The goal of this clinical trial is to investigate the effect of breathing on the processing of experimental pain in healthy participants. The main questions are: 1. Does breathing rate influence the spatial extent of thermally induced secondary hyperalgesia, a proxy of central sensitization? 2. Does resonance frequency breathing influence the autonomic nervous system, compared to baseline and compared to paced breathing at a natural frequency? 3. Is spinal excitability, measured using the magnitude of the nociception withdrawal reflex (NWR), affected by resonance frequency breathing, compared to paced breathing at a natural frequency? Participants: * will receive heat stimuli * 's skin's sensitivity will be tested using quantitative sensory testing tools. * will receive various instructions on the speed of their breathing * 's heart rate, respiratory rate and sweat response will be measured * will fill in questionnaires Researchers will compare the spatial extent of sensitivity resulting from application of heat stimuli during paced resonance frequency breathing compared to paced breathing at a natural frequency to see if the breathing rhythm influences central sensitization processes.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
200
Participants are required to pace their breathing to their pre-determined individual resonance frequency.
Participants are required to pace their breathing to their pre-determined individual breathing frequency at rest.
Participants will undergo a heat stimulation procedure on their left and right foot (the order of which is counterbalanced across participants). During this procedure, there are 10 blocks, with an inter-stimulus interval of 30 seconds between two blocks. During a block, six 6-second heat stimulations (48 degrees) are given. Between the stimulations, the temperature quickly returns to baseline (32 degrees).
University Hospital Balgrist, University Zürich
Zurich, Switzerland
RECRUITINGArea of Hypersensitivity surrounding the primary stimulation site
Before and after thermal stimulations, the sensitivity of the skin is tested using a von Frey Filament, a Pin Prick and a brush. Thermal stimulations cause hypersensitivity of the skin, resulting in an area of hypersensitivity surrounding the stimulation site. The primary outcome measure is the amount of change in the area of hypersensitivity from before to after the thermal stimulations. The measuring unit of this outcome is square centimetres.
Time frame: 40 minutes
Power in the Low-frequency Range of the Heart Rate Variability
Power is measured in units of milliseconds squared (ms 2) for a the low frequency band (Hz), ranging from 0.04 - 0.15Hz
Time frame: 25 minutes
Root Mean Square of Successive Differences of the Heart Rate Variability
The measuring unit to measure heart rate variability is the root mean square of successive differences between normal heartbeats.
Time frame: 25 minutes
Galvanic Skin Potential
Galvanic Skin potential is taken as a reflection of electrodermal activity. The measuring unit of this outcome is microsiemens
Time frame: 25 minutes
Threshold and Magnitude of the Nociceptive Withdrawal Reflex
The nociceptive withdrawal reflex is triggered using an supratheshold electrical stimulation at the nervus suralis leading muscle contraction in the ipsilateral biceps femoris, rectus femoris and tibialis anterior. Muscle contraction is measures in millivolt using electromyogram with recording electrodes attached to the respective muscles
Time frame: 25 minutes
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