Currently pregnant or breastfeeding

Nicotine use (e.g., smoking, chewing tobacco etc.), quantified as more than 100 cigarettes or cigars in a lifetime)

Known skin allergies or current rash, skin disease, disorders of pigmentation

Diabetes

Body mass index \>35kg\*m-2

Using calcium channel blockers

Raynaud's syndrome

Allergy or hypersensitivity to menthol, camphor, capsaicin or adhesive

Regular use (defined as greater than once a week) of topical analgesics that contain menthol, camphor or capsaicin

Transient Receptor Potential Channels