Effect of ThermaCare HeatWraps and Icy Hot Cream/Patches on Skin and Quadriceps Muscle Temperature and Blood Flow

Short-term cutaneous vasodilatory and thermosensory effects of topical methyl salicylate

Introduction

Methyl salicylate, the main compound of wintergreen oil, is widely used in topical applications. However, its vascular and thermosensory effects are not fully understood. The primary aim was to investigate the effects of topical methyl salicylate on skin temperature (Tskin), skin microcirculation (MCskin) and muscle oxygen saturation (SmO2) compared to a placebo gel. The secondary aim was to assess thermosensory responses (thermal sensation, thermal comfort) and to explore to which extent these sensations correspond to the physiological responses over time.

Methods

21 healthy women (22.2 ± 2.9 years) participated in this single-blind, randomized controlled trial. Custom-made natural wintergreen oil (12.9%), containing methyl salicylate (>99%) and a placebo gel, 1 g each, were applied simultaneously to two paravertebral skin areas (5 cm × 10 cm, Th4-Th7). Tskin (infrared thermal imaging), MCskin (laser speckle contrast imaging) and SmO2 (deep tissue oxygenation monitoring) and thermosensation (Likert scales) were assessed at baseline (BL) and at 5-min intervals during a 45 min post-application period (T0-T45).

Results

Both gels caused an initial decrease in Tskin, with Tskin(min) at T5 for both methyl salicylate (BL-T5: Δ-3.36°C) and placebo (BL-T5: Δ-3.90°C), followed by a gradual increase (p < .001). Methyl salicylate gel resulted in significantly higher Tskin than placebo between T5 and T40 (p < .05). For methyl salicylate, MCskin increased, with MCskin(max) at T5 (BL-T5: Δ88.7%). For placebo, MCskin decreased (BL-T5: Δ-17.5%), with significantly lower values compared to methyl salicylate between T0 and T45 (p < .05). Both gels had minimal effects on SmO2, with no significant differences between methyl salicylate and placebo (p > .05). Thermal sensation responses to topical methyl salicylate ranged from "cool" to "hot", with more intense sensations reported at T5.

Discussion

The findings indicate that topical methyl salicylate induces short-term cutaneous vasodilation, but it may not enhance skeletal muscle blood flow. This study highlights the complex sensory responses to its application, which may be based on the short-term modulation of thermosensitive transient receptor potential channels.

Rapamycin restores peripheral blood flow in aged mice and in mouse models of atherosclerosis and Alzheimer's disease

Peripheral artery disease (PAD), defined as reduced blood flow to the lower limbs, is a serious disorder that can lead to loss of function in the lower extremities and even loss of limbs. One of the main risk factors for PAD is age, with up to 25% of adults over the age of 55 and up to 40% over the age of 80 presenting with some form of the disease. While age is the largest risk factor for PAD, other risk factors include atherosclerosis, smoking, hypertension, and diabetes. Furthermore, previous studies have suggested that the incidence of PAD is significantly increased in patients with Alzheimer's disease (AD). Attenuation of mTOR with rapamycin significantly improves cerebral blood flow and heart function in aged rodents as well as in mouse models of atherosclerosis, atherosclerosis-driven cognitive impairment, and AD. In this study, we show that rapamycin treatment improves peripheral blood flow in aged mice and in mouse models of atherosclerosis and AD. Inhibition of mTOR with rapamycin ameliorates deficits in baseline hind paw perfusion in aged mice and restores levels of blood flow to levels indistinguishable from those of young controls. Furthermore, rapamycin treatment ameliorates peripheral blood flow deficits in mouse models of atherosclerosis and AD. These data indicate that mTOR is causally involved in the reduction of blood flow to lower limbs associated with aging, atherosclerosis, and AD-like progression in model mice. Rapamycin or other mTOR inhibitors may have potential as interventions to treat peripheral artery disease and other peripheral circulation-related conditions.

The Effectiveness of Thermal Neuromodulation Using Precise Heat in the Treatment of Chronic Low Back Pain Over 60 Days: An In-Home User Trial

Purpose

Two previous independent double-blind randomized studies demonstrated that thermal neuromodulation using high temperature pulsed heat reduced pain in subjects with chronic low back pain. The present study examined the effects of high temperature pulsed heat via an experimental device in a real-world In-Home Use Trial (IHUT) over a sixty-day period.

Materials and Methods

This in-home study recruited 34 subjects with chronic low back pain, provided them with an experimental device that delivered treatment session of high temperature pulsed heat up to 45°C, and followed them for eight weeks. Subjects were allowed to use the device as needed. Primary outcome was pain rating as measured by the 11-point Numeric Pain Scale at baseline, four and eight weeks of treatment. The secondary outcome measures were the interference with daily living components of the Brief Pain Inventory at baseline versus eight weeks of treatment.

Results

Thirty-two subjects completed the study. Pain levels were 5.81 at baseline, 2.79 at four weeks and 2.25 at eight weeks. All changes in pain levels between baseline and four weeks, baseline, and eight weeks and between four and eight weeks were statistically significant (p < 0.05). At eight weeks, the seven components of pain interference with activities of daily living and pain interference with walking were statistically reduced (P < 0.05). About 72% of subjects reported a single 30-minute treatment session produced over 3 hours of pain relief.

Conclusion

An eight-week in-home trial of high-temperature thermal modulation devices produced significant reductions in pain and pain interference with activities of daily living, an important measure of function. Efforts were made to control and reduce study contamination. This study provides important initial data for long-term outcome studies of thermal neuromodulation using high temperature pulsed heat to treat low back pain and to improve subject function and demonstrated that individuals with chronic pain can effectively self-manage pain.

A Role for Superficial Heat Therapy in the Management of Non-Specific, Mild-to-Moderate Low Back Pain in Current Clinical Practice: A Narrative Review

Low back pain (LBP) is a leading cause of disability. It significantly impacts the patient's quality of life, limits their daily living activities, and reduces their work productivity. To reduce the burden of LBP, several pharmacological and non-pharmacological treatment options are available. This review summarizes the role of superficial heat therapy in the management of non-specific mild-to-moderate LBP. First, we outline the common causes of LBP, then discuss the general mechanisms of heat therapy on (LBP), and finally review the published evidence regarding the impact of superficial heat therapy in patients with acute or chronic non-specific LBP. This review demonstrates that continuous, low-level heat therapy provides pain relief, improves muscular strength, and increases flexibility. Therefore, this effective, safe, easy-to-use, and cost-effective non-pharmacological pain relief option is relevant for the management of non-specific mild or moderate low back pain in current clinical practice.

Local heating of trigger points reduces neck and plantar fascia pain

BACKGROUND

Heating the skin and muscles is a commonly accepted method of pain relief and a modality to increase relaxation in muscles and increase tissue blood flow.

OBJECTIVE

The purpose of the present study was to examine the effect of local heat applied to trigger points and to determine if there was pain relief in the neck and plantar fascia.

METHODS

Forty adults were divided into 2 different groups according to their pain; twenty subjects had plantar foot pain and the other 20 had nonspecific neck pain. The 20 subjects in each group were randomly subdivided into a heat and a sham group. Sensitivity to pressure was measured with an algometer. A stopwatch was given to the subject and started when either the heat patch or placebo was applied. Heat cells were applied at trigger points on the pain area.

RESULTS

Subjective pain significantly decreased in both sham and heat group patients with neck pain (p< 0.05), however, the change was greater in the heat group and there was a significant difference between the heat and sham groups (p= 0.002, d= 0.81). For the plantar pain group, a significant decrease in subjective pain was found in the heat group but not in the sham group. Pressure pain threshold significantly decreased in the heat group patients both with neck and plantar pain but for the sham group there was an increase in the pressure after sham treatment. Pain relief during the intervention was also significantly different between the heat and sham group in both patients with neck and plantar pain.

CONCLUSION

The effect of local heat on trigger points of the body on pain relief was significantly better in the heat groups than in the sham groups. This finding is significant because using heat on trigger points could be an alternative to dry needling performed by healthcare professionals. This modality can be alternative for home use and avoids opioids.

Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound

Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p < 0.001), in TAMx of 53.2% (p < 0.001) and 38.3% (p = 0.002), and in TAMn of 84.4% (p < 0.001) and 68.2% (p < 0.001). Semiquantitative power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.