Study design: Prospective, randomized, crossover design.
Objectives: To compare the effectiveness of the Johnson & Johnson Back Plaster, the ABC Warme-Pflaster, and the ThermaCare HeatWrap on skin and paraspinal muscle temperature. Also, to compare the subjects' heat perception for the 3 products.
Background: Heat therapy is a common treatment for low back pain and disability. There are a number of products on the market that are suggested to relieve low back pain by providing warmth to the back; however, their effectiveness for increasing tissue temperature compared with heat sensation has not been tested.
Methods and measures: To measure paraspinal muscle temperature, 1 thermocouple monofilament was inserted into the paraspinal muscle 2 cm from the skin surface at the L3 level using a 20-gauge 1.25-in (3.15-cm) sterile catheter. To measure skin interface temperature, 2 thermocouples were placed on the skin at distances of 5 cm and 7 cm from the insertion site. The Isothermex was used to record temperatures to the nearest 0.1 degrees C for 120 minutes. The subjects also rated heat perception using a 10-cm visual analog scale at 0, 30, 60, 90, and 120 minutes. Analysis of covariance models were used for statistical analysis.
Results: There was a significant product x time interaction (F14,231 = 3.77, P<.0001) at the intramuscular site, but there was not a significant product x time interaction (F14,231 = 1.03, P = .4228) at the skin site. Both the main effects for product (F2,33 = 41.59, P<.0001) and time (F3,51 = 19.02, P<.0001) were significant for the visual analog scale data. The ThermaCare HeatWrap produced significant increases in both skin and intramuscular temperatures with less heat sensation. The Johnson & Johnson Back Plaster and the ABC Warme-Pflaster increased temperature at the skin surface and provided the greatest heat sensations, but they did not provide intramuscular heat.
Conclusions: The ThermaCare HeatWrap is more effective at increasing temperature at a 2-cm depth with less perceived heat compared to the Johnson & Johnson Back Plaster and the ABC Warme-Pflaster. The latter 2 products provide a sensation of heat but do not actually provide a muscle temperature change at a depth of 2 cm.