title: Effect of ThermaCare HeatWraps and Icy Hot Cream/Patches on Skin and Quadriceps Muscle Temperature and Blood Flow.
abstract: OBJECTIVE
  The purpose of this study was to compare the effects of over-the-counter treatments-ThermaCare HeatWraps (chemical reaction to produce heat above the skin), Icy Hot Patch, and Icy Hot Cream (topically applied menthol)-on skin and deep tissue temperature.
  
  
  METHODS
  This was a longitudinal crossover study. On each of 3 days, a ThermaCare HeatWrap, Icy Hot Cream, or Icy Hot Patch was applied randomly over the quadriceps muscle in 15 healthy volunteers with normal body mass. Skin and muscle temperature and blood flow were measured by laser flowmetry every 15 minutes for 2 hours.
  
  
  RESULTS
  After 2 hours, mean temperature decreased by 2.1°C (7.0%; P = .02) in skin and 1.0°C (2.9%; P = .01) in muscle with Icy Hot Cream. Icy Hot Patch decreased skin and muscle temperature by 1.7°C (5.4%; P = .03) and 1.3°C (3.8%; P = .01), respectively. In contrast, ThermaCare raised skin and muscle temperature by 7.8°C (25.8%; P = .001) and 2.7°C (7.7%; P = .002), respectively; both were significantly warmer with ThermaCare vs either Icy Hot product (all P < .007). Icy Hot products produced a net decrease in skin blood flow (Cream: 56.7 flux [39.3%; P = .003]; Patch: 19.1 flux [16.7%; P = .045]). Muscle blood flow decreased with the Patch (6.7 flux [7.0%; P = .02]). After a period of fluctuations, Icy Hot Cream produced a net increase vs baseline of 7.0 flux (16.9%; P = .02). ThermaCare more than doubled blood flow in skin (83.3 flux [109.7%; P = .0003]) and muscle (25.1 flux [148.5%; P = .004]).
  
  
  CONCLUSIONS
  In this group of 15 healthy volunteers, ThermaCare HeatWraps provided the greatest degree of tissue warming and increase in tissue blood flow.
authors.affiliation: Professor of Physical Therapy, Loma Linda University, Loma Linda, CA; Director of Research, Touro University Nevada, Henderson, NV.
authors.forename: Jerrold Scott
authors.initials: JS
authors.lastname: Petrofsky
authors.affiliation: Director, School of Physical Therapy, Touro University Nevada, Henderson, NV.
authors.forename: Michael
authors.initials: M
authors.lastname: Laymon
authors.affiliation: Director, Clinical Molecular Research Laboratory, Loma Linda University, Loma Linda, CA; Associate Professor, School of Allied Health Professions, Loma Linda University, Loma Linda, CA; Faculty of Graduate Studies, Graduate School, Loma Linda University, Loma Linda, CA; Associate Research Professor, Pathology and Human Anatomy, School of Medicine, Loma Linda University, Loma Linda, CA.
authors.forename: Lee
authors.initials: L
authors.lastname: Berk
authors.affiliation: Assistant Professor and Primary Research Coordinator for the School of Allied Health, Loma Linda University, Loma Linda, CA.
authors.forename: Gurinder
authors.initials: G
authors.lastname: Bains
keywords: Analgesics; Hyperthermia; Induced; Menthol