Comparison of the Effects of Ice and 3.5% Menthol Gel on Blood Flow and Muscle Strength of the Lower Arm

Context: Soft-tissue injuries are commonly treated with ice or menthol gels. Few studies have compared the effects of these treatments on blood flow and muscle strength. Objective: To compare blood flow and muscle strength in the forearm after an application of ice or menthol gel or no treatment. Design: Repeated-measures design in which blood-flow and muscle-strength data were collected from subjects under 3 treatment conditions. Setting: Exercise physiology laboratory. Participants: 17 healthy adults with no impediment to the blood flow or strength in their right arm, recruited through word of mouth. Intervention: Three separate treatment conditions were randomly applied topically to the right forearm: no treatment, 0.5 kg of ice, or 3.5 mL of 3.5% menthol gel. To avoid injury ice was only applied for 20 min. Main Outcome Measures: At each data-collection session blood flow (mL/min) of the right radial artery was determined at baseline before any treatment and then at 5, 10, 15, and 20 min after treatment using Doppler ultrasound. Muscle strength was assessed as maximum isokinetic flexion and extension of the wrist at 30 degrees/s 20, 25, and 30 min after treatment. Results: The menthol gel reduced (-42%, P < .05) blood flow in the radial artery 5 min after application but not at 10, 15, or 20 min after application. Ice reduced (-48%, P < .05) blood flow in the radial artery only after 20 min of application. After 15 min of the control condition blood flow increased (83%, P < .05) from baseline measures. After the removal of ice, wrist-extension strength did not increase per repeated strength assessment as it did during the control condition (9-11 %, P < .05) and menthol-gel intervention (8%, P < .05). Conclusions: Menthol has a fast-acting, short-lived effect of reducing blood flow. Ice reduces blood flow after a prolonged duration. Muscle strength appears to be inhibited after ice application.