P-102 - Investigating Thermal Skin Response to Menthol Containing Topical Products

Abstract Title: Investigating Thermal Skin Response to Menthol Containing Topical Products


Background: Musculoskeletal (MSK) injuries are associated with significant pain and require more effective treatments. Increasing or decreasing skin temperature may provide advantageous responses at different points during recovery from these injuries.^1,2 Menthol has non-thermal cooling properties and has been shown to relieve thermal strain associated with exercise.³

Purpose/Objectives: This study aims to evaluate the thermal skin response using infrared thermography in healthy, active adults with minor MSK injuries after the application of menthol containing topical products.

Methods: 13 healthy adult volunteers with recent injuries like muscle strain, bruises, simple backache, arthritis were enrolled. Participants applied topical products containing 16% menthol or its combination with 11% camphor to corresponding body parts, randomly assigned as roll-on, spray, or applicator. Data collection occurred pre-application and at 1, 5, 10, 15, 20, 30, 60, 90, and 120 minutes post-application following Thermographic Imaging in Sports and Exercise Medicine (TISEM)⁴ consensus. Anthropometrics including body composition, visual analog scale (VAS) questionnaires, and thermographic images were collected using a FLIR T530 (Teledyne FLIR, USA). Injured vs not injured counter parts of region of interest were then compared after being analyzed using ThermoHuman software (PEMA THERMO GROUP, Spain). Along with each thermal image, participants were asked to indicate any sensations of coldness or warmth experienced during data collection using VAS responses ranging from -3 (very cold) to +3 (very hot). Repeated measure of ANOVA was conducted to establish the influence of the moment of data collection and significant differences were determined using the Bonferroni post hoc test.


Results: Participants (11 male and 2 female) with average age 38.1 ± 12.2 years, height 176 ± 8 cm, weight 82.8 ± 13.6 Kg, exercise per week 8.8 ± 6 hours, showed a statistically significant decrease in skin temperature ( >1°C, p< 0.05 from 1 to 30 minutes) in the injury areas post-application of menthol-based products as compared to the symmetrical non-treated body parts. Similar temperature curves were observed for all products. Subjective cooling or warming sensations were reported up to 120 minutes post-application. Except for 1 subject, all reported immediate cooling sensation within 1 minute. Roll-on and applicator products were preferred for ease of application.

Conclusions/Implications for future research and/or clinical care: This study demonstrates the thermal skin responses of menthol containing topical products in healthy, active adults with minor MSK injuries. All three products exhibited similar thermal responses, with a significant decrease in the first 30 minutes and similar subjective sensations. Larger studies are warranted to validate the relationship between perceived coolness and skin temperature decrease caused by menthol-based products as well as the related pain relief effect.


References:

1. Malanga GA, et al. Postgrad Med. 2015;127(1):57-65.


2. Thorpe RT. Front Sports Act Living. 2021;3:707503.


3. Jeffries O, Waldron M. J Sci Med Sport. 2019;22(6):707-715.


4. Moreira DG, et al. J Therm Biol. 2017;69:155-162.