, respectively. Subjects rated the sham treatment as mild heating (although the temperature dropped) and perceived treatments using the 50/50 mixture to be warmer than treatments using 100% gel couplant. CONCLUSION: Ultrasound treatments delivered with a 50/50 Flex-all/gel couplant felt warmer to subjects; however, identical treatments with 100% ultrasound gel produced higher muscle temperatures. Clinicians desiring optimal thermal effects should use 100% ultrasound gel as the couplant.

Immediate and residual changes in dorsiflexion range of motion using an ultrasound heat and stretch routine.

OBJECTIVE: With respect to increasing ankle dorsiflexion range of motion, our objective was to examine the influence, if any, of preheating the triceps surae with ultrasound before stretching. DESIGN AND SETTING: Subjects were assigned to either group A (ultrasound and stretch) or group B (stretch alone). Group A received 3-MHz ultrasound (1.5 W/cm(2), 4 times effective radiating area) for 7 minutes to the musculotendinous junction of the triceps surae before stretching. Group B rested for 7 minutes before stretching. Both groups then performed identical calf stretches for 4 minutes. Treatment for both groups was conducted at the Brigham Young University Sports Injury Research Laboratory twice daily for 5 days with at least 3 hours between procedures. We analyzed the data with a 2 x 3 x 10 factorial analysis of variance with repeated measures. A Tukey post hoc test was used to identify significant differences in range of motion. SUBJECTS: Forty college students (male = 18, female = 22, age = 20.4 +/- 2.5 years) volunteered for the study. MEASUREMENTS: Maximal ankle dorsiflexion range of motion was measured using an inclinometer before and after each treatment. RESULTS: Immediate effects were that ultrasound and stretch increased mean dorsiflexion range of motion in all sessions significantly more than stretch alone in three treatment sessions. Residual effects were that dorsiflexion range of motion increased 3 degrees in both groups after nine treatment sessions; however, neither group significantly outperformed the other. CONCLUSION: As studied, an ultrasound and stretch routine may increase immediate range of motion more than stretch alone, possibly enhancing performance in practice and competition. This increased range of motion, however, is not maintained over the long term and is not more than the range of motion gained from stretching alone. A similar study using subjects with decreased range of motion after immobilization or injury should be conducted to see if the ultrasound and stretch regimen would produce lasting range-of-motion increases.

Pulsed ultrasound fails to diminish delayed-onset muscle soreness symptoms.

OBJECTIVE: We investigated the effects of pulsed ultrasound on swelling, muscle soreness perception, relaxed-elbow extension angle, and muscular strength. DESIGN AND SETTING: Eight sets of concentric and eccentric actions induced delayed-onset muscle soreness of the elbow flexors. Group 1 received 20% pulsed ultrasound treatments (1-MHz, 7 minutes, 1.5 W/ cm(2) temporal peak intensity) twice a day immediately after postexercise assessments and at 3, 24, 27, 48, 51, 72, and 75 hours postexercise. Group 2 received sham treatments immediately after postexercise assessments and at 3,27, 51, and 75 hours postexercise and true treatments of pulsed ultrasound at 24, 48, and 72 hours postexercise. Group 3 received sham treatments of no ultrasonic output immediately after postexercise assessments and at 3, 24, 27, 48, 51, 72, and 75 hours postexercise. SUBJECTS: Thirty-six college-age females. MEASUREMENTS: We recorded upper-arm circumference, perceived soreness, relaxed-elbow extension angle, and elbow-flexion strength before (pretest), immediately postexercise, and at 24, 48, 72, and 96 hours postexercise. RESULTS: We noted differences over time but no treatment effect between groups or interactions between time and group for upper-arm circumference, perceived soreness, relaxed-elbow extension angle, or elbow-flexion strength. CONCLUSIONS: Pulsed ultrasound as used in this study did not significantly diminish the effects of delayed-onset muscle soreness on soreness perception, swelling, relaxed-elbow extension angle, and strength.

The effects of high-volt pulsed current electrical stimulation on delayed-onset muscle soreness.

OBJECTIVE: We investigated three 30-minute high-volt pulsed current electrical stimulation (HVPC) treatments of 125 pps to reduce pain, restore range of motion (ROM), and recover strength loss associated with delayed-onset muscle soreness (DOMS). DESIGN AND SETTING: Randomized, masked comparison of three 30-minute treatment and sham HVPC regimens over a 48-hour period. SUBJECTS: Twenty-eight college students. MEASUREMENTS: Subjects performed concentric and eccentric knee extensions with the right leg to induce muscle soreness. Assessments were made before and after the exercise bout and each treatment at 24, 48, and 72 hours postexercise. RESULTS: Three separate 2 x 3 x 2 ANOVAs were used to determine significant differences (p < .05) between days, treatments, and pre-post treatment effects and significant interaction among these variables. Scheffe post hoc tests showed no significant reduction in pain perception or improvement in loss of function at 24, 48, and 72 hours postexercise. Mean pain perception assessments (0 = no pain, 10 = severe pain) for the HVPC group were 2.9, 4.5, and 3.5 and for the sham group 3.8, 4.8, and 3.5). Mean ROM losses for the HVPC group were 9.0 degrees , 22.3 degrees , and 26.2 degrees , and for the sham group were 9.5 degrees , 23.1 degrees , and 23.0 degrees . Mean strength losses (1RM) for the HVPC group were 25.9, 25.7, and 20.8 lbs and for the sham group were 22.3, 22.3, and 13.8 lbs. CONCLUSIONS: HVPC as we studied it was ineffective in providing lasting pain reduction and at reducing ROM and strength losses associated with DOMS.

The Stretching Window Part Two: Rate of Thermal Decay in Deep Muscle Following 1-MHz Ultrasound.

Thermal ultrasound can be effective in increasing extensibility of collagen, thus aiding joint mobilization and stretching. In 1995, we reported on the rate of temperature decay following 3-MHz ultrasound in subcutaneous tissues. We repeated that study at 1-MHz frequency to see if the stretching window is different for deep muscle. Twenty subjects had two 23-gauge thermistors inserted 2.5 cm and 5 cm deep into their triceps surae muscle. We administered 1-MHz continuous ultrasound at 1.5 W/cm(2) until the tissue temperature increased 4 degrees C (vigorous heating). Immediately following the treatment, we recorded the rate at which the temperature dropped at 30second intervals. We ran a stepwise nonlinear regression analysis to predict temperature decay as a function of time following ultrasound treatment. There was a significant nonlinear relationship between time and temperature decay. At 2.5 cm, the average time for the temperature to drop each degree was: 1 degrees C = 2:34; 2 degrees C = 6:35; 3 degrees C = 12:10: and 4 degrees C = 21:14. At 5 cm, the average time for the temperature to drop each degree was: 1 degrees C = 2:31, 2 degrees C = 6:50: 3 degrees C = 14:32; and 4 degrees C = 27:49. Based upon prior research, thermal decay of 1-MHz ultrasound was slower than 3 MHz, and the deeper tissue cooled at a slower rate than superficial tissue following 1-MHz ultrasound. The data illustrated that the stretching window was open longer for deep-seated structures than for superficial ones.

Examiner proficiency in performing the anterior drawer and Lachman tests.

The anterior drawer and Lachman tests are frequently used for determining anterior cruciate ligament (ACL) instability. The Lachman test is considered to be the most accurate, yet it is difficult to perform on a large person, especially by an examiner with small hands. One procedure, the alternate Lachman test, has been used with some success by examiners who have difficulty performing the Lachman test. The purpose of this study was to compare these three manual tests with respect to predicting ACL stability. These findings were compared with those of the KT-1000 knee arthrometer. Seventy-four subjects (mean age = 22 years) volunteered for the study. Girth measurements were recorded for each subject at 8 cm above and below the midpoint of the patella. An examiner with small hands (21-cm span) performed each of the three tests on both knees of the subjects and then recorded which knee he believed was the most lax of the two with respect to each test. Another examiner then tested each subject's knees with the KT-1000. A log-linear model with terms for manual test type, category, and thigh girth was used for statistical analysis. The alternate Lachman test significantly outperformed the other two tests. Subjects with > 2.5 mm bilateral laxity difference were correctly evaluated 100% of the time using the alternate Lachman test. In subjects with large thigh girth (> 43 cm), 1) the alternate Lachman test was correct 78% of the time; 2) the anterior drawer test was correct 59% of the time; and 3) the Lachman test produced only 28% correct examinations. Based upon these results, the alternate Lachman test should be included in the regimen of manual ACL tests, especially for athletes with large thigh circumference or when performed by examiners with small hands.

Rate of temperature increase in human muscle during 1 MHz and 3 MHz continuous ultrasound.

To achieve the thermal effects of ultrasound, the tissue temperature must be raised from 1 to > or = 4 degrees C, depending on the desired outcome of the treatment. In the past 25 years, there have been no in vivo studies that have measured rate of change in temperature during 1-MHz ultrasound treatments, and none have ever been performed with the 3-MHz frequency. Thus, we are left to pure speculation regarding how long to administer an ultrasound treatment. We performed this study to plot the rate of temperature increase during ultrasound treatments delivered at various intensities and frequencies. We inserted two 23-gauge thermistors into each subjects' medial triceps surae at the following depths: 1 MHz at depths of 2.5 and 5.0 cm (12 subjects) and 3 MHz at depths of .8 and 1.6 cm (12 subjects). Each subject received a total of four 10-minute treatments, one each at .5, 1.0, 1.5, and 2.0 W/cm2, and temperature was measured every 30 seconds. No significant difference was found in the rate of heating at the two depths (p = .987) within the same frequency and dose levels. The 3-MHz frequency heated significantly faster than the 1-MHz frequency at all doses tested (p < .001). On average, the rate of temperature increased per minute at the two depths of the 1-MHz frequency was: .04 degrees C at .5 W/cm2; .16 degrees C at 1.0 W/cm2; .33 degrees C at 1.5 W/cm2; and .38 degrees C at 2.0 W/cm2. The rate of temperature increase per minute at the two depths of the 3-MHz frequency was: .3 degrees C at .5 W/cm2; .58 degrees C at 1.0 W/cm2; .89 degrees C at 1.5 W/cm2; and 1.4 degrees C at 2.0 W/cm2. The results of this research should enable clinicians to choose the correct frequency, intensity, and treatment time when using thermal ultrasound.

Rate of Temperature Decay in Human Muscle Following 3 MHz Ultrasound: The Stretching Window Revealed.

Researchers have determined that when therapeutic ultrasound vigorously heats connective tissue, it can be effective in increasing extensibility of collagen affected by scar tissue. These findings give credence to the use of continuous thermal ultrasound to heat tissue before stretching, exercise, or friction massage in an effort to decrease joint contractures and increase range of motion. Before our investigation, it was not known how long following an ultrasound treatment the tissue will remain at a vigorous heating level (>3 degrees C). We conducted this study to determine the rate of temperature decay following 3 MHz ultrasound, in order to determine the time period of optimal stretching. Twenty subjects had a 23-gauge hypodermic needle microprobe inserted 1.2 cm deep into the medial aspect of their anesthetized triceps surae muscle. Subjects then received a 3 MHz ultrasound treatment at 1.5 W/cm(2) until the tissue temperature was increased at least 5 degrees C. The mean baseline temperature before each treatment was 33.8 +/- 1.3 degrees C, and it peaked at 39.1 +/- 1.2 degrees C from the ultrasound. Immediately following the treatment, we recorded the rate at which the temperature dropped at 30-second intervals. We ran a stepwise nonlinear regression analysis to predict temperature decay as a function of time following ultrasound treatment. We found a significant nonlinear relationship between time and temperature decay. The average time it took for the temperature to drop each degree as expressed in minutes and seconds was: 1 degrees C = 1:20; 2 degrees C = 3:22; 3 degrees C = 5:50; 4 degrees C = 9:13; 5 degrees C = 14:55; 5.3 degrees C = 18:00 (baseline). We conclude that under similar circumstances where the tissue temperature is raised 5 degrees C, stretching will be effective, on average, for 3.3 minutes following an ultrasound treatment. To increase this stretching window, we suggest that stretching be applied during and immediately after ultrasound application.

Temperature changes in deep muscles of humans during ice and ultrasound therapies: an in vivo study.

Therapeutic ultrasound can be a very effective treatment modality when used correctly in the treatment of musculoskeletal conditions and wound healing. However, many protocols for the administration of ultrasound have not been scientifically tested. The purpose of this study was to measure muscle temperature changes during a frequently used protocol, ie., preicing prior to ultrasound application. A 23-gauge hypodermic needle microprobe was inserted 5 cm deep into the medial aspect of the anesthetized triceps surae muscle of 16 subjects. Two groups consisting of eight subjects each were tested for temperature changes during: a) ultrasound treatment on precooled tissue or b) ultrasound with no preceding treatment. Each treatment consisted of 10 minutes of continuous ultrasound delivered topically at 1.5 watts/cm2. A significant difference between the two treatment methods was measured (F = 19.06, p < 0.01). Ultrasound alone increased tissue temperature an average of 4.0 +/- .83 degrees C, whereas ultrasound preceded by 5 minutes of ice increased tissue temperature only 1.8 +/- 1.0 degrees C above original baseline level. At a depth of 5 cm, ultrasound preceded by ice treatment yielded little or no thermal benefits.

Contrast therapy and intramuscular temperature in the human leg.

Contrast therapy, although having a long history of use in sports medicine and physical therapy, remains insufficiently researched. We investigated the thermal effects of contrast therapy on intramuscular temperature. We randomly assigned 28 college students to either a control or a contrast group, eight women and six men per group. We shaved and cleansed a 4- x 4-cm area of skin over the right medial calf and inserted a microprobe to a depth of 1 cm below the skin and subcutaneous fat in the center of the gastrocnemius. Each control subject immersed the treatment leg in a hot whirlpool (40.6 degrees C) for 20 minutes. Each contrast subject first immersed the treatment leg in a hot whirlpool (40.6 degrees C) for 4 minutes then into a cold whirlpool (15.6 degrees C) for 1 minute. Contrast subjects repeated this sequence three additional times. We recorded intramuscular temperatures every 30 seconds over the entire treatment time for both groups. The control group had a temperature increase of 2.83 +/- 1.14 degrees C over the 20-minute treatment. The contrast group temperature increased 0.39 +/- 0.46 degrees C from baseline to the end of the treatment. The largest temperature change from the end of one contrast immersion to the end of the next was only 0.15 +/- 0.10 degrees C. None of the differences between the end of one immersion to the end of the next were significant. Conversely, all differences between the same time periods in the control group had significant temperature increases. Apparently contrast therapy, as studied, is incapable of producing any significant physiological effect on the intramuscular tissue temperature 1 cm below the skin and subcutaneous tissue. We recommend that further research be done to examine the effects of longer periods in both the hot and cold environments on the intramuscular temperature of the human leg. Further investigation of intra-articular or peri-articular temperature change produced by contrast therapy should also be undertaken.

Temperature changes during therapeutic ultrasound in the precooled human gastrocnemius muscle.

Therapeutic ultrasound is frequently employed as a deep heating rehabilitation modality. It is administered in one of three ways: a) ultrasound with no preceding treatment, b) ultrasound on preheated tissues, or c) ultrasound on precooled tissues. The purpose of this study was to investigate the effect of ultrasound treatments on the tissue temperature rise of precooled human gastrocnemius muscle. Sixteen male subjects had a 23-gauge hypodermic needle microprobe inserted 3 cm deep into the medial aspect of their anesthetized gastrocnemius muscles. Data were gathered on each subject for one of two randomly assigned treatments: a) ultrasound treatment on precooled tissue, or b) ultrasound with no preceding treatment. Each treatment consisted of ultrasound delivered topically at 1.5 watts/cm(2) in a continuous mode for 10 minutes. Ultrasound was applied in an overlapping longitudinal motion at 4 cm/s, with temperature readings recorded at 30-second intervals. We discovered a difference between the two treatment methods [t(14) = 16.26, p < .0001]. Ultrasound alone increased tissue temperature an average of 2 degrees C, whereas ultrasound preceded by 15 minutes of ice did not increase tissue temperature even to the original baseline level. We concluded that, at a depth of 3 cm, ultrasound alone provided a greater heating effect than ultrasound preceded by an ice treatment.

Examination of the law of grotthus-draper: does ultrasound penetrate subcutaneous fat in humans?

One benefit of ultrasound over infrared modalities is its ability to penetrate subcutaneous fat. The purpose of this study was to compare tissue temperature rise during ultrasound treatments in humans with various thicknesses of subcutaneous fat in the medial gastrocnemius. Twenty males served as subjects. A 23-gauge hypodermic needle microprobe was inserted 3-cm deep into the medial portion of the anesthetized gastrocnemius, and connected to a thermocouple temperature gauge. We applied 15 ml of ultrasound gel, preheated to body temperature (37 degrees C), to a 10-cm-diameter target area. Continuous ultrasound was delivered topically at 1.5 W/cm(2) for 10 minutes. During this time, the soundhead was moved at a speed of 4 cm per second, and the temperature was recorded every 30 seconds. The mean baseline temperature for all subjects was 35.4 degrees C. The mean temperature increase was 4.9 degrees C. We performed a regression analysis to test for correlation between fat thickness and tissue temperature rise of subjects. There was a small positive but insignificant correlation (r=.128). This supports the claim of Grotthus and Draper. Since subcutaneous fat does not serve as a barrier to therapeutic ultrasound, athletic trainers and physical therapists can expect comparable increases in muscle temperature when using this modality on people with varying thicknesses of adipose tissue.